Reviewers: Kevin Millikin, fschneider,
Description:
Fix shortcutting bug in HInferRepresentation
* 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
Please review this at http://codereview.chromium.org/7350019/
SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/hydrogen-instructions.h
M src/hydrogen.cc
Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index
401c2e4a0376b33ad9c00df5d78b46026dbe901c..46d5393c5aef052fba48aef048529fd1123ffffc
100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -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;
Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index
887ba7360282c7f2d39904ff150b240c4a5001af..b3f428cb3a793ffbb2c940fd7040cda7d65b1c54
100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -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;
}
}
}
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