// get into trouble with cyclic PHIs here because we only consider
// instructions with a single use.
PHINode *PN = cast<PHINode>(I);
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
- if (!CanEvaluateTruncated(PN->getIncomingValue(i), Ty, IC, CxtI))
+ for (Value *IncValue : PN->incoming_values())
+ if (!CanEvaluateTruncated(IncValue, Ty, IC, CxtI))
return false;
return true;
}
if (Instruction *Result = commonCastTransforms(CI))
return Result;
+ // Test if the trunc is the user of a select which is part of a
+ // minimum or maximum operation. If so, don't do any more simplification.
+ // Even simplifying demanded bits can break the canonical form of a
+ // min/max.
+ Value *LHS, *RHS;
+ if (SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0)))
+ if (matchSelectPattern(SI, LHS, RHS).Flavor != SPF_UNKNOWN)
+ return nullptr;
+
// See if we can simplify any instructions used by the input whose sole
// purpose is to compute bits we don't care about.
if (SimplifyDemandedInstructionBits(CI))
return CastInst::CreateIntegerCast(Shift, CI.getType(), false);
}
+ // Transform trunc(lshr (sext A), Cst) to ashr A, Cst to eliminate type
+ // conversion.
+ // It works because bits coming from sign extension have the same value as
+ // sign bit of the original value; performing ashr instead of lshr
+ // generates bits of the same value as the sign bit.
+ if (Src->hasOneUse() &&
+ match(Src, m_LShr(m_SExt(m_Value(A)), m_ConstantInt(Cst))) &&
+ cast<Instruction>(Src)->getOperand(0)->hasOneUse()) {
+ const unsigned ASize = A->getType()->getPrimitiveSizeInBits();
+ // This optimization can be only performed when zero bits generated by
+ // the original lshr aren't pulled into the value after truncation, so we
+ // can only shift by values smaller then the size of destination type (in
+ // bits).
+ if (Cst->getValue().ult(ASize)) {
+ Value *Shift = Builder->CreateAShr(A, Cst->getZExtValue());
+ Shift->takeName(Src);
+ return CastInst::CreateIntegerCast(Shift, CI.getType(), false);
+ }
+ }
+
// Transform "trunc (and X, cst)" -> "and (trunc X), cst" so long as the dest
// type isn't non-native.
if (Src->hasOneUse() && isa<IntegerType>(Src->getType()) &&
// get into trouble with cyclic PHIs here because we only consider
// instructions with a single use.
PHINode *PN = cast<PHINode>(I);
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
- if (!CanEvaluateSExtd(PN->getIncomingValue(i), Ty)) return false;
+ for (Value *IncValue : PN->incoming_values())
+ if (!CanEvaluateSExtd(IncValue, Ty)) return false;
return true;
}
default:
// (fptrunc (select cond, R1, Cst)) -->
// (select cond, (fptrunc R1), (fptrunc Cst))
+ //
+ // - but only if this isn't part of a min/max operation, else we'll
+ // ruin min/max canonical form which is to have the select and
+ // compare's operands be of the same type with no casts to look through.
+ Value *LHS, *RHS;
SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0));
if (SI &&
(isa<ConstantFP>(SI->getOperand(1)) ||
- isa<ConstantFP>(SI->getOperand(2)))) {
+ isa<ConstantFP>(SI->getOperand(2))) &&
+ matchSelectPattern(SI, LHS, RHS).Flavor == SPF_UNKNOWN) {
Value *LHSTrunc = Builder->CreateFPTrunc(SI->getOperand(1),
CI.getType());
Value *RHSTrunc = Builder->CreateFPTrunc(SI->getOperand(2),
CI.setOperand(0, GEP->getOperand(0));
return &CI;
}
-
- // If the GEP has a single use, and the base pointer is a bitcast, and the
- // GEP computes a constant offset, see if we can convert these three
- // instructions into fewer. This typically happens with unions and other
- // non-type-safe code.
- unsigned AS = GEP->getPointerAddressSpace();
- unsigned OffsetBits = DL.getPointerSizeInBits(AS);
- APInt Offset(OffsetBits, 0);
- BitCastInst *BCI = dyn_cast<BitCastInst>(GEP->getOperand(0));
- if (GEP->hasOneUse() && BCI && GEP->accumulateConstantOffset(DL, Offset)) {
- // FIXME: This is insufficiently tested - just a no-crash test
- // (test/Transforms/InstCombine/2007-05-14-Crash.ll)
- //
- // Get the base pointer input of the bitcast, and the type it points to.
- Value *OrigBase = BCI->getOperand(0);
- SmallVector<Value*, 8> NewIndices;
- if (FindElementAtOffset(OrigBase->getType(), Offset.getSExtValue(),
- NewIndices)) {
- // FIXME: This codepath is completely untested - could be unreachable
- // for all I know.
- // If we were able to index down into an element, create the GEP
- // and bitcast the result. This eliminates one bitcast, potentially
- // two.
- Value *NGEP = cast<GEPOperator>(GEP)->isInBounds()
- ? Builder->CreateInBoundsGEP(OrigBase, NewIndices)
- : Builder->CreateGEP(
- OrigBase->getType()->getPointerElementType(),
- OrigBase, NewIndices);
- NGEP->takeName(GEP);
-
- if (isa<BitCastInst>(CI))
- return new BitCastInst(NGEP, CI.getType());
- assert(isa<PtrToIntInst>(CI));
- return new PtrToIntInst(NGEP, CI.getType());
- }
- }
}
return commonCastTransforms(CI);
// If the source and destination are pointers, and this cast is equivalent
// to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
// This can enhance SROA and other transforms that want type-safe pointers.
- Constant *ZeroUInt =
- Constant::getNullValue(Type::getInt32Ty(CI.getContext()));
unsigned NumZeros = 0;
while (SrcElTy != DstElTy &&
isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() &&
SrcElTy->getNumContainedTypes() /* not "{}" */) {
- SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
+ SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(0U);
++NumZeros;
}
// If we found a path from the src to dest, create the getelementptr now.
if (SrcElTy == DstElTy) {
- SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
+ SmallVector<Value *, 8> Idxs(NumZeros + 1, Builder->getInt32(0));
return GetElementPtrInst::CreateInBounds(Src, Idxs);
}
}
projects / oota-llvm.git / blobdiff