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Make ConstantFoldTerminator() handle switches with unreachable default.

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Tested by Transforms/SimplifyCFG/switch-to-br.ll's @unreachable function.

Differential Revision: http://reviews.llvm.org/D6471

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227124 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hans Wennborg 2015-01-26 19:52:24 +00:00
parent 33eac3ee53
commit 1f0c6faee9
1 changed files with 10 additions and 4 deletions
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14
lib/Transforms/Utils/Local.cpp
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@ -110,11 +110,17 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
}
if (SwitchInst *SI = dyn_cast<SwitchInst>(T)) {
// If we are switching on a constant, we can convert the switch into a
// single branch instruction!
// If we are switching on a constant, we can convert the switch to an
// unconditional branch.
ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition());
BasicBlock *TheOnlyDest = SI->getDefaultDest();
BasicBlock *DefaultDest = TheOnlyDest;
BasicBlock *DefaultDest = SI->getDefaultDest();
BasicBlock *TheOnlyDest = DefaultDest;
// If the default is unreachable, ignore it when searching for TheOnlyDest.
if (isa<UnreachableInst>(DefaultDest->getFirstNonPHIOrDbg()) &&
SI->getNumCases() > 0) {
TheOnlyDest = SI->case_begin().getCaseSuccessor();
}
// Figure out which case it goes to.
for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();