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[Clang][Codegen] Add GNU function attribute 'no_profile' and lower it to…

Authored by nickdesaulniers on Jun 18 2021, 1:33 PM.

Description

[Clang][Codegen] Add GNU function attribute 'no_profile' and lower it to noprofile

noprofile IR attribute already exists to prevent profiling with PGO;
emit that when a function uses the newly added no_profile function
attribute.

The Linux kernel would like to avoid compiler generated code in
functions annotated with such attribute. We already respect this for
libcalls to fentry() and mcount().

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80223
Link: https://lore.kernel.org/lkml/CAKwvOdmPTi93n2L0_yQkrzLdmpxzrOR7zggSzonyaw2PGshApw@mail.gmail.com/

Reviewed By: MaskRay, void, phosek, aaron.ballman

Differential Revision: https://reviews.llvm.org/D104475