[PATCH] D53586: Implement Function Multiversioning for Non-ELF Systems.

[Erich Keane via Phabricator via cfe-commits]

erichkeane created this revision.
erichkeane added reviewers: echristo, rnk, aaron.ballman.
erichkeane added a subscriber: mibintc.

Similar to how ICC handles CPU-Dispatch on Windows, this patch uses the
resolver function directly to forward the call to the proper function.
This is not nearly as efficient as IFuncs of course, but is still quite
useful for large functions specifically developed for certain
processors.

This is unfortunately still limited to x86, since it depends on
__builtin_cpu_supports and __builtin_cpu_is, which are x86 builtins.

The naming for the resolver/forwarding function for cpu-dispatch was
taken from ICC's implementation, which uses the unmodified name for this
(no mangling additions).  This is possible, since cpu-dispatch uses '.A'
for the 'default' version.

In 'target' multiversioning, this function keeps the '.resolver'
extension in order to keep the default function keeping the default
mangling.


Repository:
  rC Clang

https://reviews.llvm.org/D53586

Files:
  include/clang/AST/Decl.h
  include/clang/Basic/Attr.td
  include/clang/Basic/TargetInfo.h
  lib/AST/Decl.cpp
  lib/Basic/Targets/X86.h
  lib/CodeGen/CodeGenFunction.cpp
  lib/CodeGen/CodeGenModule.cpp
  lib/CodeGen/CodeGenModule.h
  test/CodeGen/attr-cpuspecific.c
  test/CodeGen/attr-target-mv-func-ptrs.c
  test/CodeGen/attr-target-mv-va-args.c
  test/CodeGen/attr-target-mv.c
  test/CodeGenCXX/attr-target-mv-diff-ns.cpp
  test/CodeGenCXX/attr-target-mv-func-ptrs.cpp
  test/CodeGenCXX/attr-target-mv-member-funcs.cpp
  test/CodeGenCXX/attr-target-mv-out-of-line-defs.cpp
  test/CodeGenCXX/attr-target-mv-overloads.cpp
  test/Sema/attr-target-mv-bad-target.c

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