Memory load/store constraints (#839)

evm/src/cpu/cpu_stark.rs

@@ -11,8 +11,8 @@ use plonky2::hash::hash_types::RichField;
 use crate::constraint_consumer::{ConstraintConsumer, RecursiveConstraintConsumer};
 use crate::cpu::columns::{CpuColumnsView, COL_MAP, NUM_CPU_COLUMNS};
 use crate::cpu::{
-    bootstrap_kernel, control_flow, decode, dup_swap, jumps, membus, modfp254, shift, simple_logic,
-    stack, stack_bounds, syscalls,
+    bootstrap_kernel, control_flow, decode, dup_swap, jumps, membus, memio, modfp254, shift,
+    simple_logic, stack, stack_bounds, syscalls,
 };
 use crate::cross_table_lookup::Column;
 use crate::memory::segments::Segment;
@@ -146,6 +146,7 @@ impl<F: RichField + Extendable<D>, const D: usize> Stark<F, D> for CpuStark<F, D
         dup_swap::eval_packed(local_values, yield_constr);
         jumps::eval_packed(local_values, next_values, &mut dummy_yield_constr);
         membus::eval_packed(local_values, yield_constr);
+        memio::eval_packed(local_values, yield_constr);
         modfp254::eval_packed(local_values, yield_constr);
         shift::eval_packed(local_values, yield_constr);
         simple_logic::eval_packed(local_values, yield_constr);
@@ -172,6 +173,7 @@ impl<F: RichField + Extendable<D>, const D: usize> Stark<F, D> for CpuStark<F, D
         dup_swap::eval_ext_circuit(builder, local_values, yield_constr);
         jumps::eval_ext_circuit(builder, local_values, next_values, &mut dummy_yield_constr);
         membus::eval_ext_circuit(builder, local_values, yield_constr);
+        memio::eval_ext_circuit(builder, local_values, yield_constr);
         modfp254::eval_ext_circuit(builder, local_values, yield_constr);
         shift::eval_ext_circuit(builder, local_values, yield_constr);
         simple_logic::eval_ext_circuit(builder, local_values, yield_constr);

evm/src/cpu/memio.rs

@@ -0,0 +1,171 @@
+use itertools::izip;
+use plonky2::field::extension::Extendable;
+use plonky2::field::packed::PackedField;
+use plonky2::hash::hash_types::RichField;
+use plonky2::iop::ext_target::ExtensionTarget;
+
+use crate::constraint_consumer::{ConstraintConsumer, RecursiveConstraintConsumer};
+use crate::cpu::columns::CpuColumnsView;
+use crate::cpu::membus::NUM_GP_CHANNELS;
+
+fn get_addr<T: Copy>(lv: &CpuColumnsView<T>) -> (T, T, T) {
+    let addr_context = lv.mem_channels[0].value[0];
+    let addr_segment = lv.mem_channels[1].value[0];
+    let addr_virtual = lv.mem_channels[2].value[0];
+    (addr_context, addr_segment, addr_virtual)
+}
+
+fn eval_packed_load<P: PackedField>(
+    lv: &CpuColumnsView<P>,
+    yield_constr: &mut ConstraintConsumer<P>,
+) {
+    let filter = lv.op.mload_general;
+
+    let (addr_context, addr_segment, addr_virtual) = get_addr(lv);
+
+    let load_channel = lv.mem_channels[3];
+    let push_channel = lv.mem_channels[NUM_GP_CHANNELS - 1];
+    yield_constr.constraint(filter * (load_channel.used - P::ONES));
+    yield_constr.constraint(filter * (load_channel.is_read - P::ONES));
+    yield_constr.constraint(filter * (load_channel.addr_context - addr_context));
+    yield_constr.constraint(filter * (load_channel.addr_segment - addr_segment));
+    yield_constr.constraint(filter * (load_channel.addr_virtual - addr_virtual));
+    for (load_limb, push_limb) in izip!(load_channel.value, push_channel.value) {
+        yield_constr.constraint(filter * (load_limb - push_limb));
+    }
+
+    // Disable remaining memory channels, if any.
+    for &channel in &lv.mem_channels[4..NUM_GP_CHANNELS - 1] {
+        yield_constr.constraint(filter * channel.used);
+    }
+}
+
+fn eval_ext_circuit_load<F: RichField + Extendable<D>, const D: usize>(
+    builder: &mut plonky2::plonk::circuit_builder::CircuitBuilder<F, D>,
+    lv: &CpuColumnsView<ExtensionTarget<D>>,
+    yield_constr: &mut RecursiveConstraintConsumer<F, D>,
+) {
+    let filter = lv.op.mload_general;
+
+    let (addr_context, addr_segment, addr_virtual) = get_addr(lv);
+
+    let load_channel = lv.mem_channels[3];
+    let push_channel = lv.mem_channels[NUM_GP_CHANNELS - 1];
+    {
+        let constr = builder.mul_sub_extension(filter, load_channel.used, filter);
+        yield_constr.constraint(builder, constr);
+    }
+    {
+        let constr = builder.mul_sub_extension(filter, load_channel.is_read, filter);
+        yield_constr.constraint(builder, constr);
+    }
+    for (channel_field, target) in izip!(
+        [
+            load_channel.addr_context,
+            load_channel.addr_segment,
+            load_channel.addr_virtual,
+        ],
+        [addr_context, addr_segment, addr_virtual]
+    ) {
+        let diff = builder.sub_extension(channel_field, target);
+        let constr = builder.mul_extension(filter, diff);
+        yield_constr.constraint(builder, constr);
+    }
+    for (load_limb, push_limb) in izip!(load_channel.value, push_channel.value) {
+        let diff = builder.sub_extension(load_limb, push_limb);
+        let constr = builder.mul_extension(filter, diff);
+        yield_constr.constraint(builder, constr);
+    }
+
+    // Disable remaining memory channels, if any.
+    for &channel in &lv.mem_channels[4..NUM_GP_CHANNELS - 1] {
+        let constr = builder.mul_extension(filter, channel.used);
+        yield_constr.constraint(builder, constr);
+    }
+}
+
+fn eval_packed_store<P: PackedField>(
+    lv: &CpuColumnsView<P>,
+    yield_constr: &mut ConstraintConsumer<P>,
+) {
+    let filter = lv.op.mstore_general;
+
+    let (addr_context, addr_segment, addr_virtual) = get_addr(lv);
+
+    let value_channel = lv.mem_channels[3];
+    let store_channel = lv.mem_channels[4];
+    yield_constr.constraint(filter * (store_channel.used - P::ONES));
+    yield_constr.constraint(filter * store_channel.is_read);
+    yield_constr.constraint(filter * (store_channel.addr_context - addr_context));
+    yield_constr.constraint(filter * (store_channel.addr_segment - addr_segment));
+    yield_constr.constraint(filter * (store_channel.addr_virtual - addr_virtual));
+    for (value_limb, store_limb) in izip!(value_channel.value, store_channel.value) {
+        yield_constr.constraint(filter * (value_limb - store_limb));
+    }
+
+    // Disable remaining memory channels, if any.
+    for &channel in &lv.mem_channels[5..] {
+        yield_constr.constraint(filter * channel.used);
+    }
+}
+
+fn eval_ext_circuit_store<F: RichField + Extendable<D>, const D: usize>(
+    builder: &mut plonky2::plonk::circuit_builder::CircuitBuilder<F, D>,
+    lv: &CpuColumnsView<ExtensionTarget<D>>,
+    yield_constr: &mut RecursiveConstraintConsumer<F, D>,
+) {
+    let filter = lv.op.mstore_general;
+
+    let (addr_context, addr_segment, addr_virtual) = get_addr(lv);
+
+    let value_channel = lv.mem_channels[3];
+    let store_channel = lv.mem_channels[4];
+    {
+        let constr = builder.mul_sub_extension(filter, store_channel.used, filter);
+        yield_constr.constraint(builder, constr);
+    }
+    {
+        let constr = builder.mul_extension(filter, store_channel.is_read);
+        yield_constr.constraint(builder, constr);
+    }
+    for (channel_field, target) in izip!(
+        [
+            store_channel.addr_context,
+            store_channel.addr_segment,
+            store_channel.addr_virtual,
+        ],
+        [addr_context, addr_segment, addr_virtual]
+    ) {
+        let diff = builder.sub_extension(channel_field, target);
+        let constr = builder.mul_extension(filter, diff);
+        yield_constr.constraint(builder, constr);
+    }
+    for (value_limb, store_limb) in izip!(value_channel.value, store_channel.value) {
+        let diff = builder.sub_extension(value_limb, store_limb);
+        let constr = builder.mul_extension(filter, diff);
+        yield_constr.constraint(builder, constr);
+    }
+
+    // Disable remaining memory channels, if any.
+    for &channel in &lv.mem_channels[5..] {
+        let constr = builder.mul_extension(filter, channel.used);
+        yield_constr.constraint(builder, constr);
+    }
+}
+
+pub fn eval_packed<P: PackedField>(
+    lv: &CpuColumnsView<P>,
+    yield_constr: &mut ConstraintConsumer<P>,
+) {
+    eval_packed_load(lv, yield_constr);
+    eval_packed_store(lv, yield_constr);
+}
+
+pub fn eval_ext_circuit<F: RichField + Extendable<D>, const D: usize>(
+    builder: &mut plonky2::plonk::circuit_builder::CircuitBuilder<F, D>,
+    lv: &CpuColumnsView<ExtensionTarget<D>>,
+    yield_constr: &mut RecursiveConstraintConsumer<F, D>,
+) {
+    eval_ext_circuit_load(builder, lv, yield_constr);
+    eval_ext_circuit_store(builder, lv, yield_constr);
+}

evm/src/cpu/mod.rs

@@ -7,6 +7,7 @@ mod dup_swap;
 mod jumps;
 pub mod kernel;
 pub(crate) mod membus;
+mod memio;
 mod modfp254;
 mod shift;
 pub(crate) mod simple_logic;

evm/src/cpu/stack.rs

@@ -72,12 +72,20 @@ const STACK_BEHAVIORS: OpsColumnsView<Option<StackBehavior>> = OpsColumnsView {
     push: None,           // TODO
     dup: None,
     swap: None,
-    get_context: None,    // TODO
-    set_context: None,    // TODO
-    consume_gas: None,    // TODO
-    exit_kernel: None,    // TODO
-    mload_general: None,  // TODO
-    mstore_general: None, // TODO
+    get_context: None, // TODO
+    set_context: None, // TODO
+    consume_gas: None, // TODO
+    exit_kernel: None, // TODO
+    mload_general: Some(StackBehavior {
+        num_pops: 3,
+        pushes: true,
+        disable_other_channels: false,
+    }),
+    mstore_general: Some(StackBehavior {
+        num_pops: 4,
+        pushes: false,
+        disable_other_channels: false,
+    }),
     syscall: Some(StackBehavior {
         num_pops: 0,
         pushes: true,

evm/src/generation/mod.rs

@@ -125,11 +125,12 @@ fn simulate_cpu<F: RichField + Extendable<D>, const D: usize>(state: &mut Genera
             log::info!("CPU halted after {} cycles", state.traces.clock());
         }
         already_in_halt_loop |= in_halt_loop;
+
+        transition(state);
+
         if already_in_halt_loop && state.traces.clock().is_power_of_two() {
             log::info!("CPU trace padded to {} cycles", state.traces.clock());
             break;
         }
-
-        transition(state);
     }
 }

evm/src/witness/operation.rs

@@ -518,14 +518,19 @@ pub(crate) fn generate_mload_general<F: Field>(
     let [(context, log_in0), (segment, log_in1), (virt, log_in2)] =
         stack_pop_with_log_and_fill::<3, _>(state, &mut row)?;
 
-    let val = state
-        .memory
-        .get(MemoryAddress::new_u256s(context, segment, virt));
+    let (val, log_read) = mem_read_gp_with_log_and_fill(
+        3,
+        MemoryAddress::new_u256s(context, segment, virt),
+        state,
+        &mut row,
+    );
+
     let log_out = stack_push_log_and_fill(state, &mut row, val)?;
 
     state.traces.push_memory(log_in0);
     state.traces.push_memory(log_in1);
     state.traces.push_memory(log_in2);
+    state.traces.push_memory(log_read);
     state.traces.push_memory(log_out);
     state.traces.push_cpu(row);
     Ok(())