c5b3fe2094
Certain functions require the `returns_twice` attribute in order to produce correct codegen. However, `-fno-builtin` removes all knowledge of functions that require this attribute, so this PR modifies Clang to add the `returns_twice` attribute even if `-fno-builtin` is set. This behavior is also consistent with what GCC does. It's not (easily) possible to get the builtin information from `Builtins.td` because `-fno-builtin` causes Clang to never initialize any builtins, so functions never get tokenized as functions/builtins that require `returns_twice`. Therefore, the most straightforward solution is to explicitly hard code the function names that require `returns_twice`. Fixes #122840
The LLVM Compiler Infrastructure
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