Rafael Espindola b04bc032f0 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 llvm-svn: 266062		2016-04-12 12:30:25 +00:00
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ARM	ARM: sink atomic release barrier as far as possible into cmpxchg.	2016-02-22 20:55:50 +00:00
X86	[IR] Extend cmpxchg to allow pointer type operands	2016-02-19 00:06:41 +00:00