/// 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!
// 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
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);