Vulkan-Docs/appendices/memorymodel.txt

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// Copyright (c) 2017-2019 Khronos Group. This work is licensed under a
Change log for September 19, 2018 Vulkan 1.1.85 spec update: * Update release number to 85. Public Issues: * Add self-dependency ename:VK_DEPENDENCY_BY_REGION_BIT valid usage statements for slink:VkSubpassDependency(public pull request 778). * Apply fix from pull request 742 to slink:VkSubpassDependency and slink:VkSubpassDependency2 (public pull request 779). * Specify the units of slink:VkBufferImageCopy::pname:bufferRowLength and pname:bufferImageHeight as texels (public pull request 781). * Better specify promoted parameter mapping in the `<<VK_KHR_create_renderpass2>>` appendix (public pull request 782). Internal Issues: * Only include the <<fundamentals-validusage-versions, Valid Usage for Newer Core Versions>> section in Vulkan 1.1 or later (internal issue 1381). Other Issues: * Clean up redundant valid usage language for the `VK_ANDROID_external_memory_android_hardware_buffer` extension interaction with slink:VkImageCreateInfo. * Fix error in a flag name within valid usage statements for slink:VkMemoryAllocateInfo. * Clarify that memory types are not totally ordered in slink:VkPhysicalDeviceMemoryProperties. * For slink:VkWriteDescriptorSetInlineUniformBlockEXT, set structextends="VkWriteDescriptorSet" in `vk.xml`, and make slink:VkDescriptorSetLayoutBindingFlagsCreateInfoEXT::pname:pBindingFlags optional. * Add documentation of 'provisional' XML attribute to registry.txt. New Extensions: * `VK_NV_compute_shader_derivatives` * `VK_NV_corner_sampled_image` * `VK_NV_fragment_shader_barycentric` * `VK_NV_mesh_shader` * `VK_NV_representative_fragment_test` * `VK_NV_scissor_exclusive` * `VK_NV_shader_image_footprint` * `VK_NV_shading_rate_image` * `VK_NVX_raytracing`
2018-09-16 01:35:16 +00:00
// Creative Commons Attribution 4.0 International License; see
// http://creativecommons.org/licenses/by/4.0/
[appendix]
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
[[memory-model]]
= Memory Model
[[memory-model-agent]]
== Agent
_Operation_ is a general term for any task that is executed on the system.
NOTE: An operation is by definition something that is executed, thus if an
instruction is skipped due to flow control it does not constitute an
operation.
Each operation is executed by a particular _agent_.
Possible agents include each shader invocation, each host thread, and each
fixed-function stage of the pipeline.
[[memory-model-memory-location]]
== Memory Location
A _memory location_ identifies unique storage for 8 bits of data.
Memory operations access a _set of memory locations_ consisting of one or
more memory locations at a time, e.g. an operation accessing a 32-bit
integer in memory would read/write a set of four memory locations.
Two sets of memory locations _overlap_ if the intersection of their sets of
memory locations is non-empty.
A memory operation must: not affect memory at a memory location not within
its set of memory locations.
Memory locations for buffers and images are explicitly allocated in
Change log for January 13, 2019 Vulkan 1.1.98 spec update: * Update release number to 98. Public Issues: * Fix missing markup in flink:vkDestroyPipelineLayout valid usage statement (pull request 882). * Add missing contributors for `<<VK_EXT_buffer_device_address>>` (public pull request 891). Internal Issues: * Detect nested bullet points in valid usage blocks and warn about them during VUID assignment (internal issue 1382). * Update the style guide to document the process for reserving new bits in bitmask types (internal issue 1411). * Clarify for slink:VkApplicationInfo::pname:apiVersion and in the <<fundamentals-validusage-versions, Valid Usage for Newer Core Versions>> section when it is valid for an application to use a certain version of Vulkan API functionality (for an instance and for a device/physical device); and when the validation layers must generate an error (internal issue 1412). * Add optional <<memory-model-availability-visibility, transitive availability/visibility operations to the memory model, including a new pname:vulkanMemoryModelAvailabilityVisibilityChains feature for slink:VkPhysicalDeviceVulkanMemoryModelFeaturesKHR (internal issue 1460). * Add the code:StorageBuffer storage class to those in the <<interfaces-resources-descset, Descriptor Set Interface>> (internal issue 1480). * Add missing `returnedonly` tags for a number of returned extension structures that can be passed in pname:pNext chains (internal issue 1515). * Clean up and rearrange some spec language for slink:VkRenderPassCreateInfo and slink:VkAttachmentReference.txt (internal issue 1522). * Correctly round the code:OpVectorTimesScalar and code:OpMatrixTimesScalar SPIR-V operations in the <<Precision of core SPIR-V Instructions>> table (internal merge request 2996). * Work around cases in flink:vkCmdBeginTransformFeedbackEXT, flink:vkCmdEndTransformFeedbackEXT, and slink:VkPipelineCoverageModulationStateCreateInfoNV where an array parameter is `optional` but the length is not in `vk.xml`. This is an interim fix using `noautovalidity` + handcoded VU replacing those that should be autogenerated (internal issue 2944 and https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/480). * Remove redundant capability validation of the code:float16 and code:int8 SPIR-V capabilities from the <<spirvenv-capabilities, Capabilities>> section, since they are already covered in the preceding table. * Update check_spec_links script, including validation for reference page open blocks. Fix errors identified by the script.
2019-01-13 13:53:27 +00:00
slink:VkDeviceMemory objects, and are implicitly allocated for SPIR-V
variables in each shader invocation.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
[[memory-model-allocation]]
== Allocation
The values stored in newly allocated memory locations are determined by a
SPIR-V variable's initializer, if present, or else are undefined.
At the time an allocation is created there have been no
<<memory-model-memory-operation,memory operations>> to any of its memory
locations.
The initialization is not considered to be a memory operation.
NOTE: For tessellation control shader output variables, a consequence of
initialization not being considered a memory operation is that some
implementations may need to insert a barrier between the initialization of
the output variables and any reads of those variables.
[[memory-model-memory-operation]]
== Memory Operation
For an operation A and memory location M:
* [[memory-model-access-read]] A _reads_ M if and only if the data stored
in M is an input to A.
* [[memory-model-access-write]] A _writes_ M if and only if the data
output from A is stored to M.
* [[memory-model-access-access]] A _accesses_ M if and only if it either
reads or writes (or both) M.
NOTE: A write whose value is the same as what was already in those memory
locations is still considered to be a write and has all the same effects.
[[memory-model-references]]
== Reference
A _reference_ is an object that a particular agent can: use to access a set
of memory locations.
On the host, a reference is a host virtual address.
On the device, a reference is:
* The descriptor that a variable is bound to, for variables in Image,
Uniform, or StorageBuffer storage classes.
If the variable is an array (or array of arrays, etc.) then each element
of the array may: be a unique reference.
ifdef::VK_EXT_buffer_device_address[]
* The address range for a buffer in code:PhysicalStorageBufferEXT storage
class, where the base of the address range is queried with
flink:vkGetBufferDeviceAddressEXT and the length of the range is the
size of the buffer.
endif::VK_EXT_buffer_device_address[]
* The variable itself for variables in other storage classes.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
Two memory accesses through distinct references may: require availability
and visibility operations as defined
<<memory-model-location-ordered,below>>.
[[memory-model-program-order]]
== Program-Order
A _dynamic instance_ of an instruction is defined in SPIR-V
(https://www.khronos.org/registry/spir-v/specs/unified1/SPIRV.html#DynamicInstance)
as a way of referring to a particular execution of a static instruction.
Program-order is an ordering on dynamic instances of instructions executed
by a single shader invocation:
* (Basic block): If instructions A and B are in the same basic block, and
A is listed in the module before B, then the n'th dynamic instance of A
is program-ordered before the n'th dynamic instance of B.
* (Branch): The dynamic instance of a branch or switch instruction is
program-ordered before the dynamic instance of the OpLabel instruction
to which it transfers control.
* (Call entry): The dynamic instance of a function call instruction is
program-ordered before the dynamic instances of the
code:OpFunctionParameter instructions and the body of the called
function.
* (Call exit): The dynamic instance of the instruction following a
function call instruction is program-ordered after the dynamic instance
of the return instruction executed by the called function.
* (Transitive Closure): If dynamic instance A of any instruction is
program-ordered before dynamic instance B of any instruction and B is
program-ordered before dynamic instance C of any instruction then A is
program-ordered before C.
* (Complete definition): No other dynamic instances are program-ordered.
For instructions executed on the host, the source language defines the
2018-10-08 23:12:09 +00:00
program-order relation (e.g. as "`sequenced-before`").
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
[[memory-model-scope]]
== Scope
A _scope_ describes a set of shader invocations, where each such set is a
_scope instance_.
Scopes are defined hierarchically such that a more inclusive scope includes
one or more sets of less inclusive scope instances.
The scopes defined by SPIR-V are as follows, defined from most inclusive to
least inclusive:
* code:CrossDevice identifies all shader invocations in a Vulkan instance
across all shader launches, and all host threads interacting with that
instance.
* code:Device identifes all shader invocations that execute on a given
device, including those from different shader launches.
* code:QueueFamilyKHR identifes all shader invocations that execute on any
queue in a given queue family, including those from different shader
launches.
* code:Workgroup identifies all invocations in a single workgroup.
* code:Subgroup identifies all invocations in a single subgroup.
* code:Invocation identifies a single invocation.
Atomic and barrier instructions include scopes which identify sets of shader
invocations that must: obey the requested ordering and atomicity rules of
the operation, as defined below.
[[memory-model-atomic-operation]]
== Atomic Operation
An _atomic operation_ on the device is any SPIR-V operation whose name
begins with code:OpAtomic.
An atomic operation on the host is any operation performed with an
std::atomic typed object.
Each atomic operation has a memory <<memory-model-scope,scope>> and a
<<memory-model-memory-semantics,semantics>>.
Informally, the scope determines which other agents it is atomic with
respect to, and the <<memory-model-memory-semantics,semantics>> constrains
Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 04:32:44 +00:00
its ordering against other memory accesses.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
Device atomic operations have explicit scopes and semantics.
Each host atomic operation implicitly uses the code:CrossDevice scope, and
uses a memory semantics equivalent to a C++ std::memory_order value of
relaxed, acquire, release, acq_rel, or seq_cst.
Two atomic operations A and B are _potentially-mutually-ordered_ if and only
if all of the following are true:
* They access the same set of memory locations.
* They use the same reference.
* A is in the instance of B's memory scope.
* B is in the instance of A's memory scope.
* A and B are not the same operation (irreflexive).
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
Two atomic operations A and B are _mutually-ordered_ if and only if they are
potentially-mutually-ordered and any of the following are true:
* A and B are both device operations.
* A and B are both host operations.
* A is a device operation, B is a host operation, and the implementation
supports concurrent host- and device-atomics.
(The previous commit didn't actually include internal gitlab changes since 1.1.89; fixed now). Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 06:53:18 +00:00
NOTE: If two atomic operations are not mutually-ordered, and if their sets
of memory locations overlap, then each must: be synchronized against the
other as if they were non-atomic operations.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
[[memory-model-scoped-modification-order]]
== Scoped Modification Order
For a given atomic write A, all atomic writes that are
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
mutually-ordered with A occur in an order known as A's _scoped modification
order_.
Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 04:32:44 +00:00
A's scoped modification order relates no other operations.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
NOTE: Invocations outside the instance of A's memory scope may: observe the
values at A's set of memory locations becoming visible to it in an order
that disagrees with the scoped modification order.
NOTE: It is valid to have non-atomic operations or atomics in a different
scope instance to the same set of memory locations, as long as they are
synchronized against each other as if they were non-atomic (if they are not,
it is treated as a <<memory-model-access-data-race,data race>>).
That means this definition of A's scoped modification order could include
atomic operations that occur much later, after intervening non-atomics.
That is a bit non-intuitive, but it helps to keep this definition simple and
non-circular.
[[memory-model-memory-semantics]]
== Memory Semantics
Non-atomic memory operations, by default, may: be observed by one agent in a
different order than they were written by another agent.
Atomics and some synchronization operations include _memory semantics_,
which are flags that constrain the order in which other memory accesses
(including non-atomic memory accesses and
<<memory-model-availability-visibility,availability and visibility
operations>>) performed by the same agent can: be observed by other agents,
or can: observe accesses by other agents.
Device instructions that include semantics are code:OpAtomic*,
code:OpControlBarrier, code:OpMemoryBarrier, and code:OpMemoryNamedBarrier.
Host instructions that include semantics are some std::atomic methods and
memory fences.
SPIR-V supports the following memory semantics:
* Relaxed: No constraints on order of other memory accesses.
* Acquire: A memory read with this semantic performs an _acquire
operation_.
A memory barrier with this semantic is an _acquire barrier_.
* Release: A memory write with this semantic performs a _release
operation_.
A memory barrier with this semantic is a _release barrier_.
* AcquireRelease: A memory read-modify-write operation with this semantic
performs both an acquire operation and a release operation, and inherits
the limitations on ordering from both of those operations.
A memory barrier with this semantic is both a release and acquire
barrier.
2018-10-08 23:12:09 +00:00
NOTE: SPIR-V does not support "`consume`" semantics on the device.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
The memory semantics operand also includes _storage class semantics_ which
indicate which storage classes are constrained by the synchronization.
SPIR-V storage class semantics include:
* UniformMemory
* WorkgroupMemory
* ImageMemory
* OutputMemoryKHR
Each SPIR-V memory operation accesses a single storage class.
Semantics in synchronization operations can include a combination of storage
classes.
The UniformMemory storage class semantic applies to accesses to memory in
the
ifdef::VK_EXT_buffer_device_address[]
PhysicalStorageBufferEXT,
endif::VK_EXT_buffer_device_address[]
Uniform and StorageBuffer storage classes.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
The WorkgroupMemory storage class semantic applies to accesses to memory in
the Workgroup storage class.
The ImageMemory storage class semantic applies to accesses to memory in the
Image storage class.
The OutputMemoryKHR storage class semantic applies to accesses to memory in
the Output storage class.
NOTE: Informally, these constraints limit how memory operations can be
reordered, and these limits apply not only to the order of accesses as
performed in the agent that executes the instruction, but also to the order
the effects of writes become visible to all other agents within the same
instance of the instruction's memory scope.
NOTE: Release and acquire operations in different threads can: act as
synchronization operations, to guarantee that writes that happened before
the release are visible after the acquire.
(This is not a formal definition, just an informative forward reference.)
NOTE: The OutputMemoryKHR storage class semantic is only useful in
tessellation control shaders, which is the only execution model where output
variables are shared between invocations.
The memory semantics operand also optionally includes availability and
(The previous commit didn't actually include internal gitlab changes since 1.1.89; fixed now). Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 06:53:18 +00:00
visibility flags, which apply optional availability and visibility
operations as described in
<<memory-model-availability-visibility,availability and visibility>>.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
The availability/visibility flags are:
* MakeAvailable: Semantics must: be Release or AcquireRelease.
Performs an availability operation before the release operation or
barrier.
* MakeVisible: Semantics must: be Acquire or AcquireRelease.
Performs a visibility operation after the acquire operation or barrier.
The specifics of these operations are defined in
<<memory-model-availability-visibility-semantics,Availability and Visibility
Semantics>>.
Host atomic operations may: support a different list of memory semantics and
synchronization operations, depending on the host architecture and source
language.
[[memory-model-release-sequence]]
== Release Sequence
After an atomic operation A performs a release operation on a set of memory
locations M, the _release sequence headed by A_ is the longest continuous
subsequence of A's scoped modification order that consists of:
* the atomic operation A as its first element
* atomic read-modify-write operations on M by any agent
NOTE: The atomics in the last bullet must: be mutually-ordered with A by
virtue of being in A's scoped modification order.
2018-10-08 23:12:09 +00:00
NOTE: This intentionally omits "`atomic writes to M performed by the same
agent that performed A`", which is present in the corresponding C++
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
definition.
[[memory-model-synchronizes-with]]
== Synchronizes-With
Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 04:32:44 +00:00
_Synchronizes-with_ is a relation between operations, where each operation
is either an atomic operation or a memory barrier (aka fence on the host).
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
If A and B are atomic operations, then A synchronizes-with B if and only if
all of the following are true:
* A performs a release operation
* B performs an acquire operation
* A and B are mutually-ordered
Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 04:32:44 +00:00
* B reads a value written by A or by an operation in the release sequence
headed by A
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
code:OpControlBarrier, code:OpMemoryBarrier, and code:OpMemoryNamedBarrier
are _memory barrier_ instructions in SPIR-V.
If A is a release barrier and B is an atomic operation that performs an
acquire operation, then A synchronizes-with B if and only if all of the
following are true:
* there exists an atomic write X (with any memory semantics)
* A is program-ordered before X
* X and B are mutually-ordered
Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 04:32:44 +00:00
* B reads a value written by X or by an operation in the release sequence
headed by X
** If X is relaxed, it is still considered to head a hypothetical release
sequence for this rule
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
* A and B are in the instance of each other's memory scopes
* X's storage class is in A's semantics.
If A is an atomic operation that performs a release operation and B is an
acquire barrier, then A synchronizes-with B if and only if all of the
following are true:
* there exists an atomic read X (with any memory semantics)
* X is program-ordered before B
* X and A are mutually-ordered
Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 04:32:44 +00:00
* X reads a value written by A or by an operation in the release sequence
headed by A
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
* A and B are in the instance of each other's memory scopes
* X's storage class is in B's semantics.
If A is a release barrier and B is an acquire barrier, then A
synchronizes-with B if all of the following are true:
* there exists an atomic write X (with any memory semantics)
* A is program-ordered before X
* there exists an atomic read Y (with any memory semantics)
* Y is program-ordered before B
* X and Y are mutually-ordered
(The previous commit didn't actually include internal gitlab changes since 1.1.89; fixed now). Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 06:53:18 +00:00
* Y reads the value written by X or by an operation in the release
sequence headed by X
Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 04:32:44 +00:00
** If X is relaxed, it is still considered to head a hypothetical release
sequence for this rule
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
* A and B are in the instance of each other's memory scopes
* X's and Y's storage class is in A's and B's semantics.
** NOTE: X and Y must have the same storage class, because they are
mutually ordered.
If A is a release barrier and B is an acquire barrier and C is a control
(The previous commit didn't actually include internal gitlab changes since 1.1.89; fixed now). Change log for October 28, 2018 Vulkan 1.1.90 spec update: * Update release number to 90. Public Issues: * Tag flink:vkQueueWaitIdle as `externsync` in `vk.xml` (public pull request 815). * Update README (public pull request 834). * `VK_NV_framebuffer_mixed_samples` and `VK_AMD_mixed_attachment_samples` had confusing and contradictory valid usage statements when read in the all-extensions spec build. Change them to explicitly mention which extension each is for (public issue Vulkan-ValidationLayers/issues/353). Internal Issues: * Update `COPYING.md` to clarify how externally generated Vulkan Specifications (for translations, annotations, or other reasons) must be copyrighted, and acknowledge the Exception Clause on the `vk.xml` license (internal issue 1079). * Specify that flink:vkGetPhysicalDeviceImageFormatProperties may: return pname:maxMipLevels 1 if the format is ycbcr (internal issue 1361). * Clarify previously underspecified language for flink:vkCmdPushConstants::pname:pStageFlags regarding use of push constants across multiple pipelines (internal issue 1403). * Fix typo in XML/headers for ename:VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_EXPLICIT_CREATE_INFO_EXT, which was previously etext:VK_STRUCTURE_TYPE_IMAGE_EXCPLICIT_DRM_FORMAT_MODIFIER_CREATE_INFO_EXT (internal issue 1428). * Fix markup of equations that were sporadically breaking the `optimize-pdf` step of PDF generation, due (apparently) to inconsistent treatment of unwrapped multicharacter terms by different LaTeX parsers (internal issue 1435). * For the <<memory-model-synchronizes-with synchronizes-with>> memory model relation cases involving a release barrier plus relaxed atomic write, treat the atomic as if it were a release atomic and allow the acquire side to read from its hypothetical release sequence. This is more consistent with how C++ defines synchronization for release fences (internal issue cross-api/memory-model#72). * Minor editorial changes to the <<memory-model, memory model>> appendix based on external feedback.
2018-10-29 06:53:18 +00:00
barrier (where A can optionally equal C and B can optionally equal C), then
A synchronizes-with B if all of the following are true:
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
* A is program-ordered before (or equals) C
* C is program-ordered before (or equals) B
* A and B are in the instance of each other's memory scopes
* A and B are in the instance of C's execution scope
NOTE: This is similar to the barrier-barrier synchronization above, but with
a control barrier filling the role of the relaxed atomics.
No other release and acquire barriers synchronize-with each other.
[[memory-model-system-synchronizes-with]]
== System-Synchronizes-With
_System-synchronizes-with_ is a relation between arbitrary operations on the
device or host.
Certain operations system-synchronize-with each other, which informally
means the first operation occurs before the second and that the
synchronization is performed without using application-visible memory
accesses.
If there is an <<synchronization-dependencies-execution,execution
dependency>> between two operations A and B, then the operation in the first
synchronization scope system-synchronizes-with the operation in the second
synchronization scope.
NOTE: This covers all Vulkan synchronization primitives, including device
operations executing before a synchronization primitive is signaled, wait
operations happening before subsequent device operations, signal operations
happening before host operations that wait on them, and host operations
Change log for January 13, 2019 Vulkan 1.1.98 spec update: * Update release number to 98. Public Issues: * Fix missing markup in flink:vkDestroyPipelineLayout valid usage statement (pull request 882). * Add missing contributors for `<<VK_EXT_buffer_device_address>>` (public pull request 891). Internal Issues: * Detect nested bullet points in valid usage blocks and warn about them during VUID assignment (internal issue 1382). * Update the style guide to document the process for reserving new bits in bitmask types (internal issue 1411). * Clarify for slink:VkApplicationInfo::pname:apiVersion and in the <<fundamentals-validusage-versions, Valid Usage for Newer Core Versions>> section when it is valid for an application to use a certain version of Vulkan API functionality (for an instance and for a device/physical device); and when the validation layers must generate an error (internal issue 1412). * Add optional <<memory-model-availability-visibility, transitive availability/visibility operations to the memory model, including a new pname:vulkanMemoryModelAvailabilityVisibilityChains feature for slink:VkPhysicalDeviceVulkanMemoryModelFeaturesKHR (internal issue 1460). * Add the code:StorageBuffer storage class to those in the <<interfaces-resources-descset, Descriptor Set Interface>> (internal issue 1480). * Add missing `returnedonly` tags for a number of returned extension structures that can be passed in pname:pNext chains (internal issue 1515). * Clean up and rearrange some spec language for slink:VkRenderPassCreateInfo and slink:VkAttachmentReference.txt (internal issue 1522). * Correctly round the code:OpVectorTimesScalar and code:OpMatrixTimesScalar SPIR-V operations in the <<Precision of core SPIR-V Instructions>> table (internal merge request 2996). * Work around cases in flink:vkCmdBeginTransformFeedbackEXT, flink:vkCmdEndTransformFeedbackEXT, and slink:VkPipelineCoverageModulationStateCreateInfoNV where an array parameter is `optional` but the length is not in `vk.xml`. This is an interim fix using `noautovalidity` + handcoded VU replacing those that should be autogenerated (internal issue 2944 and https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/480). * Remove redundant capability validation of the code:float16 and code:int8 SPIR-V capabilities from the <<spirvenv-capabilities, Capabilities>> section, since they are already covered in the preceding table. * Update check_spec_links script, including validation for reference page open blocks. Fix errors identified by the script.
2019-01-13 13:53:27 +00:00
happening before flink:vkQueueSubmit.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
The list is spread throughout the synchronization chapter, and is not
repeated here.
System-synchronizes-with implicitly includes all storage class semantics and
has code:CrossDevice scope.
If A system-synchronizes-with B, we also say A is
_system-synchronized-before_ B and B is _system-synchronized-after_ A.
[[memory-model-non-private]]
== Private vs. Non-Private
By default, non-atomic memory operations are treated as _private_, meaning
such a memory operation is not intended to be used for communication with
other agents.
Memory operations with the NonPrivatePointerKHR/NonPrivateTexelKHR bit set
are treated as _non-private_, and are intended to be used for communication
with other agents.
More precisely, for private memory operations to be
<<memory-model-location-ordered,Location-Ordered>> between distinct agents
requires using system-synchronizes-with rather than shader-based
synchronization.
Non-private memory operations still obey program-order.
Atomic operations are always considered non-private.
[[memory-model-inter-thread-happens-before]]
== Inter-Thread-Happens-Before
Let SC be a non-empty set of storage class semantics.
Then (using template syntax) operation A _inter-thread-happens-before_<SC>
operation B if and only if any of the following is true:
* A system-synchronizes-with B
* A synchronizes-with B, and both A and B have all of SC in their
semantics
* A is an operation on memory in a storage class in SC or that has all of
SC in its semantics, B is a release barrier or release atomic with all
of SC in its semantics, and A is program-ordered before B
* A is an acquire barrier or acquire atomic with all of SC in its
semantics, B is an operation on memory in a storage class in SC or that
has all of SC in its semantics, and A is program-ordered before B
* A and B are both host operations and A inter-thread-happens-before B as
defined in the host language spec
* A inter-thread-happens-before<SC> some X and X
inter-thread-happens-before<SC> B
[[memory-model-happens-before]]
== Happens-Before
Operation A _happens-before_ operation B if and only if any of the following
is true:
* A is program-ordered before B
* A inter-thread-happens-before<SC> B for some set of storage classes SC
_Happens-after_ is defined similarly.
NOTE: Unlike C++, happens-before is not always sufficient for a write to be
visible to a read.
Additional <<memory-model-availability-visibility,availability and
visibility>> operations may: be required for writes to be
<<memory-model-visible-to,visible-to>> other memory accesses.
NOTE: Happens-before is not transitive, but each of program-order and
inter-thread-happens-before<SC> are transitive.
2018-10-08 23:12:09 +00:00
These can be thought of as covering the "`single-threaded`" case and the
Change log for October 21, 2018 Vulkan 1.1.89 spec update: * Update release number to 89. Public Issues: * Clarify the reference to <<features-limits-mipmapPrecisionBits, mipmap precision bits>> in the <<textures-image-level-selection, Image Level(s) Selection>> section (public issue 660). * Update <<debugging-object-types,VkObjectType and Vulkan Handle Relationship>> table with missing types (public pull request 820). * Miscellaneous minor markup cleanup (public pull request 822). * Fix copy/paste bugs in the description of how implicit availability/visibility operations for atomics/barriers are ordered in the <<memory-model-availability-visibility-semantics, Availability and Visibility Semantics>> section (public issue 823). * Add missing shading_rate_image bit from mesh pipeline list in the <<synchronization-pipeline-stages-types>> list (public issue 824). Internal Issues: * Clarify that only statically used members of a push constant block need to be in the push constant range, and stop referring to block members as "`variables`" in the <<interfaces-resources-pushconst, Push Constant Interface>> section. This is related to https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/340 (internal issue 1401). * Clarify interaction between flink:vkCmdSetDeviceMask and render pass control commands in the slink:VkDeviceGroupRenderPassBeginInfo section (internal issue 1416). * Miscellaneous minor markup cleanup. * Remove types defined by `"disabled"` extensions from validextensionstructs in the XML processing scripts, so downstream code generators don't emit them.
2018-10-21 13:08:41 +00:00
"`multi-threaded`" case, and it's not necessary (and not valid) to form
chains between the two.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
[[memory-model-availability-visibility]]
== Availability and Visibility
_Availability_ and _visibility_ are states of a write operation, which
(informally) track how far the write has permeated the system, i.e. which
agents and references are able to observe the write.
Availability state is per _memory domain_.
Visibility state is per (agent,reference) pair.
Availability and visibility states are per-memory location for each write.
Memory domains are named according to the agents whose memory accesses use
the domain.
Domains used by shader invocations are organized hierarchically into
multiple smaller memory domains which correspond to the different
<<memory-model-scope, scopes>>.
The memory domains defined in Vulkan include:
* _host_ - accessible by host agents
* _device_ - accessible by all device agents for a particular device
* _shader_ - accessible by shader agents for a particular device,
corresponding to the code:Device scope
* _queue family instance_ - accessible by shader agents in a single queue
family, corresponding to the code:QueueFamilyKHR scope.
* _workgroup instance_ - accessible by shader agents in the same
workgroup, corresponding to the code:Workgroup scope.
* _subgroup instance_ - accessible by shader agents in the same subgroup,
corresponding to the code:Subgroup scope.
NOTE: These do not correspond to storage classes or device-local and
Change log for January 13, 2019 Vulkan 1.1.98 spec update: * Update release number to 98. Public Issues: * Fix missing markup in flink:vkDestroyPipelineLayout valid usage statement (pull request 882). * Add missing contributors for `<<VK_EXT_buffer_device_address>>` (public pull request 891). Internal Issues: * Detect nested bullet points in valid usage blocks and warn about them during VUID assignment (internal issue 1382). * Update the style guide to document the process for reserving new bits in bitmask types (internal issue 1411). * Clarify for slink:VkApplicationInfo::pname:apiVersion and in the <<fundamentals-validusage-versions, Valid Usage for Newer Core Versions>> section when it is valid for an application to use a certain version of Vulkan API functionality (for an instance and for a device/physical device); and when the validation layers must generate an error (internal issue 1412). * Add optional <<memory-model-availability-visibility, transitive availability/visibility operations to the memory model, including a new pname:vulkanMemoryModelAvailabilityVisibilityChains feature for slink:VkPhysicalDeviceVulkanMemoryModelFeaturesKHR (internal issue 1460). * Add the code:StorageBuffer storage class to those in the <<interfaces-resources-descset, Descriptor Set Interface>> (internal issue 1480). * Add missing `returnedonly` tags for a number of returned extension structures that can be passed in pname:pNext chains (internal issue 1515). * Clean up and rearrange some spec language for slink:VkRenderPassCreateInfo and slink:VkAttachmentReference.txt (internal issue 1522). * Correctly round the code:OpVectorTimesScalar and code:OpMatrixTimesScalar SPIR-V operations in the <<Precision of core SPIR-V Instructions>> table (internal merge request 2996). * Work around cases in flink:vkCmdBeginTransformFeedbackEXT, flink:vkCmdEndTransformFeedbackEXT, and slink:VkPipelineCoverageModulationStateCreateInfoNV where an array parameter is `optional` but the length is not in `vk.xml`. This is an interim fix using `noautovalidity` + handcoded VU replacing those that should be autogenerated (internal issue 2944 and https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/480). * Remove redundant capability validation of the code:float16 and code:int8 SPIR-V capabilities from the <<spirvenv-capabilities, Capabilities>> section, since they are already covered in the preceding table. * Update check_spec_links script, including validation for reference page open blocks. Fix errors identified by the script.
2019-01-13 13:53:27 +00:00
host-local slink:VkDeviceMemory allocations, rather they indicate whether a
write can be made visible only to agents in the same subgroup, same
workgroup, in any shader invocation, or anywhere on the device, or host.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
The shader, queue family instance, workgroup instance, and subgroup instance
domains are only used for shader-based availability/visibility operatons, in
other cases writes can be made available from/visible to the shader via the
device domain.
_Availability operations_, _visibility operations_, and _memory domain
operations_ alter the state of the write operations that happen-before them,
and which are included in their _source scope_ to be available or visible to
their _destination scope_.
* For an availability operation, the source scope is a set of
(agent,reference,memory location) tuples, and the destination scope is a
set of memory domains.
* For a memory domain operation, the source scope is a memory domain and
the destination scope is a memory domain.
* For a visibility operation, the source scope is a set of memory domains
and the destination scope is a set of (agent,reference,memory location)
tuples.
How the scopes are determined depends on the specific operation.
Availability and memory domain operations expand the set of memory domains
to which the write is available.
Visibility operations expand the set of (agent,reference,memory location)
tuples to which the write is visible.
Recall that availability and visibility states are per-memory location, and
let W be a write operation to one or more locations performed by agent A via
reference R. Let L be one of the locations written.
(W,L) (the write W to L), is initially not available to any memory domain
and only visible to (A,R,L).
An availability operation AV that happens-after W and that includes (A,R,L)
in its source scope makes (W,L) _available_ to the memory domains in its
destination scope.
A memory domain operation DOM that happens-after AV and for which (W,L) is
available in the source scope makes (W,L) available in the destination
memory domain.
A visibility operation VIS that happens-after AV (or DOM) and for which
(W,L) is available in any domain in the source scope makes (W,L) _visible_
to all (agent,reference,L) tuples included in its destination scope.
If write W~2~ happens-after W, and their sets of memory locations overlap,
then W will not be available/visible to all agents/references for those
memory locations that overlap (and future AV/DOM/VIS ops can't revive W's
write to those locations).
Availability, memory domain, and visibility operations are treated like
other non-atomic memory accesses for the purpose of
<<memory-model-memory-semantics,memory semantics>>, meaning they can be
ordered by release-acquire sequences or memory barriers.
Change log for January 13, 2019 Vulkan 1.1.98 spec update: * Update release number to 98. Public Issues: * Fix missing markup in flink:vkDestroyPipelineLayout valid usage statement (pull request 882). * Add missing contributors for `<<VK_EXT_buffer_device_address>>` (public pull request 891). Internal Issues: * Detect nested bullet points in valid usage blocks and warn about them during VUID assignment (internal issue 1382). * Update the style guide to document the process for reserving new bits in bitmask types (internal issue 1411). * Clarify for slink:VkApplicationInfo::pname:apiVersion and in the <<fundamentals-validusage-versions, Valid Usage for Newer Core Versions>> section when it is valid for an application to use a certain version of Vulkan API functionality (for an instance and for a device/physical device); and when the validation layers must generate an error (internal issue 1412). * Add optional <<memory-model-availability-visibility, transitive availability/visibility operations to the memory model, including a new pname:vulkanMemoryModelAvailabilityVisibilityChains feature for slink:VkPhysicalDeviceVulkanMemoryModelFeaturesKHR (internal issue 1460). * Add the code:StorageBuffer storage class to those in the <<interfaces-resources-descset, Descriptor Set Interface>> (internal issue 1480). * Add missing `returnedonly` tags for a number of returned extension structures that can be passed in pname:pNext chains (internal issue 1515). * Clean up and rearrange some spec language for slink:VkRenderPassCreateInfo and slink:VkAttachmentReference.txt (internal issue 1522). * Correctly round the code:OpVectorTimesScalar and code:OpMatrixTimesScalar SPIR-V operations in the <<Precision of core SPIR-V Instructions>> table (internal merge request 2996). * Work around cases in flink:vkCmdBeginTransformFeedbackEXT, flink:vkCmdEndTransformFeedbackEXT, and slink:VkPipelineCoverageModulationStateCreateInfoNV where an array parameter is `optional` but the length is not in `vk.xml`. This is an interim fix using `noautovalidity` + handcoded VU replacing those that should be autogenerated (internal issue 2944 and https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/480). * Remove redundant capability validation of the code:float16 and code:int8 SPIR-V capabilities from the <<spirvenv-capabilities, Capabilities>> section, since they are already covered in the preceding table. * Update check_spec_links script, including validation for reference page open blocks. Fix errors identified by the script.
2019-01-13 13:53:27 +00:00
An _availability chain_ is a sequence of availability operations of
increasing scope where element N+1 of the chain is performed in the same
scope instance as the destination of element N and element N happens-before
element N+1.
An example is an availability operation with destination scope of the
workgroup instance domain that happens before an availability operation to
the shader domain performed by an invocation in the same workgroup.
An availability chain AVC that happens-after W and that includes (A,R,L) in
the source scope makes (W,L) _available_ to the memory domains in its final
destination scope.
An availability chain with a single element is just the availability
operation.
Similarly, a _visibility chain_ is a sequence of visibility operations of
decreasing scope where element N of the chain is performed in the same scope
instance as the source of element N+1 and element N happens-before element
N+1.
An example is a visibility operation with source scope of the shader domain
that happens before a visibility operation with source scope of the
workgroup instance domain performance by an invocation in the same
workgroup.
A visibility chain VISC that happens-after AVC (or DOM) and for which (W,L)
is available in any domain in the source scope makes (W,L) _visible_ to all
(agent,reference,L) tuples included in its final destination scope.
A visibility chain with a single element is just the visibility operation.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
[[memory-model-vulkan-availability-visibility]]
== Availability, Visibility, and Domain Operations
The following operations generate availability, visibility, and domain
operations.
When multiple availability/visibility/domain operations are described, they
are system-synchronized-with each other in the order listed.
An operation that performs a <<synchronization-dependencies-memory,memory
dependency>> generates:
* If the source access mask includes ename:VK_ACCESS_HOST_WRITE_BIT, then
the dependency includes a memory domain operation from host domain to
device domain.
* An availability operation with source scope of all writes in the first
<<synchronization-dependencies-access-scopes,access scope>> of the
dependency and a destination scope of the device domain.
* A visibility operation with source scope of the device domain and
destination scope of the second access scope of the dependency.
* If the destination access mask includes ename:VK_ACCESS_HOST_READ_BIT or
ename:VK_ACCESS_HOST_WRITE_BIT, then the dependency includes a memory
domain operation from device domain to host domain.
flink:vkFlushMappedMemoryRanges performs an availability operation, with a
source scope of (agents,references) = (all host threads, all mapped memory
ranges passed to the command), and destination scope of the host domain.
flink:vkInvalidateMappedMemoryRanges performs a visibility operation, with a
source scope of the host domain and a destination scope of
(agents,references) = (all host threads, all mapped memory ranges passed to
the command).
flink:vkQueueSubmit performs a memory domain operation from host to device,
and a visibility operation with source scope of the device domain and
destination scope of all agents and references on the device.
[[memory-model-availability-visibility-semantics]]
== Availability and Visibility Semantics
A memory barrier or atomic operation via agent A that includes MakeAvailable
in its semantics performs an availability operation whose source scope
includes agent A and all references in the storage classes in that
instruction's storage class semantics, and all memory locations, and whose
destination scope is a set of memory domains selected as specified below.
The implicit availability operation is program-ordered between the barrier
Change log for October 21, 2018 Vulkan 1.1.89 spec update: * Update release number to 89. Public Issues: * Clarify the reference to <<features-limits-mipmapPrecisionBits, mipmap precision bits>> in the <<textures-image-level-selection, Image Level(s) Selection>> section (public issue 660). * Update <<debugging-object-types,VkObjectType and Vulkan Handle Relationship>> table with missing types (public pull request 820). * Miscellaneous minor markup cleanup (public pull request 822). * Fix copy/paste bugs in the description of how implicit availability/visibility operations for atomics/barriers are ordered in the <<memory-model-availability-visibility-semantics, Availability and Visibility Semantics>> section (public issue 823). * Add missing shading_rate_image bit from mesh pipeline list in the <<synchronization-pipeline-stages-types>> list (public issue 824). Internal Issues: * Clarify that only statically used members of a push constant block need to be in the push constant range, and stop referring to block members as "`variables`" in the <<interfaces-resources-pushconst, Push Constant Interface>> section. This is related to https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/340 (internal issue 1401). * Clarify interaction between flink:vkCmdSetDeviceMask and render pass control commands in the slink:VkDeviceGroupRenderPassBeginInfo section (internal issue 1416). * Miscellaneous minor markup cleanup. * Remove types defined by `"disabled"` extensions from validextensionstructs in the XML processing scripts, so downstream code generators don't emit them.
2018-10-21 13:08:41 +00:00
or atomic and all other operations program-ordered before the barrier or
atomic.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
A memory barrier or atomic operation via agent A that includes MakeVisible
in its semantics performs a visibility operation whose source scope is a set
of memory domains selected as specified below, and whose destination scope
includes agent A and all references in the storage classes in that
instruction's storage class semantics, and all memory locations.
The implicit visibility operation is program-ordered between the barrier or
Change log for October 21, 2018 Vulkan 1.1.89 spec update: * Update release number to 89. Public Issues: * Clarify the reference to <<features-limits-mipmapPrecisionBits, mipmap precision bits>> in the <<textures-image-level-selection, Image Level(s) Selection>> section (public issue 660). * Update <<debugging-object-types,VkObjectType and Vulkan Handle Relationship>> table with missing types (public pull request 820). * Miscellaneous minor markup cleanup (public pull request 822). * Fix copy/paste bugs in the description of how implicit availability/visibility operations for atomics/barriers are ordered in the <<memory-model-availability-visibility-semantics, Availability and Visibility Semantics>> section (public issue 823). * Add missing shading_rate_image bit from mesh pipeline list in the <<synchronization-pipeline-stages-types>> list (public issue 824). Internal Issues: * Clarify that only statically used members of a push constant block need to be in the push constant range, and stop referring to block members as "`variables`" in the <<interfaces-resources-pushconst, Push Constant Interface>> section. This is related to https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/340 (internal issue 1401). * Clarify interaction between flink:vkCmdSetDeviceMask and render pass control commands in the slink:VkDeviceGroupRenderPassBeginInfo section (internal issue 1416). * Miscellaneous minor markup cleanup. * Remove types defined by `"disabled"` extensions from validextensionstructs in the XML processing scripts, so downstream code generators don't emit them.
2018-10-21 13:08:41 +00:00
atomic and all other operations program-ordered after the barrier or atomic.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
The memory domains are selected based on the memory scope of the instruction
as follows:
* code:Device scope uses the shader domain
* code:QueueFamilyKHR scope uses the queue family instance domain
* code:Workgroup scope uses the workgroup instance domain
* code:Subgroup uses the subgroup instance domain
* code:Invocation perform no availability/visibility operations.
When an availability operation performed by an agent A includes a memory
domain D in its destination scope, where D corresponds to scope instance S,
it also includes the memory domains that correspond to each smaller scope
instance S' that is a subset of S and that includes A. Similarly for
visibility operations.
[[memory-model-instruction-av-vis]]
== Per-Instruction Availability and Visibility Semantics
A memory write instruction that includes MakePointerAvailable, or an image
write instruction that includes MakeTexelAvailable, performs an availability
operation whose source scope includes the agent and reference used to
perform the write and the memory locations written by the instruction, and
whose destination scope is a set of memory domains selected by the Scope
operand specified in <<memory-model-availability-visibility-semantics,
Availability and Visibility Semantics>>.
The implicit availability operation is program-ordered between the write and
all other operations program-ordered after the write.
A memory read instruction that includes MakePointerVisible, or an image read
instruction that includes MakeTexelVisible, performs a visibility operation
whose source scope is a set of memory domains selected by the Scope operand
as specified in <<memory-model-availability-visibility-semantics,
Availability and Visibility Semantics>>, and whose destination scope
includes the agent and reference used to perform the read and the memory
locations read by the instruction.
The implicit visibility operation is program-ordered between read and all
other operations program-ordered before the read.
NOTE: Although reads with per-instruction visibility only perform visibility
ops from the shader or workgroup instance or subgroup instance domain, they
will also see writes that were made visible via the device domain, i.e.
those writes previously performed by non-shader agents and made visible via
API commands.
NOTE: It is expected that all invocations in a subgroup execute on the same
processor with the same path to memory, and thus availability and visibility
2018-10-08 23:12:09 +00:00
operations with subgroup scope can be expected to be "`free`".
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
[[memory-model-location-ordered]]
== Location-Ordered
Let X and Y be memory accesses to overlapping sets of memory locations M,
where X != Y. Let (A~X~,R~X~) be the agent and reference used for X, and
2018-10-08 23:12:09 +00:00
(A~Y~,R~Y~) be the agent and reference used for Y. For now, let "`->`"
denote happens-before and "`->^rcpo^`" denote the reflexive closure of
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
program-ordered before.
If D~1~ and D~2~ are different memory domains, then let DOM(D~1~,D~2~) be a
memory domain operation from D~1~ to D~2~.
Otherwise, let DOM(D,D) be a placeholder such that X->DOM(D,D)->Y if and
only if X->Y.
X is _location-ordered_ before Y for a location L in M if and only if any of
the following is true:
* A~X~ == A~Y~ and R~X~ == R~Y~ and X->Y
** NOTE: this case means no availability/visibility ops required when it's
the same (agent,reference).
* X and Y are mutually-ordered atomics, and X is before Y in X's scoped
modification order
* X is a read, both X and Y are non-private, and X->Y
* X is a read, and X (transitively) system-synchronizes with Y
* If R~X~ == R~Y~ and A~X~ and A~Y~ access a common memory domain D (e.g.
are in the same workgroup instance if D is the workgroup instance
domain), and both X and Y are non-private:
Change log for January 13, 2019 Vulkan 1.1.98 spec update: * Update release number to 98. Public Issues: * Fix missing markup in flink:vkDestroyPipelineLayout valid usage statement (pull request 882). * Add missing contributors for `<<VK_EXT_buffer_device_address>>` (public pull request 891). Internal Issues: * Detect nested bullet points in valid usage blocks and warn about them during VUID assignment (internal issue 1382). * Update the style guide to document the process for reserving new bits in bitmask types (internal issue 1411). * Clarify for slink:VkApplicationInfo::pname:apiVersion and in the <<fundamentals-validusage-versions, Valid Usage for Newer Core Versions>> section when it is valid for an application to use a certain version of Vulkan API functionality (for an instance and for a device/physical device); and when the validation layers must generate an error (internal issue 1412). * Add optional <<memory-model-availability-visibility, transitive availability/visibility operations to the memory model, including a new pname:vulkanMemoryModelAvailabilityVisibilityChains feature for slink:VkPhysicalDeviceVulkanMemoryModelFeaturesKHR (internal issue 1460). * Add the code:StorageBuffer storage class to those in the <<interfaces-resources-descset, Descriptor Set Interface>> (internal issue 1480). * Add missing `returnedonly` tags for a number of returned extension structures that can be passed in pname:pNext chains (internal issue 1515). * Clean up and rearrange some spec language for slink:VkRenderPassCreateInfo and slink:VkAttachmentReference.txt (internal issue 1522). * Correctly round the code:OpVectorTimesScalar and code:OpMatrixTimesScalar SPIR-V operations in the <<Precision of core SPIR-V Instructions>> table (internal merge request 2996). * Work around cases in flink:vkCmdBeginTransformFeedbackEXT, flink:vkCmdEndTransformFeedbackEXT, and slink:VkPipelineCoverageModulationStateCreateInfoNV where an array parameter is `optional` but the length is not in `vk.xml`. This is an interim fix using `noautovalidity` + handcoded VU replacing those that should be autogenerated (internal issue 2944 and https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/480). * Remove redundant capability validation of the code:float16 and code:int8 SPIR-V capabilities from the <<spirvenv-capabilities, Capabilities>> section, since they are already covered in the preceding table. * Update check_spec_links script, including validation for reference page open blocks. Fix errors identified by the script.
2019-01-13 13:53:27 +00:00
** X is a write, Y is a write, AVC(A~X~,R~X~,D,L) is an availability chain
making (X,L) available to domain D, and X->^rcpo^AVC(A~X~,R~X~,D,L)->Y
** X is a write, Y is a read, AVC(A~X~,R~X~,D,L) is an availability chain
making (X,L) available to domain D, VISC(A~Y~,R~Y~,D,L) is a visibility
chain making writes to L available in domain D visible to Y, and
X->^rcpo^AVC(A~X~,R~X~,D,L)->VISC(A~Y~,R~Y~,D,L)->^rcpo^Y
** If
slink:VkPhysicalDeviceVulkanMemoryModelFeaturesKHR::pname:vulkanMemoryModelAvailabilityVisibilityChains
is ename:VK_FALSE, then AVC and VISC must: each only have a single
element in the chain, in each sub-bullet above.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
* Let D~X~ and D~Y~ each be either the device domain or the host domain,
depending on whether A~X~ and A~Y~ execute on the device or host:
** X is a write and Y is a write, and
X->AV(A~X~,R~X~,D~X~,L)->DOM(D~X~,D~Y~)->Y
** X is a write and Y is a read, and
X->AV(A~X~,R~X~,D~X~,L)->DOM(D~X~,D~Y~)->VIS(A~Y~,R~Y~,D~Y~,L)->Y
NOTE: The final bullet (synchronization through device/host domain) requires
API-level synchronization operations, since the device/host domains are not
accessible via shader instructions.
2018-10-08 23:12:09 +00:00
And "`device domain`" is not to be confused with "`device scope`", which
synchronizes through the "`shader domain`".
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
[[memory-model-access-data-race]]
== Data Race
Let X and Y be operations that access overlapping sets of memory locations
M, where X != Y, and at least one of X and Y is a write, and X and Y are not
mutually-ordered atomic operations.
If there does not exist a location-ordered relation between X and Y for each
location in M, then there is a _data race_.
Applications must: ensure that no data races occur during the execution of
their application.
NOTE: Data races can only occur due to instructions that are actually
executed, and for example an instruction skipped due to flow control must
not contribute to a data race.
[[memory-model-visible-to]]
== Visible-To
Let X be a write and Y be a read whose sets of memory locations overlap, and
let M be the set of memory locations that overlap.
Let M~2~ be a non-empty subset of M. Then X is _visible-to_ Y for memory
locations M~2~ if and only if all of the following are true:
* X is location-ordered before Y for each location L in M~2~.
* There does not exist another write Z to any location L in M~2~ such that
X is location-ordered before Z for location L and Z is location-ordered
before Y for location L.
If X is visible-to Y, then Y reads the value written by X for locations
M~2~.
NOTE: It is possible for there to be a write between X and Y that overwrites
a subset of the memory locations, but the remaining memory locations (M~2~)
will still be visible-to Y.
[[memory-model-scoped-modification-order-coherence]]
== Scoped Modification Order Coherence
Let A and B be mutually-ordered atomic operations, where A happens-before B,
and let O be A's scoped modification order.
Then:
* If A and B are both writes, then A must: be earlier than B in O
* If A and B are both reads, then the write that A takes its value from
must: be earlier in O than (or the same as) the write that B takes its
value from
* If A is a write and B is a read, then B must: take its value from A or a
write later than A in O
* If A is a read and B is a write, then A must: take its value from a
write earlier than B in O
[[memory-model-shader-io]]
== Shader I/O
If a shader invocation A in a shader stage other than code:Vertex performs a
memory read operation X from an object in the code:Input storage class, then
X is system-synchronized-after all writes to the corresponding code:Output
storage variable(s) in the upstream shader invocation(s) that contribute to
generating invocation A, and those writes are all visible-to X.
NOTE: It is not necessary for the upstream shader invocations to have
completed execution, they only need to have generated the output that is
being read.
[[memory-model-deallocation]]
== Deallocation
Change log for January 13, 2019 Vulkan 1.1.98 spec update: * Update release number to 98. Public Issues: * Fix missing markup in flink:vkDestroyPipelineLayout valid usage statement (pull request 882). * Add missing contributors for `<<VK_EXT_buffer_device_address>>` (public pull request 891). Internal Issues: * Detect nested bullet points in valid usage blocks and warn about them during VUID assignment (internal issue 1382). * Update the style guide to document the process for reserving new bits in bitmask types (internal issue 1411). * Clarify for slink:VkApplicationInfo::pname:apiVersion and in the <<fundamentals-validusage-versions, Valid Usage for Newer Core Versions>> section when it is valid for an application to use a certain version of Vulkan API functionality (for an instance and for a device/physical device); and when the validation layers must generate an error (internal issue 1412). * Add optional <<memory-model-availability-visibility, transitive availability/visibility operations to the memory model, including a new pname:vulkanMemoryModelAvailabilityVisibilityChains feature for slink:VkPhysicalDeviceVulkanMemoryModelFeaturesKHR (internal issue 1460). * Add the code:StorageBuffer storage class to those in the <<interfaces-resources-descset, Descriptor Set Interface>> (internal issue 1480). * Add missing `returnedonly` tags for a number of returned extension structures that can be passed in pname:pNext chains (internal issue 1515). * Clean up and rearrange some spec language for slink:VkRenderPassCreateInfo and slink:VkAttachmentReference.txt (internal issue 1522). * Correctly round the code:OpVectorTimesScalar and code:OpMatrixTimesScalar SPIR-V operations in the <<Precision of core SPIR-V Instructions>> table (internal merge request 2996). * Work around cases in flink:vkCmdBeginTransformFeedbackEXT, flink:vkCmdEndTransformFeedbackEXT, and slink:VkPipelineCoverageModulationStateCreateInfoNV where an array parameter is `optional` but the length is not in `vk.xml`. This is an interim fix using `noautovalidity` + handcoded VU replacing those that should be autogenerated (internal issue 2944 and https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/480). * Remove redundant capability validation of the code:float16 and code:int8 SPIR-V capabilities from the <<spirvenv-capabilities, Capabilities>> section, since they are already covered in the preceding table. * Update check_spec_links script, including validation for reference page open blocks. Fix errors identified by the script.
2019-01-13 13:53:27 +00:00
A call to flink:vkFreeMemory must: happen-after all memory operations on all
memory locations in that slink:VkDeviceMemory object.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
NOTE: Normally, device memory operations in a given queue are synchronized
Change log for January 13, 2019 Vulkan 1.1.98 spec update: * Update release number to 98. Public Issues: * Fix missing markup in flink:vkDestroyPipelineLayout valid usage statement (pull request 882). * Add missing contributors for `<<VK_EXT_buffer_device_address>>` (public pull request 891). Internal Issues: * Detect nested bullet points in valid usage blocks and warn about them during VUID assignment (internal issue 1382). * Update the style guide to document the process for reserving new bits in bitmask types (internal issue 1411). * Clarify for slink:VkApplicationInfo::pname:apiVersion and in the <<fundamentals-validusage-versions, Valid Usage for Newer Core Versions>> section when it is valid for an application to use a certain version of Vulkan API functionality (for an instance and for a device/physical device); and when the validation layers must generate an error (internal issue 1412). * Add optional <<memory-model-availability-visibility, transitive availability/visibility operations to the memory model, including a new pname:vulkanMemoryModelAvailabilityVisibilityChains feature for slink:VkPhysicalDeviceVulkanMemoryModelFeaturesKHR (internal issue 1460). * Add the code:StorageBuffer storage class to those in the <<interfaces-resources-descset, Descriptor Set Interface>> (internal issue 1480). * Add missing `returnedonly` tags for a number of returned extension structures that can be passed in pname:pNext chains (internal issue 1515). * Clean up and rearrange some spec language for slink:VkRenderPassCreateInfo and slink:VkAttachmentReference.txt (internal issue 1522). * Correctly round the code:OpVectorTimesScalar and code:OpMatrixTimesScalar SPIR-V operations in the <<Precision of core SPIR-V Instructions>> table (internal merge request 2996). * Work around cases in flink:vkCmdBeginTransformFeedbackEXT, flink:vkCmdEndTransformFeedbackEXT, and slink:VkPipelineCoverageModulationStateCreateInfoNV where an array parameter is `optional` but the length is not in `vk.xml`. This is an interim fix using `noautovalidity` + handcoded VU replacing those that should be autogenerated (internal issue 2944 and https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/480). * Remove redundant capability validation of the code:float16 and code:int8 SPIR-V capabilities from the <<spirvenv-capabilities, Capabilities>> section, since they are already covered in the preceding table. * Update check_spec_links script, including validation for reference page open blocks. Fix errors identified by the script.
2019-01-13 13:53:27 +00:00
with flink:vkFreeMemory by having a host thread wait on a fence signalled by
that queue, and the wait happens-before the call to flink:vkFreeMemory on
the host.
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
The deallocation of SPIR-V variables is managed by the system and
happens-after all operations on those variables.
[[memory-model-informative-descriptions]]
== Informative Descriptions
This subsection is non-normative, and offers more easily understandable
consequences of the memory model for app/compiler developers.
Let SC be the storage class(es) specified by a release or acquire operation
or barrier.
* An atomic write with release semantics must not be reordered against any
read or write to SC that is program-ordered before it (regardless of the
storage class the atomic is in).
* An atomic read with acquire semantics must not be reordered against any
read or write to SC that is program-ordered after it (regardless of the
storage class the atomic is in).
* Any write to SC program-ordered after a release barrier must not be
reordered against any read or write to SC program-ordered before that
barrier.
* Any read from SC program-ordered before an acquire barrier must not be
reordered against any read or write to SC program-ordered after the
barrier.
A control barrier (even if it has no memory semantics) must not be reordered
against any memory barriers.
This memory model allows memory accesses with and without availability and
visibility operations, as well as atomic operations, all to be performed on
the same memory location.
This is critical to allow it to reason about memory that is reused in
multiple ways, e.g. across the lifetime of different shader invocations or
draw calls.
2018-10-08 23:12:09 +00:00
While GLSL (and legacy SPIR-V) applies the "`coherent`" decoration to
Change log for September 8, 2018 Vulkan 1.1.84 spec update: * Update release number to 84. Public Issues: * Fix code sample in the `<<VK_EXT_debug_utils>>` extension (public issue 751). * Fix misleading comment in `vk.xml` for slink:VkDescriptorBufferInfo::pname:buffer (public pull request 762). * Fix formatting of deprecation attributes in schema doc (public pull request 767). * Change `can` to `may` in the description of elink:VkSparseImageFormatFlagBits, which are return values from queries (public pull request 768). * Prettify generated contact list in extension appendices, adding logos and a New Issue link (public pull request 770). * Enable sRGB conversion based on the image view format, not the image format, in the <<textures-format-conversion, Format Conversion>> section (public pull request 773). * Fix typo in equation in the <<primsrast-lines-basic, Basic Line Segment Rasterization>> section (public pull request 780). * Fix special characters in GitHub contacts links (public pull request 783). * Make clean_pdf target remove pdf folder (public pull request 784). * Fix styleguide bad markup of block continuation (public pull request 792). Other Issues: * Allow a zero vertex attribute divisor in the `<<VK_EXT_vertex_attribute_divisor>>` extension, exposed via the slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT feature. * Add missing `structextends="VkDeviceCreateInfo"` to slink:VkPhysicalDeviceShaderDrawParameterFeatures and slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT. New Extensions: * `VK_KHR_memory_model` * `VK_EXT_astc_decode_mode` * `VK_EXT_inline_uniform_block`
2018-09-08 22:52:13 +00:00
variables (for historical reasons), this model treats each memory access
instruction as having optional implicit availability/visibility operations.
GLSL to SPIR-V compilers should map all (non-atomic) operations on a
coherent variable to Make{Pointer,Texel}{Available}{Visible} flags in this
model.
Atomic operations implicitly have availability/visibility operations, and
the scope of those operations is taken from the atomic operation's scope.
[[memory-model-tessellation-output-ordering]]
== Tessellation Output Ordering
For SPIR-V that uses the Vulkan Memory Model, the code:OutputMemory storage
class is used to synchronize accesses to tessellation control output
variables.
For legacy SPIR-V that does not enable the Vulkan Memory Model via
code:OpMemoryModel, tessellation outputs can be ordered using a control
barrier with no particular memory scope or semantics, as defined below.
Let X and Y be memory operations performed by shader invocations A~X~ and
A~Y~.
Operation X is _tessellation-output-ordered_ before operation Y if and only
if all of the following are true:
* There is a dynamic instance of an code:OpControlBarrier instruction C
such that X is program-ordered before C in A~X~ and C is program-ordered
before Y in A~Y~.
* A~X~ and A~Y~ are in the same instance of C's execution scope.
If shader invocations A~X~ and A~Y~ in the code:TessellationControl
execution model execute memory operations X and Y, respectively, on the
code:Output storage class, and X is tessellation-output-ordered before Y
with a scope of code:Workgroup, then X is location-ordered before Y, and if
X is a write and Y is a read then X is visible-to Y.