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[LICM] *Actually* disable ControlFlowHoisting.

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Summary:
The remaining code paths that ControlFlowHoisting introduced that were
not disabled, increased compile time by 3x for some benchmarks.
The time is spent in DominatorTree updates.

Reviewers: john.brawn, mkazantsev

Subscribers: sanjoy, jlebar, llvm-commits

Differential Revision: https://reviews.llvm.org/D55313

llvm-svn: 348345
This commit is contained in:
Alina Sbirlea 2018-12-05 10:16:21 +00:00
parent 69ba78a8d8
commit 1897ce7884
1 changed files with 19 additions and 14 deletions
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33
lib/Transforms/Scalar/LICM.cpp
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@ -566,6 +566,8 @@ public:
}
BasicBlock *getOrCreateHoistedBlock(BasicBlock *BB) {
if (!ControlFlowHoisting)
return CurLoop->getLoopPreheader();
// If BB has already been hoisted, return that
if (HoistDestinationMap.count(BB))
return HoistDestinationMap[BB];
@ -801,21 +803,24 @@ bool llvm::hoistRegion(DomTreeNode *N, AliasAnalysis *AA, LoopInfo *LI,
// and also keep track of where in the block we are rehoisting to to make sure
// that we rehoist instructions before the instructions that use them.
Instruction *HoistPoint = nullptr;
for (Instruction *I : reverse(HoistedInstructions)) {
if (!llvm::all_of(I->uses(), [&](Use &U) { return DT->dominates(I, U); })) {
BasicBlock *Dominator =
DT->getNode(I->getParent())->getIDom()->getBlock();
LLVM_DEBUG(dbgs() << "LICM rehoisting to " << Dominator->getName() << ": "
<< *I << "\n");
if (!HoistPoint || HoistPoint->getParent() != Dominator) {
if (HoistPoint)
assert(DT->dominates(Dominator, HoistPoint->getParent()) &&
"New hoist point expected to dominate old hoist point");
HoistPoint = Dominator->getTerminator();
if (ControlFlowHoisting) {
for (Instruction *I : reverse(HoistedInstructions)) {
if (!llvm::all_of(I->uses(),
[&](Use &U) { return DT->dominates(I, U); })) {
BasicBlock *Dominator =
DT->getNode(I->getParent())->getIDom()->getBlock();
LLVM_DEBUG(dbgs() << "LICM rehoisting to " << Dominator->getName()
<< ": " << *I << "\n");
if (!HoistPoint || HoistPoint->getParent() != Dominator) {
if (HoistPoint)
assert(DT->dominates(Dominator, HoistPoint->getParent()) &&
"New hoist point expected to dominate old hoist point");
HoistPoint = Dominator->getTerminator();
}
moveInstructionBefore(*I, *HoistPoint, *SafetyInfo);
HoistPoint = I;
Changed = true;
}
moveInstructionBefore(*I, *HoistPoint, *SafetyInfo);
HoistPoint = I;
Changed = true;
}
}