feat: Stop with HeapVector (#9810)

Updates the Brillig stop opcode to return a HeapVector (pointer +
dynamic size). Also changes the transpiler, simulator and witness gen of
the AVM to support it.

avm-transpiler/src/transpile.rs

@@ -306,16 +306,12 @@ pub fn brillig_to_avm(brillig_bytecode: &[BrilligOpcode<FieldElement>]) -> (Vec<
             }
             BrilligOpcode::Return {} => avm_instrs
                 .push(AvmInstruction { opcode: AvmOpcode::INTERNALRETURN, ..Default::default() }),
-            BrilligOpcode::Stop { return_data_offset, return_data_size } => {
-                avm_instrs.push(AvmInstruction {
-                    opcode: AvmOpcode::RETURN,
-                    indirect: Some(AddressingModeBuilder::default().build()),
-                    operands: vec![
-                        AvmOperand::U16 { value: *return_data_offset as u16 },
-                        AvmOperand::U16 { value: *return_data_size as u16 },
-                    ],
-                    ..Default::default()
-                });
+            BrilligOpcode::Stop { return_data } => {
+                generate_return_instruction(
+                    &mut avm_instrs,
+                    &return_data.pointer,
+                    &return_data.size,
+                );
             }
             BrilligOpcode::Trap { revert_data } => {
                 generate_revert_instruction(
@@ -960,6 +956,28 @@ fn generate_revert_instruction(
     });
 }
 
+/// Generates an AVM RETURN instruction.
+fn generate_return_instruction(
+    avm_instrs: &mut Vec<AvmInstruction>,
+    return_data_pointer: &MemoryAddress,
+    return_data_size_offset: &MemoryAddress,
+) {
+    avm_instrs.push(AvmInstruction {
+        opcode: AvmOpcode::RETURN,
+        indirect: Some(
+            AddressingModeBuilder::default()
+                .indirect_operand(return_data_pointer)
+                .direct_operand(return_data_size_offset)
+                .build(),
+        ),
+        operands: vec![
+            AvmOperand::U16 { value: return_data_pointer.to_usize() as u16 },
+            AvmOperand::U16 { value: return_data_size_offset.to_usize() as u16 },
+        ],
+        ..Default::default()
+    });
+}
+
 /// Generates an AVM MOV instruction.
 fn generate_mov_instruction(
     indirect: Option<AvmOperand>,
@@ -1323,25 +1341,16 @@ fn handle_return(
     destinations: &Vec<ValueOrArray>,
     inputs: &Vec<ValueOrArray>,
 ) {
-    assert!(inputs.len() == 1);
+    assert!(inputs.len() == 2);
     assert!(destinations.len() == 0);
 
-    let (return_data_offset, return_data_size) = match inputs[0] {
-        ValueOrArray::HeapArray(HeapArray { pointer, size }) => (pointer, size as u32),
-        _ => panic!("Return instruction's args input should be a HeapArray"),
+    // First arg is the size, which is ignored because it's redundant.
+    let (return_data_offset, return_data_size) = match inputs[1] {
+        ValueOrArray::HeapVector(HeapVector { pointer, size }) => (pointer, size),
+        _ => panic!("Revert instruction's args input should be a HeapVector"),
     };
 
-    avm_instrs.push(AvmInstruction {
-        opcode: AvmOpcode::RETURN,
-        indirect: Some(
-            AddressingModeBuilder::default().indirect_operand(&return_data_offset).build(),
-        ),
-        operands: vec![
-            AvmOperand::U16 { value: return_data_offset.to_usize() as u16 },
-            AvmOperand::U16 { value: return_data_size as u16 },
-        ],
-        ..Default::default()
-    });
+    generate_return_instruction(avm_instrs, &return_data_offset, &return_data_size);
 }
 
 // #[oracle(avmOpcodeRevert)]

barretenberg/cpp/src/barretenberg/dsl/acir_format/avm_recursion_constraint.test.cpp

@@ -54,7 +54,8 @@ class AcirAvmRecursionConstraint : public ::testing::Test {
         trace_builder.op_add(0, 1, 2, 3);
         trace_builder.op_sub(0, 3, 2, 3);
         trace_builder.op_mul(0, 1, 1, 3);
-        trace_builder.op_return(0, 0, 0);
+        trace_builder.op_set(0, 0, 100, AvmMemoryTag::U32);
+        trace_builder.op_return(0, 0, 100);
         auto trace = trace_builder.finalize(); // Passing true enables a longer trace with lookups
 
         avm_trace::inject_end_gas_values(public_inputs, trace);

barretenberg/cpp/src/barretenberg/dsl/acir_format/serde/acir.hpp

@@ -720,8 +720,7 @@ struct BrilligOpcode {
     };
 
     struct Stop {
-        uint64_t return_data_offset;
-        uint64_t return_data_size;
+        Program::HeapVector return_data;
 
         friend bool operator==(const Stop&, const Stop&);
         std::vector<uint8_t> bincodeSerialize() const;
@@ -6401,10 +6400,7 @@ namespace Program {
 
 inline bool operator==(const BrilligOpcode::Stop& lhs, const BrilligOpcode::Stop& rhs)
 {
-    if (!(lhs.return_data_offset == rhs.return_data_offset)) {
-        return false;
-    }
-    if (!(lhs.return_data_size == rhs.return_data_size)) {
+    if (!(lhs.return_data == rhs.return_data)) {
         return false;
     }
     return true;
@@ -6434,8 +6430,7 @@ template <typename Serializer>
 void serde::Serializable<Program::BrilligOpcode::Stop>::serialize(const Program::BrilligOpcode::Stop& obj,
                                                                   Serializer& serializer)
 {
-    serde::Serializable<decltype(obj.return_data_offset)>::serialize(obj.return_data_offset, serializer);
-    serde::Serializable<decltype(obj.return_data_size)>::serialize(obj.return_data_size, serializer);
+    serde::Serializable<decltype(obj.return_data)>::serialize(obj.return_data, serializer);
 }
 
 template <>
@@ -6444,8 +6439,7 @@ Program::BrilligOpcode::Stop serde::Deserializable<Program::BrilligOpcode::Stop>
     Deserializer& deserializer)
 {
     Program::BrilligOpcode::Stop obj;
-    obj.return_data_offset = serde::Deserializable<decltype(obj.return_data_offset)>::deserialize(deserializer);
-    obj.return_data_size = serde::Deserializable<decltype(obj.return_data_size)>::deserialize(deserializer);
+    obj.return_data = serde::Deserializable<decltype(obj.return_data)>::deserialize(deserializer);
     return obj;
 }