Redundant stack spills on subsequent escaping calls separated by comments

Bug report

Bug description:

Tier 1 case generator emits stack spill for every subsequent escaping call, when subsequent escaping calls are separated by comment(s). Example:

Subsequent escaping calls without comments in between:

Bytecode definition:

pure inst(NOP, (--)) {
    escaping_call1();
    escaping_call2();
    escaping_call3();
}

Generated case:

TARGET(NOP) {
    frame->instr_ptr = next_instr;
    next_instr += 1;
    INSTRUCTION_STATS(NOP);
    _PyFrame_SetStackPointer(frame, stack_pointer);
    escaping_call1();
    escaping_call2();
    escaping_call3();
    stack_pointer = _PyFrame_GetStackPointer(frame);
    DISPATCH();
}

Subsequent escaping calls with comments in between:

Bytecode definition:

pure inst(NOP, (--)) {
    escaping_call1();
    // comment1
    escaping_call2();
    // comment2
    escaping_call3();
}

Generated case:

TARGET(NOP) {
    frame->instr_ptr = next_instr;
    next_instr += 1;
    INSTRUCTION_STATS(NOP);
    _PyFrame_SetStackPointer(frame, stack_pointer);
    escaping_call1();
    stack_pointer = _PyFrame_GetStackPointer(frame);
    // comment1
    _PyFrame_SetStackPointer(frame, stack_pointer);
    escaping_call2();
    stack_pointer = _PyFrame_GetStackPointer(frame);
    // comment2
    _PyFrame_SetStackPointer(frame, stack_pointer);
    escaping_call3();
    stack_pointer = _PyFrame_GetStackPointer(frame);
    DISPATCH();
}

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-128761

Comece pelo gerador de casos de Tier 1 e pela definição de bytecode mostrados no relatório; em seguida, revise o PR vinculado gh-128761 para ver o trabalho atual. Reproduza os exemplos com comentários entre as chamadas de escaping e verifique se o caso gerado emite apenas as operações necessárias do ponteiro de pilha.