+++ /dev/null
-//===- Expressions.cpp - Expression Analysis Utilities --------------------===//
-//
-// 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 defines a package of expression analysis utilties:
-//
-// ClassifyExpression: Analyze an expression to determine the complexity of the
-// expression, and which other variables it depends on.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Analysis/Expressions.h"
-#include "llvm/Constants.h"
-#include "llvm/Function.h"
-#include "llvm/Type.h"
-#include <iostream>
-
-using namespace llvm;
-
-ExprType::ExprType(Value *Val) {
- if (Val)
- if (ConstantInt *CPI = dyn_cast<ConstantInt>(Val)) {
- Offset = CPI;
- Var = 0;
- ExprTy = Constant;
- Scale = 0;
- return;
- }
-
- Var = Val; Offset = 0;
- ExprTy = Var ? Linear : Constant;
- Scale = 0;
-}
-
-ExprType::ExprType(const ConstantInt *scale, Value *var,
- const ConstantInt *offset) {
- Scale = var ? scale : 0; Var = var; Offset = offset;
- ExprTy = Scale ? ScaledLinear : (Var ? Linear : Constant);
- if (Scale && Scale->isNullValue()) { // Simplify 0*Var + const
- Scale = 0; Var = 0;
- ExprTy = Constant;
- }
-}
-
-
-const Type *ExprType::getExprType(const Type *Default) const {
- if (Offset) return Offset->getType();
- if (Scale) return Scale->getType();
- return Var ? Var->getType() : Default;
-}
-
-
-namespace {
- class DefVal {
- const ConstantInt * const Val;
- const Type * const Ty;
- protected:
- inline DefVal(const ConstantInt *val, const Type *ty) : Val(val), Ty(ty) {}
- public:
- inline const Type *getType() const { return Ty; }
- inline const ConstantInt *getVal() const { return Val; }
- inline operator const ConstantInt * () const { return Val; }
- inline const ConstantInt *operator->() const { return Val; }
- };
-
- struct DefZero : public DefVal {
- inline DefZero(const ConstantInt *val, const Type *ty) : DefVal(val, ty) {}
- inline DefZero(const ConstantInt *val) : DefVal(val, val->getType()) {}
- };
-
- struct DefOne : public DefVal {
- inline DefOne(const ConstantInt *val, const Type *ty) : DefVal(val, ty) {}
- };
-}
-
-
-// getUnsignedConstant - Return a constant value of the specified type. If the
-// constant value is not valid for the specified type, return null. This cannot
-// happen for values in the range of 0 to 127.
-//
-static ConstantInt *getUnsignedConstant(uint64_t V, const Type *Ty) {
- if (isa<PointerType>(Ty)) Ty = Type::ULongTy;
- if (Ty->isSigned()) {
- // If this value is not a valid unsigned value for this type, return null!
- if (V > 127 && ((int64_t)V < 0 ||
- !ConstantSInt::isValueValidForType(Ty, (int64_t)V)))
- return 0;
- return ConstantSInt::get(Ty, V);
- } else {
- // If this value is not a valid unsigned value for this type, return null!
- if (V > 255 && !ConstantUInt::isValueValidForType(Ty, V))
- return 0;
- return ConstantUInt::get(Ty, V);
- }
-}
-
-// Add - Helper function to make later code simpler. Basically it just adds
-// the two constants together, inserts the result into the constant pool, and
-// returns it. Of course life is not simple, and this is no exception. Factors
-// that complicate matters:
-// 1. Either argument may be null. If this is the case, the null argument is
-// treated as either 0 (if DefOne = false) or 1 (if DefOne = true)
-// 2. Types get in the way. We want to do arithmetic operations without
-// regard for the underlying types. It is assumed that the constants are
-// integral constants. The new value takes the type of the left argument.
-// 3. If DefOne is true, a null return value indicates a value of 1, if DefOne
-// is false, a null return value indicates a value of 0.
-//
-static const ConstantInt *Add(const ConstantInt *Arg1,
- const ConstantInt *Arg2, bool DefOne) {
- assert(Arg1 && Arg2 && "No null arguments should exist now!");
- assert(Arg1->getType() == Arg2->getType() && "Types must be compatible!");
-
- // Actually perform the computation now!
- Constant *Result = ConstantExpr::get(Instruction::Add, (Constant*)Arg1,
- (Constant*)Arg2);
- ConstantInt *ResultI = cast<ConstantInt>(Result);
-
- // Check to see if the result is one of the special cases that we want to
- // recognize...
- if (ResultI->equalsInt(DefOne ? 1 : 0))
- return 0; // Yes it is, simply return null.
-
- return ResultI;
-}
-
-static inline const ConstantInt *operator+(const DefZero &L, const DefZero &R) {
- if (L == 0) return R;
- if (R == 0) return L;
- return Add(L, R, false);
-}
-
-static inline const ConstantInt *operator+(const DefOne &L, const DefOne &R) {
- if (L == 0) {
- if (R == 0)
- return getUnsignedConstant(2, L.getType());
- else
- return Add(getUnsignedConstant(1, L.getType()), R, true);
- } else if (R == 0) {
- return Add(L, getUnsignedConstant(1, L.getType()), true);
- }
- return Add(L, R, true);
-}
-
-
-// Mul - Helper function to make later code simpler. Basically it just
-// multiplies the two constants together, inserts the result into the constant
-// pool, and returns it. Of course life is not simple, and this is no
-// exception. Factors that complicate matters:
-// 1. Either argument may be null. If this is the case, the null argument is
-// treated as either 0 (if DefOne = false) or 1 (if DefOne = true)
-// 2. Types get in the way. We want to do arithmetic operations without
-// regard for the underlying types. It is assumed that the constants are
-// integral constants.
-// 3. If DefOne is true, a null return value indicates a value of 1, if DefOne
-// is false, a null return value indicates a value of 0.
-//
-static inline const ConstantInt *Mul(const ConstantInt *Arg1,
- const ConstantInt *Arg2, bool DefOne) {
- assert(Arg1 && Arg2 && "No null arguments should exist now!");
- assert(Arg1->getType() == Arg2->getType() && "Types must be compatible!");
-
- // Actually perform the computation now!
- Constant *Result = ConstantExpr::get(Instruction::Mul, (Constant*)Arg1,
- (Constant*)Arg2);
- assert(Result && Result->getType() == Arg1->getType() &&
- "Couldn't perform multiplication!");
- ConstantInt *ResultI = cast<ConstantInt>(Result);
-
- // Check to see if the result is one of the special cases that we want to
- // recognize...
- if (ResultI->equalsInt(DefOne ? 1 : 0))
- return 0; // Yes it is, simply return null.
-
- return ResultI;
-}
-
-namespace {
- inline const ConstantInt *operator*(const DefZero &L, const DefZero &R) {
- if (L == 0 || R == 0) return 0;
- return Mul(L, R, false);
- }
- inline const ConstantInt *operator*(const DefOne &L, const DefZero &R) {
- if (R == 0) return getUnsignedConstant(0, L.getType());
- if (L == 0) return R->equalsInt(1) ? 0 : R.getVal();
- return Mul(L, R, true);
- }
- inline const ConstantInt *operator*(const DefZero &L, const DefOne &R) {
- if (L == 0 || R == 0) return L.getVal();
- return Mul(R, L, false);
- }
-}
-
-// handleAddition - Add two expressions together, creating a new expression that
-// represents the composite of the two...
-//
-static ExprType handleAddition(ExprType Left, ExprType Right, Value *V) {
- const Type *Ty = V->getType();
- if (Left.ExprTy > Right.ExprTy)
- std::swap(Left, Right); // Make left be simpler than right
-
- switch (Left.ExprTy) {
- case ExprType::Constant:
- return ExprType(Right.Scale, Right.Var,
- DefZero(Right.Offset, Ty) + DefZero(Left.Offset, Ty));
- case ExprType::Linear: // RHS side must be linear or scaled
- case ExprType::ScaledLinear: // RHS must be scaled
- if (Left.Var != Right.Var) // Are they the same variables?
- return V; // if not, we don't know anything!
-
- return ExprType(DefOne(Left.Scale , Ty) + DefOne(Right.Scale , Ty),
- Right.Var,
- DefZero(Left.Offset, Ty) + DefZero(Right.Offset, Ty));
- default:
- assert(0 && "Dont' know how to handle this case!");
- return ExprType();
- }
-}
-
-// negate - Negate the value of the specified expression...
-//
-static inline ExprType negate(const ExprType &E, Value *V) {
- const Type *Ty = V->getType();
- ConstantInt *Zero = getUnsignedConstant(0, Ty);
- ConstantInt *One = getUnsignedConstant(1, Ty);
- ConstantInt *NegOne = cast<ConstantInt>(ConstantExpr::get(Instruction::Sub,
- Zero, One));
- if (NegOne == 0) return V; // Couldn't subtract values...
-
- return ExprType(DefOne (E.Scale , Ty) * NegOne, E.Var,
- DefZero(E.Offset, Ty) * NegOne);
-}
-
-
-// ClassifyExpr: Analyze an expression to determine the complexity of the
-// expression, and which other values it depends on.
-//
-// Note that this analysis cannot get into infinite loops because it treats PHI
-// nodes as being an unknown linear expression.
-//
-ExprType llvm::ClassifyExpr(Value *Expr) {
- assert(Expr != 0 && "Can't classify a null expression!");
- if (Expr->getType()->isFloatingPoint())
- return Expr; // FIXME: Can't handle FP expressions
-
- if (Constant *C = dyn_cast<Constant>(Expr)) {
- if (ConstantInt *CPI = dyn_cast<ConstantInt>(cast<Constant>(Expr)))
- // It's an integral constant!
- return ExprType(CPI->isNullValue() ? 0 : CPI);
- return Expr;
- } else if (!isa<Instruction>(Expr)) {
- return Expr;
- }
-
-
- Instruction *I = cast<Instruction>(Expr);
- const Type *Ty = I->getType();
-
- switch (I->getOpcode()) { // Handle each instruction type separately
- case Instruction::Add: {
- ExprType Left (ClassifyExpr(I->getOperand(0)));
- ExprType Right(ClassifyExpr(I->getOperand(1)));
- return handleAddition(Left, Right, I);
- } // end case Instruction::Add
-
- case Instruction::Sub: {
- ExprType Left (ClassifyExpr(I->getOperand(0)));
- ExprType Right(ClassifyExpr(I->getOperand(1)));
- ExprType RightNeg = negate(Right, I);
- if (RightNeg.Var == I && !RightNeg.Offset && !RightNeg.Scale)
- return I; // Could not negate value...
- return handleAddition(Left, RightNeg, I);
- } // end case Instruction::Sub
-
- case Instruction::Shl: {
- ExprType Right(ClassifyExpr(I->getOperand(1)));
- if (Right.ExprTy != ExprType::Constant) break;
- ExprType Left(ClassifyExpr(I->getOperand(0)));
- if (Right.Offset == 0) return Left; // shl x, 0 = x
- assert(Right.Offset->getType() == Type::UByteTy &&
- "Shift amount must always be a unsigned byte!");
- uint64_t ShiftAmount = cast<ConstantUInt>(Right.Offset)->getValue();
- ConstantInt *Multiplier = getUnsignedConstant(1ULL << ShiftAmount, Ty);
-
- // We don't know how to classify it if they are shifting by more than what
- // is reasonable. In most cases, the result will be zero, but there is one
- // class of cases where it is not, so we cannot optimize without checking
- // for it. The case is when you are shifting a signed value by 1 less than
- // the number of bits in the value. For example:
- // %X = shl sbyte %Y, ubyte 7
- // will try to form an sbyte multiplier of 128, which will give a null
- // multiplier, even though the result is not 0. Until we can check for this
- // case, be conservative. TODO.
- //
- if (Multiplier == 0)
- return Expr;
-
- return ExprType(DefOne(Left.Scale, Ty) * Multiplier, Left.Var,
- DefZero(Left.Offset, Ty) * Multiplier);
- } // end case Instruction::Shl
-
- case Instruction::Mul: {
- ExprType Left (ClassifyExpr(I->getOperand(0)));
- ExprType Right(ClassifyExpr(I->getOperand(1)));
- if (Left.ExprTy > Right.ExprTy)
- std::swap(Left, Right); // Make left be simpler than right
-
- if (Left.ExprTy != ExprType::Constant) // RHS must be > constant
- return I; // Quadratic eqn! :(
-
- const ConstantInt *Offs = Left.Offset;
- if (Offs == 0) return ExprType();
- return ExprType( DefOne(Right.Scale , Ty) * Offs, Right.Var,
- DefZero(Right.Offset, Ty) * Offs);
- } // end case Instruction::Mul
-
- case Instruction::Cast: {
- ExprType Src(ClassifyExpr(I->getOperand(0)));
- const Type *DestTy = I->getType();
- if (isa<PointerType>(DestTy))
- DestTy = Type::ULongTy; // Pointer types are represented as ulong
-
- const Type *SrcValTy = Src.getExprType(0);
- if (!SrcValTy) return I;
- if (!SrcValTy->isLosslesslyConvertibleTo(DestTy)) {
- if (Src.ExprTy != ExprType::Constant)
- return I; // Converting cast, and not a constant value...
- }
-
- const ConstantInt *Offset = Src.Offset;
- const ConstantInt *Scale = Src.Scale;
- if (Offset) {
- const Constant *CPV = ConstantExpr::getCast((Constant*)Offset, DestTy);
- if (!isa<ConstantInt>(CPV)) return I;
- Offset = cast<ConstantInt>(CPV);
- }
- if (Scale) {
- const Constant *CPV = ConstantExpr::getCast((Constant*)Scale, DestTy);
- if (!CPV) return I;
- Scale = cast<ConstantInt>(CPV);
- }
- return ExprType(Scale, Src.Var, Offset);
- } // end case Instruction::Cast
- // TODO: Handle SUB, SHR?
-
- } // end switch
-
- // Otherwise, I don't know anything about this value!
- return I;
-}
projects / oota-llvm.git / commitdiff