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Fix the predecessor removal logic in r193045.

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Additionally some small comment/stylistic fixes are included as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193068 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Gottesman 2013-10-21 05:20:11 +00:00
parent 3e033f2923
commit 6701bb7283
1 changed files with 9 additions and 11 deletions
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20
lib/Transforms/Utils/SimplifyCFG.cpp
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@ -3741,18 +3741,20 @@ static bool SwitchToLookupTable(SwitchInst *SI,
// Compute the maximum table size representable by the integer type we are // Compute the maximum table size representable by the integer type we are
// switching upon. // switching upon.
const unsigned CaseSize = MinCaseVal->getType()->getPrimitiveSizeInBits(); unsigned CaseSize = MinCaseVal->getType()->getPrimitiveSizeInBits();
const uint64_t MaxTableSize = CaseSize > 63? UINT64_MAX : 1ULL << CaseSize; uint64_t MaxTableSize = CaseSize > 63? UINT64_MAX : 1ULL << CaseSize;
assert(MaxTableSize >= TableSize && assert(MaxTableSize >= TableSize &&
"It is impossible for a switch to have more entries than the max " "It is impossible for a switch to have more entries than the max "
"representable value of its input integer type's size."); "representable value of its input integer type's size.");
// If we have a covered lookup table, unconditionally branch to the lookup table // If we have a fully covered lookup table, unconditionally branch to the
// BB. Otherwise, check if the condition value is within the case range. If it // lookup table BB. Otherwise, check if the condition value is within the case
// is so, branch to the new BB. Otherwise branch to SI's default destination. // range. If it is so, branch to the new BB. Otherwise branch to SI's default
// destination.
const bool GeneratingCoveredLookupTable = MaxTableSize == TableSize; const bool GeneratingCoveredLookupTable = MaxTableSize == TableSize;
if (GeneratingCoveredLookupTable) { if (GeneratingCoveredLookupTable) {
Builder.CreateBr(LookupBB); Builder.CreateBr(LookupBB);
SI->getDefaultDest()->removePredecessor(SI->getParent());
} else { } else {
Value *Cmp = Builder.CreateICmpULT(TableIndex, ConstantInt::get( Value *Cmp = Builder.CreateICmpULT(TableIndex, ConstantInt::get(
MinCaseVal->getType(), TableSize)); MinCaseVal->getType(), TableSize));
@ -3786,14 +3788,10 @@ static bool SwitchToLookupTable(SwitchInst *SI,
Builder.CreateBr(CommonDest); Builder.CreateBr(CommonDest);
// Remove the switch. // Remove the switch.
for (unsigned i = 0; i < SI->getNumSuccessors(); ++i) { for (unsigned i = 0, e = SI->getNumSuccessors(); i < e; ++i) {
BasicBlock *Succ = SI->getSuccessor(i); BasicBlock *Succ = SI->getSuccessor(i);
// If we are not generating a covered lookup table, we will have a if (Succ == SI->getDefaultDest())
// conditional branch from SI's parent BB to SI's default destination if our
// input value lies outside of our case range. Thus in that case leave the
// default destination BB as a predecessor of SI's parent BB.
if (Succ == SI->getDefaultDest() && !GeneratingCoveredLookupTable)
continue; continue;
Succ->removePredecessor(SI->getParent()); Succ->removePredecessor(SI->getParent());
} }