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Update instcombine for atomic load/store.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137664 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eli Friedman
2011-08-15 22:09:40 +00:00
parent d0b5a5ece4
commit cc4a0435b7
4 changed files with 54 additions and 31 deletions
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lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+32 -29
View File
@@ -132,6 +132,7 @@ static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
LoadInst *NewLoad =
IC.Builder->CreateLoad(CastOp, LI.isVolatile(), CI->getName());
NewLoad->setAlignment(LI.getAlignment());
NewLoad->setAtomic(LI.getOrdering(), LI.getSynchScope());
// Now cast the result of the load.
return new BitCastInst(NewLoad, LI.getType());
}
@@ -162,8 +163,9 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
return Res;
// None of the following transforms are legal for volatile loads.
if (LI.isVolatile()) return 0;
// None of the following transforms are legal for volatile/atomic loads.
// FIXME: Some of it is okay for atomic loads; needs refactoring.
if (!LI.isSimple()) return 0;
// Do really simple store-to-load forwarding and load CSE, to catch cases
// where there are several consecutive memory accesses to the same location,
@@ -368,21 +370,6 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
Value *Val = SI.getOperand(0);
Value *Ptr = SI.getOperand(1);
// If the RHS is an alloca with a single use, zapify the store, making the
// alloca dead.
if (!SI.isVolatile()) {
if (Ptr->hasOneUse()) {
if (isa<AllocaInst>(Ptr))
return EraseInstFromFunction(SI);
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
if (isa<AllocaInst>(GEP->getOperand(0))) {
if (GEP->getOperand(0)->hasOneUse())
return EraseInstFromFunction(SI);
}
}
}
}
// Attempt to improve the alignment.
if (TD) {
unsigned KnownAlign =
@@ -398,6 +385,23 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
SI.setAlignment(EffectiveStoreAlign);
}
// Don't hack volatile/atomic stores.
// FIXME: Some bits are legal for atomic stores; needs refactoring.
if (!SI.isSimple()) return 0;
// If the RHS is an alloca with a single use, zapify the store, making the
// alloca dead.
if (Ptr->hasOneUse()) {
if (isa<AllocaInst>(Ptr))
return EraseInstFromFunction(SI);
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
if (isa<AllocaInst>(GEP->getOperand(0))) {
if (GEP->getOperand(0)->hasOneUse())
return EraseInstFromFunction(SI);
}
}
}
// Do really simple DSE, to catch cases where there are several consecutive
// stores to the same location, separated by a few arithmetic operations. This
// situation often occurs with bitfield accesses.
@@ -415,8 +419,8 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
// Prev store isn't volatile, and stores to the same location?
if (!PrevSI->isVolatile() &&equivalentAddressValues(PrevSI->getOperand(1),
SI.getOperand(1))) {
if (PrevSI->isSimple() && equivalentAddressValues(PrevSI->getOperand(1),
SI.getOperand(1))) {
++NumDeadStore;
++BBI;
EraseInstFromFunction(*PrevSI);
@@ -430,7 +434,7 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
// then *this* store is dead (X = load P; store X -> P).
if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr) &&
!SI.isVolatile())
LI->isSimple())
return EraseInstFromFunction(SI);
// Otherwise, this is a load from some other location. Stores before it
@@ -442,9 +446,6 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
if (BBI->mayWriteToMemory() || BBI->mayReadFromMemory())
break;
}
if (SI.isVolatile()) return 0; // Don't hack volatile stores.
// store X, null -> turns into 'unreachable' in SimplifyCFG
if (isa<ConstantPointerNull>(Ptr) && SI.getPointerAddressSpace() == 0) {
@@ -547,11 +548,11 @@ bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
return false;
--BBI;
}
// If this isn't a store, isn't a store to the same location, or if the
// alignments differ, bail out.
// If this isn't a store, isn't a store to the same location, or is not the
// right kind of store, bail out.
OtherStore = dyn_cast<StoreInst>(BBI);
if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1) ||
OtherStore->getAlignment() != SI.getAlignment())
!SI.isSameOperationAs(OtherStore))
return false;
} else {
// Otherwise, the other block ended with a conditional branch. If one of the
@@ -567,7 +568,7 @@ bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
// Check to see if we find the matching store.
if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
if (OtherStore->getOperand(1) != SI.getOperand(1) ||
OtherStore->getAlignment() != SI.getAlignment())
!SI.isSameOperationAs(OtherStore))
return false;
break;
}
@@ -601,8 +602,10 @@ bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
// insert it.
BBI = DestBB->getFirstNonPHI();
StoreInst *NewSI = new StoreInst(MergedVal, SI.getOperand(1),
OtherStore->isVolatile(),
SI.getAlignment());
SI.isVolatile(),
SI.getAlignment(),
SI.getOrdering(),
SI.getSynchScope());
InsertNewInstBefore(NewSI, *BBI);
NewSI->setDebugLoc(OtherStore->getDebugLoc());