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Generalize ScalarEvolution to be able to analyze GEPs when

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TargetData is not present. It still uses TargetData when available.
This generalization also fixed some limitations in the TargetData
case; the attached testcase covers this.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79344 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-08-18 16:46:41 +00:00
parent 4d35fce60c
commit c40f17b087
6 changed files with 566 additions and 122 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/llvm/Analysis/ScalarEvolution.h
View File

@ -433,6 +433,8 @@ namespace llvm {
const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getFieldOffsetExpr(const StructType *STy, unsigned FieldNo);
const SCEV *getAllocSizeExpr(const Type *AllocTy);
const SCEV *getUnknown(Value *V);
const SCEV *getCouldNotCompute();

4
include/llvm/Analysis/ScalarEvolutionExpander.h
View File

@ -115,6 +115,10 @@ namespace llvm {
Value *visitUMaxExpr(const SCEVUMaxExpr *S);
Value *visitFieldOffsetExpr(const SCEVFieldOffsetExpr *S);
Value *visitAllocSizeExpr(const SCEVAllocSizeExpr *S);
Value *visitUnknown(const SCEVUnknown *S) {
return S->getValue();
}

92
include/llvm/Analysis/ScalarEvolutionExpressions.h
View File

@ -26,8 +26,8 @@ namespace llvm {
// These should be ordered in terms of increasing complexity to make the
// folders simpler.
scConstant, scTruncate, scZeroExtend, scSignExtend, scAddExpr, scMulExpr,
scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr, scUnknown,
scCouldNotCompute
scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr,
scFieldOffset, scAllocSize, scUnknown, scCouldNotCompute
};
//===--------------------------------------------------------------------===//
@ -488,6 +488,90 @@ namespace llvm {
}
};
//===--------------------------------------------------------------------===//
/// SCEVTargetDataConstant - This node is the base class for representing
/// target-dependent values in a target-independent way.
///
class SCEVTargetDataConstant : public SCEV {
protected:
const Type *Ty;
SCEVTargetDataConstant(const FoldingSetNodeID &ID, enum SCEVTypes T,
const Type *ty) :
SCEV(ID, T), Ty(ty) {}
public:
virtual bool isLoopInvariant(const Loop *) const { return true; }
virtual bool hasComputableLoopEvolution(const Loop *) const {
return false; // not computable
}
virtual bool hasOperand(const SCEV *) const {
return false;
}
bool dominates(BasicBlock *, DominatorTree *) const {
return true;
}
virtual const Type *getType() const { return Ty; }
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVTargetDataConstant *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scFieldOffset ||
S->getSCEVType() == scAllocSize;
}
};
//===--------------------------------------------------------------------===//
/// SCEVFieldOffsetExpr - This node represents an offsetof expression.
///
class SCEVFieldOffsetExpr : public SCEVTargetDataConstant {
friend class ScalarEvolution;
const StructType *STy;
unsigned FieldNo;
SCEVFieldOffsetExpr(const FoldingSetNodeID &ID, const Type *ty,
const StructType *sty, unsigned fieldno) :
SCEVTargetDataConstant(ID, scFieldOffset, ty),
STy(sty), FieldNo(fieldno) {}
public:
const StructType *getStructType() const { return STy; }
unsigned getFieldNo() const { return FieldNo; }
virtual void print(raw_ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVFieldOffsetExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scFieldOffset;
}
};
//===--------------------------------------------------------------------===//
/// SCEVAllocSize - This node represents a sizeof expression.
///
class SCEVAllocSizeExpr : public SCEVTargetDataConstant {
friend class ScalarEvolution;
const Type *AllocTy;
SCEVAllocSizeExpr(const FoldingSetNodeID &ID,
const Type *ty, const Type *allocty) :
SCEVTargetDataConstant(ID, scAllocSize, ty),
AllocTy(allocty) {}
public:
const Type *getAllocType() const { return AllocTy; }
virtual void print(raw_ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVAllocSizeExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scAllocSize;
}
};
//===--------------------------------------------------------------------===//
/// SCEVUnknown - This means that we are dealing with an entirely unknown SCEV
@ -552,6 +636,10 @@ namespace llvm {
return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S);
case scUMaxExpr:
return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S);
case scFieldOffset:
return ((SC*)this)->visitFieldOffsetExpr((const SCEVFieldOffsetExpr*)S);
case scAllocSize:
return ((SC*)this)->visitAllocSizeExpr((const SCEVAllocSizeExpr*)S);
case scUnknown:
return ((SC*)this)->visitUnknown((const SCEVUnknown*)S);
case scCouldNotCompute:

200
lib/Analysis/ScalarEvolution.cpp
View File

@ -307,6 +307,15 @@ void SCEVAddRecExpr::print(raw_ostream &OS) const {
OS << "}<" << L->getHeader()->getName() + ">";
}
void SCEVFieldOffsetExpr::print(raw_ostream &OS) const {
// LLVM struct fields don't have names, so just print the field number.
OS << "offsetof(" << *STy << ", " << FieldNo << ")";
}
void SCEVAllocSizeExpr::print(raw_ostream &OS) const {
OS << "sizeof(" << *AllocTy << ")";
}
bool SCEVUnknown::isLoopInvariant(const Loop *L) const {
// All non-instruction values are loop invariant. All instructions are loop
// invariant if they are not contained in the specified loop.
@ -335,6 +344,41 @@ void SCEVUnknown::print(raw_ostream &OS) const {
// SCEV Utilities
//===----------------------------------------------------------------------===//
static bool CompareTypes(const Type *A, const Type *B) {
if (A->getTypeID() != B->getTypeID())
return A->getTypeID() < B->getTypeID();
if (const IntegerType *AI = dyn_cast<IntegerType>(A)) {
const IntegerType *BI = cast<IntegerType>(B);
return AI->getBitWidth() < BI->getBitWidth();
}
if (const PointerType *AI = dyn_cast<PointerType>(A)) {
const PointerType *BI = cast<PointerType>(B);
return CompareTypes(AI->getElementType(), BI->getElementType());
}
if (const ArrayType *AI = dyn_cast<ArrayType>(A)) {
const ArrayType *BI = cast<ArrayType>(B);
if (AI->getNumElements() != BI->getNumElements())
return AI->getNumElements() < BI->getNumElements();
return CompareTypes(AI->getElementType(), BI->getElementType());
}
if (const VectorType *AI = dyn_cast<VectorType>(A)) {
const VectorType *BI = cast<VectorType>(B);
if (AI->getNumElements() != BI->getNumElements())
return AI->getNumElements() < BI->getNumElements();
return CompareTypes(AI->getElementType(), BI->getElementType());
}
if (const StructType *AI = dyn_cast<StructType>(A)) {
const StructType *BI = cast<StructType>(B);
if (AI->getNumElements() != BI->getNumElements())
return AI->getNumElements() < BI->getNumElements();
for (unsigned i = 0, e = AI->getNumElements(); i != e; ++i)
if (CompareTypes(AI->getElementType(i), BI->getElementType(i)) ||
CompareTypes(BI->getElementType(i), AI->getElementType(i)))
return CompareTypes(AI->getElementType(i), BI->getElementType(i));
}
return false;
}
namespace {
/// SCEVComplexityCompare - Return true if the complexity of the LHS is less
/// than the complexity of the RHS. This comparator is used to canonicalize
@ -447,6 +491,21 @@ namespace {
return operator()(LC->getOperand(), RC->getOperand());
}
// Compare offsetof expressions.
if (const SCEVFieldOffsetExpr *LA = dyn_cast<SCEVFieldOffsetExpr>(LHS)) {
const SCEVFieldOffsetExpr *RA = cast<SCEVFieldOffsetExpr>(RHS);
if (CompareTypes(LA->getStructType(), RA->getStructType()) ||
CompareTypes(RA->getStructType(), LA->getStructType()))
return CompareTypes(LA->getStructType(), RA->getStructType());
return LA->getFieldNo() < RA->getFieldNo();
}
// Compare sizeof expressions by the allocation type.
if (const SCEVAllocSizeExpr *LA = dyn_cast<SCEVAllocSizeExpr>(LHS)) {
const SCEVAllocSizeExpr *RA = cast<SCEVAllocSizeExpr>(RHS);
return CompareTypes(LA->getAllocType(), RA->getAllocType());
}
llvm_unreachable("Unknown SCEV kind!");
return false;
}
@ -976,7 +1035,7 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
/// unspecified bits out to the given type.
///
const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
const Type *Ty) {
const Type *Ty) {
assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&
"This is not an extending conversion!");
assert(isSCEVable(Ty) &&
@ -2001,6 +2060,76 @@ const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
return getNotSCEV(getUMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
}
const SCEV *ScalarEvolution::getFieldOffsetExpr(const StructType *STy,
unsigned FieldNo) {
// If we have TargetData we can determine the constant offset.
if (TD) {
const Type *IntPtrTy = TD->getIntPtrType(getContext());
const StructLayout &SL = *TD->getStructLayout(STy);
uint64_t Offset = SL.getElementOffset(FieldNo);
return getIntegerSCEV(Offset, IntPtrTy);
}
// Field 0 is always at offset 0.
if (FieldNo == 0) {
const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(STy));
return getIntegerSCEV(0, Ty);
}
// Okay, it looks like we really DO need an offsetof expr. Check to see if we
// already have one, otherwise create a new one.
FoldingSetNodeID ID;
ID.AddInteger(scFieldOffset);
ID.AddPointer(STy);
ID.AddInteger(FieldNo);
void *IP = 0;
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
SCEV *S = SCEVAllocator.Allocate<SCEVFieldOffsetExpr>();
const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(STy));
new (S) SCEVFieldOffsetExpr(ID, Ty, STy, FieldNo);
UniqueSCEVs.InsertNode(S, IP);
return S;
}
const SCEV *ScalarEvolution::getAllocSizeExpr(const Type *AllocTy) {
// If we have TargetData we can determine the constant size.
if (TD && AllocTy->isSized()) {
const Type *IntPtrTy = TD->getIntPtrType(getContext());
return getIntegerSCEV(TD->getTypeAllocSize(AllocTy), IntPtrTy);
}
// Expand an array size into the element size times the number
// of elements.
if (const ArrayType *ATy = dyn_cast<ArrayType>(AllocTy)) {
const SCEV *E = getAllocSizeExpr(ATy->getElementType());
return getMulExpr(
E, getConstant(ConstantInt::get(cast<IntegerType>(E->getType()),
ATy->getNumElements())));
}
// Expand a vector size into the element size times the number
// of elements.
if (const VectorType *VTy = dyn_cast<VectorType>(AllocTy)) {
const SCEV *E = getAllocSizeExpr(VTy->getElementType());
return getMulExpr(
E, getConstant(ConstantInt::get(cast<IntegerType>(E->getType()),
VTy->getNumElements())));
}
// Okay, it looks like we really DO need a sizeof expr. Check to see if we
// already have one, otherwise create a new one.
FoldingSetNodeID ID;
ID.AddInteger(scAllocSize);
ID.AddPointer(AllocTy);
void *IP = 0;
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
SCEV *S = SCEVAllocator.Allocate<SCEVAllocSizeExpr>();
const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(AllocTy));
new (S) SCEVAllocSizeExpr(ID, Ty, AllocTy);
UniqueSCEVs.InsertNode(S, IP);
return S;
}
const SCEV *ScalarEvolution::getUnknown(Value *V) {
// Don't attempt to do anything other than create a SCEVUnknown object
// here. createSCEV only calls getUnknown after checking for all other
@ -2027,17 +2156,8 @@ const SCEV *ScalarEvolution::getUnknown(Value *V) {
/// can optionally include pointer types if the ScalarEvolution class
/// has access to target-specific information.
bool ScalarEvolution::isSCEVable(const Type *Ty) const {
// Integers are always SCEVable.
if (Ty->isInteger())
return true;
// Pointers are SCEVable if TargetData information is available
// to provide pointer size information.
if (isa<PointerType>(Ty))
return TD != NULL;
// Otherwise it's not SCEVable.
return false;
// Integers and pointers are always SCEVable.
return Ty->isInteger() || isa<PointerType>(Ty);
}
/// getTypeSizeInBits - Return the size in bits of the specified type,
@ -2049,9 +2169,14 @@ uint64_t ScalarEvolution::getTypeSizeInBits(const Type *Ty) const {
if (TD)
return TD->getTypeSizeInBits(Ty);
// Otherwise, we support only integer types.
assert(Ty->isInteger() && "isSCEVable permitted a non-SCEVable type!");
return Ty->getPrimitiveSizeInBits();
// Integer types have fixed sizes.
if (Ty->isInteger())
return Ty->getPrimitiveSizeInBits();
// The only other support type is pointer. Without TargetData, conservatively
// assume pointers are 64-bit.
assert(isa<PointerType>(Ty) && "isSCEVable permitted a non-SCEVable type!");
return 64;
}
/// getEffectiveSCEVType - Return a type with the same bitwidth as
@ -2064,8 +2189,12 @@ const Type *ScalarEvolution::getEffectiveSCEVType(const Type *Ty) const {
if (Ty->isInteger())
return Ty;
// The only other support type is pointer.
assert(isa<PointerType>(Ty) && "Unexpected non-pointer non-integer type!");
return TD->getIntPtrType(getContext());
if (TD) return TD->getIntPtrType(getContext());
// Without TargetData, conservatively assume pointers are 64-bit.
return Type::getInt64Ty(getContext());
}
const SCEV *ScalarEvolution::getCouldNotCompute() {
@ -2132,8 +2261,8 @@ const SCEV *
ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V,
const Type *Ty) {
const Type *SrcTy = V->getType();
assert((SrcTy->isInteger() || (TD && isa<PointerType>(SrcTy))) &&
(Ty->isInteger() || (TD && isa<PointerType>(Ty))) &&
assert((SrcTy->isInteger() || isa<PointerType>(SrcTy)) &&
(Ty->isInteger() || isa<PointerType>(Ty)) &&
"Cannot truncate or zero extend with non-integer arguments!");
if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
return V; // No conversion
@ -2149,8 +2278,8 @@ const SCEV *
ScalarEvolution::getTruncateOrSignExtend(const SCEV *V,
const Type *Ty) {
const Type *SrcTy = V->getType();
assert((SrcTy->isInteger() || (TD && isa<PointerType>(SrcTy))) &&
(Ty->isInteger() || (TD && isa<PointerType>(Ty))) &&
assert((SrcTy->isInteger() || isa<PointerType>(SrcTy)) &&
(Ty->isInteger() || isa<PointerType>(Ty)) &&
"Cannot truncate or zero extend with non-integer arguments!");
if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
return V; // No conversion
@ -2165,8 +2294,8 @@ ScalarEvolution::getTruncateOrSignExtend(const SCEV *V,
const SCEV *
ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, const Type *Ty) {
const Type *SrcTy = V->getType();
assert((SrcTy->isInteger() || (TD && isa<PointerType>(SrcTy))) &&
(Ty->isInteger() || (TD && isa<PointerType>(Ty))) &&
assert((SrcTy->isInteger() || isa<PointerType>(SrcTy)) &&
(Ty->isInteger() || isa<PointerType>(Ty)) &&
"Cannot noop or zero extend with non-integer arguments!");
assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrZeroExtend cannot truncate!");
@ -2181,8 +2310,8 @@ ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, const Type *Ty) {
const SCEV *
ScalarEvolution::getNoopOrSignExtend(const SCEV *V, const Type *Ty) {
const Type *SrcTy = V->getType();
assert((SrcTy->isInteger() || (TD && isa<PointerType>(SrcTy))) &&
(Ty->isInteger() || (TD && isa<PointerType>(Ty))) &&
assert((SrcTy->isInteger() || isa<PointerType>(SrcTy)) &&
(Ty->isInteger() || isa<PointerType>(Ty)) &&
"Cannot noop or sign extend with non-integer arguments!");
assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrSignExtend cannot truncate!");
@ -2198,8 +2327,8 @@ ScalarEvolution::getNoopOrSignExtend(const SCEV *V, const Type *Ty) {
const SCEV *
ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, const Type *Ty) {
const Type *SrcTy = V->getType();
assert((SrcTy->isInteger() || (TD && isa<PointerType>(SrcTy))) &&
(Ty->isInteger() || (TD && isa<PointerType>(Ty))) &&
assert((SrcTy->isInteger() || isa<PointerType>(SrcTy)) &&
(Ty->isInteger() || isa<PointerType>(Ty)) &&
"Cannot noop or any extend with non-integer arguments!");
assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrAnyExtend cannot truncate!");
@ -2213,8 +2342,8 @@ ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, const Type *Ty) {
const SCEV *
ScalarEvolution::getTruncateOrNoop(const SCEV *V, const Type *Ty) {
const Type *SrcTy = V->getType();
assert((SrcTy->isInteger() || (TD && isa<PointerType>(SrcTy))) &&
(Ty->isInteger() || (TD && isa<PointerType>(Ty))) &&
assert((SrcTy->isInteger() || isa<PointerType>(SrcTy)) &&
(Ty->isInteger() || isa<PointerType>(Ty)) &&
"Cannot truncate or noop with non-integer arguments!");
assert(getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&
"getTruncateOrNoop cannot extend!");
@ -2433,7 +2562,7 @@ const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
///
const SCEV *ScalarEvolution::createNodeForGEP(Operator *GEP) {
const Type *IntPtrTy = TD->getIntPtrType(getContext());
const Type *IntPtrTy = getEffectiveSCEVType(GEP->getType());
Value *Base = GEP->getOperand(0);
// Don't attempt to analyze GEPs over unsized objects.
if (!cast<PointerType>(Base->getType())->getElementType()->isSized())
@ -2447,19 +2576,16 @@ const SCEV *ScalarEvolution::createNodeForGEP(Operator *GEP) {
// Compute the (potentially symbolic) offset in bytes for this index.
if (const StructType *STy = dyn_cast<StructType>(*GTI++)) {
// For a struct, add the member offset.
const StructLayout &SL = *TD->getStructLayout(STy);
unsigned FieldNo = cast<ConstantInt>(Index)->getZExtValue();
uint64_t Offset = SL.getElementOffset(FieldNo);
TotalOffset = getAddExpr(TotalOffset, getIntegerSCEV(Offset, IntPtrTy));
TotalOffset = getAddExpr(TotalOffset,
getFieldOffsetExpr(STy, FieldNo));
} else {
// For an array, add the element offset, explicitly scaled.
const SCEV *LocalOffset = getSCEV(Index);
if (!isa<PointerType>(LocalOffset->getType()))
// Getelementptr indicies are signed.
LocalOffset = getTruncateOrSignExtend(LocalOffset, IntPtrTy);
LocalOffset =
getMulExpr(LocalOffset,
getIntegerSCEV(TD->getTypeAllocSize(*GTI), IntPtrTy));
LocalOffset = getMulExpr(LocalOffset, getAllocSizeExpr(*GTI));
TotalOffset = getAddExpr(TotalOffset, LocalOffset);
}
}
@ -2952,7 +3078,6 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) {
// expressions we handle are GEPs and address literals.
case Instruction::GetElementPtr:
if (!TD) break; // Without TD we can't analyze pointers.
return createNodeForGEP(U);
case Instruction::PHI:
@ -3947,6 +4072,9 @@ const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) {
return getTruncateExpr(Op, Cast->getType());
}
if (isa<SCEVTargetDataConstant>(V))
return V;
llvm_unreachable("Unknown SCEV type!");
return 0;
}

315
lib/Analysis/ScalarEvolutionExpander.cpp
View File

@ -158,53 +158,93 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
/// check to see if the divide was folded.
static bool FactorOutConstant(const SCEV *&S,
const SCEV *&Remainder,
const APInt &Factor,
ScalarEvolution &SE) {
const SCEV *Factor,
ScalarEvolution &SE,
const TargetData *TD) {
// Everything is divisible by one.
if (Factor == 1)
if (Factor->isOne())
return true;
// x/x == 1.
if (S == Factor) {
S = SE.getIntegerSCEV(1, S->getType());
return true;
}
// For a Constant, check for a multiple of the given factor.
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
ConstantInt *CI =
ConstantInt::get(SE.getContext(), C->getValue()->getValue().sdiv(Factor));
// If the quotient is zero and the remainder is non-zero, reject
// the value at this scale. It will be considered for subsequent
// smaller scales.
if (C->isZero() || !CI->isZero()) {
const SCEV *Div = SE.getConstant(CI);
S = Div;
Remainder =
SE.getAddExpr(Remainder,
SE.getConstant(C->getValue()->getValue().srem(Factor)));
// 0/x == 0.
if (C->isZero())
return true;
// Check for divisibility.
if (const SCEVConstant *FC = dyn_cast<SCEVConstant>(Factor)) {
ConstantInt *CI =
ConstantInt::get(SE.getContext(),
C->getValue()->getValue().sdiv(
FC->getValue()->getValue()));
// If the quotient is zero and the remainder is non-zero, reject
// the value at this scale. It will be considered for subsequent
// smaller scales.
if (!CI->isZero()) {
const SCEV *Div = SE.getConstant(CI);
S = Div;
Remainder =
SE.getAddExpr(Remainder,
SE.getConstant(C->getValue()->getValue().srem(
FC->getValue()->getValue())));
return true;
}
}
}
// In a Mul, check if there is a constant operand which is a multiple
// of the given factor.
if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S))
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
if (!C->getValue()->getValue().srem(Factor)) {
const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands();
SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(),
MOperands.end());
NewMulOps[0] =
SE.getConstant(C->getValue()->getValue().sdiv(Factor));
S = SE.getMulExpr(NewMulOps);
return true;
if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
if (TD) {
// With TargetData, the size is known. Check if there is a constant
// operand which is a multiple of the given factor. If so, we can
// factor it.
const SCEVConstant *FC = cast<SCEVConstant>(Factor);
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
if (!C->getValue()->getValue().srem(FC->getValue()->getValue())) {
const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands();
SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(),
MOperands.end());
NewMulOps[0] =
SE.getConstant(C->getValue()->getValue().sdiv(
FC->getValue()->getValue()));
S = SE.getMulExpr(NewMulOps);
return true;
}
} else {
// Without TargetData, check if Factor can be factored out of any of the
// Mul's operands. If so, we can just remove it.
for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
const SCEV *SOp = M->getOperand(i);
const SCEV *Remainder = SE.getIntegerSCEV(0, SOp->getType());
if (FactorOutConstant(SOp, Remainder, Factor, SE, TD) &&
Remainder->isZero()) {
const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands();
SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(),
MOperands.end());
NewMulOps[i] = SOp;
S = SE.getMulExpr(NewMulOps);
return true;
}
}
}
}
// In an AddRec, check if both start and step are divisible.
if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
const SCEV *Step = A->getStepRecurrence(SE);
const SCEV *StepRem = SE.getIntegerSCEV(0, Step->getType());
if (!FactorOutConstant(Step, StepRem, Factor, SE))
if (!FactorOutConstant(Step, StepRem, Factor, SE, TD))
return false;
if (!StepRem->isZero())
return false;
const SCEV *Start = A->getStart();
if (!FactorOutConstant(Start, Remainder, Factor, SE))
if (!FactorOutConstant(Start, Remainder, Factor, SE, TD))
return false;
S = SE.getAddRecExpr(Start, Step, A->getLoop());
return true;
@ -213,9 +253,73 @@ static bool FactorOutConstant(const SCEV *&S,
return false;
}
/// SimplifyAddOperands - Sort and simplify a list of add operands. NumAddRecs
/// is the number of SCEVAddRecExprs present, which are kept at the end of
/// the list.
///
static void SimplifyAddOperands(SmallVectorImpl<const SCEV *> &Ops,
const Type *Ty,
ScalarEvolution &SE) {
unsigned NumAddRecs = 0;
for (unsigned i = Ops.size(); i > 0 && isa<SCEVAddRecExpr>(Ops[i-1]); --i)
++NumAddRecs;
// Group Ops into non-addrecs and addrecs.
SmallVector<const SCEV *, 8> NoAddRecs(Ops.begin(), Ops.end() - NumAddRecs);
SmallVector<const SCEV *, 8> AddRecs(Ops.end() - NumAddRecs, Ops.end());
// Let ScalarEvolution sort and simplify the non-addrecs list.
const SCEV *Sum = NoAddRecs.empty() ?
SE.getIntegerSCEV(0, Ty) :
SE.getAddExpr(NoAddRecs);
// If it returned an add, use the operands. Otherwise it simplified
// the sum into a single value, so just use that.
if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Sum))
Ops = Add->getOperands();
else {
Ops.clear();
if (!Sum->isZero())
Ops.push_back(Sum);
}
// Then append the addrecs.
Ops.insert(Ops.end(), AddRecs.begin(), AddRecs.end());
}
/// SplitAddRecs - Flatten a list of add operands, moving addrec start values
/// out to the top level. For example, convert {a + b,+,c} to a, b, {0,+,d}.
/// This helps expose more opportunities for folding parts of the expressions
/// into GEP indices.
///
static void SplitAddRecs(SmallVectorImpl<const SCEV *> &Ops,
const Type *Ty,
ScalarEvolution &SE) {
// Find the addrecs.
SmallVector<const SCEV *, 8> AddRecs;
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i])) {
const SCEV *Start = A->getStart();
if (Start->isZero()) break;
const SCEV *Zero = SE.getIntegerSCEV(0, Ty);
AddRecs.push_back(SE.getAddRecExpr(Zero,
A->getStepRecurrence(SE),
A->getLoop()));
if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) {
Ops[i] = Zero;
Ops.insert(Ops.end(), Add->op_begin(), Add->op_end());
e += Add->getNumOperands();
} else {
Ops[i] = Start;
}
}
if (!AddRecs.empty()) {
// Add the addrecs onto the end of the list.
Ops.insert(Ops.end(), AddRecs.begin(), AddRecs.end());
// Resort the operand list, moving any constants to the front.
SimplifyAddOperands(Ops, Ty, SE);
}
}
/// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
/// instead of using ptrtoint+arithmetic+inttoptr. This helps
/// BasicAliasAnalysis analyze the result.
/// BasicAliasAnalysis and other passes analyze the result.
///
/// Design note: This depends on ScalarEvolution not recognizing inttoptr
/// and ptrtoint operators, as they may introduce pointer arithmetic
@ -246,52 +350,62 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
SmallVector<const SCEV *, 8> Ops(op_begin, op_end);
bool AnyNonZeroIndices = false;
// Split AddRecs up into parts as either of the parts may be usable
// without the other.
SplitAddRecs(Ops, Ty, SE);
// Decend down the pointer's type and attempt to convert the other
// operands into GEP indices, at each level. The first index in a GEP
// indexes into the array implied by the pointer operand; the rest of
// the indices index into the element or field type selected by the
// preceding index.
for (;;) {
APInt ElSize = APInt(SE.getTypeSizeInBits(Ty),
ElTy->isSized() ? SE.TD->getTypeAllocSize(ElTy) : 0);
SmallVector<const SCEV *, 8> NewOps;
const SCEV *ElSize = SE.getAllocSizeExpr(ElTy);
// If the scale size is not 0, attempt to factor out a scale for
// array indexing.
SmallVector<const SCEV *, 8> ScaledOps;
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
// Split AddRecs up into parts as either of the parts may be usable
// without the other.
if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i]))
if (!A->getStart()->isZero()) {
const SCEV *Start = A->getStart();
Ops.push_back(SE.getAddRecExpr(SE.getIntegerSCEV(0, A->getType()),
A->getStepRecurrence(SE),
A->getLoop()));
Ops[i] = Start;
++e;
}
// If the scale size is not 0, attempt to factor out a scale.
if (ElSize != 0) {
if (ElTy->isSized() && !ElSize->isZero()) {
SmallVector<const SCEV *, 8> NewOps;
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
const SCEV *Op = Ops[i];
const SCEV *Remainder = SE.getIntegerSCEV(0, Op->getType());
if (FactorOutConstant(Op, Remainder, ElSize, SE)) {
ScaledOps.push_back(Op); // Op now has ElSize factored out.
NewOps.push_back(Remainder);
continue;
const SCEV *Remainder = SE.getIntegerSCEV(0, Ty);
if (FactorOutConstant(Op, Remainder, ElSize, SE, SE.TD)) {
// Op now has ElSize factored out.
ScaledOps.push_back(Op);
if (!Remainder->isZero())
NewOps.push_back(Remainder);
AnyNonZeroIndices = true;
} else {
// The operand was not divisible, so add it to the list of operands
// we'll scan next iteration.
NewOps.push_back(Ops[i]);
}
}
// If the operand was not divisible, add it to the list of operands
// we'll scan next iteration.
NewOps.push_back(Ops[i]);
// If we made any changes, update Ops.
if (!ScaledOps.empty()) {
Ops = NewOps;
SimplifyAddOperands(Ops, Ty, SE);
}
}
Ops = NewOps;
AnyNonZeroIndices |= !ScaledOps.empty();
// Record the scaled array index for this level of the type. If
// we didn't find any operands that could be factored, tentatively
// assume that element zero was selected (since the zero offset
// would obviously be folded away).
Value *Scaled = ScaledOps.empty() ?
Constant::getNullValue(Ty) :
expandCodeFor(SE.getAddExpr(ScaledOps), Ty);
GepIndices.push_back(Scaled);
// Collect struct field index operands.
if (!Ops.empty())
while (const StructType *STy = dyn_cast<StructType>(ElTy)) {
while (const StructType *STy = dyn_cast<StructType>(ElTy)) {
bool FoundFieldNo = false;
// An empty struct has no fields.
if (STy->getNumElements() == 0) break;
if (SE.TD) {
// With TargetData, field offsets are known. See if a constant offset
// falls within any of the struct fields.
if (Ops.empty()) break;
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0]))
if (SE.getTypeSizeInBits(C->getType()) <= 64) {
const StructLayout &SL = *SE.TD->getStructLayout(STy);
@ -304,25 +418,52 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
Ops[0] =
SE.getConstant(Ty, FullOffset - SL.getElementOffset(ElIdx));
AnyNonZeroIndices = true;
continue;
FoundFieldNo = true;
}
}
break;
} else {
// Without TargetData, just check for a SCEVFieldOffsetExpr of the
// appropriate struct type.
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
if (const SCEVFieldOffsetExpr *FO =
dyn_cast<SCEVFieldOffsetExpr>(Ops[i]))
if (FO->getStructType() == STy) {
unsigned FieldNo = FO->getFieldNo();
GepIndices.push_back(
ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
FieldNo));
ElTy = STy->getTypeAtIndex(FieldNo);
Ops[i] = SE.getConstant(Ty, 0);
AnyNonZeroIndices = true;
FoundFieldNo = true;
break;
}
}
// If no struct field offsets were found, tentatively assume that
// field zero was selected (since the zero offset would obviously
// be folded away).
if (!FoundFieldNo) {
ElTy = STy->getTypeAtIndex(0u);
GepIndices.push_back(
Constant::getNullValue(Type::getInt32Ty(Ty->getContext())));
}
if (const ArrayType *ATy = dyn_cast<ArrayType>(ElTy)) {
ElTy = ATy->getElementType();
continue;
}
break;
if (const ArrayType *ATy = dyn_cast<ArrayType>(ElTy))
ElTy = ATy->getElementType();
else
break;
}
// If none of the operands were convertable to proper GEP indices, cast
// the base to i8* and do an ugly getelementptr with that. It's still
// better than ptrtoint+arithmetic+inttoptr at least.
if (!AnyNonZeroIndices) {
// Cast the base to i8*.
V = InsertNoopCastOfTo(V,
Type::getInt8Ty(Ty->getContext())->getPointerTo(PTy->getAddressSpace()));
// Expand the operands for a plain byte offset.
Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
// Fold a GEP with constant operands.
@ -345,7 +486,8 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
}
}
Value *GEP = Builder.CreateGEP(V, Idx, "scevgep");
// Emit a GEP.
Value *GEP = Builder.CreateGEP(V, Idx, "uglygep");
InsertedValues.insert(GEP);
return GEP;
}
@ -368,11 +510,10 @@ Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
// Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
// comments on expandAddToGEP for details.
if (SE.TD)
if (const PointerType *PTy = dyn_cast<PointerType>(V->getType())) {
const SmallVectorImpl<const SCEV *> &Ops = S->getOperands();
return expandAddToGEP(&Ops[0], &Ops[Ops.size() - 1], PTy, Ty, V);
}
if (const PointerType *PTy = dyn_cast<PointerType>(V->getType())) {
const SmallVectorImpl<const SCEV *> &Ops = S->getOperands();
return expandAddToGEP(&Ops[0], &Ops[Ops.size() - 1], PTy, Ty, V);
}
V = InsertNoopCastOfTo(V, Ty);
@ -484,21 +625,19 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
// Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
// comments on expandAddToGEP for details.
if (SE.TD) {
const SCEV *Base = S->getStart();
const SCEV *RestArray[1] = { Rest };
// Dig into the expression to find the pointer base for a GEP.
ExposePointerBase(Base, RestArray[0], SE);
// If we found a pointer, expand the AddRec with a GEP.
if (const PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
// Make sure the Base isn't something exotic, such as a multiplied
// or divided pointer value. In those cases, the result type isn't
// actually a pointer type.
if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) {
Value *StartV = expand(Base);
assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!");
return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV);
}
const SCEV *Base = S->getStart();
const SCEV *RestArray[1] = { Rest };
// Dig into the expression to find the pointer base for a GEP.
ExposePointerBase(Base, RestArray[0], SE);
// If we found a pointer, expand the AddRec with a GEP.
if (const PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
// Make sure the Base isn't something exotic, such as a multiplied
// or divided pointer value. In those cases, the result type isn't
// actually a pointer type.
if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) {
Value *StartV = expand(Base);
assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!");
return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV);
}
}
@ -656,6 +795,14 @@ Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
return LHS;
}
Value *SCEVExpander::visitFieldOffsetExpr(const SCEVFieldOffsetExpr *S) {
return ConstantExpr::getOffsetOf(S->getStructType(), S->getFieldNo());
}
Value *SCEVExpander::visitAllocSizeExpr(const SCEVAllocSizeExpr *S) {
return ConstantExpr::getSizeOf(S->getAllocType());
}
Value *SCEVExpander::expandCodeFor(const SCEV *SH, const Type *Ty) {
// Expand the code for this SCEV.
Value *V = expand(SH);

75
test/Transforms/IndVarSimplify/preserve-gep-nested.ll Normal file
View File

@ -0,0 +1,75 @@
; RUN: llvm-as < %s | opt -indvars | llvm-dis > %t
; Exactly one getelementptr for each load+store.
; RUN: grep getelementptr %t | count 6
; Each getelementptr using %struct.Q* %s as a base and not i8*.
; RUN: grep {getelementptr \[%\]struct\\.Q\\* \[%\]s,} %t | count 6
; No explicit integer multiplications!
; RUN: not grep {= mul} %t
; No i8* arithmetic or pointer casting anywhere!
; RUN: not grep {i8\\*} %t
; RUN: not grep bitcast %t
; RUN: not grep inttoptr %t
; RUN: not grep ptrtoint %t
; FIXME: This test should pass with or without TargetData. Until opt
; supports running tests without targetdata, just hardware this in.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
%struct.Q = type { [10 x %struct.N] }
%struct.N = type { %struct.S }
%struct.S = type { [100 x double], [100 x double] }
define void @foo(%struct.Q* %s, i64 %n) nounwind {
entry:
br label %bb1
bb1:
%i = phi i64 [ 2, %entry ], [ %i.next, %bb ]
%j = phi i64 [ 0, %entry ], [ %j.next, %bb ]
%t5 = icmp slt i64 %i, %n
br i1 %t5, label %bb, label %return
bb:
%t0 = getelementptr inbounds %struct.Q* %s, i64 0, i32 0, i64 0, i32 0, i32 0, i64 %i
%t1 = load double* %t0, align 8
%t2 = fmul double %t1, 3.200000e+00
%t3 = getelementptr inbounds %struct.Q* %s, i64 0, i32 0, i64 0, i32 0, i32 0, i64 %i
store double %t2, double* %t3, align 8
%s0 = getelementptr inbounds %struct.Q* %s, i64 13, i32 0, i64 7, i32 0, i32 1, i64 %i
%s1 = load double* %s0, align 8
%s2 = fmul double %s1, 3.200000e+00
%s3 = getelementptr inbounds %struct.Q* %s, i64 13, i32 0, i64 7, i32 0, i32 1, i64 %i
store double %s2, double* %s3, align 8
%u0 = getelementptr inbounds %struct.Q* %s, i64 0, i32 0, i64 7, i32 0, i32 1, i64 %j
%u1 = load double* %u0, align 8
%u2 = fmul double %u1, 3.200000e+00
%u3 = getelementptr inbounds %struct.Q* %s, i64 0, i32 0, i64 7, i32 0, i32 1, i64 %j
store double %u2, double* %u3, align 8
%v0 = getelementptr inbounds %struct.Q* %s, i64 0, i32 0, i64 0, i32 0, i32 1, i64 %i
%v1 = load double* %v0, align 8
%v2 = fmul double %v1, 3.200000e+00
%v3 = getelementptr inbounds %struct.Q* %s, i64 0, i32 0, i64 0, i32 0, i32 1, i64 %i
store double %v2, double* %v3, align 8
%w0 = getelementptr inbounds %struct.Q* %s, i64 0, i32 0, i64 0, i32 0, i32 0, i64 %j
%w1 = load double* %w0, align 8
%w2 = fmul double %w1, 3.200000e+00
%w3 = getelementptr inbounds %struct.Q* %s, i64 0, i32 0, i64 0, i32 0, i32 0, i64 %j
store double %w2, double* %w3, align 8
%x0 = getelementptr inbounds %struct.Q* %s, i64 0, i32 0, i64 3, i32 0, i32 0, i64 %i
%x1 = load double* %x0, align 8
%x2 = fmul double %x1, 3.200000e+00
%x3 = getelementptr inbounds %struct.Q* %s, i64 0, i32 0, i64 3, i32 0, i32 0, i64 %i
store double %x2, double* %x3, align 8
%i.next = add i64 %i, 1
%j.next = add i64 %j, 1
br label %bb1
return:
ret void
}