• Create PR with unit tests
• Post copyable unit tests in a comment

Reviewing files that changed from the base of the PR and between 0e6e256 and bce1c66.

• crates/codegen/src/snapshots/rustpython_codegen__compile__tests__nested_double_async_with.snap is excluded by !**/*.snap

• crates/codegen/src/compile.rs (14 hunks)
• crates/compiler-core/src/bytecode.rs (0 hunks)
• crates/jit/tests/common.rs (0 hunks)
• crates/vm/src/frame.rs (1 hunks)

• crates/compiler-core/src/bytecode.rs
• crates/jit/tests/common.rs

• GitHub Check: Run snippets and cpython tests (windows-latest)

crates/vm/src/frame.rs (2)

1080-1085: Good: ToBool handler correctly relocated.

The ToBool instruction handler is now active at this location with proper implementation (pop value, convert to bool, push result). The logic is sound.

---

722-731: I'll verify the review comment by checking the bytecode enum definition and frame.rs instruction handlers to confirm the concerns about removed instruction handlers.
<function_calls>

#!/bin/bash

Description: Verify bytecode enum variants and frame.rs handler consistency

echo "=== 1. Checking bytecode enum for Duplicate/Rotate variants ==="
fd bytecode.rs | head -5


</function_calls>

Let me locate the bytecode file first:
<function_calls>

#!/bin/bash

Find bytecode.rs file

fd -t f bytecode.rs


</function_calls>

Now let me search for the bytecode enum definition and check for the instruction variants:
<function_calls>

#!/bin/bash

Check bytecode enum for Duplicate, Duplicate2, Rotate variants

echo "=== Checking for Duplicate/Rotate variants in bytecode enum ==="
rg "enum Instruction" -A 100 | grep -E "(Duplicate|Rotate)" || echo "No matches for Duplicate/Rotate in enum"

echo -e "\n=== Frame.rs handler verification ==="

Check for CopyItem and Swap handlers

echo "Checking for CopyItem and Swap instruction handlers:"
rg "bytecode::Instruction::CopyItem|bytecode::Instruction::Swap" crates/vm/src/frame.rs

echo -e "\n=== Checking for catch-all match arm ==="
rg "match instruction" crates/vm/src/frame.rs -A 5 | head -20


</function_calls>

I need to execute the verification scripts to check the bytecode enum definition and frame.rs handlers. Let me do that:
<function_calls>

#!/bin/bash

First, find all bytecode-related files

echo "=== Finding bytecode files ==="
fd bytecode -t f

echo -e "\n=== Searching for enum Instruction definition ==="
rg "pub enum Instruction" -A 150 | head -200


</function_calls>

Let me try a more focused search:
<function_calls>

#!/bin/bash

echo "=== Search 1: Looking for instruction enum ==="
rg "enum Instruction" -t rust -A 2

echo -e "\n=== Search 2: Specific search for Duplicate variants ==="
rg "Duplicate|Rotate" -t rust -C 2

echo -e "\n=== Search 3: Check frame.rs around lines 722-731 ==="
sed -n '710,740p' crates/vm/src/frame.rs

echo -e "\n=== Search 4: Check frame.rs around lines 1080-1085 ==="
sed -n '1075,1090p' crates/vm/src/frame.rs


</function_calls>

Let me also verify the CopyItem and Swap handlers exist:
<function_calls>

#!/bin/bash

echo "=== Checking for CopyItem instruction handler ==="
rg "bytecode::Instruction::CopyItem" crates/vm/src/frame.rs -B 2 -A 15

echo -e "\n=== Checking for Swap instruction handler ==="
rg "bytecode::Instruction::Swap" crates/vm/src/frame.rs -B 2 -A 15

echo -e "\n=== Checking entire instruction match statement structure ==="
rg "match.*instruction" crates/vm/src/frame.rs -A 3


</function_calls>

crates/codegen/src/compile.rs (7)

1066-1067: LGTM: Correct replacement of Duplicate with CopyItem { index: 1 }.

The CopyItem { index: 1 } instruction correctly copies the top of stack, which matches the semantics of the removed Duplicate instruction.

---

4325-4326: Verify Duplicate2 replacement for augmented subscript assignment.

The pattern CopyItem { index: 2 } twice correctly replaces Duplicate2:

• Stack before: [value, slice]
• After first CopyItem { index: 2 }: [value, slice, value]
• After second CopyItem { index: 2 }: [value, slice, value, slice]

This duplicates both operands for the subscript load while preserving the originals for the subsequent store operation.

---

4354-4360: LGTM: Correct Rotate3 replacement for augmented subscript store.

The combination of Swap { index: 3 } + Swap { index: 2 } correctly rearranges the stack:

• Stack: [CONTAINER, SLICE, RESULT]
• After Swap { index: 3 }: [RESULT, SLICE, CONTAINER]
• After Swap { index: 2 }: [RESULT, CONTAINER, SLICE]

This correctly positions the operands for StoreSubscript. Similarly, the attribute case (line 4360) with Swap { index: 2 } correctly swaps [CONTAINER, RESULT] to [RESULT, CONTAINER] for StoreAttr.

---

2254-2260: LGTM: Docstring handling with CopyItem and Swap.

The pattern correctly duplicates the function object, loads the docstring, then swaps to position the docstring value for the StoreAttr operation:

• After CopyItem { index: 1 }: [func, func]
• After loading docstring: [func, func, doc]
• After Swap { index: 2 }: [func, doc, func]
• StoreAttr stores doc to func.__doc__, leaving [func]

---

1920-1921: LGTM: Type parameter compilation correctly uses CopyItem.

All three type parameter variants (TypeVar, ParamSpec, TypeVarTuple) consistently use CopyItem { index: 1 } to duplicate the type parameter value before storing it by name, ensuring it remains on the stack for building the final tuple.

Also applies to: 1946-1947, 1973-1974

---

3300-3303: Note: Pattern matching helper also uses the new CopyItem instruction.

This usage within pattern_helper_sequence_subscr is consistent with the rest of the changes and correctly duplicates the subject for element extraction.

---

4124-4125: I'll help you verify the chained comparison stack manipulation. Let me start by examining the instruction definitions and the context around the code in question.
<function_calls>


#!/bin/bash

Search for Swap and CopyItem instruction definitions

rg -n "CopyItem|Swap" crates/compiler-core/src/bytecode.rs -A 2 -B 1 | head -60


</function_calls>


#!/bin/bash

Get context around lines 4124-4125 in compile.rs

sed -n '4110,4140p' crates/codegen/src/compile.rs | cat -n


</function_calls>


#!/bin/bash

Search for Rotate2 and Duplicate instructions to understand the original operations

rg -n "Rotate2|Duplicate" crates/compiler-core/src/bytecode.rs -A 2 -B 1 | head -60


</function_calls>