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Do not add PHIs with no users when creating LCSSA form. Patch by Andrew Clinton.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127674 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Cameron Zwarich
2011-03-15 07:41:25 +00:00
parent 42e72ca3d0
commit 838b97edfa
3 changed files with 48 additions and 2 deletions
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10
lib/Transforms/Utils/LCSSA.cpp
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@@ -207,6 +207,8 @@ bool LCSSA::ProcessInstruction(Instruction *Inst,
DomTreeNode *DomNode = DT->getNode(DomBB);
SmallVector<PHINode*, 16> AddedPHIs;
SSAUpdater SSAUpdate;
SSAUpdate.Initialize(Inst->getType(), Inst->getName());
@@ -236,6 +238,8 @@ bool LCSSA::ProcessInstruction(Instruction *Inst,
&PN->getOperandUse(
PN->getOperandNumForIncomingValue(PN->getNumIncomingValues()-1)));
}
AddedPHIs.push_back(PN);
// Remember that this phi makes the value alive in this block.
SSAUpdate.AddAvailableValue(ExitBB, PN);
@@ -262,6 +266,12 @@ bool LCSSA::ProcessInstruction(Instruction *Inst,
// Otherwise, do full PHI insertion.
SSAUpdate.RewriteUse(*UsesToRewrite[i]);
}
// Remove PHI nodes that did not have any uses rewritten.
for (unsigned i = 0, e = AddedPHIs.size(); i != e; ++i) {
if (!AddedPHIs[i]->hasNUsesOrMore(1))
AddedPHIs[i]->eraseFromParent();
}
return true;
}