May 23, 2025 · May 22, 2025 · May 22, 2025
diff --git a/Python/optimizer_analysis.c b/Python/optimizer_analysis.c
 const bool op_skip[MAX_UOP_ID + 1] = {
    [_NOP] = true,
    [_CHECK_VALIDITY] = true,
    [_CHECK_PERIODIC] = true,
    [_SET_IP] = true,
 };

                    while (op_skip[last->opcode]) {
                        last--;
                    }
                    if (op_without_push[last->opcode]) {
                    if (op_without_push[last->opcode] && op_without_pop[opcode]) {
                        last->opcode = op_without_push[last->opcode];
                        opcode = buffer[pc].opcode = op_without_pop[opcode];
                        if (op_without_pop[last->opcode]) {
Original file line number	Diff line number	Diff line change
Expand Up		@@ -558,6 +558,7 @@ const uint16_t op_without_push[MAX_UOP_ID + 1] = {
		const bool op_skip[MAX_UOP_ID + 1] = {
		[_NOP] = true,
		[_CHECK_VALIDITY] = true,
		[_CHECK_PERIODIC] = true,
		[_SET_IP] = true,
		};

Expand DownExpand Up		@@ -617,7 +618,7 @@ remove_unneeded_uops(_PyUOpInstruction *buffer, int buffer_size)
		while (op_skip[last->opcode]) {
		last--;
		}
		if (op_without_push[last->opcode]) {
		if (op_without_push[last->opcode] && op_without_pop[opcode]) {
		last->opcode = op_without_push[last->opcode];
		opcode = buffer[pc].opcode = op_without_pop[opcode];
Copy link MemberAuthor tomasr8May 22, 2025 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. When we are here, we know that`op_without_pop[opcode] \|\| op_without_pop_null[opcode]` is true. But we should also make sure that`op_without_pop[opcode]` itself is true, otherwise it is possible to accidentally write`0` as the opcode.
		if (op_without_pop[last->opcode]) {
Expand Down