[MemProf] Allow hint update on existing calls to nobuiltin hot/cold new #156476
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Explicit calls to ::operator new are marked nobuiltin and cannot be elided or updated as they may call user defined versions. However, existing calls to the hot/cold versions of new only need their hint parameter value updated, which does not mutate the call.
snehasish
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Sep 2, 2025
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| // cases where the call is marked nobuiltin (because operator new called | ||
| // explicitly) and therefore cannot be replaced with a different callee. |
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Do you know why the distinction of being called explicitly matters for builtin vs no-builtin?
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C++ standard: There's a reference to that here: https://clang.llvm.org/docs/LanguageExtensions.html#builtin-operator-new-and-builtin-operator-delete. I see some older conversations about this from Richard Smith.
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Explicit calls to ::operator new are marked nobuiltin and cannot be
elided or updated as they may call user defined versions. However,
existing calls to the hot/cold versions of new only need their hint
parameter value updated, which does not mutate the call.