tree 0edbc0a291104817c854578c28ef2c7ee20811ee
parent 0e7e412eed5f508be05dc28c360797bd817e193e
author Jim Stichnoth <stichnot@chromium.org> 1430760137 -0700
committer Jim Stichnoth <stichnot@chromium.org> 1430760137 -0700

Subzero: Use a setcc sequence for better icmp lowering.

For an example like:
  %a = icmp eq i32 %b, %c

The original icmp lowering sequence for i8/i16/i32 was something like:

  cmpl b, c
  movb 1, a
  je label
  movb 0, a
label:

The improved sequence is:
  cmpl b, c
  sete a

In O2 mode, this doesn't help when successive compare/branch instructions are fused, but it does help when the boolean result needs to be saved and later used.

BUG= none
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/1118353005