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Revert r85667. LoopUnroll currently can't call utility functions which

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auto-update the DominatorTree because it doesn't keep the DominatorTree
current while it works.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85670 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2009-10-31 17:33:01 +00:00
parent dca094100b
commit 438b583dbd
4 changed files with 99 additions and 33 deletions
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74
lib/Transforms/Utils/BasicBlockUtils.cpp
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@ -92,28 +92,54 @@ void llvm::DeleteDeadPHIs(BasicBlock *BB) {
RecursivelyDeleteDeadPHINode(PN);
}
/// MergeBlockIntoPredecessor - Folds a basic block into its predecessor if it
/// only has one predecessor, and that predecessor only has one successor.
/// If a Pass is given, the LoopInfo and DominatorTree analyses will be kept
/// current. Returns the combined block, or null if no merging was performed.
BasicBlock *llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) {
// Don't merge if the block has multiple predecessors.
BasicBlock *PredBB = BB->getSinglePredecessor();
if (!PredBB) return 0;
// Don't merge if the predecessor has multiple successors.
if (PredBB->getTerminator()->getNumSuccessors() != 1) return 0;
// Don't break self-loops.
if (PredBB == BB) return 0;
// Don't break invokes.
if (isa<InvokeInst>(PredBB->getTerminator())) return 0;
/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,
/// if possible. The return value indicates success or failure.
bool llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) {
pred_iterator PI(pred_begin(BB)), PE(pred_end(BB));
// Can't merge the entry block.
if (pred_begin(BB) == pred_end(BB)) return false;
// Resolve any PHI nodes at the start of the block. They are all
// guaranteed to have exactly one entry if they exist, unless there are
// multiple duplicate (but guaranteed to be equal) entries for the
// incoming edges. This occurs when there are multiple edges from
// PredBB to BB.
FoldSingleEntryPHINodes(BB);
BasicBlock *PredBB = *PI++;
for (; PI != PE; ++PI) // Search all predecessors, see if they are all same
if (*PI != PredBB) {
PredBB = 0; // There are multiple different predecessors...
break;
}
// Can't merge if there are multiple predecessors.
if (!PredBB) return false;
// Don't break self-loops.
if (PredBB == BB) return false;
// Don't break invokes.
if (isa<InvokeInst>(PredBB->getTerminator())) return false;
succ_iterator SI(succ_begin(PredBB)), SE(succ_end(PredBB));
BasicBlock* OnlySucc = BB;
for (; SI != SE; ++SI)
if (*SI != OnlySucc) {
OnlySucc = 0; // There are multiple distinct successors!
break;
}
// Can't merge if there are multiple successors.
if (!OnlySucc) return false;
// Can't merge if there is PHI loop.
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE; ++BI) {
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) == PN)
return false;
} else
break;
}
// Begin by getting rid of unneeded PHIs.
while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
PN->replaceAllUsesWith(PN->getIncomingValue(0));
BB->getInstList().pop_front(); // Delete the phi node...
}
// Delete the unconditional branch from the predecessor...
PredBB->getInstList().pop_back();
@ -124,7 +150,7 @@ BasicBlock *llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) {
// source...
BB->replaceAllUsesWith(PredBB);
// If the predecessor doesn't have a name, take the successor's name.
// Inherit predecessors name if it exists.
if (!PredBB->hasName())
PredBB->takeName(BB);
@ -143,14 +169,12 @@ BasicBlock *llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) {
DT->eraseNode(BB);
}
}
// Notify LoopInfo that the block is removed.
if (LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>())
LI->removeBlock(BB);
}
BB->eraseFromParent();
return PredBB;
return true;
}
/// ReplaceInstWithValue - Replace all uses of an instruction (specified by BI)