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llvm-mirror/include/llvm/Analysis/ScalarEvolutionExpressions.h
Chris Lattner a76347d917 Fix Transforms/IndVarsSimplify/2006-03-31-NegativeStride.ll and 
PR726 by performing consistent signed division, not consistent unsigned
division when evaluating scev's.  Do not touch udivs.

llvm-svn: 27326
2006-04-01 04:48:52 +00:00

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//===- llvm/Analysis/ScalarEvolutionExpressions.h - SCEV Exprs --*- C++ -*-===//
//
// 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 the classes used to represent and build scalar expressions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPRESSIONS_H
#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPRESSIONS_H
#include "llvm/Analysis/ScalarEvolution.h"
namespace llvm {
class ConstantInt;
class ConstantRange;
enum SCEVTypes {
// These should be ordered in terms of increasing complexity to make the
// folders simpler.
scConstant, scTruncate, scZeroExtend, scAddExpr, scMulExpr, scSDivExpr,
scAddRecExpr, scUnknown, scCouldNotCompute
};
//===--------------------------------------------------------------------===//
/// SCEVConstant - This class represents a constant integer value.
///
class SCEVConstant : public SCEV {
ConstantInt *V;
SCEVConstant(ConstantInt *v) : SCEV(scConstant), V(v) {}
virtual ~SCEVConstant();
public:
/// get method - This just gets and returns a new SCEVConstant object.
///
static SCEVHandle get(ConstantInt *V);
ConstantInt *getValue() const { return V; }
/// getValueRange - Return the tightest constant bounds that this value is
/// known to have. This method is only valid on integer SCEV objects.
virtual ConstantRange getValueRange() const;
virtual bool isLoopInvariant(const Loop *L) const {
return true;
}
virtual bool hasComputableLoopEvolution(const Loop *L) const {
return false; // Not loop variant
}
virtual const Type *getType() const;
SCEVHandle replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
const SCEVHandle &Conc) const {
return this;
}
virtual void print(std::ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVConstant *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scConstant;
}
};
//===--------------------------------------------------------------------===//
/// SCEVTruncateExpr - This class represents a truncation of an integer value
/// to a smaller integer value.
///
class SCEVTruncateExpr : public SCEV {
SCEVHandle Op;
const Type *Ty;
SCEVTruncateExpr(const SCEVHandle &op, const Type *ty);
virtual ~SCEVTruncateExpr();
public:
/// get method - This just gets and returns a new SCEVTruncate object
///
static SCEVHandle get(const SCEVHandle &Op, const Type *Ty);
const SCEVHandle &getOperand() const { return Op; }
virtual const Type *getType() const { return Ty; }
virtual bool isLoopInvariant(const Loop *L) const {
return Op->isLoopInvariant(L);
}
virtual bool hasComputableLoopEvolution(const Loop *L) const {
return Op->hasComputableLoopEvolution(L);
}
SCEVHandle replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
const SCEVHandle &Conc) const {
SCEVHandle H = Op->replaceSymbolicValuesWithConcrete(Sym, Conc);
if (H == Op)
return this;
return get(H, Ty);
}
/// getValueRange - Return the tightest constant bounds that this value is
/// known to have. This method is only valid on integer SCEV objects.
virtual ConstantRange getValueRange() const;
virtual void print(std::ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVTruncateExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scTruncate;
}
};
//===--------------------------------------------------------------------===//
/// SCEVZeroExtendExpr - This class represents a zero extension of a small
/// integer value to a larger integer value.
///
class SCEVZeroExtendExpr : public SCEV {
SCEVHandle Op;
const Type *Ty;
SCEVZeroExtendExpr(const SCEVHandle &op, const Type *ty);
virtual ~SCEVZeroExtendExpr();
public:
/// get method - This just gets and returns a new SCEVZeroExtend object
///
static SCEVHandle get(const SCEVHandle &Op, const Type *Ty);
const SCEVHandle &getOperand() const { return Op; }
virtual const Type *getType() const { return Ty; }
virtual bool isLoopInvariant(const Loop *L) const {
return Op->isLoopInvariant(L);
}
virtual bool hasComputableLoopEvolution(const Loop *L) const {
return Op->hasComputableLoopEvolution(L);
}
/// getValueRange - Return the tightest constant bounds that this value is
/// known to have. This method is only valid on integer SCEV objects.
virtual ConstantRange getValueRange() const;
SCEVHandle replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
const SCEVHandle &Conc) const {
SCEVHandle H = Op->replaceSymbolicValuesWithConcrete(Sym, Conc);
if (H == Op)
return this;
return get(H, Ty);
}
virtual void print(std::ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVZeroExtendExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scZeroExtend;
}
};
//===--------------------------------------------------------------------===//
/// SCEVCommutativeExpr - This node is the base class for n'ary commutative
/// operators.
///
class SCEVCommutativeExpr : public SCEV {
std::vector<SCEVHandle> Operands;
protected:
SCEVCommutativeExpr(enum SCEVTypes T, const std::vector<SCEVHandle> &ops)
: SCEV(T) {
Operands.reserve(ops.size());
Operands.insert(Operands.end(), ops.begin(), ops.end());
}
~SCEVCommutativeExpr();
public:
unsigned getNumOperands() const { return Operands.size(); }
const SCEVHandle &getOperand(unsigned i) const {
assert(i < Operands.size() && "Operand index out of range!");
return Operands[i];
}
const std::vector<SCEVHandle> &getOperands() const { return Operands; }
typedef std::vector<SCEVHandle>::const_iterator op_iterator;
op_iterator op_begin() const { return Operands.begin(); }
op_iterator op_end() const { return Operands.end(); }
virtual bool isLoopInvariant(const Loop *L) const {
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
if (!getOperand(i)->isLoopInvariant(L)) return false;
return true;
}
// hasComputableLoopEvolution - Commutative expressions have computable loop
// evolutions iff they have at least one operand that varies with the loop,
// but that all varying operands are computable.
virtual bool hasComputableLoopEvolution(const Loop *L) const {
bool HasVarying = false;
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
if (!getOperand(i)->isLoopInvariant(L))
if (getOperand(i)->hasComputableLoopEvolution(L))
HasVarying = true;
else
return false;
return HasVarying;
}
SCEVHandle replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
const SCEVHandle &Conc) const;
virtual const char *getOperationStr() const = 0;
virtual const Type *getType() const { return getOperand(0)->getType(); }
virtual void print(std::ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVCommutativeExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scAddExpr ||
S->getSCEVType() == scMulExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVAddExpr - This node represents an addition of some number of SCEVs.
///
class SCEVAddExpr : public SCEVCommutativeExpr {
SCEVAddExpr(const std::vector<SCEVHandle> &ops)
: SCEVCommutativeExpr(scAddExpr, ops) {
}
public:
static SCEVHandle get(std::vector<SCEVHandle> &Ops);
static SCEVHandle get(const SCEVHandle &LHS, const SCEVHandle &RHS) {
std::vector<SCEVHandle> Ops;
Ops.push_back(LHS);
Ops.push_back(RHS);
return get(Ops);
}
static SCEVHandle get(const SCEVHandle &Op0, const SCEVHandle &Op1,
const SCEVHandle &Op2) {
std::vector<SCEVHandle> Ops;
Ops.push_back(Op0);
Ops.push_back(Op1);
Ops.push_back(Op2);
return get(Ops);
}
virtual const char *getOperationStr() const { return " + "; }
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVAddExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scAddExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVMulExpr - This node represents multiplication of some number of SCEVs.
///
class SCEVMulExpr : public SCEVCommutativeExpr {
SCEVMulExpr(const std::vector<SCEVHandle> &ops)
: SCEVCommutativeExpr(scMulExpr, ops) {
}
public:
static SCEVHandle get(std::vector<SCEVHandle> &Ops);
static SCEVHandle get(const SCEVHandle &LHS, const SCEVHandle &RHS) {
std::vector<SCEVHandle> Ops;
Ops.push_back(LHS);
Ops.push_back(RHS);
return get(Ops);
}
virtual const char *getOperationStr() const { return " * "; }
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVMulExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scMulExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVSDivExpr - This class represents a binary unsigned division operation.
///
class SCEVSDivExpr : public SCEV {
SCEVHandle LHS, RHS;
SCEVSDivExpr(const SCEVHandle &lhs, const SCEVHandle &rhs)
: SCEV(scSDivExpr), LHS(lhs), RHS(rhs) {}
virtual ~SCEVSDivExpr();
public:
/// get method - This just gets and returns a new SCEVSDiv object.
///
static SCEVHandle get(const SCEVHandle &LHS, const SCEVHandle &RHS);
const SCEVHandle &getLHS() const { return LHS; }
const SCEVHandle &getRHS() const { return RHS; }
virtual bool isLoopInvariant(const Loop *L) const {
return LHS->isLoopInvariant(L) && RHS->isLoopInvariant(L);
}
virtual bool hasComputableLoopEvolution(const Loop *L) const {
return LHS->hasComputableLoopEvolution(L) &&
RHS->hasComputableLoopEvolution(L);
}
SCEVHandle replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
const SCEVHandle &Conc) const {
SCEVHandle L = LHS->replaceSymbolicValuesWithConcrete(Sym, Conc);
SCEVHandle R = RHS->replaceSymbolicValuesWithConcrete(Sym, Conc);
if (L == LHS && R == RHS)
return this;
else
return get(L, R);
}
virtual const Type *getType() const;
void print(std::ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVSDivExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scSDivExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVAddRecExpr - This node represents a polynomial recurrence on the trip
/// count of the specified loop.
///
/// All operands of an AddRec are required to be loop invariant.
///
class SCEVAddRecExpr : public SCEV {
std::vector<SCEVHandle> Operands;
const Loop *L;
SCEVAddRecExpr(const std::vector<SCEVHandle> &ops, const Loop *l)
: SCEV(scAddRecExpr), Operands(ops), L(l) {
for (unsigned i = 0, e = Operands.size(); i != e; ++i)
assert(Operands[i]->isLoopInvariant(l) &&
"Operands of AddRec must be loop-invariant!");
}
~SCEVAddRecExpr();
public:
static SCEVHandle get(const SCEVHandle &Start, const SCEVHandle &Step,
const Loop *);
static SCEVHandle get(std::vector<SCEVHandle> &Operands,
const Loop *);
static SCEVHandle get(const std::vector<SCEVHandle> &Operands,
const Loop *L) {
std::vector<SCEVHandle> NewOp(Operands);
return get(NewOp, L);
}
typedef std::vector<SCEVHandle>::const_iterator op_iterator;
op_iterator op_begin() const { return Operands.begin(); }
op_iterator op_end() const { return Operands.end(); }
unsigned getNumOperands() const { return Operands.size(); }
const SCEVHandle &getOperand(unsigned i) const { return Operands[i]; }
const SCEVHandle &getStart() const { return Operands[0]; }
const Loop *getLoop() const { return L; }
/// getStepRecurrence - This method constructs and returns the recurrence
/// indicating how much this expression steps by. If this is a polynomial
/// of degree N, it returns a chrec of degree N-1.
SCEVHandle getStepRecurrence() const {
if (getNumOperands() == 2) return getOperand(1);
return SCEVAddRecExpr::get(std::vector<SCEVHandle>(op_begin()+1,op_end()),
getLoop());
}
virtual bool hasComputableLoopEvolution(const Loop *QL) const {
if (L == QL) return true;
return false;
}
virtual bool isLoopInvariant(const Loop *QueryLoop) const;
virtual const Type *getType() const { return Operands[0]->getType(); }
/// isAffine - Return true if this is an affine AddRec (i.e., it represents
/// an expressions A+B*x where A and B are loop invariant values.
bool isAffine() const {
// We know that the start value is invariant. This expression is thus
// affine iff the step is also invariant.
return getNumOperands() == 2;
}
/// isQuadratic - Return true if this is an quadratic AddRec (i.e., it
/// represents an expressions A+B*x+C*x^2 where A, B and C are loop
/// invariant values. This corresponds to an addrec of the form {L,+,M,+,N}
bool isQuadratic() const {
return getNumOperands() == 3;
}
/// evaluateAtIteration - Return the value of this chain of recurrences at
/// the specified iteration number.
SCEVHandle evaluateAtIteration(SCEVHandle It) const;
/// getNumIterationsInRange - Return the number of iterations of this loop
/// that produce values in the specified constant range. Another way of
/// looking at this is that it returns the first iteration number where the
/// value is not in the condition, thus computing the exit count. If the
/// iteration count can't be computed, an instance of SCEVCouldNotCompute is
/// returned.
SCEVHandle getNumIterationsInRange(ConstantRange Range) const;
SCEVHandle replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
const SCEVHandle &Conc) const;
virtual void print(std::ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVAddRecExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scAddRecExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVUnknown - This means that we are dealing with an entirely unknown SCEV
/// value, and only represent it as it's LLVM Value. This is the "bottom"
/// value for the analysis.
///
class SCEVUnknown : public SCEV {
Value *V;
SCEVUnknown(Value *v) : SCEV(scUnknown), V(v) {}
protected:
~SCEVUnknown();
public:
/// get method - For SCEVUnknown, this just gets and returns a new
/// SCEVUnknown.
static SCEVHandle get(Value *V);
/// getIntegerSCEV - Given an integer or FP type, create a constant for the
/// specified signed integer value and return a SCEV for the constant.
static SCEVHandle getIntegerSCEV(int Val, const Type *Ty);
Value *getValue() const { return V; }
virtual bool isLoopInvariant(const Loop *L) const;
virtual bool hasComputableLoopEvolution(const Loop *QL) const {
return false; // not computable
}
SCEVHandle replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
const SCEVHandle &Conc) const {
if (&*Sym == this) return Conc;
return this;
}
virtual const Type *getType() const;
virtual void print(std::ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVUnknown *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scUnknown;
}
};
/// SCEVVisitor - This class defines a simple visitor class that may be used
/// for various SCEV analysis purposes.
template<typename SC, typename RetVal=void>
struct SCEVVisitor {
RetVal visit(SCEV *S) {
switch (S->getSCEVType()) {
case scConstant:
return ((SC*)this)->visitConstant((SCEVConstant*)S);
case scTruncate:
return ((SC*)this)->visitTruncateExpr((SCEVTruncateExpr*)S);
case scZeroExtend:
return ((SC*)this)->visitZeroExtendExpr((SCEVZeroExtendExpr*)S);
case scAddExpr:
return ((SC*)this)->visitAddExpr((SCEVAddExpr*)S);
case scMulExpr:
return ((SC*)this)->visitMulExpr((SCEVMulExpr*)S);
case scSDivExpr:
return ((SC*)this)->visitSDivExpr((SCEVSDivExpr*)S);
case scAddRecExpr:
return ((SC*)this)->visitAddRecExpr((SCEVAddRecExpr*)S);
case scUnknown:
return ((SC*)this)->visitUnknown((SCEVUnknown*)S);
case scCouldNotCompute:
return ((SC*)this)->visitCouldNotCompute((SCEVCouldNotCompute*)S);
default:
assert(0 && "Unknown SCEV type!");
abort();
}
}
RetVal visitCouldNotCompute(SCEVCouldNotCompute *S) {
assert(0 && "Invalid use of SCEVCouldNotCompute!");
abort();
return RetVal();
}
};
}
#endif
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