Reviewers: Jakob,
Description:
Remove dead constants not in block #0.
BUG=
Please review this at https://codereview.chromium.org/27473004/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+6, -4 lines):
M src/hydrogen-dce.cc
Index: src/hydrogen-dce.cc
diff --git a/src/hydrogen-dce.cc b/src/hydrogen-dce.cc
index
cba9e42b67a560f11e65ecc092ac73cdd07534df..3b64107fa119fe1c0245bd33313b80c1809c33d4
100644
--- a/src/hydrogen-dce.cc
+++ b/src/hydrogen-dce.cc
@@ -97,10 +97,12 @@ void
HDeadCodeEliminationPhase::RemoveDeadInstructions() {
for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
HInstruction* instr = it.Current();
if (!instr->CheckFlag(HValue::kIsLive)) {
- // Instruction has not been marked live; assume it is dead and
remove.
- // TODO(titzer): we don't remove constants because some special
ones
- // might be used by later phases and are assumed to be in the graph
- if (!instr->IsConstant()) instr->DeleteAndReplaceWith(NULL);
+ // Instruction has not been marked live, so remove it.
+ if (!instr->IsConstant() || instr->block()->block_id() != 0) {
+ // TODO(titzer): Some global constants in block 0 can be used
+ // again later, and can't currently be removed. Fix that.
+ instr->DeleteAndReplaceWith(NULL);
+ }
} else {
// Clear the liveness flag to leave the graph clean for the next
DCE.
instr->ClearFlag(HValue::kIsLive);
--
--
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