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Bug 845068 - IonMonkey: GVN: When a value in the set has a differing dependence, overwrite it r=nbp

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This commit is contained in:
Dan Gohman 2014-07-16 10:53:40 -07:00
parent 74ce265aad
commit b4e55c30d8
1 changed files with 8 additions and 9 deletions
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17
js/src/jit/ValueNumbering.cpp
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@ -50,11 +50,6 @@ ValueNumberer::VisibleValues::ValueHasher::hash(Lookup ins)
bool
ValueNumberer::VisibleValues::ValueHasher::match(Key k, Lookup l)
{
// If one of the instructions depends on a store, and the other instruction
// does not depend on the same store, the instructions are not congruent.
if (k->dependency() != l->dependency())
return false;
return k->congruentTo(l); // Ask the values themselves what they think.
}
@ -411,15 +406,19 @@ ValueNumberer::leader(MDefinition *def)
// Look for a match.
VisibleValues::AddPtr p = values_.findLeaderForAdd(def);
if (p) {
// We found a congruent value.
MDefinition *rep = *p;
if (rep->block()->dominates(def->block())) {
// We found a dominating congruent value.
if (rep->block()->dominates(def->block()) &&
rep->dependency() == def->dependency())
{
// It dominates and has the same dependency. Use it!
MOZ_ASSERT(!rep->isInWorklist(), "Dead value in set");
return rep;
}
// The congruent value doesn't dominate. It never will again in this
// dominator tree, so overwrite it.
// The congruent value doesn't dominate or it has a different
// dependency. It won't be suitable for replacing anything else
// we'll see in this dominator tree walk, so overwrite it.
values_.overwrite(p, def);
} else {
// No match. Add a new entry.