llvm-6502/include/llvm/Analysis/ScalarEvolutionExpressions.h
Dan Gohman ab37f50838 Make SCEVUnknown a CallbackVH, so that it can be notified directly
of Value deletions and RAUWs, instead of relying on ScalarEvolution's
Scalars map being notified, as that's complicated at best, and
insufficient in general.

This means SCEVUnknown needs a non-trivial destructor, so introduce
a mechanism to allow ScalarEvolution to locate all the SCEVUnknowns.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110086 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-02 23:49:30 +00:00

623 lines
22 KiB
C++

//===- llvm/Analysis/ScalarEvolutionExpressions.h - SCEV Exprs --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file 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"
#include "llvm/Support/ErrorHandling.h"
namespace llvm {
class ConstantInt;
class ConstantRange;
class DominatorTree;
enum SCEVTypes {
// These should be ordered in terms of increasing complexity to make the
// folders simpler.
scConstant, scTruncate, scZeroExtend, scSignExtend, scAddExpr, scMulExpr,
scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr,
scUnknown, scCouldNotCompute
};
//===--------------------------------------------------------------------===//
/// SCEVConstant - This class represents a constant integer value.
///
class SCEVConstant : public SCEV {
friend class ScalarEvolution;
ConstantInt *V;
SCEVConstant(const FoldingSetNodeIDRef ID, ConstantInt *v) :
SCEV(ID, scConstant), V(v) {}
public:
ConstantInt *getValue() const { return V; }
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;
virtual bool hasOperand(const SCEV *) const {
return false;
}
bool dominates(BasicBlock *BB, DominatorTree *DT) const {
return true;
}
bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
return true;
}
virtual void print(raw_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;
}
};
//===--------------------------------------------------------------------===//
/// SCEVCastExpr - This is the base class for unary cast operator classes.
///
class SCEVCastExpr : public SCEV {
protected:
const SCEV *Op;
const Type *Ty;
SCEVCastExpr(const FoldingSetNodeIDRef ID,
unsigned SCEVTy, const SCEV *op, const Type *ty);
public:
const SCEV *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);
}
virtual bool hasOperand(const SCEV *O) const {
return Op == O || Op->hasOperand(O);
}
virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const;
virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVCastExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scTruncate ||
S->getSCEVType() == scZeroExtend ||
S->getSCEVType() == scSignExtend;
}
};
//===--------------------------------------------------------------------===//
/// SCEVTruncateExpr - This class represents a truncation of an integer value
/// to a smaller integer value.
///
class SCEVTruncateExpr : public SCEVCastExpr {
friend class ScalarEvolution;
SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
const SCEV *op, const Type *ty);
public:
virtual void print(raw_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 SCEVCastExpr {
friend class ScalarEvolution;
SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
const SCEV *op, const Type *ty);
public:
virtual void print(raw_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;
}
};
//===--------------------------------------------------------------------===//
/// SCEVSignExtendExpr - This class represents a sign extension of a small
/// integer value to a larger integer value.
///
class SCEVSignExtendExpr : public SCEVCastExpr {
friend class ScalarEvolution;
SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
const SCEV *op, const Type *ty);
public:
virtual void print(raw_ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVSignExtendExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scSignExtend;
}
};
//===--------------------------------------------------------------------===//
/// SCEVNAryExpr - This node is a base class providing common
/// functionality for n'ary operators.
///
class SCEVNAryExpr : public SCEV {
protected:
// Since SCEVs are immutable, ScalarEvolution allocates operand
// arrays with its SCEVAllocator, so this class just needs a simple
// pointer rather than a more elaborate vector-like data structure.
// This also avoids the need for a non-trivial destructor.
const SCEV *const *Operands;
size_t NumOperands;
SCEVNAryExpr(const FoldingSetNodeIDRef ID,
enum SCEVTypes T, const SCEV *const *O, size_t N)
: SCEV(ID, T), Operands(O), NumOperands(N) {}
public:
size_t getNumOperands() const { return NumOperands; }
const SCEV *getOperand(unsigned i) const {
assert(i < NumOperands && "Operand index out of range!");
return Operands[i];
}
typedef const SCEV *const *op_iterator;
op_iterator op_begin() const { return Operands; }
op_iterator op_end() const { return Operands + NumOperands; }
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 - N-ary 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;
}
virtual bool hasOperand(const SCEV *O) const {
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
if (O == getOperand(i) || getOperand(i)->hasOperand(O))
return true;
return false;
}
bool dominates(BasicBlock *BB, DominatorTree *DT) const;
bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const;
virtual const Type *getType() const { return getOperand(0)->getType(); }
bool hasNoUnsignedWrap() const { return SubclassData & (1 << 0); }
void setHasNoUnsignedWrap(bool B) {
SubclassData = (SubclassData & ~(1 << 0)) | (B << 0);
}
bool hasNoSignedWrap() const { return SubclassData & (1 << 1); }
void setHasNoSignedWrap(bool B) {
SubclassData = (SubclassData & ~(1 << 1)) | (B << 1);
}
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVNAryExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scAddExpr ||
S->getSCEVType() == scMulExpr ||
S->getSCEVType() == scSMaxExpr ||
S->getSCEVType() == scUMaxExpr ||
S->getSCEVType() == scAddRecExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVCommutativeExpr - This node is the base class for n'ary commutative
/// operators.
///
class SCEVCommutativeExpr : public SCEVNAryExpr {
protected:
SCEVCommutativeExpr(const FoldingSetNodeIDRef ID,
enum SCEVTypes T, const SCEV *const *O, size_t N)
: SCEVNAryExpr(ID, T, O, N) {}
public:
virtual const char *getOperationStr() const = 0;
virtual void print(raw_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 ||
S->getSCEVType() == scSMaxExpr ||
S->getSCEVType() == scUMaxExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVAddExpr - This node represents an addition of some number of SCEVs.
///
class SCEVAddExpr : public SCEVCommutativeExpr {
friend class ScalarEvolution;
SCEVAddExpr(const FoldingSetNodeIDRef ID,
const SCEV *const *O, size_t N)
: SCEVCommutativeExpr(ID, scAddExpr, O, N) {
}
public:
virtual const char *getOperationStr() const { return " + "; }
virtual const Type *getType() const {
// Use the type of the last operand, which is likely to be a pointer
// type, if there is one. This doesn't usually matter, but it can help
// reduce casts when the expressions are expanded.
return getOperand(getNumOperands() - 1)->getType();
}
/// 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 {
friend class ScalarEvolution;
SCEVMulExpr(const FoldingSetNodeIDRef ID,
const SCEV *const *O, size_t N)
: SCEVCommutativeExpr(ID, scMulExpr, O, N) {
}
public:
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;
}
};
//===--------------------------------------------------------------------===//
/// SCEVUDivExpr - This class represents a binary unsigned division operation.
///
class SCEVUDivExpr : public SCEV {
friend class ScalarEvolution;
const SCEV *LHS;
const SCEV *RHS;
SCEVUDivExpr(const FoldingSetNodeIDRef ID, const SCEV *lhs, const SCEV *rhs)
: SCEV(ID, scUDivExpr), LHS(lhs), RHS(rhs) {}
public:
const SCEV *getLHS() const { return LHS; }
const SCEV *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);
}
virtual bool hasOperand(const SCEV *O) const {
return O == LHS || O == RHS || LHS->hasOperand(O) || RHS->hasOperand(O);
}
bool dominates(BasicBlock *BB, DominatorTree *DT) const;
bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const;
virtual const Type *getType() const;
void print(raw_ostream &OS) const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVUDivExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scUDivExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVAddRecExpr - This node represents a polynomial recurrence on the trip
/// count of the specified loop. This is the primary focus of the
/// ScalarEvolution framework; all the other SCEV subclasses are mostly just
/// supporting infrastructure to allow SCEVAddRecExpr expressions to be
/// created and analyzed.
///
/// All operands of an AddRec are required to be loop invariant.
///
class SCEVAddRecExpr : public SCEVNAryExpr {
friend class ScalarEvolution;
const Loop *L;
SCEVAddRecExpr(const FoldingSetNodeIDRef ID,
const SCEV *const *O, size_t N, const Loop *l)
: SCEVNAryExpr(ID, scAddRecExpr, O, N), L(l) {
for (size_t i = 0, e = NumOperands; i != e; ++i)
assert(Operands[i]->isLoopInvariant(l) &&
"Operands of AddRec must be loop-invariant!");
}
public:
const SCEV *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.
const SCEV *getStepRecurrence(ScalarEvolution &SE) const {
if (isAffine()) return getOperand(1);
return SE.getAddRecExpr(SmallVector<const SCEV *, 3>(op_begin()+1,
op_end()),
getLoop());
}
virtual bool hasComputableLoopEvolution(const Loop *QL) const {
return L == QL;
}
virtual bool isLoopInvariant(const Loop *QueryLoop) const;
bool dominates(BasicBlock *BB, DominatorTree *DT) const;
bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const;
/// 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.
const SCEV *evaluateAtIteration(const SCEV *It, ScalarEvolution &SE) 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.
const SCEV *getNumIterationsInRange(ConstantRange Range,
ScalarEvolution &SE) const;
/// getPostIncExpr - Return an expression representing the value of
/// this expression one iteration of the loop ahead.
const SCEVAddRecExpr *getPostIncExpr(ScalarEvolution &SE) const {
return cast<SCEVAddRecExpr>(SE.getAddExpr(this, getStepRecurrence(SE)));
}
virtual void print(raw_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;
}
};
//===--------------------------------------------------------------------===//
/// SCEVSMaxExpr - This class represents a signed maximum selection.
///
class SCEVSMaxExpr : public SCEVCommutativeExpr {
friend class ScalarEvolution;
SCEVSMaxExpr(const FoldingSetNodeIDRef ID,
const SCEV *const *O, size_t N)
: SCEVCommutativeExpr(ID, scSMaxExpr, O, N) {
// Max never overflows.
setHasNoUnsignedWrap(true);
setHasNoSignedWrap(true);
}
public:
virtual const char *getOperationStr() const { return " smax "; }
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVSMaxExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scSMaxExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVUMaxExpr - This class represents an unsigned maximum selection.
///
class SCEVUMaxExpr : public SCEVCommutativeExpr {
friend class ScalarEvolution;
SCEVUMaxExpr(const FoldingSetNodeIDRef ID,
const SCEV *const *O, size_t N)
: SCEVCommutativeExpr(ID, scUMaxExpr, O, N) {
// Max never overflows.
setHasNoUnsignedWrap(true);
setHasNoSignedWrap(true);
}
public:
virtual const char *getOperationStr() const { return " umax "; }
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVUMaxExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scUMaxExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVUnknown - This means that we are dealing with an entirely unknown SCEV
/// value, and only represent it as its LLVM Value. This is the "bottom"
/// value for the analysis.
///
class SCEVUnknown : public SCEV, private CallbackVH {
friend class ScalarEvolution;
// Implement CallbackVH.
virtual void deleted();
virtual void allUsesReplacedWith(Value *New);
/// SE - The parent ScalarEvolution value. This is used to update
/// the parent's maps when the value associated with a SCEVUnknown
/// is deleted or RAUW'd.
ScalarEvolution *SE;
/// Next - The next pointer in the linked list of all
/// SCEVUnknown instances owned by a ScalarEvolution.
SCEVUnknown *Next;
SCEVUnknown(const FoldingSetNodeIDRef ID, Value *V,
ScalarEvolution *se, SCEVUnknown *next) :
SCEV(ID, scUnknown), CallbackVH(V), SE(se), Next(next) {}
public:
Value *getValue() const { return getValPtr(); }
/// isSizeOf, isAlignOf, isOffsetOf - Test whether this is a special
/// constant representing a type size, alignment, or field offset in
/// a target-independent manner, and hasn't happened to have been
/// folded with other operations into something unrecognizable. This
/// is mainly only useful for pretty-printing and other situations
/// where it isn't absolutely required for these to succeed.
bool isSizeOf(const Type *&AllocTy) const;
bool isAlignOf(const Type *&AllocTy) const;
bool isOffsetOf(const Type *&STy, Constant *&FieldNo) const;
virtual bool isLoopInvariant(const Loop *L) const;
virtual bool hasComputableLoopEvolution(const Loop *QL) const {
return false; // not computable
}
virtual bool hasOperand(const SCEV *) const {
return false;
}
bool dominates(BasicBlock *BB, DominatorTree *DT) const;
bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const;
virtual const Type *getType() const;
virtual void print(raw_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(const SCEV *S) {
switch (S->getSCEVType()) {
case scConstant:
return ((SC*)this)->visitConstant((const SCEVConstant*)S);
case scTruncate:
return ((SC*)this)->visitTruncateExpr((const SCEVTruncateExpr*)S);
case scZeroExtend:
return ((SC*)this)->visitZeroExtendExpr((const SCEVZeroExtendExpr*)S);
case scSignExtend:
return ((SC*)this)->visitSignExtendExpr((const SCEVSignExtendExpr*)S);
case scAddExpr:
return ((SC*)this)->visitAddExpr((const SCEVAddExpr*)S);
case scMulExpr:
return ((SC*)this)->visitMulExpr((const SCEVMulExpr*)S);
case scUDivExpr:
return ((SC*)this)->visitUDivExpr((const SCEVUDivExpr*)S);
case scAddRecExpr:
return ((SC*)this)->visitAddRecExpr((const SCEVAddRecExpr*)S);
case scSMaxExpr:
return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S);
case scUMaxExpr:
return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S);
case scUnknown:
return ((SC*)this)->visitUnknown((const SCEVUnknown*)S);
case scCouldNotCompute:
return ((SC*)this)->visitCouldNotCompute((const SCEVCouldNotCompute*)S);
default:
llvm_unreachable("Unknown SCEV type!");
}
}
RetVal visitCouldNotCompute(const SCEVCouldNotCompute *S) {
llvm_unreachable("Invalid use of SCEVCouldNotCompute!");
return RetVal();
}
};
}
#endif