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Use a new helper to split critical edges, making the code simpler.

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Do not claim to not change the CFG.  We do change the cfg to split critical
edges.  This isn't causing us a problem now, but could likely do so in the
future.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22824 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-08-17 06:35:16 +00:00
parent bb20372e70
commit aa96ae780a
1 changed files with 21 additions and 18 deletions
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39
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -119,7 +119,15 @@ namespace {
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
// We split critical edges, so we change the CFG. However, we do update
// many analyses if they are around.
AU.addPreservedID(LoopSimplifyID);
AU.addPreserved<LoopInfo>();
AU.addPreserved<DominatorSet>();
AU.addPreserved<ImmediateDominators>();
AU.addPreserved<DominanceFrontier>();
AU.addPreserved<DominatorTree>();
AU.addRequiredID(LoopSimplifyID);
AU.addRequired<LoopInfo>();
AU.addRequired<DominatorSet>();
@ -440,25 +448,20 @@ void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase,
// code on all predecessor/successor paths.
if (e != 1 &&
PN->getIncomingBlock(i)->getTerminator()->getNumSuccessors() > 1) {
TerminatorInst *PredTI = PN->getIncomingBlock(i)->getTerminator();
for (unsigned Succ = 0; ; ++Succ) {
assert(Succ != PredTI->getNumSuccessors() &&"Didn't find successor?");
if (PredTI->getSuccessor(Succ) == PN->getParent()) {
// First step, split the critical edge.
SplitCriticalEdge(PredTI, Succ, P);
// First step, split the critical edge.
SplitCriticalEdge(PN->getIncomingBlock(i), PN->getParent(), P);
// Next step: move the basic block. In particular, if the PHI node
// is outside of the loop, and PredTI is in the loop, we want to
// move the block to be immediately before the PHI block, not
// immediately after PredTI.
if (L->contains(PredTI->getParent()) &&
!L->contains(PN->getParent())) {
BasicBlock *NewBB = PN->getIncomingBlock(i);
NewBB->moveBefore(PN->getParent());
}
break;
}
// Next step: move the basic block. In particular, if the PHI node
// is outside of the loop, and PredTI is in the loop, we want to
// move the block to be immediately before the PHI block, not
// immediately after PredTI.
if (L->contains(PN->getIncomingBlock(i)) &&
!L->contains(PN->getParent())) {
BasicBlock *NewBB = PN->getIncomingBlock(i);
NewBB->moveBefore(PN->getParent());
}
break;
}
Value *&Code = InsertedCode[PN->getIncomingBlock(i)];