Port 2d4aeaad

Original commit message:
    The stack manipulation was expensive. Two virtual registers are better.

R=mvstanton@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1390343004

Cr-Commit-Position: refs/heads/master@{#31213}