[MemorySSA] Teach LoopSimplify to preserve MemorySSA.
Summary:
Preserve MemorySSA in LoopSimplify, in the old pass manager, if the analysis is available.
Do not preserve it in the new pass manager.
Update tests.
Subscribers: nemanjai, jlebar, javed.absar, Prazek, kbarton, zzheng, jsji, llvm-commits, george.burgess.iv, chandlerc
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60833
llvm-svn: 360270
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index e388454..d571648 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -25,8 +25,9 @@
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/EHPersonalities.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/MemorySSA.h"
+#include "llvm/Analysis/MemorySSAUpdater.h"
#include "llvm/Analysis/TargetTransformInfo.h"
-#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
@@ -65,6 +66,7 @@
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <algorithm>
#include <cassert>
@@ -291,9 +293,13 @@
/// will be the same as those coming in from ExistPred, an existing predecessor
/// of Succ.
static void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred,
- BasicBlock *ExistPred) {
+ BasicBlock *ExistPred,
+ MemorySSAUpdater *MSSAU = nullptr) {
for (PHINode &PN : Succ->phis())
PN.addIncoming(PN.getIncomingValueForBlock(ExistPred), NewPred);
+ if (MSSAU)
+ if (auto *MPhi = MSSAU->getMemorySSA()->getMemoryAccess(Succ))
+ MPhi->addIncoming(MPhi->getIncomingValueForBlock(ExistPred), NewPred);
}
/// Compute an abstract "cost" of speculating the given instruction,
@@ -669,7 +675,8 @@
} // end anonymous namespace
-static void EraseTerminatorAndDCECond(Instruction *TI) {
+static void EraseTerminatorAndDCECond(Instruction *TI,
+ MemorySSAUpdater *MSSAU = nullptr) {
Instruction *Cond = nullptr;
if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
Cond = dyn_cast<Instruction>(SI->getCondition());
@@ -682,7 +689,7 @@
TI->eraseFromParent();
if (Cond)
- RecursivelyDeleteTriviallyDeadInstructions(Cond);
+ RecursivelyDeleteTriviallyDeadInstructions(Cond, nullptr, MSSAU);
}
/// Return true if the specified terminator checks
@@ -2546,7 +2553,8 @@
/// If this basic block is simple enough, and if a predecessor branches to us
/// and one of our successors, fold the block into the predecessor and use
/// logical operations to pick the right destination.
-bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) {
+bool llvm::FoldBranchToCommonDest(BranchInst *BI, MemorySSAUpdater *MSSAU,
+ unsigned BonusInstThreshold) {
BasicBlock *BB = BI->getParent();
const unsigned PredCount = pred_size(BB);
@@ -2757,7 +2765,7 @@
(SuccFalseWeight + SuccTrueWeight) +
PredTrueWeight * SuccFalseWeight);
}
- AddPredecessorToBlock(TrueDest, PredBlock, BB);
+ AddPredecessorToBlock(TrueDest, PredBlock, BB, MSSAU);
PBI->setSuccessor(0, TrueDest);
}
if (PBI->getSuccessor(1) == BB) {
@@ -2772,7 +2780,7 @@
// FalseWeight is FalseWeight for PBI * FalseWeight for BI.
NewWeights.push_back(PredFalseWeight * SuccFalseWeight);
}
- AddPredecessorToBlock(FalseDest, PredBlock, BB);
+ AddPredecessorToBlock(FalseDest, PredBlock, BB, MSSAU);
PBI->setSuccessor(1, FalseDest);
}
if (NewWeights.size() == 2) {
@@ -2820,9 +2828,15 @@
PHIs[i]->setIncomingValue(PHIs[i]->getBasicBlockIndex(PBI->getParent()),
MergedCond);
}
+
+ // PBI is changed to branch to TrueDest below. Remove itself from
+ // potential phis from all other successors.
+ if (MSSAU)
+ MSSAU->changeCondBranchToUnconditionalTo(PBI, TrueDest);
+
// Change PBI from Conditional to Unconditional.
BranchInst *New_PBI = BranchInst::Create(TrueDest, PBI);
- EraseTerminatorAndDCECond(PBI);
+ EraseTerminatorAndDCECond(PBI, MSSAU);
PBI = New_PBI;
}
@@ -5805,7 +5819,7 @@
// branches to us and our successor, fold the comparison into the
// predecessor and use logical operations to update the incoming value
// for PHI nodes in common successor.
- if (FoldBranchToCommonDest(BI, Options.BonusInstThreshold))
+ if (FoldBranchToCommonDest(BI, nullptr, Options.BonusInstThreshold))
return requestResimplify();
return false;
}
@@ -5869,7 +5883,7 @@
// If this basic block is ONLY a compare and a branch, and if a predecessor
// branches to us and one of our successors, fold the comparison into the
// predecessor and use logical operations to pick the right destination.
- if (FoldBranchToCommonDest(BI, Options.BonusInstThreshold))
+ if (FoldBranchToCommonDest(BI, nullptr, Options.BonusInstThreshold))
return requestResimplify();
// We have a conditional branch to two blocks that are only reachable