Don't replace all dominated uses if there is only one use, since that
use can't be dominated, saving one domtree lookup. llvm-svn: 142066
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@ -1935,10 +1935,15 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS, BasicBlock *Root) {
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// to 'LHS' then ensure it will be turned into 'RHS'.
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addToLeaderTable(VN.lookup_or_add(LHS), RHS, Root);
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// Replace all occurrences of 'LHS' with 'RHS' everywhere in the scope.
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unsigned NumReplacements = replaceAllDominatedUsesWith(LHS, RHS, Root);
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bool Changed = NumReplacements > 0;
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NumGVNEqProp += NumReplacements;
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// Replace all occurrences of 'LHS' with 'RHS' everywhere in the scope. As
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// LHS always has at least one use that is not dominated by Root, this will
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// never do anything if LHS has only one use.
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bool Changed = false;
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if (!LHS->hasOneUse()) {
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unsigned NumReplacements = replaceAllDominatedUsesWith(LHS, RHS, Root);
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Changed |= NumReplacements > 0;
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NumGVNEqProp += NumReplacements;
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}
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// Now try to deduce additional equalities from this one. For example, if the
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// known equality was "(A != B)" == "false" then it follows that A and B are
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