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Don't use runtime bounds check between address spaces.

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Don't vectorize with a runtime check if it requires a
comparison between pointers with different address spaces.
The values can't be assumed to be directly comparable.
Previously it would create an illegal bitcast.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191862 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Matt Arsenault
2013-10-02 22:38:17 +00:00
parent 62faf2f9d0
commit 407847f130
3 changed files with 426 additions and 11 deletions
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lib/Transforms/Vectorize/LoopVectorize.cpp
+49 -11
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@@ -1385,11 +1385,9 @@ InnerLoopVectorizer::addRuntimeCheck(LoopVectorizationLegality *Legal,
SmallVector<TrackingVH<Value> , 2> Starts;
SmallVector<TrackingVH<Value> , 2> Ends;
LLVMContext &Ctx = Loc->getContext();
SCEVExpander Exp(*SE, "induction");
// Use this type for pointer arithmetic.
Type* PtrArithTy = Type::getInt8PtrTy(Loc->getContext(), 0);
for (unsigned i = 0; i < NumPointers; ++i) {
Value *Ptr = PtrRtCheck->Pointers[i];
const SCEV *Sc = SE->getSCEV(Ptr);
@@ -1401,6 +1399,10 @@ InnerLoopVectorizer::addRuntimeCheck(LoopVectorizationLegality *Legal,
Ends.push_back(Ptr);
} else {
DEBUG(dbgs() << "LV: Adding RT check for range:" << *Ptr << '\n');
unsigned AS = Ptr->getType()->getPointerAddressSpace();
// Use this type for pointer arithmetic.
Type *PtrArithTy = Type::getInt8PtrTy(Ctx, AS);
Value *Start = Exp.expandCodeFor(PtrRtCheck->Starts[i], PtrArithTy, Loc);
Value *End = Exp.expandCodeFor(PtrRtCheck->Ends[i], PtrArithTy, Loc);
@@ -1422,10 +1424,20 @@ InnerLoopVectorizer::addRuntimeCheck(LoopVectorizationLegality *Legal,
if (PtrRtCheck->DependencySetId[i] == PtrRtCheck->DependencySetId[j])
continue;
Value *Start0 = ChkBuilder.CreateBitCast(Starts[i], PtrArithTy, "bc");
Value *Start1 = ChkBuilder.CreateBitCast(Starts[j], PtrArithTy, "bc");
Value *End0 = ChkBuilder.CreateBitCast(Ends[i], PtrArithTy, "bc");
Value *End1 = ChkBuilder.CreateBitCast(Ends[j], PtrArithTy, "bc");
unsigned AS0 = Starts[i]->getType()->getPointerAddressSpace();
unsigned AS1 = Starts[j]->getType()->getPointerAddressSpace();
assert((AS0 == Ends[j]->getType()->getPointerAddressSpace()) &&
(AS1 == Ends[i]->getType()->getPointerAddressSpace()) &&
"Trying to bounds check pointers with different address spaces");
Type *PtrArithTy0 = Type::getInt8PtrTy(Ctx, AS0);
Type *PtrArithTy1 = Type::getInt8PtrTy(Ctx, AS1);
Value *Start0 = ChkBuilder.CreateBitCast(Starts[i], PtrArithTy0, "bc");
Value *Start1 = ChkBuilder.CreateBitCast(Starts[j], PtrArithTy1, "bc");
Value *End0 = ChkBuilder.CreateBitCast(Ends[i], PtrArithTy1, "bc");
Value *End1 = ChkBuilder.CreateBitCast(Ends[j], PtrArithTy0, "bc");
Value *Cmp0 = ChkBuilder.CreateICmpULE(Start0, End1, "bound0");
Value *Cmp1 = ChkBuilder.CreateICmpULE(Start1, End0, "bound1");
@@ -1440,9 +1452,8 @@ InnerLoopVectorizer::addRuntimeCheck(LoopVectorizationLegality *Legal,
// We have to do this trickery because the IRBuilder might fold the check to a
// constant expression in which case there is no Instruction anchored in a
// the block.
LLVMContext &Ctx = Loc->getContext();
Instruction * Check = BinaryOperator::CreateAnd(MemoryRuntimeCheck,
ConstantInt::getTrue(Ctx));
Instruction *Check = BinaryOperator::CreateAnd(MemoryRuntimeCheck,
ConstantInt::getTrue(Ctx));
ChkBuilder.Insert(Check, "memcheck.conflict");
return Check;
}
@@ -3166,9 +3177,36 @@ bool AccessAnalysis::canCheckPtrAtRT(
if (IsDepCheckNeeded && CanDoRT && RunningDepId == 2)
NumComparisons = 0; // Only one dependence set.
else
else {
NumComparisons = (NumWritePtrChecks * (NumReadPtrChecks +
NumWritePtrChecks - 1));
}
// If the pointers that we would use for the bounds comparison have different
// address spaces, assume the values aren't directly comparable, so we can't
// use them for the runtime check. We also have to assume they could
// overlap. In the future there should be metadata for whether address spaces
// are disjoint.
unsigned NumPointers = RtCheck.Pointers.size();
for (unsigned i = 0; i < NumPointers; ++i) {
for (unsigned j = i + 1; j < NumPointers; ++j) {
// Only need to check pointers between two different dependency sets.
if (RtCheck.DependencySetId[i] == RtCheck.DependencySetId[j])
continue;
Value *PtrI = RtCheck.Pointers[i];
Value *PtrJ = RtCheck.Pointers[j];
unsigned ASi = PtrI->getType()->getPointerAddressSpace();
unsigned ASj = PtrJ->getType()->getPointerAddressSpace();
if (ASi != ASj) {
DEBUG(dbgs() << "LV: Runtime check would require comparison between"
" different address spaces\n");
return false;
}
}
}
return CanDoRT;
}