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Revert "[SimplifyCFG] Improve FoldValueComparisonIntoPredecessors to handle more cases" 

This reverts commit r280218. This *also* causes buildbot errors. Sigh. Not a successful day all around!

llvm-svn: 280239
This commit is contained in:
James Molloy 2016-08-31 13:32:28 +00:00
parent 655e5a41e1
commit 3c1137c639
1 changed files with 6 additions and 20 deletions
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26
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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@ -174,8 +174,7 @@ public:
/// Return true if it is safe to merge these two
/// terminator instructions together.
static bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2,
std::vector<BasicBlock*> *FailBlocks = nullptr) {
static bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2) {
if (SI1 == SI2)
return false; // Can't merge with self!
@ -184,22 +183,18 @@ static bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2,
// conflicting incoming values from the two switch blocks.
BasicBlock *SI1BB = SI1->getParent();
BasicBlock *SI2BB = SI2->getParent();
SmallPtrSet<BasicBlock *, 16> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB));
bool Fail = false;
for (BasicBlock *Succ : successors(SI2BB))
if (SI1Succs.count(Succ))
for (BasicBlock::iterator BBI = Succ->begin(); isa<PHINode>(BBI); ++BBI) {
PHINode *PN = cast<PHINode>(BBI);
if (PN->getIncomingValueForBlock(SI1BB) !=
PN->getIncomingValueForBlock(SI2BB)) {
if (FailBlocks)
FailBlocks->push_back(Succ);
Fail = true;
}
PN->getIncomingValueForBlock(SI2BB))
return false;
}
return !Fail;
return true;
}
/// Return true if it is safe and profitable to merge these two terminator
@ -959,16 +954,7 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
TerminatorInst *PTI = Pred->getTerminator();
Value *PCV = isValueEqualityComparison(PTI); // PredCondVal
if (PCV == CV && TI != PTI) {
std::vector<BasicBlock*> FailBlocks;
if (!SafeToMergeTerminators(TI, PTI, &FailBlocks)) {
for (auto *Succ : FailBlocks) {
std::vector<BasicBlock*> Blocks = { TI->getParent() };
if (!SplitBlockPredecessors(Succ, Blocks, ".fold.split"))
return false;
}
}
if (PCV == CV && SafeToMergeTerminators(TI, PTI)) {
// Figure out which 'cases' to copy from SI to PSI.
std::vector<ValueEqualityComparisonCase> BBCases;
BasicBlock *BBDefault = GetValueEqualityComparisonCases(TI, BBCases);