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a memdep query on a volatile load/store will always return 

clobber with the current implementation.  Instead of returning
a "precise clobber" just return a fuzzy one.  This doesn't 
matter to any clients anyway and should speed up analysis time
very very slightly.

llvm-svn: 60641
This commit is contained in:
Chris Lattner 2008-12-07 00:28:02 +00:00
parent 5df5b4cc2e
commit d4d9588abc
1 changed files with 10 additions and 11 deletions
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21
llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
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@ -116,16 +116,23 @@ getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt,
// Get the pointer value for which dependence will be determined
Value *MemPtr = 0;
uint64_t MemSize = 0;
bool MemVolatile = false;
if (StoreInst* S = dyn_cast<StoreInst>(QueryInst)) {
// If this is a volatile store, don't mess around with it. Just return the
// previous instruction as a clobber.
if (S->isVolatile())
return MemDepResult::getClobber(--ScanIt);
MemPtr = S->getPointerOperand();
MemSize = TD->getTypeStoreSize(S->getOperand(0)->getType());
MemVolatile = S->isVolatile();
} else if (LoadInst* LI = dyn_cast<LoadInst>(QueryInst)) {
// If this is a volatile load, don't mess around with it. Just return the
// previous instruction as a clobber.
if (S->isVolatile())
return MemDepResult::getClobber(--ScanIt);
MemPtr = LI->getPointerOperand();
MemSize = TD->getTypeStoreSize(LI->getType());
MemVolatile = LI->isVolatile();
} else if (FreeInst* F = dyn_cast<FreeInst>(QueryInst)) {
MemPtr = F->getPointerOperand();
// FreeInsts erase the entire structure, not just a field.
@ -145,10 +152,6 @@ getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt,
// Values depend on loads if the pointers are must aliased. This means that
// a load depends on another must aliased load from the same value.
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
// If the access is volatile and this is volatile, return a dependence.
if (MemVolatile && LI->isVolatile())
return MemDepResult::getClobber(LI);
Value *Pointer = LI->getPointerOperand();
uint64_t PointerSize = TD->getTypeStoreSize(LI->getType());
@ -165,10 +168,6 @@ getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt,
}
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
// If the access is volatile and this is volatile, return a dependence.
if (MemVolatile && SI->isVolatile())
return MemDepResult::getClobber(SI);
Value *Pointer = SI->getPointerOperand();
uint64_t PointerSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());