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Fix SimplifyCFG/2005-12-03-IncorrectPHIFold.ll
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24581 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -82,7 +82,7 @@ static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
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//
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if (isa<PHINode>(Succ->front())) {
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std::set<BasicBlock*> BBPreds(pred_begin(BB), pred_end(BB));
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for (pred_iterator PI = pred_begin(Succ), PE = pred_end(Succ);\
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for (pred_iterator PI = pred_begin(Succ), PE = pred_end(Succ);
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PI != PE; ++PI)
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if (std::find(BBPreds.begin(), BBPreds.end(), *PI) != BBPreds.end()) {
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// Loop over all of the PHI nodes checking to see if there are
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@ -115,19 +115,25 @@ static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
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}
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if (IsSafe) return true;
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// If the PHI nodes in BB are only used by instructions in Succ, we are ok.
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IsSafe = true;
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// If the PHI nodes in BB are only used by instructions in Succ, we are ok if
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// BB and Succ have no common predecessors.
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for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I) && IsSafe; ++I) {
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PHINode *PN = cast<PHINode>(I);
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for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end(); UI != E;
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++UI)
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if (cast<Instruction>(*UI)->getParent() != Succ) {
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IsSafe = false;
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break;
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}
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if (cast<Instruction>(*UI)->getParent() != Succ)
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return false;
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}
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return IsSafe;
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// Scan the predecessor sets of BB and Succ, making sure there are no common
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// predecessors. Common predecessors would cause us to build a phi node with
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// differing incoming values, which is not legal.
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std::set<BasicBlock*> BBPreds(pred_begin(BB), pred_end(BB));
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for (pred_iterator PI = pred_begin(Succ), E = pred_end(Succ); PI != E; ++PI)
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if (BBPreds.count(*PI))
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return false;
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return true;
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}
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/// TryToSimplifyUncondBranchFromEmptyBlock - BB contains an unconditional
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