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Handle fallout from the recent branch-on-undef changes. This fixes

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Prolangs-C/agrep and SCCP/2006-10-23-IPSCCP-Crash.ll


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31132 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-10-23 18:57:02 +00:00
parent e285d59ee6
commit ddaaa37487
1 changed files with 24 additions and 1 deletions
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25
lib/Transforms/Scalar/SCCP.cpp
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@ -1360,7 +1360,30 @@ bool IPSCCP::runOnModule(Module &M) {
while (!DeadBB->use_empty()) {
Instruction *I = cast<Instruction>(DeadBB->use_back());
bool Folded = ConstantFoldTerminator(I->getParent());
assert(Folded && "Didn't fold away reference to block!");
if (!Folded) {
// The constant folder may not have been able to fold the termiantor
// if this is a branch or switch on undef. Fold it manually as a
// branch to the first successor.
if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
assert(BI->isConditional() && isa<UndefValue>(BI->getCondition()) &&
"Branch should be foldable!");
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
assert(isa<UndefValue>(SI->getCondition()) && "Switch should fold");
} else {
assert(0 && "Didn't fold away reference to block!");
}
// Make this an uncond branch to the first successor.
TerminatorInst *TI = I->getParent()->getTerminator();
new BranchInst(TI->getSuccessor(0), TI);
// Remove entries in successor phi nodes to remove edges.
for (unsigned i = 1, e = TI->getNumSuccessors(); i != e; ++i)
TI->getSuccessor(i)->removePredecessor(TI->getParent());
// Remove the old terminator.
TI->eraseFromParent();
}
}
// Finally, delete the basic block.