tree b36058347783b05a1cddf7bba02e0a98d822c8e8
parent c2648c2db7f2d0c10ef54393098fe74f65296c45
author Qining Lu <qining@google.com> 1438361914 -0700
committer Qining Lu <qining@google.com> 1438361914 -0700

Add -reorder-basic-blocks option and fix nop insertion

1. Basic block reordering can be enabled with -reorder-basic-blocks option enabled.

Blocks will be sorted according to the Reversed Post Traversal Order, but the next
node to visit among all candidate children nodes is selected 'randomly'.

Example:
  A
 / \
B   C
 \ /
  D

This CFG can generate two possible layouts:
A-B-C-D or A-C-B-D

2. Fix nop insetion

Add checks to avoiding insertions in empty basic blocks(dead blocks) and bundle locked instructions.

BUG=
R=jpp@chromium.org, jvoung@chromium.org, stichnot@chromium.org

Review URL: https://codereview.chromium.org/1255303004.