[llvm-branch-commits] [llvm] 8e8d214 - [NFCI][SimplifyCFG] Prefer to add Insert edges before Delete edges into DomTreeUpdater, if reasonable
Roman Lebedev via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Sun Jan 10 13:35:47 PST 2021
Author: Roman Lebedev
Date: 2021-01-11T00:30:44+03:00
New Revision: 8e8d214c4a6c417e42996faeb9211a5c2e32111f
URL: https://github.com/llvm/llvm-project/commit/8e8d214c4a6c417e42996faeb9211a5c2e32111f
DIFF: https://github.com/llvm/llvm-project/commit/8e8d214c4a6c417e42996faeb9211a5c2e32111f.diff
LOG: [NFCI][SimplifyCFG] Prefer to add Insert edges before Delete edges into DomTreeUpdater, if reasonable
This has a measurable impact on the number of DomTree recalculations.
While this doesn't handle all the cases,
it deals with the most obvious ones.
Added:
Modified:
llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
llvm/lib/Transforms/Utils/Local.cpp
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
index c0edde8648f5..44b9ddd3e1ee 100644
--- a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
+++ b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
@@ -141,11 +141,11 @@ static bool mergeEmptyReturnBlocks(Function &F, DomTreeUpdater *DTU) {
// All predecessors of BB should now branch to RetBlock instead.
if (DTU) {
for (auto *Predecessor : predecessors(&BB)) {
- Updates.push_back({DominatorTree::Delete, Predecessor, &BB});
// But, iff Predecessor already branches to RetBlock,
// don't (re-)add DomTree edge, because it already exists.
if (!is_contained(successors(Predecessor), RetBlock))
Updates.push_back({DominatorTree::Insert, Predecessor, RetBlock});
+ Updates.push_back({DominatorTree::Delete, Predecessor, &BB});
}
}
BB.replaceAllUsesWith(RetBlock);
diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index 0b3a25902c69..bfad88f64c7d 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -1395,11 +1395,11 @@ BasicBlock *llvm::CreateControlFlowHub(
SmallVector<DominatorTree::UpdateType, 16> Updates;
if (DTU) {
for (auto In : Incoming) {
+ Updates.push_back({DominatorTree::Insert, In, FirstGuardBlock});
for (auto Succ : successors(In)) {
if (Outgoing.count(Succ))
Updates.push_back({DominatorTree::Delete, In, Succ});
}
- Updates.push_back({DominatorTree::Insert, In, FirstGuardBlock});
}
}
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 76bc8369fe5b..52e71ad164a5 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -735,13 +735,13 @@ void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB,
SmallVector<DominatorTree::UpdateType, 32> Updates;
if (DTU) {
- Updates.push_back({DominatorTree::Delete, PredBB, DestBB});
for (auto I = pred_begin(PredBB), E = pred_end(PredBB); I != E; ++I) {
- Updates.push_back({DominatorTree::Delete, *I, PredBB});
// This predecessor of PredBB may already have DestBB as a successor.
if (!llvm::is_contained(successors(*I), DestBB))
Updates.push_back({DominatorTree::Insert, *I, DestBB});
+ Updates.push_back({DominatorTree::Delete, *I, PredBB});
}
+ Updates.push_back({DominatorTree::Delete, PredBB, DestBB});
}
// Zap anything that took the address of DestBB. Not doing this will give the
@@ -1046,16 +1046,16 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
SmallVector<DominatorTree::UpdateType, 32> Updates;
if (DTU) {
- Updates.push_back({DominatorTree::Delete, BB, Succ});
// All predecessors of BB will be moved to Succ.
SmallSetVector<BasicBlock *, 8> Predecessors(pred_begin(BB), pred_end(BB));
Updates.reserve(Updates.size() + 2 * Predecessors.size());
for (auto *Predecessor : Predecessors) {
- Updates.push_back({DominatorTree::Delete, Predecessor, BB});
// This predecessor of BB may already have Succ as a successor.
if (!llvm::is_contained(successors(Predecessor), Succ))
Updates.push_back({DominatorTree::Insert, Predecessor, Succ});
+ Updates.push_back({DominatorTree::Delete, Predecessor, BB});
}
+ Updates.push_back({DominatorTree::Delete, BB, Succ});
}
if (isa<PHINode>(Succ->begin())) {
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 4bcbffda6a61..62cab573a819 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2495,8 +2495,8 @@ static bool FoldCondBranchOnPHI(BranchInst *BI, DomTreeUpdater *DTU,
PredBBTI->setSuccessor(i, EdgeBB);
}
- Updates.push_back({DominatorTree::Delete, PredBB, BB});
Updates.push_back({DominatorTree::Insert, PredBB, EdgeBB});
+ Updates.push_back({DominatorTree::Delete, PredBB, BB});
if (DTU)
DTU->applyUpdates(Updates);
@@ -2664,9 +2664,9 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI,
SmallVector<DominatorTree::UpdateType, 3> Updates;
if (DTU) {
+ Updates.push_back({DominatorTree::Insert, DomBlock, BB});
for (auto *Successor : successors(DomBlock))
Updates.push_back({DominatorTree::Delete, DomBlock, Successor});
- Updates.push_back({DominatorTree::Insert, DomBlock, BB});
}
OldTI->eraseFromParent();
@@ -3149,8 +3149,8 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, DomTreeUpdater *DTU,
} else
PBI->setMetadata(LLVMContext::MD_prof, nullptr);
- Updates.push_back({DominatorTree::Delete, PredBlock, BB});
Updates.push_back({DominatorTree::Insert, PredBlock, UniqueSucc});
+ Updates.push_back({DominatorTree::Delete, PredBlock, BB});
} else {
// Update PHI nodes in the common successors.
for (unsigned i = 0, e = PHIs.size(); i != e; ++i) {
@@ -3581,8 +3581,9 @@ static bool tryWidenCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI,
OldSuccessor->removePredecessor(BI->getParent());
BI->setSuccessor(1, IfFalseBB);
if (DTU)
- DTU->applyUpdates({{DominatorTree::Delete, BI->getParent(), OldSuccessor},
- {DominatorTree::Insert, BI->getParent(), IfFalseBB}});
+ DTU->applyUpdates(
+ {{DominatorTree::Insert, BI->getParent(), IfFalseBB},
+ {DominatorTree::Delete, BI->getParent(), OldSuccessor}});
return true;
}
if (BI->getSuccessor(0) != IfFalseBB && // no inf looping
@@ -3592,8 +3593,9 @@ static bool tryWidenCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI,
OldSuccessor->removePredecessor(BI->getParent());
BI->setSuccessor(0, IfFalseBB);
if (DTU)
- DTU->applyUpdates({{DominatorTree::Delete, BI->getParent(), OldSuccessor},
- {DominatorTree::Insert, BI->getParent(), IfFalseBB}});
+ DTU->applyUpdates(
+ {{DominatorTree::Insert, BI->getParent(), IfFalseBB},
+ {DominatorTree::Delete, BI->getParent(), OldSuccessor}});
return true;
}
return false;
@@ -3711,6 +3713,7 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI,
// case, it would be unsafe to hoist the operation into a select instruction.
BasicBlock *CommonDest = PBI->getSuccessor(PBIOp);
+ BasicBlock *RemovedDest = PBI->getSuccessor(PBIOp ^ 1);
unsigned NumPhis = 0;
for (BasicBlock::iterator II = CommonDest->begin(); isa<PHINode>(II);
++II, ++NumPhis) {
@@ -3773,16 +3776,13 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI,
// Merge the conditions.
Value *Cond = Builder.CreateOr(PBICond, BICond, "brmerge");
- for (auto *Successor : successors(PBI->getParent()))
- Updates.push_back({DominatorTree::Delete, PBI->getParent(), Successor});
-
// Modify PBI to branch on the new condition to the new dests.
PBI->setCondition(Cond);
PBI->setSuccessor(0, CommonDest);
PBI->setSuccessor(1, OtherDest);
- for (auto *Successor : successors(PBI->getParent()))
- Updates.push_back({DominatorTree::Insert, PBI->getParent(), Successor});
+ Updates.push_back({DominatorTree::Insert, PBI->getParent(), OtherDest});
+ Updates.push_back({DominatorTree::Delete, PBI->getParent(), RemovedDest});
if (DTU)
DTU->applyUpdates(Updates);
@@ -4503,8 +4503,8 @@ static bool removeEmptyCleanup(CleanupReturnInst *RI, DomTreeUpdater *DTU) {
} else {
Instruction *TI = PredBB->getTerminator();
TI->replaceUsesOfWith(BB, UnwindDest);
- Updates.push_back({DominatorTree::Delete, PredBB, BB});
Updates.push_back({DominatorTree::Insert, PredBB, UnwindDest});
+ Updates.push_back({DominatorTree::Delete, PredBB, BB});
}
}
@@ -4764,10 +4764,10 @@ bool SimplifyCFGOpt::simplifyUnreachable(UnreachableInst *UI) {
// Redirect all predecessors of the block containing CatchSwitchInst
// to instead branch to the CatchSwitchInst's unwind destination.
for (auto *PredecessorOfPredecessor : predecessors(Predecessor)) {
- Updates.push_back(
- {DominatorTree::Delete, PredecessorOfPredecessor, Predecessor});
Updates.push_back({DominatorTree::Insert, PredecessorOfPredecessor,
CSI->getUnwindDest()});
+ Updates.push_back(
+ {DominatorTree::Delete, PredecessorOfPredecessor, Predecessor});
}
Predecessor->replaceAllUsesWith(CSI->getUnwindDest());
} else {
@@ -4834,8 +4834,8 @@ static void createUnreachableSwitchDefault(SwitchInst *Switch,
auto *OrigDefaultBlock = Switch->getDefaultDest();
Switch->setDefaultDest(&*NewDefaultBlock);
if (DTU)
- DTU->applyUpdates({{DominatorTree::Delete, BB, OrigDefaultBlock},
- {DominatorTree::Insert, BB, &*NewDefaultBlock}});
+ DTU->applyUpdates({{DominatorTree::Insert, BB, &*NewDefaultBlock},
+ {DominatorTree::Delete, BB, OrigDefaultBlock}});
SplitBlock(&*NewDefaultBlock, &NewDefaultBlock->front(),
DTU ? &DTU->getDomTree() : nullptr);
SmallVector<DominatorTree::UpdateType, 2> Updates;
@@ -6344,8 +6344,8 @@ static bool TryToMergeLandingPad(LandingPadInst *LPad, BranchInst *BI,
assert(II->getNormalDest() != BB && II->getUnwindDest() == BB &&
"unexpected successor");
II->setUnwindDest(OtherPred);
- Updates.push_back({DominatorTree::Delete, Pred, BB});
Updates.push_back({DominatorTree::Insert, Pred, OtherPred});
+ Updates.push_back({DominatorTree::Delete, Pred, BB});
}
// The debug info in OtherPred doesn't cover the merged control flow that
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