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[DependenceAnalysis] Allow subscripts of different types

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Summary:
Several places in DependenceAnalysis assumes both SCEVs in a subscript pair
share the same integer type. For instance, isKnownPredicate calls
SE->getMinusSCEV(X, Y) which asserts X and Y share the same type. However,
DependenceAnalysis fails to ensure this assumption when producing a subscript
pair, causing tests such as NonCanonicalizedSubscript to crash. With this
patch, DependenceAnalysis runs unifySubscriptType before producing any
subscript pair, ensuring the assumption.

Test Plan:
Added NonCanonicalizedSubscript.ll on which DependenceAnalysis before the fix
crashed because subscripts have different types.

Reviewers: spop, sebpop, jingyue

Reviewed By: jingyue

Subscribers: eliben, meheff, llvm-commits

Differential Revision: http://reviews.llvm.org/D6289

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222100 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jingyue Wu
2014-11-16 16:52:44 +00:00
parent a51382a63a
commit ec3cfb00dc
3 changed files with 74 additions and 5 deletions
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31
lib/Analysis/DependenceAnalysis.cpp
View File

@ -781,6 +781,25 @@ void DependenceAnalysis::collectCommonLoops(const SCEV *Expression,
}
}
void DependenceAnalysis::unifySubscriptType(Subscript *Pair) {
const SCEV *Src = Pair->Src;
const SCEV *Dst = Pair->Dst;
IntegerType *SrcTy = dyn_cast<IntegerType>(Src->getType());
IntegerType *DstTy = dyn_cast<IntegerType>(Dst->getType());
if (SrcTy == nullptr || DstTy == nullptr) {
assert(SrcTy == DstTy && "This function only unify integer types and "
"expect Src and Dst share the same type "
"otherwise.");
return;
}
if (SrcTy->getBitWidth() > DstTy->getBitWidth()) {
// Sign-extend Dst to typeof(Src) if typeof(Src) is wider than typeof(Dst).
Pair->Dst = SE->getSignExtendExpr(Dst, SrcTy);
} else if (SrcTy->getBitWidth() < DstTy->getBitWidth()) {
// Sign-extend Src to typeof(Dst) if typeof(Dst) is wider than typeof(Src).
Pair->Src = SE->getSignExtendExpr(Src, DstTy);
}
}
// removeMatchingExtensions - Examines a subscript pair.
// If the source and destination are identically sign (or zero)
@ -793,9 +812,11 @@ void DependenceAnalysis::removeMatchingExtensions(Subscript *Pair) {
(isa<SCEVSignExtendExpr>(Src) && isa<SCEVSignExtendExpr>(Dst))) {
const SCEVCastExpr *SrcCast = cast<SCEVCastExpr>(Src);
const SCEVCastExpr *DstCast = cast<SCEVCastExpr>(Dst);
if (SrcCast->getType() == DstCast->getType()) {
Pair->Src = SrcCast->getOperand();
Pair->Dst = DstCast->getOperand();
const SCEV *SrcCastOp = SrcCast->getOperand();
const SCEV *DstCastOp = DstCast->getOperand();
if (SrcCastOp->getType() == DstCastOp->getType()) {
Pair->Src = SrcCastOp;
Pair->Dst = DstCastOp;
}
}
}
@ -3178,7 +3199,7 @@ void DependenceAnalysis::updateDirection(Dependence::DVEntry &Level,
bool DependenceAnalysis::tryDelinearize(const SCEV *SrcSCEV,
const SCEV *DstSCEV,
SmallVectorImpl<Subscript> &Pair,
const SCEV *ElementSize) const {
const SCEV *ElementSize) {
const SCEVUnknown *SrcBase =
dyn_cast<SCEVUnknown>(SE->getPointerBase(SrcSCEV));
const SCEVUnknown *DstBase =
@ -3233,6 +3254,7 @@ bool DependenceAnalysis::tryDelinearize(const SCEV *SrcSCEV,
for (int i = 0; i < size; ++i) {
Pair[i].Src = SrcSubscripts[i];
Pair[i].Dst = DstSubscripts[i];
unifySubscriptType(&Pair[i]);
// FIXME: we should record the bounds SrcSizes[i] and DstSizes[i] that the
// delinearization has found, and add these constraints to the dependence
@ -3341,6 +3363,7 @@ DependenceAnalysis::depends(Instruction *Src, Instruction *Dst,
++SrcIdx, ++DstIdx, ++P) {
Pair[P].Src = SE->getSCEV(*SrcIdx);
Pair[P].Dst = SE->getSCEV(*DstIdx);
unifySubscriptType(&Pair[P]);
}
}
else {