[llvm-commits] [llvm] r53052 - /llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp
Devang Patel
dpatel at apple.com
Wed Jul 2 15:58:55 PDT 2008
Author: dpatel
Date: Wed Jul 2 17:58:54 2008
New Revision: 53052
URL: http://llvm.org/viewvc/llvm-project?rev=53052&view=rev
Log:
Preserve dom info while simplifing loop after the unswitch.
Modified:
llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp?rev=53052&r1=53051&r2=53052&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp Wed Jul 2 17:58:54 2008
@@ -757,6 +757,22 @@
}
+/// addBBToDomFrontier - Helper function. Insert DFBB in Basic Block BB's
+/// dominance frontier using iterator DFI.
+static void addBBToDomFrontier(DominanceFrontier &DF,
+ DominanceFrontier::iterator &DFI,
+ BasicBlock *BB, BasicBlock *DFBB) {
+ if (DFI != DF.end()) {
+ DF.addToFrontier(DFI, DFBB);
+ return;
+ }
+
+ DominanceFrontier::DomSetType NSet;
+ NSet.insert(DFBB);
+ DF.addBasicBlock(BB, NSet);
+ DFI = DF.find(BB);
+}
+
/// UnswitchNontrivialCondition - We determined that the loop is profitable
/// to unswitch when LIC equal Val. Split it into loop versions and test the
/// condition outside of either loop. Return the loops created as Out1/Out2.
@@ -1188,18 +1204,32 @@
// trying to update it is complicated. So instead we preserve the
// loop structure and put the block on an dead code path.
+ BasicBlock *SISucc = SI->getSuccessor(i);
BasicBlock* Old = SI->getParent();
BasicBlock* Split = SplitBlock(Old, SI, this);
Instruction* OldTerm = Old->getTerminator();
- BranchInst::Create(Split, SI->getSuccessor(i),
+ BranchInst::Create(Split, SISucc,
ConstantInt::getTrue(), OldTerm);
+ if (DT) {
+ // Now, SISucc is dominated by Old.
+ DT->changeImmediateDominator(SISucc, Old);
+ if (DF) {
+ // Now, Split does not dominate SISucc.
+ // SISucc is the only member in Split's DF.
+ DominanceFrontier::iterator S_DFI = DF->find(Split);
+ if (S_DFI != DF->end())
+ S_DFI->second.clear();
+ addBBToDomFrontier(*DF, S_DFI, Split, SISucc);
+ }
+ }
+
LPM->deleteSimpleAnalysisValue(Old->getTerminator(), L);
Old->getTerminator()->eraseFromParent();
PHINode *PN;
- for (BasicBlock::iterator II = SI->getSuccessor(i)->begin();
+ for (BasicBlock::iterator II = SISucc->begin();
(PN = dyn_cast<PHINode>(II)); ++II) {
Value *InVal = PN->removeIncomingValue(Split, false);
PN->addIncoming(InVal, Old);
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