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Fix the MemorySSA updating API to enable people to create memory accesses before removing old ones

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llvm-svn: 277309
This commit is contained in:
Daniel Berlin 2016-07-31 21:08:20 +00:00
parent bbc3ad10ae
commit 8f0b850cc7
3 changed files with 46 additions and 4 deletions
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4
include/llvm/Transforms/Utils/MemorySSA.h
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@ -552,6 +552,8 @@ public:
/// will be placed. The caller is expected to keep ordering the same as
/// instructions.
/// It will return the new MemoryAccess.
/// Note: If a MemoryAccess already exists for I, this function will make it
/// inaccessible and it *must* have removeMemoryAccess called on it.
MemoryAccess *createMemoryAccessInBB(Instruction *I, MemoryAccess *Definition,
const BasicBlock *BB,
InsertionPlace Point);
@ -563,6 +565,8 @@ public:
/// used to replace an existing memory instruction. It will *not* create PHI
/// nodes, or verify the clobbering definition. The clobbering definition
/// must be non-null.
/// Note: If a MemoryAccess already exists for I, this function will make it
/// inaccessible and it *must* have removeMemoryAccess called on it.
MemoryAccess *createMemoryAccessBefore(Instruction *I,
MemoryAccess *Definition,
MemoryAccess *InsertPt);

10
lib/Transforms/Utils/MemorySSA.cpp
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@ -1147,7 +1147,7 @@ void MemorySSA::buildMemorySSA() {
// Insert phi node
AccessList *Accesses = getOrCreateAccessList(BB);
MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++);
ValueToMemoryAccess.insert(std::make_pair(BB, Phi));
ValueToMemoryAccess[BB] = Phi;
// Phi's always are placed at the front of the block.
Accesses->push_front(Phi);
}
@ -1204,7 +1204,7 @@ MemoryPhi *MemorySSA::createMemoryPhi(BasicBlock *BB) {
assert(!getMemoryAccess(BB) && "MemoryPhi already exists for this BB");
AccessList *Accesses = getOrCreateAccessList(BB);
MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++);
ValueToMemoryAccess.insert(std::make_pair(BB, Phi));
ValueToMemoryAccess[BB] = Phi;
// Phi's always are placed at the front of the block.
Accesses->push_front(Phi);
BlockNumberingValid.erase(BB);
@ -1293,7 +1293,7 @@ MemoryUseOrDef *MemorySSA::createNewAccess(Instruction *I) {
MUD = new MemoryDef(I->getContext(), nullptr, I, I->getParent(), NextID++);
else
MUD = new MemoryUse(I->getContext(), nullptr, I, I->getParent());
ValueToMemoryAccess.insert(std::make_pair(I, MUD));
ValueToMemoryAccess[I] = MUD;
return MUD;
}
@ -1376,7 +1376,9 @@ void MemorySSA::removeFromLookups(MemoryAccess *MA) {
} else {
MemoryInst = MA->getBlock();
}
ValueToMemoryAccess.erase(MemoryInst);
auto VMA = ValueToMemoryAccess.find(MemoryInst);
if (VMA->second == MA)
ValueToMemoryAccess.erase(VMA);
auto AccessIt = PerBlockAccesses.find(MA->getBlock());
std::unique_ptr<AccessList> &Accesses = AccessIt->second;

36
unittests/Transforms/Utils/MemorySSA.cpp
View File

@ -106,6 +106,42 @@ TEST_F(MemorySSATest, CreateALoadAndPhi) {
MSSA.verifyMemorySSA();
}
TEST_F(MemorySSATest, MoveAStore) {
// We create a diamond where there is a in the entry, a store on one side, and
// a load at the end. After building MemorySSA, we test updating by moving
// the store from the side block to the entry block.
F = Function::Create(
FunctionType::get(B.getVoidTy(), {B.getInt8PtrTy()}, false),
GlobalValue::ExternalLinkage, "F", &M);
BasicBlock *Entry(BasicBlock::Create(C, "", F));
BasicBlock *Left(BasicBlock::Create(C, "", F));
BasicBlock *Right(BasicBlock::Create(C, "", F));
BasicBlock *Merge(BasicBlock::Create(C, "", F));
B.SetInsertPoint(Entry);
Argument *PointerArg = &*F->arg_begin();
StoreInst *EntryStore = B.CreateStore(B.getInt8(16), PointerArg);
B.CreateCondBr(B.getTrue(), Left, Right);
B.SetInsertPoint(Left);
StoreInst *SideStore = B.CreateStore(B.getInt8(16), PointerArg);
BranchInst::Create(Merge, Left);
BranchInst::Create(Merge, Right);
B.SetInsertPoint(Merge);
B.CreateLoad(PointerArg);
setupAnalyses();
MemorySSA &MSSA = Analyses->MSSA;
// Move the store
SideStore->moveBefore(Entry->getTerminator());
MemoryAccess *EntryStoreAccess = MSSA.getMemoryAccess(EntryStore);
MemoryAccess *SideStoreAccess = MSSA.getMemoryAccess(SideStore);
MemoryAccess *NewStoreAccess = MSSA.createMemoryAccessAfter(SideStore,
EntryStoreAccess,
EntryStoreAccess);
EntryStoreAccess->replaceAllUsesWith(NewStoreAccess);
MSSA.removeMemoryAccess(SideStoreAccess);
MSSA.verifyMemorySSA();
}
TEST_F(MemorySSATest, RemoveAPhi) {
// We create a diamond where there is a store on one side, and then a load
// after the merge point. This enables us to test a bunch of different