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[EarlyCSE & MSSA] Cleanup special handling for removing MemoryAccesses. 

Summary: Moving special handling to MemorySSAUpdater in D57199.

Reviewers: gberry, george.burgess.iv

Subscribers: sanjoy, jlebar, Prazek, llvm-commits

Differential Revision: https://reviews.llvm.org/D57200

llvm-svn: 352794
This commit is contained in:
Alina Sbirlea 2019-01-31 21:12:41 +00:00
parent 88058d4e1e
commit e271889291
1 changed files with 5 additions and 30 deletions
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35
llvm/lib/Transforms/Scalar/EarlyCSE.cpp
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@ -607,36 +607,11 @@ private:
MSSA->verifyMemorySSA();
// Removing a store here can leave MemorySSA in an unoptimized state by
// creating MemoryPhis that have identical arguments and by creating
// MemoryUses whose defining access is not an actual clobber. We handle the
// phi case eagerly here. The non-optimized MemoryUse case is lazily
// updated by MemorySSA getClobberingMemoryAccess.
if (MemoryAccess *MA = MSSA->getMemoryAccess(Inst)) {
// Optimize MemoryPhi nodes that may become redundant by having all the
// same input values once MA is removed.
SmallSetVector<MemoryPhi *, 4> PhisToCheck;
SmallVector<MemoryAccess *, 8> WorkQueue;
WorkQueue.push_back(MA);
// Process MemoryPhi nodes in FIFO order using a ever-growing vector since
// we shouldn't be processing that many phis and this will avoid an
// allocation in almost all cases.
for (unsigned I = 0; I < WorkQueue.size(); ++I) {
MemoryAccess *WI = WorkQueue[I];
for (auto *U : WI->users())
if (MemoryPhi *MP = dyn_cast<MemoryPhi>(U))
PhisToCheck.insert(MP);
MSSAUpdater->removeMemoryAccess(WI);
for (MemoryPhi *MP : PhisToCheck) {
MemoryAccess *FirstIn = MP->getIncomingValue(0);
if (llvm::all_of(MP->incoming_values(),
[=](Use &In) { return In == FirstIn; }))
WorkQueue.push_back(MP);
}
PhisToCheck.clear();
}
}
// MemoryUses whose defining access is not an actual clobber. The phi case
// is handled by MemorySSA when passing OptimizePhis = true to
// removeMemoryAccess. The non-optimized MemoryUse case is lazily updated
// by MemorySSA's getClobberingMemoryAccess.
MSSAUpdater->removeMemoryAccess(Inst, true);
}
};