diff options
Diffstat (limited to 'llvm/lib/Analysis/BasicAliasAnalysis.cpp')
| -rw-r--r-- | llvm/lib/Analysis/BasicAliasAnalysis.cpp | 51 |
1 files changed, 26 insertions, 25 deletions
diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp index cb62654..5d9a5f6 100644 --- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp +++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp @@ -314,6 +314,22 @@ struct ExtendedValue { return N; } + KnownBits evaluateWith(KnownBits N) const { + assert(N.getBitWidth() == V->getType()->getPrimitiveSizeInBits() && + "Incompatible bit width"); + if (SExtBits) N = N.sext(N.getBitWidth() + SExtBits); + if (ZExtBits) N = N.zext(N.getBitWidth() + ZExtBits); + return N; + } + + ConstantRange evaluateWith(ConstantRange N) const { + assert(N.getBitWidth() == V->getType()->getPrimitiveSizeInBits() && + "Incompatible bit width"); + if (SExtBits) N = N.signExtend(N.getBitWidth() + SExtBits); + if (ZExtBits) N = N.zeroExtend(N.getBitWidth() + ZExtBits); + return N; + } + bool canDistributeOver(bool NUW, bool NSW) const { // zext(x op<nuw> y) == zext(x) op<nuw> zext(y) // sext(x op<nsw> y) == sext(x) op<nsw> sext(y) @@ -1247,9 +1263,10 @@ AliasResult BasicAAResult::aliasGEP( bool AllNonNegative = DecompGEP1.Offset.isNonNegative(); bool AllNonPositive = DecompGEP1.Offset.isNonPositive(); for (unsigned i = 0, e = DecompGEP1.VarIndices.size(); i != e; ++i) { - APInt Scale = DecompGEP1.VarIndices[i].Scale; - APInt ScaleForGCD = DecompGEP1.VarIndices[i].Scale; - if (!DecompGEP1.VarIndices[i].IsNSW) + const VariableGEPIndex &Index = DecompGEP1.VarIndices[i]; + const APInt &Scale = Index.Scale; + APInt ScaleForGCD = Scale; + if (!Index.IsNSW) ScaleForGCD = APInt::getOneBitSet(Scale.getBitWidth(), Scale.countTrailingZeros()); @@ -1259,23 +1276,11 @@ AliasResult BasicAAResult::aliasGEP( GCD = APIntOps::GreatestCommonDivisor(GCD, ScaleForGCD.abs()); if (AllNonNegative || AllNonPositive) { - // If the Value could change between cycles, then any reasoning about - // the Value this cycle may not hold in the next cycle. We'll just - // give up if we can't determine conditions that hold for every cycle: - const Value *V = DecompGEP1.VarIndices[i].Val.V; - const Instruction *CxtI = DecompGEP1.VarIndices[i].CxtI; - - KnownBits Known = computeKnownBits(V, DL, 0, &AC, CxtI, DT); + KnownBits Known = Index.Val.evaluateWith( + computeKnownBits(Index.Val.V, DL, 0, &AC, Index.CxtI, DT)); + // TODO: Account for implicit trunc. bool SignKnownZero = Known.isNonNegative(); bool SignKnownOne = Known.isNegative(); - - // Zero-extension widens the variable, and so forces the sign - // bit to zero. - bool IsZExt = - DecompGEP1.VarIndices[i].Val.ZExtBits > 0 || isa<ZExtInst>(V); - SignKnownZero |= IsZExt; - SignKnownOne &= !IsZExt; - AllNonNegative &= (SignKnownZero && Scale.isNonNegative()) || (SignKnownOne && Scale.isNonPositive()); AllNonPositive &= (SignKnownZero && Scale.isNonPositive()) || @@ -1326,15 +1331,11 @@ AliasResult BasicAAResult::aliasGEP( // If V != 0 then abs(VarIndex) >= abs(Scale). MinAbsVarIndex = Var.Scale.abs(); } - ConstantRange R = computeConstantRange(Var.Val.V, true, &AC, Var.CxtI); - if (!R.isFullSet() && !R.isEmptySet()) { - if (Var.Val.SExtBits) - R = R.signExtend(R.getBitWidth() + Var.Val.SExtBits); - if (Var.Val.ZExtBits) - R = R.zeroExtend(R.getBitWidth() + Var.Val.ZExtBits); + ConstantRange R = Var.Val.evaluateWith( + computeConstantRange(Var.Val.V, true, &AC, Var.CxtI)); + if (!R.isFullSet() && !R.isEmptySet()) VarIndexRange = R.sextOrTrunc(Var.Scale.getBitWidth()) .multiply(ConstantRange(Var.Scale)); - } } else if (DecompGEP1.VarIndices.size() == 2) { // VarIndex = Scale*V0 + (-Scale)*V1. // If V0 != V1 then abs(VarIndex) >= abs(Scale). |