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The JIT's "pure" _BINARY_OP evaluation produces UB (and incorrect results) #136183

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@brandtbucher

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@brandtbucher

Crash report

This code snippet crashes when the JIT is enabled:

for _ in range(4096):
    2 ** 65

I believe this is caused by GH-132733. Specifically, the abstract interpreter generator "thinks" that the operation itself can escape, and spills res to the stack before it has been defined:

stack_pointer[-2] = res;

It also never writes the actual result to the stack once it has been computed, leaving the garbage value in its place.

The fix is probably to teach the code generator that nothing using this "pure" constant evaluation mechanism can escape.

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    3.15new features, bugs and security fixesinterpreter-core(Objects, Python, Grammar, and Parser dirs)topic-JITtype-crashA hard crash of the interpreter, possibly with a core dump

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