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Fix shortcutting bug in HInferRepresentation

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* src/hydrogen.cc (HInferRepresentation::Analyze): Fix iterative loop
  over phis; the shortcutting behavior of || appears to be accidental
  here, causing O(n^2) convergence.  Not that it matters much, but hey!

While I'm at it, a minor comment fix:

* src/hydrogen-instructions.h (EnsureAndPropagateNotMinusZero): Fix a
  comment about the kinds of instructions that propagate to multiple
  inputs.

BUG=
TEST=passes tools/test.py

Review URL: http://codereview.chromium.org/7350019
Patch from Andy Wingo <wingo@igalia.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8645 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
ager@chromium.org 2011-07-13 14:43:09 +00:00
parent 391ef3be33
commit 9c233c711e
2 changed files with 5 additions and 5 deletions
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6
src/hydrogen-instructions.h
View File

@ -588,9 +588,9 @@ class HValue: public ZoneObject {
// it would otherwise output what should be a minus zero as an int32 zero.
// If the operation also exists in a form that takes int32 and outputs int32
// then the operation should return its input value so that we can propagate
// back. There are two operations that need to propagate back to more than
// one input. They are phi and binary add. They always return NULL and
// expect the caller to take care of things.
// back. There are three operations that need to propagate back to more than
// one input. They are phi and binary div and mul. They always return NULL
// and expect the caller to take care of things.
virtual HValue* EnsureAndPropagateNotMinusZero(BitVector* visited) {
visited->Add(id());
return NULL;

4
src/hydrogen.cc
View File

@ -1666,8 +1666,8 @@ void HInferRepresentation::Analyze() {
HValue* use = it.value();
if (use->IsPhi()) {
int id = HPhi::cast(use)->phi_id();
change = change ||
connected_phis[i]->UnionIsChanged(*connected_phis[id]);
if (connected_phis[i]->UnionIsChanged(*connected_phis[id]))
change = true;
}
}
}