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Fix LICM's memory promotion optimization to preserve TBAA tags when

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promoting a store in a loop.  This was noticed when working on PR14753,
but isn't directly related.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171281 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2012-12-31 08:37:17 +00:00
parent 240b9b1d80
commit 503fc1c488
2 changed files with 58 additions and 8 deletions
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lib/Transforms/Scalar/LICM.cpp
+18 -6
View File
@@ -665,16 +665,18 @@ namespace {
AliasSetTracker *
DebugLoc DL;
int Alignment;
MDNode *TBAATag;
public:
LoopPromoter(Value *SP,
const SmallVectorImpl<Instruction*> &Insts, SSAUpdater &S,
SmallPtrSet<Value*, 4> &PMA,
SmallVectorImpl<BasicBlock*> &LEB,
SmallVectorImpl<Instruction*> &LIP,
AliasSetTracker &ast, DebugLoc dl, int alignment)
AliasSetTracker &ast, DebugLoc dl, int alignment,
MDNode *TBAATag)
: LoadAndStorePromoter(Insts, S), SomePtr(SP),
PointerMustAliases(PMA), LoopExitBlocks(LEB), LoopInsertPts(LIP),
AST(ast), DL(dl), Alignment(alignment) {}
AST(ast), DL(dl), Alignment(alignment), TBAATag(TBAATag) {}
virtual bool isInstInList(Instruction *I,
const SmallVectorImpl<Instruction*> &) const {
@@ -698,6 +700,7 @@ namespace {
StoreInst *NewSI = new StoreInst(LiveInValue, SomePtr, InsertPos);
NewSI->setAlignment(Alignment);
NewSI->setDebugLoc(DL);
if (TBAATag) NewSI->setMetadata(LLVMContext::MD_tbaa, TBAATag);
}
}
@@ -751,10 +754,11 @@ void LICM::PromoteAliasSet(AliasSet &AS,
// We start with an alignment of one and try to find instructions that allow
// us to prove better alignment.
unsigned Alignment = 1;
MDNode *TBAATag = 0;
// Check that all of the pointers in the alias set have the same type. We
// cannot (yet) promote a memory location that is loaded and stored in
// different sizes.
// different sizes. While we are at it, collect alignment and TBAA info.
for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
Value *ASIV = ASI->getValue();
PointerMustAliases.insert(ASIV);
@@ -796,8 +800,7 @@ void LICM::PromoteAliasSet(AliasSet &AS,
// instruction will be executed, update the alignment.
// Larger is better, with the exception of 0 being the best alignment.
unsigned InstAlignment = store->getAlignment();
if ((InstAlignment > Alignment || InstAlignment == 0)
&& (Alignment != 0))
if ((InstAlignment > Alignment || InstAlignment == 0) && Alignment != 0)
if (isGuaranteedToExecute(*Use)) {
GuaranteedToExecute = true;
Alignment = InstAlignment;
@@ -809,6 +812,14 @@ void LICM::PromoteAliasSet(AliasSet &AS,
} else
return; // Not a load or store.
// Merge the TBAA tags.
if (LoopUses.empty()) {
// On the first load/store, just take its TBAA tag.
TBAATag = Use->getMetadata(LLVMContext::MD_tbaa);
} else if (TBAATag && TBAATag != Use->getMetadata(LLVMContext::MD_tbaa)) {
TBAATag = 0;
}
LoopUses.push_back(Use);
}
}
@@ -841,7 +852,7 @@ void LICM::PromoteAliasSet(AliasSet &AS,
SmallVector<PHINode*, 16> NewPHIs;
SSAUpdater SSA(&NewPHIs);
LoopPromoter Promoter(SomePtr, LoopUses, SSA, PointerMustAliases, ExitBlocks,
InsertPts, *CurAST, DL, Alignment);
InsertPts, *CurAST, DL, Alignment, TBAATag);
// Set up the preheader to have a definition of the value. It is the live-out
// value from the preheader that uses in the loop will use.
@@ -850,6 +861,7 @@ void LICM::PromoteAliasSet(AliasSet &AS,
Preheader->getTerminator());
PreheaderLoad->setAlignment(Alignment);
PreheaderLoad->setDebugLoc(DL);
if (TBAATag) PreheaderLoad->setMetadata(LLVMContext::MD_tbaa, TBAATag);
SSA.AddAvailableValue(Preheader, PreheaderLoad);
// Rewrite all the loads in the loop and remember all the definitions from