tree c55c502f5c491d706df987cadc4c0fcec91dbb8d
parent 839c4cea9facd5bdc51b027bfb89ad778f06fc39
author Jan Voung <jvoung@chromium.org> 1406669931 -0700
committer Jan Voung <jvoung@chromium.org> 1406669931 -0700

Add a peephole to fuse cmpxchg w/ later cmp+branch.

The cmpxchg instruction already sets ZF for comparing the return value
vs the expected value. So there is no need to compare eq again.

Lots of pexes-in-the-wild have this pattern. Some compare against
a constant, some compare against a variable.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3882
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/413903002