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Fixup PHIs in LowerSwitch when a Leaf node is not emitted.

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This commit fixes bug http://llvm.org/bugs/show_bug.cgi?id=20103.

Thanks to Qwertyuiop for the report and the proposed fix.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212802 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Marcello Maggioni 2014-07-11 10:34:36 +00:00
parent 11c9a50611
commit a533de6f59
1 changed files with 31 additions and 10 deletions
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41
lib/Transforms/Utils/LowerSwitch.cpp
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@ -67,8 +67,8 @@ namespace {
BasicBlock *switchConvert(CaseItr Begin, CaseItr End,
ConstantInt *LowerBound, ConstantInt *UpperBound,
Value *Val, BasicBlock *OrigBlock,
BasicBlock *Default);
Value *Val, BasicBlock *Predecessor,
BasicBlock *OrigBlock, BasicBlock *Default);
BasicBlock *newLeafBlock(CaseRange &Leaf, Value *Val, BasicBlock *OrigBlock,
BasicBlock *Default);
unsigned Clusterify(CaseVector &Cases, SwitchInst *SI);
@ -131,6 +131,21 @@ static raw_ostream& operator<<(raw_ostream &O,
return O << "]";
}
static void fixPhis(BasicBlock *Succ,
BasicBlock *OrigBlock,
BasicBlock *NewNode) {
for (BasicBlock::iterator I = Succ->begin(),
E = Succ->getFirstNonPHI();
I != E; ++I) {
PHINode *PN = cast<PHINode>(I);
for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
if (PN->getIncomingBlock(I) == OrigBlock)
PN->setIncomingBlock(I, NewNode);
}
}
}
// switchConvert - Convert the switch statement into a binary lookup of
// the case values. The function recursively builds this tree.
// LowerBound and UpperBound are used to keep track of the bounds for Val
@ -139,6 +154,7 @@ static raw_ostream& operator<<(raw_ostream &O,
BasicBlock *LowerSwitch::switchConvert(CaseItr Begin, CaseItr End,
ConstantInt *LowerBound,
ConstantInt *UpperBound, Value *Val,
BasicBlock *Predecessor,
BasicBlock *OrigBlock,
BasicBlock *Default) {
unsigned Size = End - Begin;
@ -149,6 +165,7 @@ BasicBlock *LowerSwitch::switchConvert(CaseItr Begin, CaseItr End,
// emitting the code that checks if the value actually falls in the range
// because the bounds already tell us so.
if (Begin->Low == LowerBound && Begin->High == UpperBound) {
fixPhis(Begin->BB, OrigBlock, Predecessor);
return Begin->BB;
}
return newLeafBlock(*Begin, Val, OrigBlock, Default);
@ -200,21 +217,25 @@ BasicBlock *LowerSwitch::switchConvert(CaseItr Begin, CaseItr End,
dbgs() << "NONE\n";
});
BasicBlock *LBranch = switchConvert(LHS.begin(), LHS.end(), LowerBound,
NewUpperBound, Val, OrigBlock, Default);
BasicBlock *RBranch = switchConvert(RHS.begin(), RHS.end(), NewLowerBound,
UpperBound, Val, OrigBlock, Default);
// Create a new node that checks if the value is < pivot. Go to the
// left branch if it is and right branch if not.
Function* F = OrigBlock->getParent();
BasicBlock* NewNode = BasicBlock::Create(Val->getContext(), "NodeBlock");
Function::iterator FI = OrigBlock;
F->getBasicBlockList().insert(++FI, NewNode);
ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_SLT,
Val, Pivot.Low, "Pivot");
BasicBlock *LBranch = switchConvert(LHS.begin(), LHS.end(), LowerBound,
NewUpperBound, Val, NewNode, OrigBlock,
Default);
BasicBlock *RBranch = switchConvert(RHS.begin(), RHS.end(), NewLowerBound,
UpperBound, Val, NewNode, OrigBlock,
Default);
Function::iterator FI = OrigBlock;
F->getBasicBlockList().insert(++FI, NewNode);
NewNode->getInstList().push_back(Comp);
BranchInst::Create(LBranch, RBranch, Comp, NewNode);
return NewNode;
}
@ -386,7 +407,7 @@ void LowerSwitch::processSwitchInst(SwitchInst *SI) {
}
BasicBlock *SwitchBlock =
switchConvert(Cases.begin(), Cases.end(), LowerBound, UpperBound, Val,
OrigBlock, NewDefault);
OrigBlock, OrigBlock, NewDefault);
// Branch to our shiny new if-then stuff...
BranchInst::Create(SwitchBlock, OrigBlock);