Make GVN side effect analysis more precise.

Make GVN side effect analysis more precise.

When descending the dominator tree we used to collect side effects from all blocks between the dominator and the dominated blocks in the block ordering. This could include blocks that do not appear on paths from the dominator to the dominated and unnecessarily removed available values from the GVN map.

Committed: http://code.google.com/p/v8/source/detail?r=7943

[fschneider, 2011-05-18 16:25:02]

LGTM.

http://codereview.chromium.org/7036010/diff/2001/src/hydrogen.cc
File src/hydrogen.cc (right):

http://codereview.chromium.org/7036010/diff/2001/src/hydrogen.cc#newcode1512
src/hydrogen.cc:1512: 
Remove extra new-line.

http://codereview.chromium.org/7036010/diff/2001/src/hydrogen.cc#newcode1524
src/hydrogen.cc:1524: block->block_id() + 1 < dominated->block_id()) {
Maybe assert that (block->block_id() + 1) is always a direct successor of block.

You skip the first successor here, which is correct. Not sure if it's worth
finding the other successors and skip as well.