-//===- ConstantHandling.cpp - Implement ConstantHandling.h ----------------===//
+//===- 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
+// (internal) ConstantFolding.h interface, which is used by the
+// ConstantExpr::get* methods to automatically fold constants when possible.
//
-// This file implements the various intrinsic operations, on constant values.
+// The current constant folding implementation is implemented in two pieces: the
+// template-based folder for simple primitive constants like ConstantInt, and
+// the special case hackery that we use to symbolically evaluate expressions
+// that use ConstantExprs.
//
//===----------------------------------------------------------------------===//
-#include "llvm/ConstantHandling.h"
-#include "llvm/Instruction.h"
+#include "ConstantFolding.h"
+#include "llvm/Constants.h"
+#include "llvm/Instructions.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Function.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
#include <cmath>
+using namespace llvm;
-AnnotationID ConstRules::AID(AnnotationManager::getID("opt::ConstRules",
- &ConstRules::find));
-
-// ConstantFoldInstruction - Attempt to constant fold the specified instruction.
-// If successful, the constant result is returned, if not, null is returned.
-//
-Constant *ConstantFoldInstruction(Instruction *I) {
- Constant *Op0 = 0;
- Constant *Op1 = 0;
-
- if (I->getNumOperands() != 0) { // Get first operand if it's a constant...
- Op0 = dyn_cast<Constant>(I->getOperand(0));
- if (Op0 == 0) return 0; // Not a constant?, can't fold
-
- if (I->getNumOperands() != 1) { // Get second operand if it's a constant...
- Op1 = dyn_cast<Constant>(I->getOperand(1));
- if (Op1 == 0) return 0; // Not a constant?, can't fold
- }
- }
+namespace {
+ struct ConstRules {
+ 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 *mul(const Constant *V1, const Constant *V2) const = 0;
+ virtual Constant *div(const Constant *V1, const Constant *V2) const = 0;
+ virtual Constant *rem(const Constant *V1, const Constant *V2) const = 0;
+ virtual Constant *op_and(const Constant *V1, const Constant *V2) const = 0;
+ virtual Constant *op_or (const Constant *V1, const Constant *V2) const = 0;
+ virtual Constant *op_xor(const Constant *V1, const Constant *V2) const = 0;
+ virtual Constant *shl(const Constant *V1, const Constant *V2) const = 0;
+ virtual Constant *shr(const Constant *V1, const Constant *V2) const = 0;
+ virtual Constant *lessthan(const Constant *V1, const Constant *V2) const =0;
+ virtual Constant *equalto(const Constant *V1, const Constant *V2) const = 0;
- switch (I->getOpcode()) {
- case Instruction::Cast:
- return ConstRules::get(*Op0)->castTo(Op0, I->getType());
- case Instruction::Not: return ~*Op0;
- case Instruction::Add: return *Op0 + *Op1;
- case Instruction::Sub: return *Op0 - *Op1;
- case Instruction::Mul: return *Op0 * *Op1;
- case Instruction::Div: return *Op0 / *Op1;
- case Instruction::Rem: return *Op0 % *Op1;
-
- case Instruction::SetEQ: return *Op0 == *Op1;
- case Instruction::SetNE: return *Op0 != *Op1;
- case Instruction::SetLE: return *Op0 <= *Op1;
- case Instruction::SetGE: return *Op0 >= *Op1;
- case Instruction::SetLT: return *Op0 < *Op1;
- case Instruction::SetGT: return *Op0 > *Op1;
- case Instruction::Shl: return *Op0 << *Op1;
- case Instruction::Shr: return *Op0 >> *Op1;
- default:
- return 0;
- }
-}
-
-Constant *ConstantFoldCastInstruction(const Constant *V, const Type *DestTy) {
- return ConstRules::get(*V)->castTo(V, DestTy);
-}
-
-Constant *ConstantFoldUnaryInstruction(unsigned Opcode, const Constant *V) {
- switch (Opcode) {
- case Instruction::Not: return ~*V;
- }
- return 0;
-}
-
-Constant *ConstantFoldBinaryInstruction(unsigned Opcode, const Constant *V1,
- const Constant *V2) {
- switch (Opcode) {
- case Instruction::Add: return *V1 + *V2;
- case Instruction::Sub: return *V1 - *V2;
- case Instruction::Mul: return *V1 * *V2;
- case Instruction::Div: return *V1 / *V2;
- case Instruction::Rem: return *V1 % *V2;
-
- case Instruction::SetEQ: return *V1 == *V2;
- case Instruction::SetNE: return *V1 != *V2;
- case Instruction::SetLE: return *V1 <= *V2;
- case Instruction::SetGE: return *V1 >= *V2;
- case Instruction::SetLT: return *V1 < *V2;
- case Instruction::SetGT: return *V1 > *V2;
- }
- return 0;
-}
-
-Constant *ConstantFoldShiftInstruction(unsigned Opcode, const Constant *V1,
- const Constant *V2) {
- switch (Opcode) {
- case Instruction::Shl: return *V1 << *V2;
- case Instruction::Shr: return *V1 >> *V2;
- default: return 0;
- }
+ // Casting operators.
+ virtual Constant *castToBool (const Constant *V) const = 0;
+ virtual Constant *castToSByte (const Constant *V) const = 0;
+ virtual Constant *castToUByte (const Constant *V) const = 0;
+ virtual Constant *castToShort (const Constant *V) const = 0;
+ virtual Constant *castToUShort(const Constant *V) const = 0;
+ virtual Constant *castToInt (const Constant *V) const = 0;
+ virtual Constant *castToUInt (const Constant *V) const = 0;
+ virtual Constant *castToLong (const Constant *V) const = 0;
+ virtual Constant *castToULong (const Constant *V) const = 0;
+ virtual Constant *castToFloat (const Constant *V) 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.
+ //
+ static ConstRules &get(const Constant *V1, const Constant *V2);
+ private:
+ ConstRules(const ConstRules &); // Do not implement
+ ConstRules &operator=(const ConstRules &); // Do not implement
+ };
}
// Redirecting functions that cast to the appropriate types
//===--------------------------------------------------------------------===//
- virtual Constant *op_not(const Constant *V) const {
- return SubClassName::Not((const ArgType *)V);
- }
-
-
- virtual Constant *add(const Constant *V1,
- const Constant *V2) const {
+ 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 {
+ 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 {
+ 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 {
+ 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 {
+ virtual Constant *rem(const Constant *V1, const Constant *V2) const {
return SubClassName::Rem((const ArgType *)V1, (const ArgType *)V2);
}
- virtual Constant *shl(const Constant *V1,
- const Constant *V2) const {
+ 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_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 *shr(const Constant *V1,
- const Constant *V2) const {
+ virtual Constant *shr(const Constant *V1, const Constant *V2) const {
return SubClassName::Shr((const ArgType *)V1, (const ArgType *)V2);
}
- virtual ConstantBool *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 {
+ return SubClassName::EqualTo((const ArgType *)V1, (const ArgType *)V2);
+ }
// Casting operators. ick
- virtual ConstantBool *castToBool(const Constant *V) const {
+ virtual Constant *castToBool(const Constant *V) const {
return SubClassName::CastToBool((const ArgType*)V);
}
- virtual ConstantSInt *castToSByte(const Constant *V) const {
+ virtual Constant *castToSByte(const Constant *V) const {
return SubClassName::CastToSByte((const ArgType*)V);
}
- virtual ConstantUInt *castToUByte(const Constant *V) const {
+ virtual Constant *castToUByte(const Constant *V) const {
return SubClassName::CastToUByte((const ArgType*)V);
}
- virtual ConstantSInt *castToShort(const Constant *V) const {
+ virtual Constant *castToShort(const Constant *V) const {
return SubClassName::CastToShort((const ArgType*)V);
}
- virtual ConstantUInt *castToUShort(const Constant *V) const {
+ virtual Constant *castToUShort(const Constant *V) const {
return SubClassName::CastToUShort((const ArgType*)V);
}
- virtual ConstantSInt *castToInt(const Constant *V) const {
+ virtual Constant *castToInt(const Constant *V) const {
return SubClassName::CastToInt((const ArgType*)V);
}
- virtual ConstantUInt *castToUInt(const Constant *V) const {
+ virtual Constant *castToUInt(const Constant *V) const {
return SubClassName::CastToUInt((const ArgType*)V);
}
- virtual ConstantSInt *castToLong(const Constant *V) const {
+ virtual Constant *castToLong(const Constant *V) const {
return SubClassName::CastToLong((const ArgType*)V);
}
- virtual ConstantUInt *castToULong(const Constant *V) const {
+ virtual Constant *castToULong(const Constant *V) const {
return SubClassName::CastToULong((const ArgType*)V);
}
- virtual ConstantFP *castToFloat(const Constant *V) const {
+ virtual Constant *castToFloat(const Constant *V) const {
return SubClassName::CastToFloat((const ArgType*)V);
}
- virtual ConstantFP *castToDouble(const Constant *V) const {
+ virtual Constant *castToDouble(const Constant *V) const {
return SubClassName::CastToDouble((const ArgType*)V);
}
- virtual ConstantPointer *castToPointer(const Constant *V,
- const PointerType *Ty) const {
+ virtual Constant *castToPointer(const Constant *V,
+ const PointerType *Ty) const {
return SubClassName::CastToPointer((const ArgType*)V, Ty);
}
// Default "noop" implementations
//===--------------------------------------------------------------------===//
- inline static Constant *Not(const ArgType *V) { return 0; }
-
- inline static Constant *Add(const ArgType *V1, const ArgType *V2) {
- return 0;
- }
- inline static Constant *Sub(const ArgType *V1, const ArgType *V2) {
- return 0;
- }
- inline static Constant *Mul(const ArgType *V1, const ArgType *V2) {
- return 0;
- }
- inline static Constant *Div(const ArgType *V1, const ArgType *V2) {
+ static Constant *Add(const ArgType *V1, const ArgType *V2) { return 0; }
+ static Constant *Sub(const ArgType *V1, const ArgType *V2) { return 0; }
+ static Constant *Mul(const ArgType *V1, const ArgType *V2) { return 0; }
+ static Constant *Div(const ArgType *V1, const ArgType *V2) { return 0; }
+ static Constant *Rem(const ArgType *V1, const ArgType *V2) { return 0; }
+ static Constant *And(const ArgType *V1, const ArgType *V2) { return 0; }
+ static Constant *Or (const ArgType *V1, const ArgType *V2) { return 0; }
+ static Constant *Xor(const ArgType *V1, const ArgType *V2) { return 0; }
+ static Constant *Shl(const ArgType *V1, const ArgType *V2) { return 0; }
+ static Constant *Shr(const ArgType *V1, const ArgType *V2) { return 0; }
+ static Constant *LessThan(const ArgType *V1, const ArgType *V2) {
return 0;
}
- inline static Constant *Rem(const ArgType *V1, const ArgType *V2) {
- return 0;
- }
- inline static Constant *Shl(const ArgType *V1, const ArgType *V2) {
- return 0;
- }
- inline static Constant *Shr(const ArgType *V1, const ArgType *V2) {
- return 0;
- }
- inline static ConstantBool *LessThan(const ArgType *V1, const ArgType *V2) {
+ static Constant *EqualTo(const ArgType *V1, const ArgType *V2) {
return 0;
}
// Casting operators. ick
- inline static ConstantBool *CastToBool (const Constant *V) { return 0; }
- inline static ConstantSInt *CastToSByte (const Constant *V) { return 0; }
- inline static ConstantUInt *CastToUByte (const Constant *V) { return 0; }
- inline static ConstantSInt *CastToShort (const Constant *V) { return 0; }
- inline static ConstantUInt *CastToUShort(const Constant *V) { return 0; }
- inline static ConstantSInt *CastToInt (const Constant *V) { return 0; }
- inline static ConstantUInt *CastToUInt (const Constant *V) { return 0; }
- inline static ConstantSInt *CastToLong (const Constant *V) { return 0; }
- inline static ConstantUInt *CastToULong (const Constant *V) { return 0; }
- inline static ConstantFP *CastToFloat (const Constant *V) { return 0; }
- inline static ConstantFP *CastToDouble(const Constant *V) { return 0; }
- inline static ConstantPointer *CastToPointer(const Constant *,
- const PointerType *) {return 0;}
+ static Constant *CastToBool (const Constant *V) { return 0; }
+ static Constant *CastToSByte (const Constant *V) { return 0; }
+ static Constant *CastToUByte (const Constant *V) { return 0; }
+ static Constant *CastToShort (const Constant *V) { return 0; }
+ static Constant *CastToUShort(const Constant *V) { return 0; }
+ static Constant *CastToInt (const Constant *V) { return 0; }
+ static Constant *CastToUInt (const Constant *V) { return 0; }
+ static Constant *CastToLong (const Constant *V) { return 0; }
+ static Constant *CastToULong (const Constant *V) { return 0; }
+ static Constant *CastToFloat (const Constant *V) { return 0; }
+ static Constant *CastToDouble(const Constant *V) { return 0; }
+ static Constant *CastToPointer(const Constant *,
+ const PointerType *) {return 0;}
};
// EmptyRules provides a concrete base class of ConstRules that does nothing
//
struct EmptyRules : public TemplateRules<Constant, EmptyRules> {
+ static Constant *EqualTo(const Constant *V1, const Constant *V2) {
+ if (V1 == V2) return ConstantBool::True;
+ return 0;
+ }
};
//
struct BoolRules : public TemplateRules<ConstantBool, BoolRules> {
- inline static Constant *Not(const ConstantBool *V) {
- return ConstantBool::get(!V->getValue());
+ static Constant *LessThan(const ConstantBool *V1, const ConstantBool *V2){
+ return ConstantBool::get(V1->getValue() < V2->getValue());
}
- inline static Constant *Or(const ConstantBool *V1,
- const ConstantBool *V2) {
- return ConstantBool::get(V1->getValue() | V2->getValue());
+ static Constant *EqualTo(const Constant *V1, const Constant *V2) {
+ return ConstantBool::get(V1 == V2);
}
- inline static Constant *And(const ConstantBool *V1,
- const ConstantBool *V2) {
+ static Constant *And(const ConstantBool *V1, const ConstantBool *V2) {
return ConstantBool::get(V1->getValue() & V2->getValue());
}
+
+ static Constant *Or(const ConstantBool *V1, const ConstantBool *V2) {
+ return ConstantBool::get(V1->getValue() | V2->getValue());
+ }
+
+ static Constant *Xor(const ConstantBool *V1, const ConstantBool *V2) {
+ return ConstantBool::get(V1->getValue() ^ V2->getValue());
+ }
+
+ // Casting operators. ick
+#define DEF_CAST(TYPE, CLASS, CTYPE) \
+ static Constant *CastTo##TYPE (const ConstantBool *V) { \
+ return CLASS::get(Type::TYPE##Ty, (CTYPE)(bool)V->getValue()); \
+ }
+
+ DEF_CAST(Bool , ConstantBool, bool)
+ DEF_CAST(SByte , ConstantSInt, signed char)
+ DEF_CAST(UByte , ConstantUInt, unsigned char)
+ DEF_CAST(Short , ConstantSInt, signed short)
+ DEF_CAST(UShort, ConstantUInt, unsigned short)
+ DEF_CAST(Int , ConstantSInt, signed int)
+ DEF_CAST(UInt , ConstantUInt, unsigned int)
+ DEF_CAST(Long , ConstantSInt, int64_t)
+ DEF_CAST(ULong , ConstantUInt, uint64_t)
+ DEF_CAST(Float , ConstantFP , float)
+ DEF_CAST(Double, ConstantFP , double)
+#undef DEF_CAST
};
//===----------------------------------------------------------------------===//
-// PointerRules Class
+// NullPointerRules Class
//===----------------------------------------------------------------------===//
//
-// PointerRules provides a concrete base class of ConstRules for pointer types
+// NullPointerRules provides a concrete base class of ConstRules for null
+// pointers.
//
-struct PointerRules : public TemplateRules<ConstantPointer, PointerRules> {
- inline static ConstantBool *CastToBool (const Constant *V) {
- if (V->isNullValue()) return ConstantBool::False;
- return 0; // Can't const prop other types of pointers
+struct NullPointerRules : public TemplateRules<ConstantPointerNull,
+ NullPointerRules> {
+ static Constant *EqualTo(const Constant *V1, const Constant *V2) {
+ return ConstantBool::True; // Null pointers are always equal
}
- inline static ConstantSInt *CastToSByte (const Constant *V) {
- if (V->isNullValue()) return ConstantSInt::get(Type::SByteTy, 0);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToBool(const Constant *V) {
+ return ConstantBool::False;
}
- inline static ConstantUInt *CastToUByte (const Constant *V) {
- if (V->isNullValue()) return ConstantUInt::get(Type::UByteTy, 0);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToSByte (const Constant *V) {
+ return ConstantSInt::get(Type::SByteTy, 0);
}
- inline static ConstantSInt *CastToShort (const Constant *V) {
- if (V->isNullValue()) return ConstantSInt::get(Type::ShortTy, 0);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToUByte (const Constant *V) {
+ return ConstantUInt::get(Type::UByteTy, 0);
}
- inline static ConstantUInt *CastToUShort(const Constant *V) {
- if (V->isNullValue()) return ConstantUInt::get(Type::UShortTy, 0);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToShort (const Constant *V) {
+ return ConstantSInt::get(Type::ShortTy, 0);
}
- inline static ConstantSInt *CastToInt (const Constant *V) {
- if (V->isNullValue()) return ConstantSInt::get(Type::IntTy, 0);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToUShort(const Constant *V) {
+ return ConstantUInt::get(Type::UShortTy, 0);
}
- inline static ConstantUInt *CastToUInt (const Constant *V) {
- if (V->isNullValue()) return ConstantUInt::get(Type::UIntTy, 0);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToInt (const Constant *V) {
+ return ConstantSInt::get(Type::IntTy, 0);
}
- inline static ConstantSInt *CastToLong (const Constant *V) {
- if (V->isNullValue()) return ConstantSInt::get(Type::LongTy, 0);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToUInt (const Constant *V) {
+ return ConstantUInt::get(Type::UIntTy, 0);
}
- inline static ConstantUInt *CastToULong (const Constant *V) {
- if (V->isNullValue()) return ConstantUInt::get(Type::ULongTy, 0);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToLong (const Constant *V) {
+ return ConstantSInt::get(Type::LongTy, 0);
}
- inline static ConstantFP *CastToFloat (const Constant *V) {
- if (V->isNullValue()) return ConstantFP::get(Type::FloatTy, 0);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToULong (const Constant *V) {
+ return ConstantUInt::get(Type::ULongTy, 0);
}
- inline static ConstantFP *CastToDouble(const Constant *V) {
- if (V->isNullValue()) return ConstantFP::get(Type::DoubleTy, 0);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToFloat (const Constant *V) {
+ return ConstantFP::get(Type::FloatTy, 0);
+ }
+ static Constant *CastToDouble(const Constant *V) {
+ return ConstantFP::get(Type::DoubleTy, 0);
}
- inline static ConstantPointer *CastToPointer(const ConstantPointer *V,
- const PointerType *PTy) {
- if (V->getType() == PTy)
- return const_cast<ConstantPointer*>(V); // Allow cast %PTy %ptr to %PTy
- if (V->isNullValue())
- return ConstantPointerNull::get(PTy);
- return 0; // Can't const prop other types of pointers
+ static Constant *CastToPointer(const ConstantPointerNull *V,
+ const PointerType *PTy) {
+ return ConstantPointerNull::get(PTy);
}
};
//
template<class ConstantClass, class BuiltinType, Type **Ty, class SuperClass>
struct DirectRules : public TemplateRules<ConstantClass, SuperClass> {
- inline static Constant *Add(const ConstantClass *V1,
- const ConstantClass *V2) {
- BuiltinType Result = (BuiltinType)V1->getValue() +
- (BuiltinType)V2->getValue();
- return ConstantClass::get(*Ty, Result);
+ static Constant *Add(const ConstantClass *V1, const ConstantClass *V2) {
+ BuiltinType R = (BuiltinType)V1->getValue() + (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
}
- inline static Constant *Sub(const ConstantClass *V1,
- const ConstantClass *V2) {
- BuiltinType Result = (BuiltinType)V1->getValue() -
- (BuiltinType)V2->getValue();
- return ConstantClass::get(*Ty, Result);
+ static Constant *Sub(const ConstantClass *V1, const ConstantClass *V2) {
+ BuiltinType R = (BuiltinType)V1->getValue() - (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
}
- inline static Constant *Mul(const ConstantClass *V1,
- const ConstantClass *V2) {
- BuiltinType Result = (BuiltinType)V1->getValue() *
- (BuiltinType)V2->getValue();
- return ConstantClass::get(*Ty, Result);
+ static Constant *Mul(const ConstantClass *V1, const ConstantClass *V2) {
+ BuiltinType R = (BuiltinType)V1->getValue() * (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
}
- inline static Constant *Div(const ConstantClass *V1,
- const ConstantClass *V2) {
+ static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
if (V2->isNullValue()) return 0;
- BuiltinType Result = (BuiltinType)V1->getValue() /
- (BuiltinType)V2->getValue();
- return ConstantClass::get(*Ty, Result);
+ BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
}
- inline static ConstantBool *LessThan(const ConstantClass *V1,
- const ConstantClass *V2) {
- bool Result = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue();
- return ConstantBool::get(Result);
+ static Constant *LessThan(const ConstantClass *V1, const ConstantClass *V2) {
+ bool R = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue();
+ return ConstantBool::get(R);
}
- inline static ConstantPointer *CastToPointer(const ConstantClass *V,
- const PointerType *PTy) {
+ static Constant *EqualTo(const ConstantClass *V1, const ConstantClass *V2) {
+ bool R = (BuiltinType)V1->getValue() == (BuiltinType)V2->getValue();
+ return ConstantBool::get(R);
+ }
+
+ static Constant *CastToPointer(const ConstantClass *V,
+ const PointerType *PTy) {
if (V->isNullValue()) // Is it a FP or Integral null value?
return ConstantPointerNull::get(PTy);
return 0; // Can't const prop other types of pointers
// Casting operators. ick
#define DEF_CAST(TYPE, CLASS, CTYPE) \
- inline static CLASS *CastTo##TYPE (const ConstantClass *V) { \
+ static Constant *CastTo##TYPE (const ConstantClass *V) { \
return CLASS::get(Type::TYPE##Ty, (CTYPE)(BuiltinType)V->getValue()); \
}
struct DirectIntRules
: public DirectRules<ConstantClass, BuiltinType, Ty,
DirectIntRules<ConstantClass, BuiltinType, Ty> > {
- inline static Constant *Not(const ConstantClass *V) {
- return ConstantClass::get(*Ty, ~(BuiltinType)V->getValue());;
- }
- inline static Constant *Rem(const ConstantClass *V1,
- const ConstantClass *V2) {
+ static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
if (V2->isNullValue()) return 0;
- BuiltinType Result = (BuiltinType)V1->getValue() %
- (BuiltinType)V2->getValue();
- return ConstantClass::get(*Ty, Result);
+ if (V2->isAllOnesValue() && // MIN_INT / -1
+ (BuiltinType)V1->getValue() == -(BuiltinType)V1->getValue())
+ return 0;
+ BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
}
- inline static Constant *Shl(const ConstantClass *V1,
- const ConstantClass *V2) {
- BuiltinType Result = (BuiltinType)V1->getValue() <<
- (BuiltinType)V2->getValue();
- return ConstantClass::get(*Ty, Result);
+ static Constant *Rem(const ConstantClass *V1,
+ const ConstantClass *V2) {
+ if (V2->isNullValue()) return 0; // X / 0
+ if (V2->isAllOnesValue() && // MIN_INT / -1
+ (BuiltinType)V1->getValue() == -(BuiltinType)V1->getValue())
+ return 0;
+ BuiltinType R = (BuiltinType)V1->getValue() % (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
}
- inline static Constant *Shr(const ConstantClass *V1,
- const ConstantClass *V2) {
- BuiltinType Result = (BuiltinType)V1->getValue() >>
- (BuiltinType)V2->getValue();
- return ConstantClass::get(*Ty, Result);
+ static Constant *And(const ConstantClass *V1, const ConstantClass *V2) {
+ BuiltinType R = (BuiltinType)V1->getValue() & (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
+ }
+ static Constant *Or(const ConstantClass *V1, const ConstantClass *V2) {
+ BuiltinType R = (BuiltinType)V1->getValue() | (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
+ }
+ static Constant *Xor(const ConstantClass *V1, const ConstantClass *V2) {
+ BuiltinType R = (BuiltinType)V1->getValue() ^ (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
+ }
+
+ static Constant *Shl(const ConstantClass *V1, const ConstantClass *V2) {
+ BuiltinType R = (BuiltinType)V1->getValue() << (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
+ }
+
+ static Constant *Shr(const ConstantClass *V1, const ConstantClass *V2) {
+ BuiltinType R = (BuiltinType)V1->getValue() >> (BuiltinType)V2->getValue();
+ return ConstantClass::get(*Ty, R);
}
};
// DirectFPRules Class
//===----------------------------------------------------------------------===//
//
-// DirectFPRules provides implementations of functions that are valid on
-// floating point types, but not all types in general.
-//
+/// DirectFPRules provides implementations of functions that are valid on
+/// floating point types, but not all types in general.
+///
template <class ConstantClass, class BuiltinType, Type **Ty>
struct DirectFPRules
: public DirectRules<ConstantClass, BuiltinType, Ty,
DirectFPRules<ConstantClass, BuiltinType, Ty> > {
- inline static Constant *Rem(const ConstantClass *V1,
- const ConstantClass *V2) {
+ static Constant *Rem(const ConstantClass *V1, const ConstantClass *V2) {
if (V2->isNullValue()) return 0;
BuiltinType Result = std::fmod((BuiltinType)V1->getValue(),
(BuiltinType)V2->getValue());
};
+/// ConstRules::get - This method returns the constant rules implementation that
+/// implements the semantics of the two specified constants.
+ConstRules &ConstRules::get(const Constant *V1, const Constant *V2) {
+ static EmptyRules EmptyR;
+ static BoolRules BoolR;
+ static NullPointerRules NullPointerR;
+ 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 DirectIntRules<ConstantUInt, unsigned short, &Type::UShortTy> UShortR;
+ static DirectIntRules<ConstantSInt, signed int , &Type::IntTy> IntR;
+ static DirectIntRules<ConstantUInt, unsigned int , &Type::UIntTy> UIntR;
+ static DirectIntRules<ConstantSInt, int64_t , &Type::LongTy> LongR;
+ static DirectIntRules<ConstantUInt, uint64_t , &Type::ULongTy> ULongR;
+ static DirectFPRules <ConstantFP , float , &Type::FloatTy> FloatR;
+ static DirectFPRules <ConstantFP , double , &Type::DoubleTy> DoubleR;
+
+ if (isa<ConstantExpr>(V1) || isa<ConstantExpr>(V2) ||
+ isa<ConstantPointerRef>(V1) || isa<ConstantPointerRef>(V2))
+ return EmptyR;
+
+ switch (V1->getType()->getPrimitiveID()) {
+ default: assert(0 && "Unknown value type for constant folding!");
+ case Type::BoolTyID: return BoolR;
+ case Type::PointerTyID: return NullPointerR;
+ case Type::SByteTyID: return SByteR;
+ case Type::UByteTyID: return UByteR;
+ case Type::ShortTyID: return ShortR;
+ case Type::UShortTyID: return UShortR;
+ case Type::IntTyID: return IntR;
+ case Type::UIntTyID: return UIntR;
+ case Type::LongTyID: return LongR;
+ case Type::ULongTyID: return ULongR;
+ case Type::FloatTyID: return FloatR;
+ case Type::DoubleTyID: return DoubleR;
+ }
+}
+
+
//===----------------------------------------------------------------------===//
-// DirectRules Subclasses
+// ConstantFold*Instruction Implementations
//===----------------------------------------------------------------------===//
//
-// Given the DirectRules class we can now implement lots of types with little
-// code. Thank goodness C++ compilers are great at stomping out layers of
-// templates... can you imagine having to do this all by hand? (/me is lazy :)
+// These methods contain the special case hackery required to symbolically
+// evaluate some constant expression cases, and use the ConstantRules class to
+// evaluate normal constants.
//
+static unsigned getSize(const Type *Ty) {
+ unsigned S = Ty->getPrimitiveSize();
+ return S ? S : 8; // Treat pointers at 8 bytes
+}
-// ConstRules::find - Return the constant rules that take care of the specified
-// type.
-//
-Annotation *ConstRules::find(AnnotationID AID, const Annotable *TyA, void *) {
- assert(AID == ConstRules::AID && "Bad annotation for factory!");
- const Type *Ty = cast<Type>((const Value*)TyA);
+Constant *llvm::ConstantFoldCastInstruction(const Constant *V,
+ const Type *DestTy) {
+ 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 (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))
+ 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 (!Op->getType()->isFloatingPoint() &&
+ !CE->getType()->isFloatingPoint() &&
+ !DestTy->getType()->isFloatingPoint()) {
+ unsigned S1 = getSize(Op->getType()), S2 = getSize(CE->getType());
+ unsigned S3 = getSize(DestTy);
+ if (Op->getType() == DestTy && S3 >= S2)
+ return Op;
+ if (S1 >= S2 && S2 >= S3)
+ return ConstantExpr::getCast(Op, DestTy);
+ if (S1 <= S2 && S2 >= S3 && S1 <= S3)
+ return ConstantExpr::getCast(Op, DestTy);
+ }
+ } else if (CE->getOpcode() == Instruction::GetElementPtr) {
+ // If all of the indexes in the GEP are null values, there is no pointer
+ // adjustment going on. We might as well cast the source pointer.
+ bool isAllNull = true;
+ for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
+ if (!CE->getOperand(i)->isNullValue()) {
+ isAllNull = false;
+ break;
+ }
+ if (isAllNull)
+ return ConstantExpr::getCast(CE->getOperand(0), DestTy);
+ }
+
+ ConstRules &Rules = ConstRules::get(V, V);
+
+ switch (DestTy->getPrimitiveID()) {
+ case Type::BoolTyID: return Rules.castToBool(V);
+ case Type::UByteTyID: return Rules.castToUByte(V);
+ case Type::SByteTyID: return Rules.castToSByte(V);
+ case Type::UShortTyID: return Rules.castToUShort(V);
+ case Type::ShortTyID: return Rules.castToShort(V);
+ case Type::UIntTyID: return Rules.castToUInt(V);
+ case Type::IntTyID: return Rules.castToInt(V);
+ case Type::ULongTyID: return Rules.castToULong(V);
+ case Type::LongTyID: return Rules.castToLong(V);
+ case Type::FloatTyID: return Rules.castToFloat(V);
+ case Type::DoubleTyID: return Rules.castToDouble(V);
+ case Type::PointerTyID:
+ return Rules.castToPointer(V, cast<PointerType>(DestTy));
+ default: return 0;
+ }
+}
+
+Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
+ const Constant *V1,
+ const Constant *V2) {
+ if (Cond == ConstantBool::True)
+ return const_cast<Constant*>(V1);
+ else if (Cond == ConstantBool::False)
+ return const_cast<Constant*>(V2);
+ return 0;
+}
+
+
+/// IdxCompare - Compare the two constants as though they were getelementptr
+/// indices. This allows coersion of the types to be the same thing.
+///
+/// If the two constants are the "same" (after coersion), return 0. If the
+/// 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) {
+ 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!
- switch (Ty->getPrimitiveID()) {
- case Type::BoolTyID: return new BoolRules();
- case Type::PointerTyID: return new PointerRules();
- case Type::SByteTyID:
- return new DirectIntRules<ConstantSInt, signed char , &Type::SByteTy>();
- case Type::UByteTyID:
- return new DirectIntRules<ConstantUInt, unsigned char , &Type::UByteTy>();
- case Type::ShortTyID:
- return new DirectIntRules<ConstantSInt, signed short, &Type::ShortTy>();
- case Type::UShortTyID:
- return new DirectIntRules<ConstantUInt, unsigned short, &Type::UShortTy>();
- case Type::IntTyID:
- return new DirectIntRules<ConstantSInt, signed int , &Type::IntTy>();
- case Type::UIntTyID:
- return new DirectIntRules<ConstantUInt, unsigned int , &Type::UIntTy>();
- case Type::LongTyID:
- return new DirectIntRules<ConstantSInt, int64_t , &Type::LongTy>();
- case Type::ULongTyID:
- return new DirectIntRules<ConstantUInt, uint64_t , &Type::ULongTy>();
- case Type::FloatTyID:
- return new DirectFPRules<ConstantFP , float , &Type::FloatTy>();
- case Type::DoubleTyID:
- return new DirectFPRules<ConstantFP , double , &Type::DoubleTy>();
- default:
- return new EmptyRules();
+ // 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 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())
+ return -1;
+ else
+ return 1;
+}
+
+/// 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
+/// 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).
+///
+static Instruction::BinaryOps evaluateRelation(const Constant *V1,
+ const 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 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)){
+ 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;
+ }
+
+ // Now we know that the RHS is a ConstantPointerRef 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??");
+ // FIXME: If both globals are external weak, they might both be null!
+ return Instruction::SetNE;
+ } else {
+ assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
+ // Global can never be null. FIXME: if we implement external weak
+ // linkage, this is not necessarily true!
+ return Instruction::SetNE;
+ }
+
+ } 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);
+ Constant *CE1Op0 = CE1->getOperand(0);
+
+ switch (CE1->getOpcode()) {
+ case Instruction::Cast:
+ // 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()))
+ return evaluateRelation(CE1Op0,
+ Constant::getNullValue(CE1Op0->getType()));
+
+ case Instruction::GetElementPtr:
+ // Ok, since this is a getelementptr, we know that the constant has a
+ // pointer type. Check the various cases.
+ 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)) {
+ // 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;
+ } else if (isa<ConstantPointerNull>(CE1Op0)) {
+ // If we are indexing from a null pointer, check to see if we have any
+ // non-zero indices.
+ for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
+ if (!CE1->getOperand(i)->isNullValue())
+ // Offsetting from null, must not be equal.
+ return Instruction::SetGT;
+ // Only zero indexes from null, must still be zero.
+ 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)) {
+ 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)) {
+ 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
+ // only have at most one index, and because we fold getelementptr's
+ // with a single zero index, it must be nonzero.
+ assert(CE1->getNumOperands() == 2 &&
+ !CE1->getOperand(1)->isNullValue() &&
+ "Suprising getelementptr!");
+ return Instruction::SetGT;
+ } else {
+ // If they are different globals, we don't know what the value is,
+ // but they can't be equal.
+ return Instruction::SetNE;
+ }
+ }
+ } else {
+ const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
+ const Constant *CE2Op0 = CE2->getOperand(0);
+
+ // There are MANY other foldings that we could perform here. They will
+ // probably be added on demand, as they seem needed.
+ switch (CE2->getOpcode()) {
+ default: break;
+ 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 (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))) {
+ case -1: return Instruction::SetLT;
+ case 1: return Instruction::SetGT;
+ case -2: return Instruction::BinaryOpsEnd;
+ }
+
+ // Ok, we ran out of things they have in common. If any leftovers
+ // 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;
+ for (; i < CE2->getNumOperands(); ++i)
+ if (!CE2->getOperand(i)->isNullValue())
+ return Instruction::SetLT;
+ return Instruction::SetEQ;
+ }
+ }
+ }
+
+ default:
+ break;
+ }
+ }
+
+ return Instruction::BinaryOpsEnd;
+}
+
+Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
+ const Constant *V1,
+ const Constant *V2) {
+ Constant *C = 0;
+ switch (Opcode) {
+ default: break;
+ case Instruction::Add: C = ConstRules::get(V1, V2).add(V1, V2); break;
+ case Instruction::Sub: C = ConstRules::get(V1, V2).sub(V1, V2); break;
+ case Instruction::Mul: C = ConstRules::get(V1, V2).mul(V1, V2); break;
+ case Instruction::Div: C = ConstRules::get(V1, V2).div(V1, V2); break;
+ case Instruction::Rem: C = ConstRules::get(V1, V2).rem(V1, V2); break;
+ case Instruction::And: C = ConstRules::get(V1, V2).op_and(V1, V2); break;
+ case Instruction::Or: C = ConstRules::get(V1, V2).op_or (V1, V2); break;
+ case Instruction::Xor: C = ConstRules::get(V1, V2).op_xor(V1, V2); break;
+ case Instruction::Shl: C = ConstRules::get(V1, V2).shl(V1, V2); break;
+ case Instruction::Shr: C = ConstRules::get(V1, V2).shr(V1, V2); break;
+ case Instruction::SetEQ: C = ConstRules::get(V1, V2).equalto(V1, V2); break;
+ case Instruction::SetLT: C = ConstRules::get(V1, V2).lessthan(V1, V2);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);
+ 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);
+ 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);
+ break;
+ }
+
+ // If we successfully folded the expression, return it now.
+ if (C) return C;
+
+ if (SetCondInst::isRelational(Opcode))
+ switch (evaluateRelation(V1, V2)) {
+ default: assert(0 && "Unknown relational!");
+ case Instruction::BinaryOpsEnd:
+ break; // Couldn't determine anything about these constants.
+ case Instruction::SetEQ: // We know the constants are equal!
+ // If we know the constants are equal, we can decide the result of this
+ // computation precisely.
+ return ConstantBool::get(Opcode == Instruction::SetEQ ||
+ Opcode == Instruction::SetLE ||
+ Opcode == Instruction::SetGE);
+ case Instruction::SetLT:
+ // If we know that V1 < V2, we can decide the result of this computation
+ // precisely.
+ return ConstantBool::get(Opcode == Instruction::SetLT ||
+ Opcode == Instruction::SetNE ||
+ Opcode == Instruction::SetLE);
+ case Instruction::SetGT:
+ // If we know that V1 > V2, we can decide the result of this computation
+ // precisely.
+ return ConstantBool::get(Opcode == Instruction::SetGT ||
+ Opcode == Instruction::SetNE ||
+ Opcode == Instruction::SetGE);
+ case Instruction::SetLE:
+ // If we know that V1 <= V2, we can only partially decide this relation.
+ if (Opcode == Instruction::SetGT) return ConstantBool::False;
+ if (Opcode == Instruction::SetLT) return ConstantBool::True;
+ break;
+
+ case Instruction::SetGE:
+ // If we know that V1 >= V2, we can only partially decide this relation.
+ 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 (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(V1)) {
+ if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
+ // There are many possible foldings we could do here. We should probably
+ // at least fold add of a pointer with an integer into the appropriate
+ // getelementptr. This will improve alias analysis a bit.
+
+
+
+
+ } else {
+ // Just implement a couple of simple identities.
+ switch (Opcode) {
+ case Instruction::Add:
+ if (V2->isNullValue()) return const_cast<Constant*>(V1); // X + 0 == X
+ break;
+ case Instruction::Sub:
+ if (V2->isNullValue()) return const_cast<Constant*>(V1); // X - 0 == X
+ break;
+ case Instruction::Mul:
+ if (V2->isNullValue()) return const_cast<Constant*>(V2); // X * 0 == 0
+ if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
+ if (CI->getRawValue() == 1)
+ return const_cast<Constant*>(V1); // X * 1 == X
+ break;
+ case Instruction::Div:
+ if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
+ if (CI->getRawValue() == 1)
+ return const_cast<Constant*>(V1); // X / 1 == X
+ break;
+ case Instruction::Rem:
+ if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
+ if (CI->getRawValue() == 1)
+ return Constant::getNullValue(CI->getType()); // X % 1 == 0
+ break;
+ case Instruction::And:
+ if (cast<ConstantIntegral>(V2)->isAllOnesValue())
+ 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));
+
+ // 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()))
+ return Constant::getNullValue(CI->getType());
+ }
+ break;
+ case Instruction::Or:
+ if (V2->isNullValue()) return const_cast<Constant*>(V1); // X | 0 == X
+ if (cast<ConstantIntegral>(V2)->isAllOnesValue())
+ return const_cast<Constant*>(V2); // X | -1 == -1
+ break;
+ case Instruction::Xor:
+ if (V2->isNullValue()) return const_cast<Constant*>(V1); // X ^ 0 == X
+ break;
+ }
+ }
+
+ } else if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
+ // If V2 is a constant expr and V1 isn't, flop them around and fold the
+ // other way if possible.
+ switch (Opcode) {
+ case Instruction::Add:
+ case Instruction::Mul:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::SetEQ:
+ case Instruction::SetNE:
+ // No change of opcode required.
+ return ConstantFoldBinaryInstruction(Opcode, V2, V1);
+
+ case Instruction::SetLT:
+ case Instruction::SetGT:
+ case Instruction::SetLE:
+ case Instruction::SetGE:
+ // Change the opcode as necessary to swap the operands.
+ Opcode = SetCondInst::getSwappedCondition((Instruction::BinaryOps)Opcode);
+ return ConstantFoldBinaryInstruction(Opcode, V2, V1);
+
+ case Instruction::Shl:
+ case Instruction::Shr:
+ case Instruction::Sub:
+ case Instruction::Div:
+ case Instruction::Rem:
+ default: // These instructions cannot be flopped around.
+ break;
+ }
+ }
+ return 0;
+}
+
+Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
+ const std::vector<Constant*> &IdxList) {
+ if (IdxList.size() == 0 ||
+ (IdxList.size() == 1 && IdxList[0]->isNullValue()))
+ return const_cast<Constant*>(C);
+
+ if (C->isNullValue()) {
+ bool isNull = true;
+ for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
+ if (!IdxList[i]->isNullValue()) {
+ isNull = false;
+ break;
+ }
+ if (isNull) {
+ std::vector<Value*> VIdxList(IdxList.begin(), IdxList.end());
+ const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), VIdxList,
+ true);
+ assert(Ty != 0 && "Invalid indices for GEP!");
+ return ConstantPointerNull::get(PointerType::get(Ty));
+ }
}
+
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
+ // Combine Indices - If the source pointer to this getelementptr instruction
+ // is a getelementptr instruction, combine the indices of the two
+ // getelementptr instructions into a single instruction.
+ //
+ if (CE->getOpcode() == Instruction::GetElementPtr) {
+ const Type *LastTy = 0;
+ for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
+ I != E; ++I)
+ LastTy = *I;
+
+ if ((LastTy && isa<ArrayType>(LastTy)) || IdxList[0]->isNullValue()) {
+ std::vector<Constant*> 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)));
+
+ // 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
+ Combined =
+ ConstantExpr::get(Instruction::Add,
+ ConstantExpr::getCast(IdxList[0], Type::LongTy),
+ ConstantExpr::getCast(Combined, Type::LongTy));
+
+ NewIndices.push_back(Combined);
+ NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
+ return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
+ }
+ }
+
+ // Implement folding of:
+ // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
+ // long 0, long 0)
+ // 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 =
+ dyn_cast<PointerType>(CE->getOperand(0)->getType()))
+ if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
+ if (const ArrayType *CAT =
+ dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
+ if (CAT->getElementType() == SAT->getElementType())
+ return ConstantExpr::getGetElementPtr(
+ (Constant*)CE->getOperand(0), IdxList);
+ }
+ return 0;
}
+
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