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[PM] Refactor how the LoopRotation pass access the DominatorTree.

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Instead of querying the pass every where we need to, do that once and
cache a pointer in the pass object. This is both simpler and I'm about
to add yet another place where we need to dig out that pointer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226391 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2015-01-18 02:08:05 +00:00
parent b7f66977be
commit d39e52bef7
1 changed files with 18 additions and 20 deletions
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38
lib/Transforms/Scalar/LoopRotation.cpp
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@ -75,6 +75,7 @@ namespace {
LoopInfo *LI;
const TargetTransformInfo *TTI;
AssumptionCache *AC;
DominatorTree *DT;
};
}
@ -104,6 +105,8 @@ bool LoopRotate::runOnLoop(Loop *L, LPPassManager &LPM) {
TTI = &getAnalysis<TargetTransformInfo>();
AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(
*L->getHeader()->getParent());
auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
DT = DTWP ? &DTWP->getDomTree() : nullptr;
// Simplify the loop latch before attempting to rotate the header
// upward. Rotation may not be needed if the loop tail can be folded into the
@ -308,9 +311,8 @@ bool LoopRotate::simplifyLoopLatch(Loop *L) {
// Nuke the Latch block.
assert(Latch->empty() && "unable to evacuate Latch");
LI->removeBlock(Latch);
if (DominatorTreeWrapperPass *DTWP =
getAnalysisIfAvailable<DominatorTreeWrapperPass>())
DTWP->getDomTree().eraseNode(Latch);
if (DT)
DT->eraseNode(Latch);
Latch->eraseFromParent();
return true;
}
@ -495,25 +497,23 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
// The conditional branch can't be folded, handle the general case.
// Update DominatorTree to reflect the CFG change we just made. Then split
// edges as necessary to preserve LoopSimplify form.
if (DominatorTreeWrapperPass *DTWP =
getAnalysisIfAvailable<DominatorTreeWrapperPass>()) {
DominatorTree &DT = DTWP->getDomTree();
if (DT) {
// Everything that was dominated by the old loop header is now dominated
// by the original loop preheader. Conceptually the header was merged
// into the preheader, even though we reuse the actual block as a new
// loop latch.
DomTreeNode *OrigHeaderNode = DT.getNode(OrigHeader);
DomTreeNode *OrigHeaderNode = DT->getNode(OrigHeader);
SmallVector<DomTreeNode *, 8> HeaderChildren(OrigHeaderNode->begin(),
OrigHeaderNode->end());
DomTreeNode *OrigPreheaderNode = DT.getNode(OrigPreheader);
DomTreeNode *OrigPreheaderNode = DT->getNode(OrigPreheader);
for (unsigned I = 0, E = HeaderChildren.size(); I != E; ++I)
DT.changeImmediateDominator(HeaderChildren[I], OrigPreheaderNode);
DT->changeImmediateDominator(HeaderChildren[I], OrigPreheaderNode);
assert(DT.getNode(Exit)->getIDom() == OrigPreheaderNode);
assert(DT.getNode(NewHeader)->getIDom() == OrigPreheaderNode);
assert(DT->getNode(Exit)->getIDom() == OrigPreheaderNode);
assert(DT->getNode(NewHeader)->getIDom() == OrigPreheaderNode);
// Update OrigHeader to be dominated by the new header block.
DT.changeImmediateDominator(OrigHeader, OrigLatch);
DT->changeImmediateDominator(OrigHeader, OrigLatch);
}
// Right now OrigPreHeader has two successors, NewHeader and ExitBlock, and
@ -550,17 +550,15 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
PHBI->eraseFromParent();
// With our CFG finalized, update DomTree if it is available.
if (DominatorTreeWrapperPass *DTWP =
getAnalysisIfAvailable<DominatorTreeWrapperPass>()) {
DominatorTree &DT = DTWP->getDomTree();
if (DT) {
// Update OrigHeader to be dominated by the new header block.
DT.changeImmediateDominator(NewHeader, OrigPreheader);
DT.changeImmediateDominator(OrigHeader, OrigLatch);
DT->changeImmediateDominator(NewHeader, OrigPreheader);
DT->changeImmediateDominator(OrigHeader, OrigLatch);
// Brute force incremental dominator tree update. Call
// findNearestCommonDominator on all CFG predecessors of each child of the
// original header.
DomTreeNode *OrigHeaderNode = DT.getNode(OrigHeader);
DomTreeNode *OrigHeaderNode = DT->getNode(OrigHeader);
SmallVector<DomTreeNode *, 8> HeaderChildren(OrigHeaderNode->begin(),
OrigHeaderNode->end());
bool Changed;
@ -573,11 +571,11 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
pred_iterator PI = pred_begin(BB);
BasicBlock *NearestDom = *PI;
for (pred_iterator PE = pred_end(BB); PI != PE; ++PI)
NearestDom = DT.findNearestCommonDominator(NearestDom, *PI);
NearestDom = DT->findNearestCommonDominator(NearestDom, *PI);
// Remember if this changes the DomTree.
if (Node->getIDom()->getBlock() != NearestDom) {
DT.changeImmediateDominator(BB, NearestDom);
DT->changeImmediateDominator(BB, NearestDom);
Changed = true;
}
}