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Ahmed Bougacha 81616a72ea [ARM] Emit clrex in the expanded cmpxchg fail block. ARM counterpart to r248291: In the comparison failure block of a cmpxchg expansion, the initial ldrex/ldxr will not be followed by a matching strex/stxr. On ARM/AArch64, this unnecessarily ties up the execution monitor, which might have a negative performance impact on some uarchs. Instead, release the monitor in the failure block. The clrex instruction was designed for this: use it. Also see ARMARM v8-A B2.10.2: "Exclusive access instructions and Shareable memory locations". Differential Revision: http://reviews.llvm.org/D13033 llvm-svn: 248294	2015-09-22 17:22:58 +00:00
..
ARM	[ARM] Emit clrex in the expanded cmpxchg fail block.	2015-09-22 17:22:58 +00:00
X86	Fix an alignment error in `llvm::expandAtomicRMWToCmpXchg` without breaking the build where X86 isn't enabled.	2015-08-06 16:55:03 +00:00

Ahmed Bougacha 81616a72ea [ARM] Emit clrex in the expanded cmpxchg fail block.

ARM counterpart to r248291:

In the comparison failure block of a cmpxchg expansion, the initial
ldrex/ldxr will not be followed by a matching strex/stxr.
On ARM/AArch64, this unnecessarily ties up the execution monitor,
which might have a negative performance impact on some uarchs.

Instead, release the monitor in the failure block.
The clrex instruction was designed for this: use it.

Also see ARMARM v8-A B2.10.2:
"Exclusive access instructions and Shareable memory locations".

Differential Revision: http://reviews.llvm.org/D13033

llvm-svn: 248294

2015-09-22 17:22:58 +00:00

ARM

[ARM] Emit clrex in the expanded cmpxchg fail block.

2015-09-22 17:22:58 +00:00

X86

Fix an alignment error in `llvm::expandAtomicRMWToCmpXchg` without breaking the build where X86 isn't enabled.

2015-08-06 16:55:03 +00:00