Pass *llvm::createLoopIdiomPass() { return new LoopIdiomRecognize(); }
-/// DeleteDeadInstruction - Delete this instruction. Before we do, go through
+/// deleteDeadInstruction - Delete this instruction. Before we do, go through
/// and zero out all the operands of this instruction. If any of them become
/// dead, delete them and the computation tree that feeds them.
///
-static void DeleteDeadInstruction(Instruction *I, ScalarEvolution &SE) {
+static void deleteDeadInstruction(Instruction *I, ScalarEvolution &SE) {
SmallVector<Instruction*, 32> NowDeadInsts;
NowDeadInsts.push_back(I);
} while (!NowDeadInsts.empty());
}
+/// deleteIfDeadInstruction - If the specified value is a dead instruction,
+/// delete it and any recursively used instructions.
+static void deleteIfDeadInstruction(Value *V, ScalarEvolution &SE) {
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ if (isInstructionTriviallyDead(I))
+ deleteDeadInstruction(I, SE);
+}
+
bool LoopIdiomRecognize::runOnLoop(Loop *L, LPPassManager &LPM) {
CurLoop = L;
+ // Disable loop idiom recognition if the function's name is a common idiom.
+ StringRef Name = L->getHeader()->getParent()->getName();
+ if (Name == "memset" || Name == "memcpy")
+ return false;
+
// The trip count of the loop must be analyzable.
SE = &getAnalysis<ScalarEvolution>();
if (!SE->hasLoopInvariantBackedgeTakenCount(L))
return false;
}
+ // The trip count of the loop and the base pointer of the addrec SCEV is
+ // guaranteed to be loop invariant, which means that it should dominate the
+ // header. This allows us to insert code for it in the preheader.
+ BasicBlock *Preheader = CurLoop->getLoopPreheader();
+ IRBuilder<> Builder(Preheader->getTerminator());
+ SCEVExpander Expander(*SE, "loop-idiom");
// Okay, we have a strided store "p[i]" of a splattable value. We can turn
// this into a memset in the loop preheader now if we want. However, this
// would be unsafe to do if there is anything else in the loop that may read
- // or write to the aliased location. Check for an alias.
- if (mayLoopAccessLocation(DestPtr, AliasAnalysis::ModRef,
- CurLoop, BECount,
- StoreSize, getAnalysis<AliasAnalysis>(), TheStore))
- return false;
-
- // Okay, everything looks good, insert the memset.
- BasicBlock *Preheader = CurLoop->getLoopPreheader();
-
- IRBuilder<> Builder(Preheader->getTerminator());
-
- // The trip count of the loop and the base pointer of the addrec SCEV is
- // guaranteed to be loop invariant, which means that it should dominate the
- // header. Just insert code for it in the preheader.
- SCEVExpander Expander(*SE);
-
+ // or write to the aliased location. Check for any overlap by generating the
+ // base pointer and checking the region.
unsigned AddrSpace = cast<PointerType>(DestPtr->getType())->getAddressSpace();
Value *BasePtr =
Expander.expandCodeFor(Ev->getStart(), Builder.getInt8PtrTy(AddrSpace),
Preheader->getTerminator());
+
+ if (mayLoopAccessLocation(BasePtr, AliasAnalysis::ModRef,
+ CurLoop, BECount,
+ StoreSize, getAnalysis<AliasAnalysis>(), TheStore)){
+ Expander.clear();
+ // If we generated new code for the base pointer, clean up.
+ deleteIfDeadInstruction(BasePtr, *SE);
+ return false;
+ }
+
+ // Okay, everything looks good, insert the memset.
+
// The # stored bytes is (BECount+1)*Size. Expand the trip count out to
// pointer size if it isn't already.
- const Type *IntPtr = TD->getIntPtrType(DestPtr->getContext());
+ Type *IntPtr = TD->getIntPtrType(DestPtr->getContext());
BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr);
const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1),
// Okay, the memset has been formed. Zap the original store and anything that
// feeds into it.
- DeleteDeadInstruction(TheStore, *SE);
+ deleteDeadInstruction(TheStore, *SE);
++NumMemSet;
return true;
}
LoadInst *LI = cast<LoadInst>(SI->getValueOperand());
+ // The trip count of the loop and the base pointer of the addrec SCEV is
+ // guaranteed to be loop invariant, which means that it should dominate the
+ // header. This allows us to insert code for it in the preheader.
+ BasicBlock *Preheader = CurLoop->getLoopPreheader();
+ IRBuilder<> Builder(Preheader->getTerminator());
+ SCEVExpander Expander(*SE, "loop-idiom");
+
// Okay, we have a strided store "p[i]" of a loaded value. We can turn
// this into a memcpy in the loop preheader now if we want. However, this
// would be unsafe to do if there is anything else in the loop that may read
- // or write to the stored location (including the load feeding the stores).
- // Check for an alias.
- if (mayLoopAccessLocation(SI->getPointerOperand(), AliasAnalysis::ModRef,
+ // or write the memory region we're storing to. This includes the load that
+ // feeds the stores. Check for an alias by generating the base address and
+ // checking everything.
+ Value *StoreBasePtr =
+ Expander.expandCodeFor(StoreEv->getStart(),
+ Builder.getInt8PtrTy(SI->getPointerAddressSpace()),
+ Preheader->getTerminator());
+
+ if (mayLoopAccessLocation(StoreBasePtr, AliasAnalysis::ModRef,
CurLoop, BECount, StoreSize,
- getAnalysis<AliasAnalysis>(), SI))
+ getAnalysis<AliasAnalysis>(), SI)) {
+ Expander.clear();
+ // If we generated new code for the base pointer, clean up.
+ deleteIfDeadInstruction(StoreBasePtr, *SE);
return false;
+ }
// For a memcpy, we have to make sure that the input array is not being
// mutated by the loop.
- if (mayLoopAccessLocation(LI->getPointerOperand(), AliasAnalysis::Mod,
- CurLoop, BECount, StoreSize,
- getAnalysis<AliasAnalysis>(), SI))
- return false;
-
- // Okay, everything looks good, insert the memcpy.
- BasicBlock *Preheader = CurLoop->getLoopPreheader();
-
- IRBuilder<> Builder(Preheader->getTerminator());
-
- // The trip count of the loop and the base pointer of the addrec SCEV is
- // guaranteed to be loop invariant, which means that it should dominate the
- // header. Just insert code for it in the preheader.
- SCEVExpander Expander(*SE);
-
Value *LoadBasePtr =
Expander.expandCodeFor(LoadEv->getStart(),
Builder.getInt8PtrTy(LI->getPointerAddressSpace()),
Preheader->getTerminator());
- Value *StoreBasePtr =
- Expander.expandCodeFor(StoreEv->getStart(),
- Builder.getInt8PtrTy(SI->getPointerAddressSpace()),
- Preheader->getTerminator());
+
+ if (mayLoopAccessLocation(LoadBasePtr, AliasAnalysis::Mod, CurLoop, BECount,
+ StoreSize, getAnalysis<AliasAnalysis>(), SI)) {
+ Expander.clear();
+ // If we generated new code for the base pointer, clean up.
+ deleteIfDeadInstruction(LoadBasePtr, *SE);
+ deleteIfDeadInstruction(StoreBasePtr, *SE);
+ return false;
+ }
+
+ // Okay, everything is safe, we can transform this!
+
// The # stored bytes is (BECount+1)*Size. Expand the trip count out to
// pointer size if it isn't already.
- const Type *IntPtr = TD->getIntPtrType(SI->getContext());
+ Type *IntPtr = TD->getIntPtrType(SI->getContext());
BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr);
const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1),
Value *NumBytes =
Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator());
- Value *NewCall =
+ CallInst *NewCall =
Builder.CreateMemCpy(StoreBasePtr, LoadBasePtr, NumBytes,
std::min(SI->getAlignment(), LI->getAlignment()));
+ NewCall->setDebugLoc(SI->getDebugLoc());
DEBUG(dbgs() << " Formed memcpy: " << *NewCall << "\n"
<< " from load ptr=" << *LoadEv << " at: " << *LI << "\n"
<< " from store ptr=" << *StoreEv << " at: " << *SI << "\n");
- (void)NewCall;
+
// Okay, the memset has been formed. Zap the original store and anything that
// feeds into it.
- DeleteDeadInstruction(SI, *SE);
+ deleteDeadInstruction(SI, *SE);
++NumMemCpy;
return true;
}
projects / oota-llvm.git / blobdiff