tree 18f41d886e435880d5dfc6c6b1a43c748feafec7
parent c930d59b0be761c76d875d7bae9ba7891f395f72
author Manasij Mukherjee <manasijm@google.com> 1468367957 -0700
committer Manasij Mukherjee <manasijm@google.com> 1468367957 -0700

Loop Invariant Code Motion

Implemented behind the new -licm flag.
Hoists invariant arithmetic instructions from loop bodies to pre-headers.
Does not trigger for loops where headers have two incoming edges from
outside the loop.
Also enables multi block address optimization, because most of the
instructions hoisted are address calculations coming from gep.

Does not touch memory operations.
This algorithm does not seem to work well for load-hoisting.

BUG=none
R=jpp@chromium.org, stichnot@chromium.org

Review URL: https://codereview.chromium.org/2138443002 .