//===- ConstantFolding.cpp - LLVM constant folder -------------------------===//
-//
+//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
+//
//===----------------------------------------------------------------------===//
//
// This file implements folding of constants for LLVM. This implements the
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include <limits>
#include <cmath>
using namespace llvm;
namespace {
struct ConstRules {
ConstRules() {}
-
+ virtual ~ConstRules() {}
+
// Binary Operators...
virtual Constant *add(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *sub(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *castToDouble(const Constant *V) const = 0;
virtual Constant *castToPointer(const Constant *V,
const PointerType *Ty) const = 0;
-
+
// ConstRules::get - Return an instance of ConstRules for the specified
// constant operands.
//
// TemplateRules Class
//===----------------------------------------------------------------------===//
//
-// TemplateRules - Implement a subclass of ConstRules that provides all
-// operations as noops. All other rules classes inherit from this class so
-// that if functionality is needed in the future, it can simply be added here
+// TemplateRules - Implement a subclass of ConstRules that provides all
+// operations as noops. All other rules classes inherit from this class so
+// that if functionality is needed in the future, it can simply be added here
// and to ConstRules without changing anything else...
-//
+//
// This class also provides subclasses with typesafe implementations of methods
// so that don't have to do type casting.
//
template<class ArgType, class SubClassName>
class TemplateRules : public ConstRules {
+
//===--------------------------------------------------------------------===//
// Redirecting functions that cast to the appropriate types
//===--------------------------------------------------------------------===//
- virtual Constant *add(const Constant *V1, const Constant *V2) const {
- return SubClassName::Add((const ArgType *)V1, (const ArgType *)V2);
+ virtual Constant *add(const Constant *V1, const Constant *V2) const {
+ return SubClassName::Add((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *sub(const Constant *V1, const Constant *V2) const {
- return SubClassName::Sub((const ArgType *)V1, (const ArgType *)V2);
+ virtual Constant *sub(const Constant *V1, const Constant *V2) const {
+ return SubClassName::Sub((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *mul(const Constant *V1, const Constant *V2) const {
- return SubClassName::Mul((const ArgType *)V1, (const ArgType *)V2);
+ virtual Constant *mul(const Constant *V1, const Constant *V2) const {
+ return SubClassName::Mul((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *div(const Constant *V1, const Constant *V2) const {
- return SubClassName::Div((const ArgType *)V1, (const ArgType *)V2);
+ virtual Constant *div(const Constant *V1, const Constant *V2) const {
+ return SubClassName::Div((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *rem(const Constant *V1, const Constant *V2) const {
- return SubClassName::Rem((const ArgType *)V1, (const ArgType *)V2);
+ virtual Constant *rem(const Constant *V1, const Constant *V2) const {
+ return SubClassName::Rem((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *op_and(const Constant *V1, const Constant *V2) const {
- return SubClassName::And((const ArgType *)V1, (const ArgType *)V2);
+ virtual Constant *op_and(const Constant *V1, const Constant *V2) const {
+ return SubClassName::And((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *op_or(const Constant *V1, const Constant *V2) const {
- return SubClassName::Or((const ArgType *)V1, (const ArgType *)V2);
+ virtual Constant *op_or(const Constant *V1, const Constant *V2) const {
+ return SubClassName::Or((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *op_xor(const Constant *V1, const Constant *V2) const {
- return SubClassName::Xor((const ArgType *)V1, (const ArgType *)V2);
+ virtual Constant *op_xor(const Constant *V1, const Constant *V2) const {
+ return SubClassName::Xor((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *shl(const Constant *V1, const Constant *V2) const {
- return SubClassName::Shl((const ArgType *)V1, (const ArgType *)V2);
+ virtual Constant *shl(const Constant *V1, const Constant *V2) const {
+ return SubClassName::Shl((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *shr(const Constant *V1, const Constant *V2) const {
- return SubClassName::Shr((const ArgType *)V1, (const ArgType *)V2);
+ virtual Constant *shr(const Constant *V1, const Constant *V2) const {
+ return SubClassName::Shr((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *lessthan(const Constant *V1, const Constant *V2) const {
+ virtual Constant *lessthan(const Constant *V1, const Constant *V2) const {
return SubClassName::LessThan((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *equalto(const Constant *V1, const Constant *V2) const {
+ virtual Constant *equalto(const Constant *V1, const Constant *V2) const {
return SubClassName::EqualTo((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *castToDouble(const Constant *V) const {
return SubClassName::CastToDouble((const ArgType*)V);
}
- virtual Constant *castToPointer(const Constant *V,
+ virtual Constant *castToPointer(const Constant *V,
const PointerType *Ty) const {
return SubClassName::CastToPointer((const ArgType*)V, Ty);
}
static Constant *CastToDouble(const Constant *V) { return 0; }
static Constant *CastToPointer(const Constant *,
const PointerType *) {return 0;}
+
+public:
+ virtual ~TemplateRules() {}
};
//
struct BoolRules : public TemplateRules<ConstantBool, BoolRules> {
- static Constant *LessThan(const ConstantBool *V1, const ConstantBool *V2){
+ static Constant *LessThan(const ConstantBool *V1, const ConstantBool *V2) {
return ConstantBool::get(V1->getValue() < V2->getValue());
}
}
};
+//===----------------------------------------------------------------------===//
+// ConstantPackedRules Class
+//===----------------------------------------------------------------------===//
+
+/// DoVectorOp - Given two packed constants and a function pointer, apply the
+/// function pointer to each element pair, producing a new ConstantPacked
+/// constant.
+static Constant *EvalVectorOp(const ConstantPacked *V1,
+ const ConstantPacked *V2,
+ Constant *(*FP)(Constant*, Constant*)) {
+ std::vector<Constant*> Res;
+ for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
+ Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
+ const_cast<Constant*>(V2->getOperand(i))));
+ return ConstantPacked::get(Res);
+}
+
+/// PackedTypeRules provides a concrete base class of ConstRules for
+/// ConstantPacked operands.
+///
+struct ConstantPackedRules
+ : public TemplateRules<ConstantPacked, ConstantPackedRules> {
+
+ static Constant *Add(const ConstantPacked *V1, const ConstantPacked *V2) {
+ return EvalVectorOp(V1, V2, ConstantExpr::getAdd);
+ }
+ static Constant *Sub(const ConstantPacked *V1, const ConstantPacked *V2) {
+ return EvalVectorOp(V1, V2, ConstantExpr::getSub);
+ }
+ static Constant *Mul(const ConstantPacked *V1, const ConstantPacked *V2) {
+ return EvalVectorOp(V1, V2, ConstantExpr::getMul);
+ }
+ static Constant *Div(const ConstantPacked *V1, const ConstantPacked *V2) {
+ return EvalVectorOp(V1, V2, ConstantExpr::getDiv);
+ }
+ static Constant *Rem(const ConstantPacked *V1, const ConstantPacked *V2) {
+ return EvalVectorOp(V1, V2, ConstantExpr::getRem);
+ }
+ static Constant *And(const ConstantPacked *V1, const ConstantPacked *V2) {
+ return EvalVectorOp(V1, V2, ConstantExpr::getAnd);
+ }
+ static Constant *Or (const ConstantPacked *V1, const ConstantPacked *V2) {
+ return EvalVectorOp(V1, V2, ConstantExpr::getOr);
+ }
+ static Constant *Xor(const ConstantPacked *V1, const ConstantPacked *V2) {
+ return EvalVectorOp(V1, V2, ConstantExpr::getXor);
+ }
+ static Constant *Shl(const ConstantPacked *V1, const ConstantPacked *V2) {
+ return EvalVectorOp(V1, V2, ConstantExpr::getShl);
+ }
+ static Constant *Shr(const ConstantPacked *V1, const ConstantPacked *V2) {
+ return EvalVectorOp(V1, V2, ConstantExpr::getShr);
+ }
+ static Constant *LessThan(const ConstantPacked *V1, const ConstantPacked *V2){
+ return 0;
+ }
+ static Constant *EqualTo(const ConstantPacked *V1, const ConstantPacked *V2) {
+ for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i) {
+ Constant *C =
+ ConstantExpr::getSetEQ(const_cast<Constant*>(V1->getOperand(i)),
+ const_cast<Constant*>(V2->getOperand(i)));
+ if (ConstantBool *CB = dyn_cast<ConstantBool>(C))
+ return CB;
+ }
+ // Otherwise, could not decide from any element pairs.
+ return 0;
+ }
+};
+
+
+//===----------------------------------------------------------------------===//
+// GeneralPackedRules Class
+//===----------------------------------------------------------------------===//
+
+/// GeneralPackedRules provides a concrete base class of ConstRules for
+/// PackedType operands, where both operands are not ConstantPacked. The usual
+/// cause for this is that one operand is a ConstantAggregateZero.
+///
+struct GeneralPackedRules : public TemplateRules<Constant, GeneralPackedRules> {
+};
+
//===----------------------------------------------------------------------===//
// DirectRules Class
static Constant *LessThan(const ConstantClass *V1, const ConstantClass *V2) {
bool R = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue();
return ConstantBool::get(R);
- }
+ }
static Constant *EqualTo(const ConstantClass *V1, const ConstantClass *V2) {
bool R = (BuiltinType)V1->getValue() == (BuiltinType)V2->getValue();
(BuiltinType)V2->getValue());
return ConstantClass::get(*Ty, Result);
}
+ static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
+ BuiltinType inf = std::numeric_limits<BuiltinType>::infinity();
+ if (V2->isExactlyValue(0.0)) return ConstantClass::get(*Ty, inf);
+ if (V2->isExactlyValue(-0.0)) return ConstantClass::get(*Ty, -inf);
+ BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
+ }
};
static EmptyRules EmptyR;
static BoolRules BoolR;
static NullPointerRules NullPointerR;
+ static ConstantPackedRules ConstantPackedR;
+ static GeneralPackedRules GeneralPackedR;
static DirectIntRules<ConstantSInt, signed char , &Type::SByteTy> SByteR;
static DirectIntRules<ConstantUInt, unsigned char , &Type::UByteTy> UByteR;
static DirectIntRules<ConstantSInt, signed short, &Type::ShortTy> ShortR;
static DirectFPRules <ConstantFP , double , &Type::DoubleTy> DoubleR;
if (isa<ConstantExpr>(V1) || isa<ConstantExpr>(V2) ||
- isa<ConstantPointerRef>(V1) || isa<ConstantPointerRef>(V2))
+ isa<GlobalValue>(V1) || isa<GlobalValue>(V2) ||
+ isa<UndefValue>(V1) || isa<UndefValue>(V2))
return EmptyR;
switch (V1->getType()->getTypeID()) {
case Type::ULongTyID: return ULongR;
case Type::FloatTyID: return FloatR;
case Type::DoubleTyID: return DoubleR;
+ case Type::PackedTyID:
+ if (isa<ConstantPacked>(V1) && isa<ConstantPacked>(V2))
+ return ConstantPackedR;
+ return GeneralPackedR; // Constant folding rules for ConstantAggregateZero.
}
}
if (V->getType() == DestTy) return (Constant*)V;
// Cast of a global address to boolean is always true.
- if (const ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(V))
+ if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
if (DestTy == Type::BoolTy)
// FIXME: When we support 'external weak' references, we have to prevent
- // this transformation from happening. In the meantime we avoid folding
- // any cast of an external symbol.
- if (!CPR->getValue()->isExternal())
- return ConstantBool::True;
-
- if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
+ // this transformation from happening. This code will need to be updated
+ // to ignore external weak symbols when we support it.
+ return ConstantBool::True;
+ } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() == Instruction::Cast) {
Constant *Op = const_cast<Constant*>(CE->getOperand(0));
// Try to not produce a cast of a cast, which is almost always redundant.
if (isAllNull)
return ConstantExpr::getCast(CE->getOperand(0), DestTy);
}
+ } else if (isa<UndefValue>(V)) {
+ return UndefValue::get(DestTy);
+ }
+
+ // Check to see if we are casting an pointer to an aggregate to a pointer to
+ // the first element. If so, return the appropriate GEP instruction.
+ if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
+ if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
+ std::vector<Value*> IdxList;
+ IdxList.push_back(Constant::getNullValue(Type::IntTy));
+ const Type *ElTy = PTy->getElementType();
+ while (ElTy != DPTy->getElementType()) {
+ if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
+ if (STy->getNumElements() == 0) break;
+ ElTy = STy->getElementType(0);
+ IdxList.push_back(Constant::getNullValue(Type::UIntTy));
+ } else if (const SequentialType *STy = dyn_cast<SequentialType>(ElTy)) {
+ if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
+ ElTy = STy->getElementType();
+ IdxList.push_back(IdxList[0]);
+ } else {
+ break;
+ }
+ }
+
+ if (ElTy == DPTy->getElementType())
+ return ConstantExpr::getGetElementPtr(const_cast<Constant*>(V),IdxList);
+ }
ConstRules &Rules = ConstRules::get(V, V);
return const_cast<Constant*>(V1);
else if (Cond == ConstantBool::False)
return const_cast<Constant*>(V2);
+
+ if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
+ if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
+ if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
+ if (V1 == V2) return const_cast<Constant*>(V1);
+ return 0;
+}
+
+Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
+ const Constant *Idx) {
+ if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
+ if (const ConstantUInt *CIdx = dyn_cast<ConstantUInt>(Idx)) {
+ return const_cast<Constant*>(CVal->getOperand(CIdx->getValue()));
+ }
+ }
+ return 0;
+}
+
+Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
+ const Constant *Elt,
+ const Constant *Idx) {
+ const ConstantUInt *CIdx = dyn_cast<ConstantUInt>(Idx);
+ if (!CIdx) return 0;
+ unsigned idxVal = CIdx->getValue();
+ if (const UndefValue *UVal = dyn_cast<UndefValue>(Val)) {
+ // Insertion of scalar constant into packed undef
+ // Optimize away insertion of undef
+ if (isa<UndefValue>(Elt))
+ return const_cast<Constant*>(Val);
+ // Otherwise break the aggregate undef into multiple undefs and do
+ // the insertion
+ unsigned numOps =
+ cast<PackedType>(Val->getType())->getNumElements();
+ std::vector<Constant*> Ops;
+ Ops.reserve(numOps);
+ for (unsigned i = 0; i < numOps; ++i) {
+ const Constant *Op =
+ (i == idxVal) ? Elt : UndefValue::get(Elt->getType());
+ Ops.push_back(const_cast<Constant*>(Op));
+ }
+ return ConstantPacked::get(Ops);
+ }
+ if (const ConstantAggregateZero *CVal =
+ dyn_cast<ConstantAggregateZero>(Val)) {
+ // Insertion of scalar constant into packed aggregate zero
+ // Optimize away insertion of zero
+ if (Elt->isNullValue())
+ return const_cast<Constant*>(Val);
+ // Otherwise break the aggregate zero into multiple zeros and do
+ // the insertion
+ unsigned numOps =
+ cast<PackedType>(Val->getType())->getNumElements();
+ std::vector<Constant*> Ops;
+ Ops.reserve(numOps);
+ for (unsigned i = 0; i < numOps; ++i) {
+ const Constant *Op =
+ (i == idxVal) ? Elt : Constant::getNullValue(Elt->getType());
+ Ops.push_back(const_cast<Constant*>(Op));
+ }
+ return ConstantPacked::get(Ops);
+ }
+ if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
+ // Insertion of scalar constant into packed constant
+ std::vector<Constant*> Ops;
+ Ops.reserve(CVal->getNumOperands());
+ for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
+ const Constant *Op =
+ (i == idxVal) ? Elt : cast<Constant>(CVal->getOperand(i));
+ Ops.push_back(const_cast<Constant*>(Op));
+ }
+ return ConstantPacked::get(Ops);
+ }
return 0;
}
+/// isZeroSizedType - This type is zero sized if its an array or structure of
+/// zero sized types. The only leaf zero sized type is an empty structure.
+static bool isMaybeZeroSizedType(const Type *Ty) {
+ if (isa<OpaqueType>(Ty)) return true; // Can't say.
+ if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+
+ // If all of elements have zero size, this does too.
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
+ if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
+ return true;
+
+ } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+ return isMaybeZeroSizedType(ATy->getElementType());
+ }
+ return false;
+}
/// IdxCompare - Compare the two constants as though they were getelementptr
/// indices. This allows coersion of the types to be the same thing.
/// first is less than the second, return -1, if the second is less than the
/// first, return 1. If the constants are not integral, return -2.
///
-static int IdxCompare(Constant *C1, Constant *C2) {
+static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
if (C1 == C2) return 0;
// Ok, we found a different index. Are either of the operands
// ConstantExprs? If so, we can't do anything with them.
if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
return -2; // don't know!
-
+
// Ok, we have two differing integer indices. Sign extend them to be the same
// type. Long is always big enough, so we use it.
C1 = ConstantExpr::getSignExtend(C1, Type::LongTy);
C2 = ConstantExpr::getSignExtend(C2, Type::LongTy);
if (C1 == C2) return 0; // Are they just differing types?
+ // If the type being indexed over is really just a zero sized type, there is
+ // no pointer difference being made here.
+ if (isMaybeZeroSizedType(ElTy))
+ return -2; // dunno.
+
// If they are really different, now that they are the same type, then we
// found a difference!
if (cast<ConstantSInt>(C1)->getValue() < cast<ConstantSInt>(C2)->getValue())
/// evaluateRelation - This function determines if there is anything we can
/// decide about the two constants provided. This doesn't need to handle simple
-/// things like integer comparisons, but should instead handle ConstantExpr's
-/// and ConstantPointerRef's. If we can determine that the two constants have a
+/// things like integer comparisons, but should instead handle ConstantExprs
+/// and GlobalValuess. If we can determine that the two constants have a
/// particular relation to each other, we should return the corresponding SetCC
/// code, otherwise return Instruction::BinaryOpsEnd.
///
/// To simplify this code we canonicalize the relation so that the first
/// operand is always the most "complex" of the two. We consider simple
/// constants (like ConstantInt) to be the simplest, followed by
-/// ConstantPointerRef's, followed by ConstantExpr's (the most complex).
+/// GlobalValues, followed by ConstantExpr's (the most complex).
///
-static Instruction::BinaryOps evaluateRelation(const Constant *V1,
- const Constant *V2) {
+static Instruction::BinaryOps evaluateRelation(Constant *V1, Constant *V2) {
assert(V1->getType() == V2->getType() &&
"Cannot compare different types of values!");
if (V1 == V2) return Instruction::SetEQ;
- if (!isa<ConstantExpr>(V1) && !isa<ConstantPointerRef>(V1)) {
+ if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
+ if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
+ // We distilled this down to a simple case, use the standard constant
+ // folder.
+ ConstantBool *R = dyn_cast<ConstantBool>(ConstantExpr::getSetEQ(V1, V2));
+ if (R == ConstantBool::True) return Instruction::SetEQ;
+ R = dyn_cast<ConstantBool>(ConstantExpr::getSetLT(V1, V2));
+ if (R == ConstantBool::True) return Instruction::SetLT;
+ R = dyn_cast<ConstantBool>(ConstantExpr::getSetGT(V1, V2));
+ if (R == ConstantBool::True) return Instruction::SetGT;
+
+ // If we couldn't figure it out, bail.
+ return Instruction::BinaryOpsEnd;
+ }
+
// If the first operand is simple, swap operands.
- assert((isa<ConstantPointerRef>(V2) || isa<ConstantExpr>(V2)) &&
- "Simple cases should have been handled by caller!");
Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
if (SwappedRelation != Instruction::BinaryOpsEnd)
return SetCondInst::getSwappedCondition(SwappedRelation);
- } else if (const ConstantPointerRef *CPR1 = dyn_cast<ConstantPointerRef>(V1)){
+ } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
if (isa<ConstantExpr>(V2)) { // Swap as necessary.
- Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
- if (SwappedRelation != Instruction::BinaryOpsEnd)
- return SetCondInst::getSwappedCondition(SwappedRelation);
- else
- return Instruction::BinaryOpsEnd;
+ Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
+ if (SwappedRelation != Instruction::BinaryOpsEnd)
+ return SetCondInst::getSwappedCondition(SwappedRelation);
+ else
+ return Instruction::BinaryOpsEnd;
}
- // Now we know that the RHS is a ConstantPointerRef or simple constant,
+ // Now we know that the RHS is a GlobalValue or simple constant,
// which (since the types must match) means that it's a ConstantPointerNull.
- if (const ConstantPointerRef *CPR2 = dyn_cast<ConstantPointerRef>(V2)) {
- assert(CPR1->getValue() != CPR2->getValue() &&
- "CPRs for the same value exist at different addresses??");
+ if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
+ assert(CPR1 != CPR2 &&
+ "GVs for the same value exist at different addresses??");
// FIXME: If both globals are external weak, they might both be null!
return Instruction::SetNE;
} else {
} else {
// Ok, the LHS is known to be a constantexpr. The RHS can be any of a
// constantexpr, a CPR, or a simple constant.
- const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
+ ConstantExpr *CE1 = cast<ConstantExpr>(V1);
Constant *CE1Op0 = CE1->getOperand(0);
switch (CE1->getOpcode()) {
// If the cast is not actually changing bits, and the second operand is a
// null pointer, do the comparison with the pre-casted value.
if (V2->isNullValue() &&
- CE1->getType()->isLosslesslyConvertibleTo(CE1Op0->getType()))
+ (isa<PointerType>(CE1->getType()) || CE1->getType()->isIntegral()))
return evaluateRelation(CE1Op0,
Constant::getNullValue(CE1Op0->getType()));
+
+ // If the dest type is a pointer type, and the RHS is a constantexpr cast
+ // from the same type as the src of the LHS, evaluate the inputs. This is
+ // important for things like "seteq (cast 4 to int*), (cast 5 to int*)",
+ // which happens a lot in compilers with tagged integers.
+ if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
+ if (isa<PointerType>(CE1->getType()) &&
+ CE2->getOpcode() == Instruction::Cast &&
+ CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
+ CE1->getOperand(0)->getType()->isIntegral()) {
+ return evaluateRelation(CE1->getOperand(0), CE2->getOperand(0));
+ }
break;
case Instruction::GetElementPtr:
if (isa<ConstantPointerNull>(V2)) {
// If we are comparing a GEP to a null pointer, check to see if the base
// of the GEP equals the null pointer.
- if (isa<ConstantPointerRef>(CE1Op0)) {
+ if (isa<GlobalValue>(CE1Op0)) {
// FIXME: this is not true when we have external weak references!
// No offset can go from a global to a null pointer.
return Instruction::SetGT;
return Instruction::SetEQ;
}
// Otherwise, we can't really say if the first operand is null or not.
- } else if (const ConstantPointerRef *CPR2 =
- dyn_cast<ConstantPointerRef>(V2)) {
+ } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
if (isa<ConstantPointerNull>(CE1Op0)) {
// FIXME: This is not true with external weak references.
return Instruction::SetLT;
- } else if (const ConstantPointerRef *CPR1 =
- dyn_cast<ConstantPointerRef>(CE1Op0)) {
+ } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
if (CPR1 == CPR2) {
// If this is a getelementptr of the same global, then it must be
// different. Because the types must match, the getelementptr could
case Instruction::GetElementPtr:
// By far the most common case to handle is when the base pointers are
// obviously to the same or different globals.
- if (isa<ConstantPointerRef>(CE1Op0) &&
- isa<ConstantPointerRef>(CE2Op0)) {
+ if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
return Instruction::SetNE;
// Ok, we know that both getelementptr instructions are based on the
// same global. From this, we can precisely determine the relative
// ordering of the resultant pointers.
unsigned i = 1;
-
+
// Compare all of the operands the GEP's have in common.
- for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); ++i)
- switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i))) {
+ gep_type_iterator GTI = gep_type_begin(CE1);
+ for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
+ ++i, ++GTI)
+ switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
+ GTI.getIndexedType())) {
case -1: return Instruction::SetLT;
case 1: return Instruction::SetGT;
case -2: return Instruction::BinaryOpsEnd;
// are non-zero then we have a difference, otherwise we are equal.
for (; i < CE1->getNumOperands(); ++i)
if (!CE1->getOperand(i)->isNullValue())
- return Instruction::SetGT;
+ if (isa<ConstantIntegral>(CE1->getOperand(i)))
+ return Instruction::SetGT;
+ else
+ return Instruction::BinaryOpsEnd; // Might be equal.
+
for (; i < CE2->getNumOperands(); ++i)
if (!CE2->getOperand(i)->isNullValue())
- return Instruction::SetLT;
+ if (isa<ConstantIntegral>(CE2->getOperand(i)))
+ return Instruction::SetLT;
+ else
+ return Instruction::BinaryOpsEnd; // Might be equal.
return Instruction::SetEQ;
}
}
}
-
+
default:
break;
}
case Instruction::SetGT: C = ConstRules::get(V1, V2).lessthan(V2, V1);break;
case Instruction::SetNE: // V1 != V2 === !(V1 == V2)
C = ConstRules::get(V1, V2).equalto(V1, V2);
- if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
+ if (C) return ConstantExpr::getNot(C);
break;
case Instruction::SetLE: // V1 <= V2 === !(V2 < V1)
C = ConstRules::get(V1, V2).lessthan(V2, V1);
- if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
+ if (C) return ConstantExpr::getNot(C);
break;
case Instruction::SetGE: // V1 >= V2 === !(V1 < V2)
C = ConstRules::get(V1, V2).lessthan(V1, V2);
- if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
+ if (C) return ConstantExpr::getNot(C);
break;
}
// If we successfully folded the expression, return it now.
if (C) return C;
- if (SetCondInst::isRelational(Opcode))
- switch (evaluateRelation(V1, V2)) {
+ if (SetCondInst::isRelational(Opcode)) {
+ if (isa<UndefValue>(V1) || isa<UndefValue>(V2))
+ return UndefValue::get(Type::BoolTy);
+ switch (evaluateRelation(const_cast<Constant*>(V1),
+ const_cast<Constant*>(V2))) {
default: assert(0 && "Unknown relational!");
case Instruction::BinaryOpsEnd:
break; // Couldn't determine anything about these constants.
if (Opcode == Instruction::SetLT) return ConstantBool::False;
if (Opcode == Instruction::SetGT) return ConstantBool::True;
break;
-
+
case Instruction::SetNE:
// If we know that V1 != V2, we can only partially decide this relation.
if (Opcode == Instruction::SetEQ) return ConstantBool::False;
if (Opcode == Instruction::SetNE) return ConstantBool::True;
break;
}
+ }
+
+ if (isa<UndefValue>(V1) || isa<UndefValue>(V2)) {
+ switch (Opcode) {
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Xor:
+ return UndefValue::get(V1->getType());
+
+ case Instruction::Mul:
+ case Instruction::And:
+ return Constant::getNullValue(V1->getType());
+ case Instruction::Div:
+ case Instruction::Rem:
+ if (!isa<UndefValue>(V2)) // undef/X -> 0
+ return Constant::getNullValue(V1->getType());
+ return const_cast<Constant*>(V2); // X/undef -> undef
+ case Instruction::Or: // X|undef -> -1
+ return ConstantInt::getAllOnesValue(V1->getType());
+ case Instruction::Shr:
+ if (!isa<UndefValue>(V2)) {
+ if (V1->getType()->isSigned())
+ return const_cast<Constant*>(V1); // undef >>s X -> undef
+ // undef >>u X -> 0
+ } else if (isa<UndefValue>(V1)) {
+ return const_cast<Constant*>(V1); // undef >> undef -> undef
+ } else {
+ if (V1->getType()->isSigned())
+ return const_cast<Constant*>(V1); // X >>s undef -> X
+ // X >>u undef -> 0
+ }
+ return Constant::getNullValue(V1->getType());
+
+ case Instruction::Shl:
+ // undef << X -> 0 X << undef -> 0
+ return Constant::getNullValue(V1->getType());
+ }
+ }
if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(V1)) {
if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
return const_cast<Constant*>(V1); // X & -1 == X
if (V2->isNullValue()) return const_cast<Constant*>(V2); // X & 0 == 0
if (CE1->getOpcode() == Instruction::Cast &&
- isa<ConstantPointerRef>(CE1->getOperand(0))) {
- ConstantPointerRef *CPR =cast<ConstantPointerRef>(CE1->getOperand(0));
+ isa<GlobalValue>(CE1->getOperand(0))) {
+ GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
// Functions are at least 4-byte aligned. If and'ing the address of a
// function with a constant < 4, fold it to zero.
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
- if (CI->getRawValue() < 4 && isa<Function>(CPR->getValue()))
+ if (CI->getRawValue() < 4 && isa<Function>(CPR))
return Constant::getNullValue(CI->getType());
}
break;
}
Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
- const std::vector<Constant*> &IdxList) {
+ const std::vector<Value*> &IdxList) {
if (IdxList.size() == 0 ||
- (IdxList.size() == 1 && IdxList[0]->isNullValue()))
+ (IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
return const_cast<Constant*>(C);
+ if (isa<UndefValue>(C)) {
+ const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
+ true);
+ assert(Ty != 0 && "Invalid indices for GEP!");
+ return UndefValue::get(PointerType::get(Ty));
+ }
+
+ Constant *Idx0 = cast<Constant>(IdxList[0]);
if (C->isNullValue()) {
bool isNull = true;
for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
- if (!IdxList[i]->isNullValue()) {
+ if (!cast<Constant>(IdxList[i])->isNullValue()) {
isNull = false;
break;
}
if (isNull) {
- std::vector<Value*> VIdxList(IdxList.begin(), IdxList.end());
- const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), VIdxList,
+ const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
true);
assert(Ty != 0 && "Invalid indices for GEP!");
return ConstantPointerNull::get(PointerType::get(Ty));
}
+
+ if (IdxList.size() == 1) {
+ const Type *ElTy = cast<PointerType>(C->getType())->getElementType();
+ if (unsigned ElSize = ElTy->getPrimitiveSize()) {
+ // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm
+ // type, we can statically fold this.
+ Constant *R = ConstantUInt::get(Type::UIntTy, ElSize);
+ R = ConstantExpr::getCast(R, Idx0->getType());
+ R = ConstantExpr::getMul(R, Idx0);
+ return ConstantExpr::getCast(R, C->getType());
+ }
+ }
}
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
I != E; ++I)
LastTy = *I;
- if ((LastTy && isa<ArrayType>(LastTy)) || IdxList[0]->isNullValue()) {
- std::vector<Constant*> NewIndices;
+ if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
+ std::vector<Value*> NewIndices;
NewIndices.reserve(IdxList.size() + CE->getNumOperands());
for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
- NewIndices.push_back(cast<Constant>(CE->getOperand(i)));
+ NewIndices.push_back(CE->getOperand(i));
// Add the last index of the source with the first index of the new GEP.
// Make sure to handle the case when they are actually different types.
Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
- if (!IdxList[0]->isNullValue()) { // Otherwise it must be an array
+ // Otherwise it must be an array.
+ if (!Idx0->isNullValue()) {
const Type *IdxTy = Combined->getType();
- if (IdxTy != IdxList[0]->getType()) IdxTy = Type::LongTy;
- Combined =
+ if (IdxTy != Idx0->getType()) IdxTy = Type::LongTy;
+ Combined =
ConstantExpr::get(Instruction::Add,
- ConstantExpr::getCast(IdxList[0], IdxTy),
+ ConstantExpr::getCast(Idx0, IdxTy),
ConstantExpr::getCast(Combined, IdxTy));
}
-
+
NewIndices.push_back(Combined);
NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
// To: int* getelementptr ([3 x int]* %X, long 0, long 0)
//
if (CE->getOpcode() == Instruction::Cast && IdxList.size() > 1 &&
- IdxList[0]->isNullValue())
- if (const PointerType *SPT =
+ Idx0->isNullValue())
+ if (const PointerType *SPT =
dyn_cast<PointerType>(CE->getOperand(0)->getType()))
if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
if (const ArrayType *CAT =
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