Force checking sizes at compile-time

src/private/size_mpuintimpl.nim

@@ -0,0 +1,36 @@
+# Copyright 2018 Status Research & Development GmbH
+# Licensed under either of
+#
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+#
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+import ./uint_type, macros
+
+
+proc size_mpuintimpl*(x: NimNode): static[int] =
+
+  # Size of doesn't always work at compile-time, pending PR https://github.com/nim-lang/Nim/pull/5664
+
+  var multiplier = 1
+  var node = x.getTypeInst
+
+  while node.kind == nnkBracketExpr:
+    assert eqIdent(node[0], "MpuintImpl")
+    multiplier *= 2
+    node = node[1]
+
+  # node[1] has the type
+  # size(node[1]) * multiplier is the size in byte
+
+  # For optimization we cast to the biggest possible uint
+  result =  if eqIdent(node, "uint64"): multiplier * 64
+            elif eqIdent(node, "uint32"): multiplier * 32
+            elif eqIdent(node, "uint16"): multiplier * 16
+            else: multiplier * 8
+
+macro size_mpuintimpl*(x: typed): untyped =
+  let size = size_mpuintimpl(x)
+  result = quote do:
+    `size`

src/private/uint_binary_ops.nim

@@ -78,8 +78,8 @@ proc naiveMulImpl[T: MpUintImpl](x, y: T): MpUintImpl[T] {.noSideEffect, noInit,
   #     and introduce branching
   #   - More total operations means more register moves
 
+  const halfSize = x.size_mpuintimpl div 2
   let
-    halfSize = T.sizeof * 4
     z0 = naiveMul(x.lo, y.lo)
     tmp = naiveMul(x.hi, y.lo)
 

src/private/uint_bitwise_ops.nim

@@ -7,7 +7,7 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import  ./uint_type
+import  ./uint_type, size_mpuintimpl
 
 
 proc `not`*(x: MpUintImpl): MpUintImpl {.noInit, noSideEffect, inline.}=
@@ -33,8 +33,7 @@ proc `xor`*(x, y: MpUintImpl): MpUintImpl {.noInit, noSideEffect, inline.}=
 proc `shl`*[T: MpUintImpl](x: T, y: SomeInteger): T {.noInit, inline, noSideEffect.}=
   ## Compute the `shift left` operation of x and y
   # Note: inlining this poses codegen/aliasing issue when doing `x = x shl 1`
-  let
-    halfSize = T.sizeof * 4
+  const halfSize = size_mpuintimpl(x) div 2
 
   type SubTy = type x.lo
 
@@ -46,8 +45,7 @@ proc `shl`*[T: MpUintImpl](x: T, y: SomeInteger): T {.noInit, inline, noSideEffe
 proc `shr`*[T: MpUintImpl](x: T, y: SomeInteger): T {.noInit, inline, noSideEffect.}=
   ## Compute the `shift right` operation of x and y
   # Note: inlining this poses codegen/aliasing issue when doing `x = x shl 1`
-  let
-    halfSize = T.sizeof * 4
+  const halfSize = size_mpuintimpl(x) div 2
 
   type SubTy = type x.lo
 

src/private/uint_comparison.nim

@@ -7,27 +7,10 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import  ./uint_type, macros
+import  ./uint_type, ./size_mpuintimpl, macros
 
 macro cast_optim(x: typed): untyped =
-  # Size of doesn't always work at compile-time, pending PR https://github.com/nim-lang/Nim/pull/5664
-
-  var multiplier = 1
-  var node = x.getTypeInst
-
-  while node.kind == nnkBracketExpr:
-    assert eqIdent(node[0], "MpuintImpl")
-    multiplier *= 2
-    node = node[1]
-
-  # node[1] has the type
-  # size(node[1]) * multiplier is the size in byte
-
-  # For optimization we cast to the biggest possible uint
-  let size = if eqIdent(node, "uint64"): multiplier * 64
-             elif eqIdent(node, "uint32"): multiplier * 32
-             elif eqIdent(node, "uint16"): multiplier * 16
-             else: multiplier * 8
+  let size = size_mpuintimpl(x)
 
   if size > 64:
     result = quote do: