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JIT: Fix compiler warning from visibility attribute in typedef #139981

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JIT: Fix compiler warning from visibility attribute in typedef #139981

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b738d5c
Fix compiler warning from misusing DECLARE_TARGET in typedef
savannahostrowski Oct 12, 2025
2aeaaf3
Remove extraneous files
savannahostrowski Oct 12, 2025
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2 changes: 1 addition & 1 deletion Tools/jit/trampoline.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ _Py_CODEUNIT *
_JIT_ENTRY(
_PyExecutorObject *exec, _PyInterpreterFrame *frame, _PyStackRef *stack_pointer, PyThreadState *tstate
) {
typedef DECLARE_TARGET((*jit_func));
typedef _Py_CODEUNIT *__attribute__((preserve_none)) (*jit_func)(_PyInterpreterFrame *, _PyStackRef *, PyThreadState *);
jit_func jitted = (jit_func)exec->jit_code;
Comment on lines +13 to 14
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@chris-eibl chris-eibl Oct 18, 2025 •
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Suggested change
typedef _Py_CODEUNIT *__attribute__((preserve_none)) (*jit_func)(_PyInterpreterFrame *, _PyStackRef *, PyThreadState *);
jit_func jitted = (jit_func)exec->jit_code;
jit_func_preserve_none jitted = (jit_func_preserve_none)exec->jit_code;

I suggest to use

cpython/Tools/jit/jit.h

Lines 1 to 4 in f937468

// To use preserve_none in JIT builds, we need to declare a separate function
// pointer with __attribute__((preserve_none)), since this attribute may not be
// supported by the compiler used to build the rest of the interpreter.
typedef jit_func __attribute__((preserve_none)) jit_func_preserve_none;

which builds on top of

cpython/Include/internal/pycore_jit.h

Line 18 in d86ad87

typedef _Py_CODEUNIT *(*jit_func)(_PyInterpreterFrame *frame, _PyStackRef *stack_pointer, PyThreadState *tstate);

and IMHO is better than duplicating?

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@chris-eibl chris-eibl Oct 18, 2025 •
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Looking at the other usage of jit_func_preserve_none in

cpython/Tools/jit/template.c

Lines 50 to 56 in f937468

#define TIER2_TO_TIER2(EXECUTOR) \
do { \
OPT_STAT_INC(traces_executed); \
_PyExecutorObject *_executor = (EXECUTOR); \
jit_func_preserve_none jitted = _executor->jit_code; \
__attribute__((musttail)) return jitted(frame, stack_pointer, tstate); \
} while (0)

suggests that it is even possible to omit the cast in

jit_func_preserve_none jitted = (jit_func_preserve_none)exec->jit_code;

and indeed the same code is generated for emit_trampoline in the stencils header 1.

Footnotes

  1. Tested only for x86_64-pc-windows-msvc. ↩

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Sorry for the back and forth, but having a closer look and playing on Godbolt suggests that the cast is better in case of -Wpedantic, since strictly speaking void *jit_code

cpython/Include/internal/pycore_optimizer.h

Lines 52 to 61 in d86ad87

typedef struct _PyExecutorObject {
PyObject_VAR_HEAD
const _PyUOpInstruction *trace;
_PyVMData vm_data; /* Used by the VM, but opaque to the optimizer */
uint32_t exit_count;
uint32_t code_size;
size_t jit_size;
void *jit_code;
_PyExitData exits[1];
} _PyExecutorObject;

is a data pointer. So maybe change to a cast in TIER2_TO_TIER2, too?

return jitted(frame, stack_pointer, tstate);
}
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