Commit Graph

2 Commits

Author SHA1 Message Date
JF Bastien 2cdd5e4710 x86: preserve flags when folding atomic operations
D4796 taught LLVM to fold some atomic integer operations into a single
instruction. The pattern was unaware that the instructions clobbered
flags. I fixed some of this issue in D13680 but had missed INC/DEC.

This patch adds the missing EFLAGS definition.

llvm-svn: 250438
2015-10-15 18:24:52 +00:00
JF Bastien 986ed68eed x86: preserve flags when folding atomic operations
Summary:
D4796 taught LLVM to fold some atomic integer operations into a single
instruction. The pattern was unaware that the instructions clobbered
flags.

This patch adds the missing EFLAGS definition.

Floating point operations don't set flags, the subsequent fadd
optimization is therefore correct. The same applies for surrounding
load/store optimizations.

Reviewers: rsmith, rtrieu

Subscribers: llvm-commits, reames, morisset

Differential Revision: http://reviews.llvm.org/D13680

llvm-svn: 250135
2015-10-13 00:28:47 +00:00