llvm/include
Rafael Espindola 586f018931 This reverts commit r266002, r266011 and r266016.
They broke the msan bot.

Original message:

Add __atomic_* lowering to AtomicExpandPass.

AtomicExpandPass can now lower atomic load, atomic store, atomicrmw,and
cmpxchg instructions to __atomic_* library calls, when the target
doesn't support atomics of a given size.

This is the first step towards moving all atomic lowering from clang
into llvm. When all is done, the behavior of __sync_* builtins,
__atomic_* builtins, and C11 atomics will be unified.

Previously LLVM would pass everything through to the ISelLowering
code. There, unsupported atomic instructions would turn into __sync_*
library calls. Because of that behavior, Clang currently avoids emitting
llvm IR atomic instructions when this would happen, and emits __atomic_*
library functions itself, in the frontend.

This change makes LLVM able to emit __atomic_* libcalls, and thus will
eventually allow clang to depend on LLVM to do the right thing.

It is advantageous to do the new lowering to atomic libcalls in
AtomicExpandPass, before ISel time, because it's important that all
atomic operations for a given size either lower to __atomic_*
libcalls (which may use locks), or native instructions which won't. No
mixing and matching.

At the moment, this code is enabled only for SPARC, as a
demonstration. The next commit will expand support to all of the other
targets.

Differential Revision: http://reviews.llvm.org/D18200

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266062 91177308-0d34-0410-b5e6-96231b3b80d8
2016-04-12 12:30:25 +00:00
..
llvm This reverts commit r266002, r266011 and r266016. 2016-04-12 12:30:25 +00:00
llvm-c [llvm-c] Expose LLVMContextGetDiagnostic{Handler,Context} 2016-04-08 09:19:02 +00:00