//===- ScalarEvolution.cpp - Scalar Evolution Analysis ----------*- 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 contains the implementation of the scalar evolution analysis
// have folders that are used to build the *canonical* representation for a
// particular expression. These folders are capable of using a variety of
// rewrite rules to simplify the expressions.
-//
+//
// Once the folders are defined, we can implement the more interesting
// higher-level code, such as the code that recognizes PHI nodes of various
// types, computes the execution count of a loop, etc.
//
-// Orthogonal to the analysis of code above, this file also implements the
-// ScalarEvolutionRewriter class, which is used to emit code that represents the
-// various recurrences present in a loop, in canonical forms.
-//
// TODO: We should use these routines and value representations to implement
// dependence analysis!
//
//
//===----------------------------------------------------------------------===//
-#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
+#include "llvm/GlobalVariable.h"
#include "llvm/Instructions.h"
-#include "llvm/Type.h"
-#include "llvm/Value.h"
+#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Support/CFG.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Compiler.h"
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/InstIterator.h"
-#include "Support/Statistic.h"
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/ADT/Statistic.h"
+#include <cmath>
+#include <iostream>
+#include <algorithm>
using namespace llvm;
namespace {
- RegisterAnalysis<ScalarEvolution>
- R("scalar-evolution", "Scalar Evolution Analysis Printer");
+ RegisterPass<ScalarEvolution>
+ R("scalar-evolution", "Scalar Evolution Analysis");
Statistic<>
NumBruteForceEvaluations("scalar-evolution",
- "Number of brute force evaluations needed to calculate high-order polynomial exit values");
+ "Number of brute force evaluations needed to "
+ "calculate high-order polynomial exit values");
+ Statistic<>
+ NumArrayLenItCounts("scalar-evolution",
+ "Number of trip counts computed with array length");
Statistic<>
NumTripCountsComputed("scalar-evolution",
"Number of loops with predictable loop counts");
Statistic<>
NumTripCountsNotComputed("scalar-evolution",
"Number of loops without predictable loop counts");
+ Statistic<>
+ NumBruteForceTripCountsComputed("scalar-evolution",
+ "Number of loops with trip counts computed by force");
+
+ cl::opt<unsigned>
+ MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
+ cl::desc("Maximum number of iterations SCEV will "
+ "symbolically execute a constant derived loop"),
+ cl::init(100));
}
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
// Implementation of the SCEV class.
//
-namespace {
- enum SCEVTypes {
- // These should be ordered in terms of increasing complexity to make the
- // folders simpler.
- scConstant, scTruncate, scZeroExtend, scAddExpr, scMulExpr, scUDivExpr,
- scAddRecExpr, scUnknown, scCouldNotCompute
- };
-
- /// SCEVComplexityCompare - Return true if the complexity of the LHS is less
- /// than the complexity of the RHS. If the SCEVs have identical complexity,
- /// order them by their addresses. This comparator is used to canonicalize
- /// expressions.
- struct SCEVComplexityCompare {
- bool operator()(SCEV *LHS, SCEV *RHS) {
- if (LHS->getSCEVType() < RHS->getSCEVType())
- return true;
- if (LHS->getSCEVType() == RHS->getSCEVType())
- return LHS < RHS;
- return false;
- }
- };
-}
-
SCEV::~SCEV() {}
void SCEV::dump() const {
print(std::cerr);
bool SCEVCouldNotCompute::isLoopInvariant(const Loop *L) const {
assert(0 && "Attempt to use a SCEVCouldNotCompute object!");
+ return false;
}
const Type *SCEVCouldNotCompute::getType() const {
assert(0 && "Attempt to use a SCEVCouldNotCompute object!");
+ return 0;
}
bool SCEVCouldNotCompute::hasComputableLoopEvolution(const Loop *L) const {
return false;
}
-Value *SCEVCouldNotCompute::expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt) {
- assert(0 && "Attempt to use a SCEVCouldNotCompute object!");
- return 0;
+SCEVHandle SCEVCouldNotCompute::
+replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
+ const SCEVHandle &Conc) const {
+ return this;
}
-
void SCEVCouldNotCompute::print(std::ostream &OS) const {
OS << "***COULDNOTCOMPUTE***";
}
}
-//===----------------------------------------------------------------------===//
-// SCEVConstant - This class represents a constant integer value.
-//
-namespace {
- class SCEVConstant;
- // SCEVConstants - Only allow the creation of one SCEVConstant for any
- // particular value. Don't use a SCEVHandle here, or else the object will
- // never be deleted!
- std::map<ConstantInt*, SCEVConstant*> SCEVConstants;
-
- class SCEVConstant : public SCEV {
- ConstantInt *V;
- SCEVConstant(ConstantInt *v) : SCEV(scConstant), V(v) {}
-
- virtual ~SCEVConstant() {
- SCEVConstants.erase(V);
- }
- public:
- /// get method - This just gets and returns a new SCEVConstant object.
- ///
- static SCEVHandle get(ConstantInt *V) {
- // Make sure that SCEVConstant instances are all unsigned.
- if (V->getType()->isSigned()) {
- const Type *NewTy = V->getType()->getUnsignedVersion();
- V = cast<ConstantUInt>(ConstantExpr::getCast(V, NewTy));
- }
-
- SCEVConstant *&R = SCEVConstants[V];
- if (R == 0) R = new SCEVConstant(V);
- return R;
- }
-
- 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 {
- return ConstantRange(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 { return V->getType(); }
+// SCEVConstants - Only allow the creation of one SCEVConstant for any
+// particular value. Don't use a SCEVHandle here, or else the object will
+// never be deleted!
+static ManagedStatic<std::map<ConstantInt*, SCEVConstant*> > SCEVConstants;
- Value *expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt) {
- return getValue();
- }
-
- virtual void print(std::ostream &OS) const {
- WriteAsOperand(OS, V, false);
- }
- /// 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;
- }
- };
+SCEVConstant::~SCEVConstant() {
+ SCEVConstants->erase(V);
}
+SCEVHandle SCEVConstant::get(ConstantInt *V) {
+ // Make sure that SCEVConstant instances are all unsigned.
+ if (V->getType()->isSigned()) {
+ const Type *NewTy = V->getType()->getUnsignedVersion();
+ V = cast<ConstantInt>(ConstantExpr::getCast(V, NewTy));
+ }
-//===----------------------------------------------------------------------===//
-// SCEVTruncateExpr - This class represents a truncation of an integer value to
-// a smaller integer value.
-//
-namespace {
- class SCEVTruncateExpr;
- // SCEVTruncates - Only allow the creation of one SCEVTruncateExpr for any
- // particular input. Don't use a SCEVHandle here, or else the object will
- // never be deleted!
- std::map<std::pair<SCEV*, const Type*>, SCEVTruncateExpr*> SCEVTruncates;
-
- class SCEVTruncateExpr : public SCEV {
- SCEVHandle Op;
- const Type *Ty;
- SCEVTruncateExpr(const SCEVHandle &op, const Type *ty)
- : SCEV(scTruncate), Op(op), Ty(ty) {
- assert(Op->getType()->isInteger() && Ty->isInteger() &&
- Ty->isUnsigned() &&
- "Cannot truncate non-integer value!");
- assert(Op->getType()->getPrimitiveSize() > Ty->getPrimitiveSize() &&
- "This is not a truncating conversion!");
- }
-
- virtual ~SCEVTruncateExpr() {
- SCEVTruncates.erase(std::make_pair(Op, Ty));
- }
- 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);
- }
-
- /// 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 {
- return getOperand()->getValueRange().truncate(getType());
- }
-
- Value *expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt);
-
- virtual void print(std::ostream &OS) const {
- OS << "(truncate " << *Op << " to " << *Ty << ")";
- }
-
- /// 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;
- }
- };
+ SCEVConstant *&R = (*SCEVConstants)[V];
+ if (R == 0) R = new SCEVConstant(V);
+ return R;
}
-
-//===----------------------------------------------------------------------===//
-// SCEVZeroExtendExpr - This class represents a zero extension of a small
-// integer value to a larger integer value.
-//
-namespace {
- class SCEVZeroExtendExpr;
- // SCEVZeroExtends - Only allow the creation of one SCEVZeroExtendExpr for any
- // particular input. Don't use a SCEVHandle here, or else the object will
- // never be deleted!
- std::map<std::pair<SCEV*, const Type*>, SCEVZeroExtendExpr*> SCEVZeroExtends;
-
- class SCEVZeroExtendExpr : public SCEV {
- SCEVHandle Op;
- const Type *Ty;
- SCEVZeroExtendExpr(const SCEVHandle &op, const Type *ty)
- : SCEV(scTruncate), Op(Op), Ty(ty) {
- assert(Op->getType()->isInteger() && Ty->isInteger() &&
- Ty->isUnsigned() &&
- "Cannot zero extend non-integer value!");
- assert(Op->getType()->getPrimitiveSize() < Ty->getPrimitiveSize() &&
- "This is not an extending conversion!");
- }
-
- virtual ~SCEVZeroExtendExpr() {
- SCEVZeroExtends.erase(std::make_pair(Op, Ty));
- }
- 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 {
- return getOperand()->getValueRange().zeroExtend(getType());
- }
-
- Value *expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt);
-
- virtual void print(std::ostream &OS) const {
- OS << "(zeroextend " << *Op << " to " << *Ty << ")";
- }
-
- /// 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;
- }
- };
+ConstantRange SCEVConstant::getValueRange() const {
+ return ConstantRange(V);
}
+const Type *SCEVConstant::getType() const { return V->getType(); }
-//===----------------------------------------------------------------------===//
-// SCEVCommutativeExpr - This node is the base class for n'ary commutative
-// operators.
-
-namespace {
- class SCEVCommutativeExpr;
- // SCEVCommExprs - Only allow the creation of one SCEVCommutativeExpr for any
- // particular input. Don't use a SCEVHandle here, or else the object will
- // never be deleted!
- std::map<std::pair<unsigned, std::vector<SCEV*> >,
- SCEVCommutativeExpr*> SCEVCommExprs;
-
- class SCEVCommutativeExpr : public SCEV {
- std::vector<SCEVHandle> Operands;
+void SCEVConstant::print(std::ostream &OS) const {
+ WriteAsOperand(OS, V, false);
+}
- protected:
- SCEVCommutativeExpr(enum SCEVTypes T, const std::vector<SCEVHandle> &ops)
- : SCEV(T) {
- Operands.reserve(ops.size());
- Operands.insert(Operands.end(), ops.begin(), ops.end());
- }
+// SCEVTruncates - Only allow the creation of one SCEVTruncateExpr for any
+// particular input. Don't use a SCEVHandle here, or else the object will
+// never be deleted!
+static ManagedStatic<std::map<std::pair<SCEV*, const Type*>,
+ SCEVTruncateExpr*> > SCEVTruncates;
- ~SCEVCommutativeExpr() {
- SCEVCommExprs.erase(std::make_pair(getSCEVType(),
- std::vector<SCEV*>(Operands.begin(),
- Operands.end())));
- }
+SCEVTruncateExpr::SCEVTruncateExpr(const SCEVHandle &op, const Type *ty)
+ : SCEV(scTruncate), Op(op), Ty(ty) {
+ assert(Op->getType()->isInteger() && Ty->isInteger() &&
+ Ty->isUnsigned() &&
+ "Cannot truncate non-integer value!");
+ assert(Op->getType()->getPrimitiveSize() > Ty->getPrimitiveSize() &&
+ "This is not a truncating conversion!");
+}
- 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];
- }
+SCEVTruncateExpr::~SCEVTruncateExpr() {
+ SCEVTruncates->erase(std::make_pair(Op, Ty));
+}
- 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(); }
+ConstantRange SCEVTruncateExpr::getValueRange() const {
+ return getOperand()->getValueRange().truncate(getType());
+}
+void SCEVTruncateExpr::print(std::ostream &OS) const {
+ OS << "(truncate " << *Op << " to " << *Ty << ")";
+}
- 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;
- }
+// SCEVZeroExtends - Only allow the creation of one SCEVZeroExtendExpr for any
+// particular input. Don't use a SCEVHandle here, or else the object will never
+// be deleted!
+static ManagedStatic<std::map<std::pair<SCEV*, const Type*>,
+ SCEVZeroExtendExpr*> > SCEVZeroExtends;
- virtual bool hasComputableLoopEvolution(const Loop *L) const {
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
- if (getOperand(i)->hasComputableLoopEvolution(L)) return true;
- return false;
- }
+SCEVZeroExtendExpr::SCEVZeroExtendExpr(const SCEVHandle &op, const Type *ty)
+ : SCEV(scTruncate), Op(op), Ty(ty) {
+ assert(Op->getType()->isInteger() && Ty->isInteger() &&
+ Ty->isUnsigned() &&
+ "Cannot zero extend non-integer value!");
+ assert(Op->getType()->getPrimitiveSize() < Ty->getPrimitiveSize() &&
+ "This is not an extending conversion!");
+}
- virtual const Type *getType() const { return getOperand(0)->getType(); }
+SCEVZeroExtendExpr::~SCEVZeroExtendExpr() {
+ SCEVZeroExtends->erase(std::make_pair(Op, Ty));
+}
- virtual const char *getOperationStr() const = 0;
-
- virtual void print(std::ostream &OS) const {
- assert(Operands.size() > 1 && "This plus expr shouldn't exist!");
- const char *OpStr = getOperationStr();
- OS << "(" << *Operands[0];
- for (unsigned i = 1, e = Operands.size(); i != e; ++i)
- OS << OpStr << *Operands[i];
- OS << ")";
- }
+ConstantRange SCEVZeroExtendExpr::getValueRange() const {
+ return getOperand()->getValueRange().zeroExtend(getType());
+}
- /// 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;
- }
- };
+void SCEVZeroExtendExpr::print(std::ostream &OS) const {
+ OS << "(zeroextend " << *Op << " to " << *Ty << ")";
}
-//===----------------------------------------------------------------------===//
-// SCEVAddExpr - This node represents an addition of some number of SCEV's.
-//
-namespace {
- class SCEVAddExpr : public SCEVCommutativeExpr {
- SCEVAddExpr(const std::vector<SCEVHandle> &ops)
- : SCEVCommutativeExpr(scAddExpr, ops) {
- }
+// SCEVCommExprs - Only allow the creation of one SCEVCommutativeExpr for any
+// particular input. Don't use a SCEVHandle here, or else the object will never
+// be deleted!
+static ManagedStatic<std::map<std::pair<unsigned, std::vector<SCEV*> >,
+ SCEVCommutativeExpr*> > SCEVCommExprs;
- public:
- static SCEVHandle get(std::vector<SCEVHandle> &Ops);
+SCEVCommutativeExpr::~SCEVCommutativeExpr() {
+ SCEVCommExprs->erase(std::make_pair(getSCEVType(),
+ std::vector<SCEV*>(Operands.begin(),
+ Operands.end())));
+}
- static SCEVHandle get(const SCEVHandle &LHS, const SCEVHandle &RHS) {
- std::vector<SCEVHandle> Ops;
- Ops.push_back(LHS);
- Ops.push_back(RHS);
- return get(Ops);
- }
+void SCEVCommutativeExpr::print(std::ostream &OS) const {
+ assert(Operands.size() > 1 && "This plus expr shouldn't exist!");
+ const char *OpStr = getOperationStr();
+ OS << "(" << *Operands[0];
+ for (unsigned i = 1, e = Operands.size(); i != e; ++i)
+ OS << OpStr << *Operands[i];
+ OS << ")";
+}
- 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);
+SCEVHandle SCEVCommutativeExpr::
+replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
+ const SCEVHandle &Conc) const {
+ for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
+ SCEVHandle H = getOperand(i)->replaceSymbolicValuesWithConcrete(Sym, Conc);
+ if (H != getOperand(i)) {
+ std::vector<SCEVHandle> NewOps;
+ NewOps.reserve(getNumOperands());
+ for (unsigned j = 0; j != i; ++j)
+ NewOps.push_back(getOperand(j));
+ NewOps.push_back(H);
+ for (++i; i != e; ++i)
+ NewOps.push_back(getOperand(i)->
+ replaceSymbolicValuesWithConcrete(Sym, Conc));
+
+ if (isa<SCEVAddExpr>(this))
+ return SCEVAddExpr::get(NewOps);
+ else if (isa<SCEVMulExpr>(this))
+ return SCEVMulExpr::get(NewOps);
+ else
+ assert(0 && "Unknown commutative expr!");
}
+ }
+ return this;
+}
- virtual const char *getOperationStr() const { return " + "; }
- Value *expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt);
+// SCEVSDivs - Only allow the creation of one SCEVSDivExpr for any particular
+// input. Don't use a SCEVHandle here, or else the object will never be
+// deleted!
+static ManagedStatic<std::map<std::pair<SCEV*, SCEV*>,
+ SCEVSDivExpr*> > SCEVSDivs;
- /// 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;
- }
- };
+SCEVSDivExpr::~SCEVSDivExpr() {
+ SCEVSDivs->erase(std::make_pair(LHS, RHS));
}
-//===----------------------------------------------------------------------===//
-// SCEVMulExpr - This node represents multiplication of some number of SCEV's.
-//
-namespace {
- class SCEVMulExpr : public SCEVCommutativeExpr {
- SCEVMulExpr(const std::vector<SCEVHandle> &ops)
- : SCEVCommutativeExpr(scMulExpr, ops) {
- }
+void SCEVSDivExpr::print(std::ostream &OS) const {
+ OS << "(" << *LHS << " /s " << *RHS << ")";
+}
- public:
- static SCEVHandle get(std::vector<SCEVHandle> &Ops);
+const Type *SCEVSDivExpr::getType() const {
+ const Type *Ty = LHS->getType();
+ if (Ty->isUnsigned()) Ty = Ty->getSignedVersion();
+ return Ty;
+}
- static SCEVHandle get(const SCEVHandle &LHS, const SCEVHandle &RHS) {
- std::vector<SCEVHandle> Ops;
- Ops.push_back(LHS);
- Ops.push_back(RHS);
- return get(Ops);
- }
+// SCEVAddRecExprs - Only allow the creation of one SCEVAddRecExpr for any
+// particular input. Don't use a SCEVHandle here, or else the object will never
+// be deleted!
+static ManagedStatic<std::map<std::pair<const Loop *, std::vector<SCEV*> >,
+ SCEVAddRecExpr*> > SCEVAddRecExprs;
- virtual const char *getOperationStr() const { return " * "; }
+SCEVAddRecExpr::~SCEVAddRecExpr() {
+ SCEVAddRecExprs->erase(std::make_pair(L,
+ std::vector<SCEV*>(Operands.begin(),
+ Operands.end())));
+}
- Value *expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt);
+SCEVHandle SCEVAddRecExpr::
+replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
+ const SCEVHandle &Conc) const {
+ for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
+ SCEVHandle H = getOperand(i)->replaceSymbolicValuesWithConcrete(Sym, Conc);
+ if (H != getOperand(i)) {
+ std::vector<SCEVHandle> NewOps;
+ NewOps.reserve(getNumOperands());
+ for (unsigned j = 0; j != i; ++j)
+ NewOps.push_back(getOperand(j));
+ NewOps.push_back(H);
+ for (++i; i != e; ++i)
+ NewOps.push_back(getOperand(i)->
+ replaceSymbolicValuesWithConcrete(Sym, Conc));
- /// 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;
+ return get(NewOps, L);
}
- };
+ }
+ return this;
}
-//===----------------------------------------------------------------------===//
-// SCEVUDivExpr - This class represents a binary unsigned division operation.
-//
-namespace {
- class SCEVUDivExpr;
- // SCEVUDivs - Only allow the creation of one SCEVUDivExpr for any particular
- // input. Don't use a SCEVHandle here, or else the object will never be
- // deleted!
- std::map<std::pair<SCEV*, SCEV*>, SCEVUDivExpr*> SCEVUDivs;
-
- class SCEVUDivExpr : public SCEV {
- SCEVHandle LHS, RHS;
- SCEVUDivExpr(const SCEVHandle &lhs, const SCEVHandle &rhs)
- : SCEV(scUDivExpr), LHS(lhs), RHS(rhs) {}
-
- virtual ~SCEVUDivExpr() {
- SCEVUDivs.erase(std::make_pair(LHS, RHS));
- }
- public:
- /// get method - This just gets and returns a new SCEVUDiv object.
- ///
- static SCEVHandle get(const SCEVHandle &LHS, const SCEVHandle &RHS);
+bool SCEVAddRecExpr::isLoopInvariant(const Loop *QueryLoop) const {
+ // This recurrence is invariant w.r.t to QueryLoop iff QueryLoop doesn't
+ // contain L and if the start is invariant.
+ return !QueryLoop->contains(L->getHeader()) &&
+ getOperand(0)->isLoopInvariant(QueryLoop);
+}
- 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);
- }
+void SCEVAddRecExpr::print(std::ostream &OS) const {
+ OS << "{" << *Operands[0];
+ for (unsigned i = 1, e = Operands.size(); i != e; ++i)
+ OS << ",+," << *Operands[i];
+ OS << "}<" << L->getHeader()->getName() + ">";
+}
- virtual bool hasComputableLoopEvolution(const Loop *L) const {
- return LHS->hasComputableLoopEvolution(L) &&
- RHS->hasComputableLoopEvolution(L);
- }
+// SCEVUnknowns - Only allow the creation of one SCEVUnknown for any particular
+// value. Don't use a SCEVHandle here, or else the object will never be
+// deleted!
+static ManagedStatic<std::map<Value*, SCEVUnknown*> > SCEVUnknowns;
- virtual const Type *getType() const {
- const Type *Ty = LHS->getType();
- if (Ty->isSigned()) Ty = Ty->getUnsignedVersion();
- return Ty;
- }
+SCEVUnknown::~SCEVUnknown() { SCEVUnknowns->erase(V); }
- Value *expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt);
-
- virtual void print(std::ostream &OS) const {
- OS << "(" << *LHS << " /u " << *RHS << ")";
- }
+bool SCEVUnknown::isLoopInvariant(const Loop *L) const {
+ // All non-instruction values are loop invariant. All instructions are loop
+ // invariant if they are not contained in the specified loop.
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ return !L->contains(I->getParent());
+ return true;
+}
- /// 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;
- }
- };
+const Type *SCEVUnknown::getType() const {
+ return V->getType();
}
+void SCEVUnknown::print(std::ostream &OS) const {
+ WriteAsOperand(OS, V, false);
+}
+//===----------------------------------------------------------------------===//
+// SCEV Utilities
//===----------------------------------------------------------------------===//
-// 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.
-//
namespace {
- class SCEVAddRecExpr;
- // SCEVAddRecExprs - Only allow the creation of one SCEVAddRecExpr for any
- // particular input. Don't use a SCEVHandle here, or else the object will
- // never be deleted!
- std::map<std::pair<const Loop *, std::vector<SCEV*> >,
- SCEVAddRecExpr*> SCEVAddRecExprs;
-
- 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() {
- SCEVAddRecExprs.erase(std::make_pair(L,
- std::vector<SCEV*>(Operands.begin(),
- Operands.end())));
- }
- 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;
- /// FIXME: What if the start or step value a recurrence for the specified
- /// loop?
- return false;
- }
-
-
- virtual bool isLoopInvariant(const Loop *QueryLoop) const {
- // This recurrence is invariant w.r.t to QueryLoop iff QueryLoop doesn't
- // contain L.
- return !QueryLoop->contains(L->getHeader());
- }
-
- virtual const Type *getType() const { return Operands[0]->getType(); }
-
- Value *expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt);
-
-
- /// 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;
-
-
- virtual void print(std::ostream &OS) const {
- OS << "{" << *Operands[0];
- for (unsigned i = 1, e = Operands.size(); i != e; ++i)
- OS << ",+," << *Operands[i];
- OS << "}<" << L->getHeader()->getName() + ">";
- }
-
- /// 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;
+ /// SCEVComplexityCompare - Return true if the complexity of the LHS is less
+ /// than the complexity of the RHS. This comparator is used to canonicalize
+ /// expressions.
+ struct VISIBILITY_HIDDEN SCEVComplexityCompare {
+ bool operator()(SCEV *LHS, SCEV *RHS) {
+ return LHS->getSCEVType() < RHS->getSCEVType();
}
};
}
+/// GroupByComplexity - Given a list of SCEV objects, order them by their
+/// complexity, and group objects of the same complexity together by value.
+/// When this routine is finished, we know that any duplicates in the vector are
+/// consecutive and that complexity is monotonically increasing.
+///
+/// Note that we go take special precautions to ensure that we get determinstic
+/// results from this routine. In other words, we don't want the results of
+/// this to depend on where the addresses of various SCEV objects happened to
+/// land in memory.
+///
+static void GroupByComplexity(std::vector<SCEVHandle> &Ops) {
+ if (Ops.size() < 2) return; // Noop
+ if (Ops.size() == 2) {
+ // This is the common case, which also happens to be trivially simple.
+ // Special case it.
+ if (Ops[0]->getSCEVType() > Ops[1]->getSCEVType())
+ std::swap(Ops[0], Ops[1]);
+ return;
+ }
-//===----------------------------------------------------------------------===//
-// 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.
-//
-namespace {
- class SCEVUnknown;
- // SCEVUnknowns - Only allow the creation of one SCEVUnknown for any
- // particular value. Don't use a SCEVHandle here, or else the object will
- // never be deleted!
- std::map<Value*, SCEVUnknown*> SCEVUnknowns;
-
- class SCEVUnknown : public SCEV {
- Value *V;
- SCEVUnknown(Value *v) : SCEV(scUnknown), V(v) {}
-
- protected:
- ~SCEVUnknown() { SCEVUnknowns.erase(V); }
- public:
- /// get method - For SCEVUnknown, this just gets and returns a new
- /// SCEVUnknown.
- static SCEVHandle get(Value *V) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
- return SCEVConstant::get(CI);
- SCEVUnknown *&Result = SCEVUnknowns[V];
- if (Result == 0) Result = new SCEVUnknown(V);
- return Result;
- }
-
- Value *getValue() const { return V; }
-
- Value *expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt) {
- return V;
- }
-
- virtual bool isLoopInvariant(const Loop *L) const {
- // All non-instruction values are loop invariant. All instructions are
- // loop invariant if they are not contained in the specified loop.
- if (Instruction *I = dyn_cast<Instruction>(V))
- return !L->contains(I->getParent());
- return true;
- }
+ // Do the rough sort by complexity.
+ std::sort(Ops.begin(), Ops.end(), SCEVComplexityCompare());
- virtual bool hasComputableLoopEvolution(const Loop *QL) const {
- return false; // not computable
+ // Now that we are sorted by complexity, group elements of the same
+ // complexity. Note that this is, at worst, N^2, but the vector is likely to
+ // be extremely short in practice. Note that we take this approach because we
+ // do not want to depend on the addresses of the objects we are grouping.
+ for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
+ SCEV *S = Ops[i];
+ unsigned Complexity = S->getSCEVType();
+
+ // If there are any objects of the same complexity and same value as this
+ // one, group them.
+ for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
+ if (Ops[j] == S) { // Found a duplicate.
+ // Move it to immediately after i'th element.
+ std::swap(Ops[i+1], Ops[j]);
+ ++i; // no need to rescan it.
+ if (i == e-2) return; // Done!
+ }
}
+ }
+}
- virtual const Type *getType() const { return V->getType(); }
- virtual void print(std::ostream &OS) const {
- WriteAsOperand(OS, V, false);
- }
-
- /// 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;
- }
- };
-}
//===----------------------------------------------------------------------===//
// Simple SCEV method implementations
/// 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) {
+SCEVHandle SCEVUnknown::getIntegerSCEV(int Val, const Type *Ty) {
Constant *C;
- if (Val == 0)
+ if (Val == 0)
C = Constant::getNullValue(Ty);
else if (Ty->isFloatingPoint())
C = ConstantFP::get(Ty, Val);
else if (Ty->isSigned())
- C = ConstantSInt::get(Ty, Val);
+ C = ConstantInt::get(Ty, Val);
else {
- C = ConstantSInt::get(Ty->getSignedVersion(), Val);
+ C = ConstantInt::get(Ty->getSignedVersion(), Val);
C = ConstantExpr::getCast(C, Ty);
}
return SCEVUnknown::get(C);
/// getNegativeSCEV - Return a SCEV corresponding to -V = -1*V
///
-static SCEVHandle getNegativeSCEV(const SCEVHandle &V) {
+SCEVHandle SCEV::getNegativeSCEV(const SCEVHandle &V) {
if (SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
return SCEVUnknown::get(ConstantExpr::getNeg(VC->getValue()));
-
- return SCEVMulExpr::get(V, getIntegerSCEV(-1, V->getType()));
+
+ return SCEVMulExpr::get(V, SCEVUnknown::getIntegerSCEV(-1, V->getType()));
}
/// getMinusSCEV - Return a SCEV corresponding to LHS - RHS.
///
-static SCEVHandle getMinusSCEV(const SCEVHandle &LHS, const SCEVHandle &RHS) {
+SCEVHandle SCEV::getMinusSCEV(const SCEVHandle &LHS, const SCEVHandle &RHS) {
// X - Y --> X + -Y
- return SCEVAddExpr::get(LHS, getNegativeSCEV(RHS));
+ return SCEVAddExpr::get(LHS, SCEV::getNegativeSCEV(RHS));
}
-/// Binomial - Evaluate N!/((N-M)!*M!) . Note that N is often large and M is
-/// often very small, so we try to reduce the number of N! terms we need to
-/// evaluate by evaluating this as (N!/(N-M)!)/M!
-static ConstantInt *Binomial(ConstantInt *N, unsigned M) {
- uint64_t NVal = N->getRawValue();
- uint64_t FirstTerm = 1;
- for (unsigned i = 0; i != M; ++i)
- FirstTerm *= NVal-i;
-
- unsigned MFactorial = 1;
- for (; M; --M)
- MFactorial *= M;
-
- Constant *Result = ConstantUInt::get(Type::ULongTy, FirstTerm/MFactorial);
- Result = ConstantExpr::getCast(Result, N->getType());
- assert(isa<ConstantInt>(Result) && "Cast of integer not folded??");
- return cast<ConstantInt>(Result);
-}
-
/// PartialFact - Compute V!/(V-NumSteps)!
static SCEVHandle PartialFact(SCEVHandle V, unsigned NumSteps) {
// Handle this case efficiently, it is common to have constant iteration
// counts while computing loop exit values.
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(V)) {
- uint64_t Val = SC->getValue()->getRawValue();
+ uint64_t Val = SC->getValue()->getZExtValue();
uint64_t Result = 1;
for (; NumSteps; --NumSteps)
Result *= Val-(NumSteps-1);
- Constant *Res = ConstantUInt::get(Type::ULongTy, Result);
+ Constant *Res = ConstantInt::get(Type::ULongTy, Result);
return SCEVUnknown::get(ConstantExpr::getCast(Res, V->getType()));
}
const Type *Ty = V->getType();
if (NumSteps == 0)
- return getIntegerSCEV(1, Ty);
-
+ return SCEVUnknown::getIntegerSCEV(1, Ty);
+
SCEVHandle Result = V;
for (unsigned i = 1; i != NumSteps; ++i)
- Result = SCEVMulExpr::get(Result, getMinusSCEV(V, getIntegerSCEV(i, Ty)));
+ Result = SCEVMulExpr::get(Result, SCEV::getMinusSCEV(V,
+ SCEVUnknown::getIntegerSCEV(i, Ty)));
return Result;
}
for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
SCEVHandle BC = PartialFact(It, i);
Divisor *= i;
- SCEVHandle Val = SCEVUDivExpr::get(SCEVMulExpr::get(BC, getOperand(i)),
- getIntegerSCEV(Divisor, Ty));
+ SCEVHandle Val = SCEVSDivExpr::get(SCEVMulExpr::get(BC, getOperand(i)),
+ SCEVUnknown::getIntegerSCEV(Divisor,Ty));
Result = SCEVAddExpr::get(Result, Val);
}
return Result;
return SCEVAddRecExpr::get(Operands, AddRec->getLoop());
}
- SCEVTruncateExpr *&Result = SCEVTruncates[std::make_pair(Op, Ty)];
+ SCEVTruncateExpr *&Result = (*SCEVTruncates)[std::make_pair(Op, Ty)];
if (Result == 0) Result = new SCEVTruncateExpr(Op, Ty);
return Result;
}
// operands (often constants). This would allow analysis of something like
// this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
- SCEVZeroExtendExpr *&Result = SCEVZeroExtends[std::make_pair(Op, Ty)];
+ SCEVZeroExtendExpr *&Result = (*SCEVZeroExtends)[std::make_pair(Op, Ty)];
if (Result == 0) Result = new SCEVZeroExtendExpr(Op, Ty);
return Result;
}
// get - Get a canonical add expression, or something simpler if possible.
SCEVHandle SCEVAddExpr::get(std::vector<SCEVHandle> &Ops) {
assert(!Ops.empty() && "Cannot get empty add!");
+ if (Ops.size() == 1) return Ops[0];
// Sort by complexity, this groups all similar expression types together.
- std::sort(Ops.begin(), Ops.end(), SCEVComplexityCompare());
+ GroupByComplexity(Ops);
// If there are any constants, fold them together.
unsigned Idx = 0;
if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
++Idx;
+ assert(Idx < Ops.size());
while (SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
// We found two constants, fold them together!
Constant *Fold = ConstantExpr::getAdd(LHSC->getValue(), RHSC->getValue());
Ops[0] = SCEVConstant::get(CI);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
+ LHSC = cast<SCEVConstant>(Ops[0]);
} else {
// If we couldn't fold the expression, move to the next constant. Note
// that this is impossible to happen in practice because we always
}
}
- if (Ops.size() == 1)
- return Ops[0];
-
+ if (Ops.size() == 1) return Ops[0];
+
// Okay, check to see if the same value occurs in the operand list twice. If
// so, merge them together into an multiply expression. Since we sorted the
// list, these values are required to be adjacent.
if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
// Found a match, merge the two values into a multiply, and add any
// remaining values to the result.
- SCEVHandle Two = getIntegerSCEV(2, Ty);
+ SCEVHandle Two = SCEVUnknown::getIntegerSCEV(2, Ty);
SCEVHandle Mul = SCEVMulExpr::get(Ops[i], Two);
if (Ops.size() == 2)
return Mul;
for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
SCEV *MulOpSCEV = Mul->getOperand(MulOp);
for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
- if (MulOpSCEV == Ops[AddOp] &&
- (Mul->getNumOperands() != 2 || !isa<SCEVConstant>(MulOpSCEV))) {
+ if (MulOpSCEV == Ops[AddOp] && !isa<SCEVConstant>(MulOpSCEV)) {
// Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
SCEVHandle InnerMul = Mul->getOperand(MulOp == 0);
if (Mul->getNumOperands() != 2) {
MulOps.erase(MulOps.begin()+MulOp);
InnerMul = SCEVMulExpr::get(MulOps);
}
- SCEVHandle One = getIntegerSCEV(1, Ty);
+ SCEVHandle One = SCEVUnknown::getIntegerSCEV(1, Ty);
SCEVHandle AddOne = SCEVAddExpr::get(InnerMul, One);
SCEVHandle OuterMul = SCEVMulExpr::get(AddOne, Ops[AddOp]);
if (Ops.size() == 2) return OuterMul;
Ops.push_back(OuterMul);
return SCEVAddExpr::get(Ops);
}
-
+
// Check this multiply against other multiplies being added together.
for (unsigned OtherMulIdx = Idx+1;
OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
// Okay, it looks like we really DO need an add expr. Check to see if we
// already have one, otherwise create a new one.
std::vector<SCEV*> SCEVOps(Ops.begin(), Ops.end());
- SCEVCommutativeExpr *&Result = SCEVCommExprs[std::make_pair(scAddExpr,
- SCEVOps)];
+ SCEVCommutativeExpr *&Result = (*SCEVCommExprs)[std::make_pair(scAddExpr,
+ SCEVOps)];
if (Result == 0) Result = new SCEVAddExpr(Ops);
return Result;
}
assert(!Ops.empty() && "Cannot get empty mul!");
// Sort by complexity, this groups all similar expression types together.
- std::sort(Ops.begin(), Ops.end(), SCEVComplexityCompare());
+ GroupByComplexity(Ops);
// If there are any constants, fold them together.
unsigned Idx = 0;
Ops[0] = SCEVConstant::get(CI);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
+ LHSC = cast<SCEVConstant>(Ops[0]);
} else {
// If we couldn't fold the expression, move to the next constant. Note
// that this is impossible to happen in practice because we always
if (Ops.size() == 1)
return Ops[0];
-
+
// If there are mul operands inline them all into this expression.
if (Idx < Ops.size()) {
bool DeletedMul = false;
// Okay, it looks like we really DO need an mul expr. Check to see if we
// already have one, otherwise create a new one.
std::vector<SCEV*> SCEVOps(Ops.begin(), Ops.end());
- SCEVCommutativeExpr *&Result = SCEVCommExprs[std::make_pair(scMulExpr,
- SCEVOps)];
- if (Result == 0) Result = new SCEVMulExpr(Ops);
+ SCEVCommutativeExpr *&Result = (*SCEVCommExprs)[std::make_pair(scMulExpr,
+ SCEVOps)];
+ if (Result == 0)
+ Result = new SCEVMulExpr(Ops);
return Result;
}
-SCEVHandle SCEVUDivExpr::get(const SCEVHandle &LHS, const SCEVHandle &RHS) {
+SCEVHandle SCEVSDivExpr::get(const SCEVHandle &LHS, const SCEVHandle &RHS) {
if (SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
if (RHSC->getValue()->equalsInt(1))
- return LHS; // X /u 1 --> x
+ return LHS; // X /s 1 --> x
if (RHSC->getValue()->isAllOnesValue())
- return getNegativeSCEV(LHS); // X /u -1 --> -x
+ return SCEV::getNegativeSCEV(LHS); // X /s -1 --> -x
if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
Constant *LHSCV = LHSC->getValue();
Constant *RHSCV = RHSC->getValue();
- if (LHSCV->getType()->isSigned())
+ if (LHSCV->getType()->isUnsigned())
LHSCV = ConstantExpr::getCast(LHSCV,
- LHSCV->getType()->getUnsignedVersion());
- if (RHSCV->getType()->isSigned())
+ LHSCV->getType()->getSignedVersion());
+ if (RHSCV->getType()->isUnsigned())
RHSCV = ConstantExpr::getCast(RHSCV, LHSCV->getType());
return SCEVUnknown::get(ConstantExpr::getDiv(LHSCV, RHSCV));
}
// FIXME: implement folding of (X*4)/4 when we know X*4 doesn't overflow.
- SCEVUDivExpr *&Result = SCEVUDivs[std::make_pair(LHS, RHS)];
- if (Result == 0) Result = new SCEVUDivExpr(LHS, RHS);
+ SCEVSDivExpr *&Result = (*SCEVSDivs)[std::make_pair(LHS, RHS)];
+ if (Result == 0) Result = new SCEVSDivExpr(LHS, RHS);
return Result;
}
}
SCEVAddRecExpr *&Result =
- SCEVAddRecExprs[std::make_pair(L, std::vector<SCEV*>(Operands.begin(),
- Operands.end()))];
+ (*SCEVAddRecExprs)[std::make_pair(L, std::vector<SCEV*>(Operands.begin(),
+ Operands.end()))];
if (Result == 0) Result = new SCEVAddRecExpr(Operands, L);
return Result;
}
-
-//===----------------------------------------------------------------------===//
-// Non-trivial closed-form SCEV Expanders
-//===----------------------------------------------------------------------===//
-
-Value *SCEVTruncateExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt) {
- Value *V = SER.ExpandCodeFor(getOperand(), InsertPt);
- return new CastInst(V, getType(), "tmp.", InsertPt);
-}
-
-Value *SCEVZeroExtendExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt) {
- Value *V = SER.ExpandCodeFor(getOperand(), InsertPt,
- getOperand()->getType()->getUnsignedVersion());
- return new CastInst(V, getType(), "tmp.", InsertPt);
-}
-
-Value *SCEVAddExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt) {
- const Type *Ty = getType();
- Value *V = SER.ExpandCodeFor(getOperand(getNumOperands()-1), InsertPt, Ty);
-
- // Emit a bunch of add instructions
- for (int i = getNumOperands()-2; i >= 0; --i)
- V = BinaryOperator::create(Instruction::Add, V,
- SER.ExpandCodeFor(getOperand(i), InsertPt, Ty),
- "tmp.", InsertPt);
- return V;
-}
-
-Value *SCEVMulExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt) {
- const Type *Ty = getType();
- int FirstOp = 0; // Set if we should emit a subtract.
- if (SCEVConstant *SC = dyn_cast<SCEVConstant>(getOperand(0)))
- if (SC->getValue()->isAllOnesValue())
- FirstOp = 1;
-
- int i = getNumOperands()-2;
- Value *V = SER.ExpandCodeFor(getOperand(i+1), InsertPt, Ty);
-
- // Emit a bunch of multiply instructions
- for (; i >= FirstOp; --i)
- V = BinaryOperator::create(Instruction::Mul, V,
- SER.ExpandCodeFor(getOperand(i), InsertPt, Ty),
- "tmp.", InsertPt);
- // -1 * ... ---> 0 - ...
- if (FirstOp == 1)
- V = BinaryOperator::create(Instruction::Sub, Constant::getNullValue(Ty), V,
- "tmp.", InsertPt);
- return V;
-}
-
-Value *SCEVUDivExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt) {
- const Type *Ty = getType();
- Value *LHS = SER.ExpandCodeFor(getLHS(), InsertPt, Ty);
- Value *RHS = SER.ExpandCodeFor(getRHS(), InsertPt, Ty);
- return BinaryOperator::create(Instruction::Div, LHS, RHS, "tmp.", InsertPt);
-}
-
-Value *SCEVAddRecExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
- Instruction *InsertPt) {
- const Type *Ty = getType();
- // We cannot yet do fp recurrences, e.g. the xform of {X,+,F} --> X+{0,+,F}
- assert(Ty->isIntegral() && "Cannot expand fp recurrences yet!");
-
- // {X,+,F} --> X + {0,+,F}
- if (!isa<SCEVConstant>(getStart()) ||
- !cast<SCEVConstant>(getStart())->getValue()->isNullValue()) {
- Value *Start = SER.ExpandCodeFor(getStart(), InsertPt, Ty);
- std::vector<SCEVHandle> NewOps(op_begin(), op_end());
- NewOps[0] = getIntegerSCEV(0, getType());
- Value *Rest = SER.ExpandCodeFor(SCEVAddRecExpr::get(NewOps, getLoop()),
- InsertPt, getType());
-
- // FIXME: look for an existing add to use.
- return BinaryOperator::create(Instruction::Add, Rest, Start, "tmp.",
- InsertPt);
- }
-
- // {0,+,1} --> Insert a canonical induction variable into the loop!
- if (getNumOperands() == 2 && getOperand(1) == getIntegerSCEV(1, getType())) {
- // Create and insert the PHI node for the induction variable in the
- // specified loop.
- BasicBlock *Header = getLoop()->getHeader();
- PHINode *PN = new PHINode(Ty, "indvar", Header->begin());
- PN->addIncoming(Constant::getNullValue(Ty), L->getLoopPreheader());
-
- // Insert a unit add instruction after the PHI nodes in the header block.
- BasicBlock::iterator I = PN;
- while (isa<PHINode>(I)) ++I;
-
- Constant *One = Ty->isFloatingPoint() ?(Constant*)ConstantFP::get(Ty, 1.0)
- :(Constant*)ConstantInt::get(Ty, 1);
- Instruction *Add = BinaryOperator::create(Instruction::Add, PN, One,
- "indvar.next", I);
-
- pred_iterator PI = pred_begin(Header);
- if (*PI == L->getLoopPreheader())
- ++PI;
- PN->addIncoming(Add, *PI);
- return PN;
- }
-
- // Get the canonical induction variable I for this loop.
- Value *I = SER.GetOrInsertCanonicalInductionVariable(getLoop(), Ty);
-
- if (getNumOperands() == 2) { // {0,+,F} --> i*F
- Value *F = SER.ExpandCodeFor(getOperand(1), InsertPt, Ty);
- return BinaryOperator::create(Instruction::Mul, I, F, "tmp.", InsertPt);
- }
-
- // If this is a chain of recurrences, turn it into a closed form, using the
- // folders, then expandCodeFor the closed form. This allows the folders to
- // simplify the expression without having to build a bunch of special code
- // into this folder.
- SCEVHandle IH = SCEVUnknown::get(I); // Get I as a "symbolic" SCEV.
-
- SCEVHandle V = evaluateAtIteration(IH);
- //std::cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
-
- return SER.ExpandCodeFor(V, InsertPt, Ty);
+SCEVHandle SCEVUnknown::get(Value *V) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
+ return SCEVConstant::get(CI);
+ SCEVUnknown *&Result = (*SCEVUnknowns)[V];
+ if (Result == 0) Result = new SCEVUnknown(V);
+ return Result;
}
/// evolution code.
///
namespace {
- struct ScalarEvolutionsImpl {
+ struct VISIBILITY_HIDDEN ScalarEvolutionsImpl {
/// F - The function we are analyzing.
///
Function &F;
/// function as they are computed.
std::map<const Loop*, SCEVHandle> IterationCounts;
+ /// ConstantEvolutionLoopExitValue - This map contains entries for all of
+ /// the PHI instructions that we attempt to compute constant evolutions for.
+ /// This allows us to avoid potentially expensive recomputation of these
+ /// properties. An instruction maps to null if we are unable to compute its
+ /// exit value.
+ std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue;
+
public:
ScalarEvolutionsImpl(Function &f, LoopInfo &li)
: F(f), LI(li), UnknownValue(new SCEVCouldNotCompute()) {}
/// expression and create a new one.
SCEVHandle getSCEV(Value *V);
+ /// hasSCEV - Return true if the SCEV for this value has already been
+ /// computed.
+ bool hasSCEV(Value *V) const {
+ return Scalars.count(V);
+ }
+
+ /// setSCEV - Insert the specified SCEV into the map of current SCEVs for
+ /// the specified value.
+ void setSCEV(Value *V, const SCEVHandle &H) {
+ bool isNew = Scalars.insert(std::make_pair(V, H)).second;
+ assert(isNew && "This entry already existed!");
+ }
+
+
/// getSCEVAtScope - Compute the value of the specified expression within
/// the indicated loop (which may be null to indicate in no loop). If the
/// expression cannot be evaluated, return UnknownValue itself.
/// createNodeForPHI - Provide the special handling we need to analyze PHI
/// SCEVs.
SCEVHandle createNodeForPHI(PHINode *PN);
- void UpdatePHIUserScalarEntries(Instruction *I, PHINode *PN,
- std::set<Instruction*> &UpdatedInsts);
+
+ /// ReplaceSymbolicValueWithConcrete - This looks up the computed SCEV value
+ /// for the specified instruction and replaces any references to the
+ /// symbolic value SymName with the specified value. This is used during
+ /// PHI resolution.
+ void ReplaceSymbolicValueWithConcrete(Instruction *I,
+ const SCEVHandle &SymName,
+ const SCEVHandle &NewVal);
/// ComputeIterationCount - Compute the number of times the specified loop
/// will iterate.
SCEVHandle ComputeIterationCount(const Loop *L);
+ /// ComputeLoadConstantCompareIterationCount - Given an exit condition of
+ /// 'setcc load X, cst', try to se if we can compute the trip count.
+ SCEVHandle ComputeLoadConstantCompareIterationCount(LoadInst *LI,
+ Constant *RHS,
+ const Loop *L,
+ unsigned SetCCOpcode);
+
+ /// ComputeIterationCountExhaustively - If the trip is known to execute a
+ /// constant number of times (the condition evolves only from constants),
+ /// try to evaluate a few iterations of the loop until we get the exit
+ /// condition gets a value of ExitWhen (true or false). If we cannot
+ /// evaluate the trip count of the loop, return UnknownValue.
+ SCEVHandle ComputeIterationCountExhaustively(const Loop *L, Value *Cond,
+ bool ExitWhen);
+
/// HowFarToZero - Return the number of times a backedge comparing the
/// specified value to zero will execute. If not computable, return
- /// UnknownValue
+ /// UnknownValue.
SCEVHandle HowFarToZero(SCEV *V, const Loop *L);
/// HowFarToNonZero - Return the number of times a backedge checking the
/// specified value for nonzero will execute. If not computable, return
- /// UnknownValue
+ /// UnknownValue.
SCEVHandle HowFarToNonZero(SCEV *V, const Loop *L);
+
+ /// HowManyLessThans - Return the number of times a backedge containing the
+ /// specified less-than comparison will execute. If not computable, return
+ /// UnknownValue.
+ SCEVHandle HowManyLessThans(SCEV *LHS, SCEV *RHS, const Loop *L);
+
+ /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
+ /// in the header of its containing loop, we know the loop executes a
+ /// constant number of times, and the PHI node is just a recurrence
+ /// involving constants, fold it.
+ Constant *getConstantEvolutionLoopExitValue(PHINode *PN, uint64_t Its,
+ const Loop *L);
};
}
/// that no dangling references are left around.
void ScalarEvolutionsImpl::deleteInstructionFromRecords(Instruction *I) {
Scalars.erase(I);
+ if (PHINode *PN = dyn_cast<PHINode>(I))
+ ConstantEvolutionLoopExitValue.erase(PN);
}
return S;
}
-
-/// UpdatePHIUserScalarEntries - After PHI node analysis, we have a bunch of
-/// entries in the scalar map that refer to the "symbolic" PHI value instead of
-/// the recurrence value. After we resolve the PHI we must loop over all of the
-/// using instructions that have scalar map entries and update them.
-void ScalarEvolutionsImpl::UpdatePHIUserScalarEntries(Instruction *I,
- PHINode *PN,
- std::set<Instruction*> &UpdatedInsts) {
+/// ReplaceSymbolicValueWithConcrete - This looks up the computed SCEV value for
+/// the specified instruction and replaces any references to the symbolic value
+/// SymName with the specified value. This is used during PHI resolution.
+void ScalarEvolutionsImpl::
+ReplaceSymbolicValueWithConcrete(Instruction *I, const SCEVHandle &SymName,
+ const SCEVHandle &NewVal) {
std::map<Value*, SCEVHandle>::iterator SI = Scalars.find(I);
- if (SI == Scalars.end()) return; // This scalar wasn't previous processed.
- if (UpdatedInsts.insert(I).second) {
- Scalars.erase(SI); // Remove the old entry
- getSCEV(I); // Calculate the new entry
-
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
- UI != E; ++UI)
- UpdatePHIUserScalarEntries(cast<Instruction>(*UI), PN, UpdatedInsts);
- }
-}
+ if (SI == Scalars.end()) return;
+
+ SCEVHandle NV =
+ SI->second->replaceSymbolicValuesWithConcrete(SymName, NewVal);
+ if (NV == SI->second) return; // No change.
+ SI->second = NV; // Update the scalars map!
+
+ // Any instruction values that use this instruction might also need to be
+ // updated!
+ for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
+ UI != E; ++UI)
+ ReplaceSymbolicValueWithConcrete(cast<Instruction>(*UI), SymName, NewVal);
+}
/// createNodeForPHI - PHI nodes have two cases. Either the PHI node exists in
/// a loop header, making it a potential recurrence, or it doesn't.
// from outside the loop, and one from inside.
unsigned IncomingEdge = L->contains(PN->getIncomingBlock(0));
unsigned BackEdge = IncomingEdge^1;
-
+
// While we are analyzing this PHI node, handle its value symbolically.
SCEVHandle SymbolicName = SCEVUnknown::get(PN);
assert(Scalars.find(PN) == Scalars.end() &&
// entries for the scalars that use the PHI (except for the PHI
// itself) to use the new analyzed value instead of the "symbolic"
// value.
- Scalars.find(PN)->second = PHISCEV; // Update the PHI value
- std::set<Instruction*> UpdatedInsts;
- UpdatedInsts.insert(PN);
- for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
- UI != E; ++UI)
- UpdatePHIUserScalarEntries(cast<Instruction>(*UI), PN,
- UpdatedInsts);
+ ReplaceSymbolicValueWithConcrete(PN, SymbolicName, PHISCEV);
+ return PHISCEV;
+ }
+ }
+ } else if (SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(BEValue)) {
+ // Otherwise, this could be a loop like this:
+ // i = 0; for (j = 1; ..; ++j) { .... i = j; }
+ // In this case, j = {1,+,1} and BEValue is j.
+ // Because the other in-value of i (0) fits the evolution of BEValue
+ // i really is an addrec evolution.
+ if (AddRec->getLoop() == L && AddRec->isAffine()) {
+ SCEVHandle StartVal = getSCEV(PN->getIncomingValue(IncomingEdge));
+
+ // If StartVal = j.start - j.stride, we can use StartVal as the
+ // initial step of the addrec evolution.
+ if (StartVal == SCEV::getMinusSCEV(AddRec->getOperand(0),
+ AddRec->getOperand(1))) {
+ SCEVHandle PHISCEV =
+ SCEVAddRecExpr::get(StartVal, AddRec->getOperand(1), L);
+
+ // Okay, for the entire analysis of this edge we assumed the PHI
+ // to be symbolic. We now need to go back and update all of the
+ // entries for the scalars that use the PHI (except for the PHI
+ // itself) to use the new analyzed value instead of the "symbolic"
+ // value.
+ ReplaceSymbolicValueWithConcrete(PN, SymbolicName, PHISCEV);
return PHISCEV;
}
}
return SymbolicName;
}
-
+
// If it's not a loop phi, we can't handle it yet.
return SCEVUnknown::get(PN);
}
SCEVHandle ScalarEvolutionsImpl::createNodeForCast(CastInst *CI) {
const Type *SrcTy = CI->getOperand(0)->getType();
const Type *DestTy = CI->getType();
-
+
// If this is a noop cast (ie, conversion from int to uint), ignore it.
if (SrcTy->isLosslesslyConvertibleTo(DestTy))
return getSCEV(CI->getOperand(0));
-
+
if (SrcTy->isInteger() && DestTy->isInteger()) {
// Otherwise, if this is a truncating integer cast, we can represent this
// cast.
return SCEVMulExpr::get(getSCEV(I->getOperand(0)),
getSCEV(I->getOperand(1)));
case Instruction::Div:
- if (V->getType()->isInteger() && V->getType()->isUnsigned())
- return SCEVUDivExpr::get(getSCEV(I->getOperand(0)),
+ if (V->getType()->isInteger() && V->getType()->isSigned())
+ return SCEVSDivExpr::get(getSCEV(I->getOperand(0)),
getSCEV(I->getOperand(1)));
break;
case Instruction::Sub:
- return getMinusSCEV(getSCEV(I->getOperand(0)), getSCEV(I->getOperand(1)));
+ return SCEV::getMinusSCEV(getSCEV(I->getOperand(0)),
+ getSCEV(I->getOperand(1)));
case Instruction::Shl:
// Turn shift left of a constant amount into a multiply.
}
break;
- case Instruction::Shr:
- if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
- if (V->getType()->isUnsigned()) {
- Constant *X = ConstantInt::get(V->getType(), 1);
- X = ConstantExpr::getShl(X, SA);
- return SCEVUDivExpr::get(getSCEV(I->getOperand(0)), getSCEV(X));
- }
- break;
-
case Instruction::Cast:
return createNodeForCast(cast<CastInst>(I));
/// will iterate.
SCEVHandle ScalarEvolutionsImpl::ComputeIterationCount(const Loop *L) {
// If the loop has a non-one exit block count, we can't analyze it.
- if (L->getExitBlocks().size() != 1) return UnknownValue;
+ std::vector<BasicBlock*> ExitBlocks;
+ L->getExitBlocks(ExitBlocks);
+ if (ExitBlocks.size() != 1) return UnknownValue;
// Okay, there is one exit block. Try to find the condition that causes the
// loop to be exited.
- BasicBlock *ExitBlock = L->getExitBlocks()[0];
+ BasicBlock *ExitBlock = ExitBlocks[0];
BasicBlock *ExitingBlock = 0;
for (pred_iterator PI = pred_begin(ExitBlock), E = pred_end(ExitBlock);
if (ExitBr == 0) return UnknownValue;
assert(ExitBr->isConditional() && "If unconditional, it can't be in loop!");
SetCondInst *ExitCond = dyn_cast<SetCondInst>(ExitBr->getCondition());
- if (ExitCond == 0) return UnknownValue;
+ if (ExitCond == 0) // Not a setcc
+ return ComputeIterationCountExhaustively(L, ExitBr->getCondition(),
+ ExitBr->getSuccessor(0) == ExitBlock);
+
+ // If the condition was exit on true, convert the condition to exit on false.
+ Instruction::BinaryOps Cond;
+ if (ExitBr->getSuccessor(1) == ExitBlock)
+ Cond = ExitCond->getOpcode();
+ else
+ Cond = ExitCond->getInverseCondition();
+
+ // Handle common loops like: for (X = "string"; *X; ++X)
+ if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
+ if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) {
+ SCEVHandle ItCnt =
+ ComputeLoadConstantCompareIterationCount(LI, RHS, L, Cond);
+ if (!isa<SCEVCouldNotCompute>(ItCnt)) return ItCnt;
+ }
SCEVHandle LHS = getSCEV(ExitCond->getOperand(0));
SCEVHandle RHS = getSCEV(ExitCond->getOperand(1));
Tmp = getSCEVAtScope(RHS, L);
if (!isa<SCEVCouldNotCompute>(Tmp)) RHS = Tmp;
- // If the condition was exit on true, convert the condition to exit on false.
- Instruction::BinaryOps Cond;
- if (ExitBr->getSuccessor(1) == ExitBlock)
- Cond = ExitCond->getOpcode();
- else
- Cond = ExitCond->getInverseCondition();
-
// At this point, we would like to compute how many iterations of the loop the
// predicate will return true for these inputs.
if (isa<SCEVConstant>(LHS) && !isa<SCEVConstant>(RHS)) {
if (CompVal) {
// Form the constant range.
ConstantRange CompRange(Cond, CompVal);
-
+
// Now that we have it, if it's signed, convert it to an unsigned
// range.
if (CompRange.getLower()->getType()->isSigned()) {
Constant *NewU = ConstantExpr::getCast(CompRange.getUpper(), NewTy);
CompRange = ConstantRange(NewL, NewU);
}
-
+
SCEVHandle Ret = AddRec->getNumIterationsInRange(CompRange);
if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
}
}
-
+
switch (Cond) {
case Instruction::SetNE: // while (X != Y)
// Convert to: while (X-Y != 0)
- if (LHS->getType()->isInteger())
- return HowFarToZero(getMinusSCEV(LHS, RHS), L);
+ if (LHS->getType()->isInteger()) {
+ SCEVHandle TC = HowFarToZero(SCEV::getMinusSCEV(LHS, RHS), L);
+ if (!isa<SCEVCouldNotCompute>(TC)) return TC;
+ }
break;
case Instruction::SetEQ:
// Convert to: while (X-Y == 0) // while (X == Y)
- if (LHS->getType()->isInteger())
- return HowFarToNonZero(getMinusSCEV(LHS, RHS), L);
+ if (LHS->getType()->isInteger()) {
+ SCEVHandle TC = HowFarToNonZero(SCEV::getMinusSCEV(LHS, RHS), L);
+ if (!isa<SCEVCouldNotCompute>(TC)) return TC;
+ }
+ break;
+ case Instruction::SetLT:
+ if (LHS->getType()->isInteger() &&
+ ExitCond->getOperand(0)->getType()->isSigned()) {
+ SCEVHandle TC = HowManyLessThans(LHS, RHS, L);
+ if (!isa<SCEVCouldNotCompute>(TC)) return TC;
+ }
+ break;
+ case Instruction::SetGT:
+ if (LHS->getType()->isInteger() &&
+ ExitCond->getOperand(0)->getType()->isSigned()) {
+ SCEVHandle TC = HowManyLessThans(RHS, LHS, L);
+ if (!isa<SCEVCouldNotCompute>(TC)) return TC;
+ }
break;
default:
#if 0
#endif
break;
}
+
+ return ComputeIterationCountExhaustively(L, ExitCond,
+ ExitBr->getSuccessor(0) == ExitBlock);
+}
+
+static ConstantInt *
+EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, Constant *C) {
+ SCEVHandle InVal = SCEVConstant::get(cast<ConstantInt>(C));
+ SCEVHandle Val = AddRec->evaluateAtIteration(InVal);
+ assert(isa<SCEVConstant>(Val) &&
+ "Evaluation of SCEV at constant didn't fold correctly?");
+ return cast<SCEVConstant>(Val)->getValue();
+}
+
+/// GetAddressedElementFromGlobal - Given a global variable with an initializer
+/// and a GEP expression (missing the pointer index) indexing into it, return
+/// the addressed element of the initializer or null if the index expression is
+/// invalid.
+static Constant *
+GetAddressedElementFromGlobal(GlobalVariable *GV,
+ const std::vector<ConstantInt*> &Indices) {
+ Constant *Init = GV->getInitializer();
+ for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
+ uint64_t Idx = Indices[i]->getZExtValue();
+ if (ConstantStruct *CS = dyn_cast<ConstantStruct>(Init)) {
+ assert(Idx < CS->getNumOperands() && "Bad struct index!");
+ Init = cast<Constant>(CS->getOperand(Idx));
+ } else if (ConstantArray *CA = dyn_cast<ConstantArray>(Init)) {
+ if (Idx >= CA->getNumOperands()) return 0; // Bogus program
+ Init = cast<Constant>(CA->getOperand(Idx));
+ } else if (isa<ConstantAggregateZero>(Init)) {
+ if (const StructType *STy = dyn_cast<StructType>(Init->getType())) {
+ assert(Idx < STy->getNumElements() && "Bad struct index!");
+ Init = Constant::getNullValue(STy->getElementType(Idx));
+ } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Init->getType())) {
+ if (Idx >= ATy->getNumElements()) return 0; // Bogus program
+ Init = Constant::getNullValue(ATy->getElementType());
+ } else {
+ assert(0 && "Unknown constant aggregate type!");
+ }
+ return 0;
+ } else {
+ return 0; // Unknown initializer type
+ }
+ }
+ return Init;
+}
+
+/// ComputeLoadConstantCompareIterationCount - Given an exit condition of
+/// 'setcc load X, cst', try to se if we can compute the trip count.
+SCEVHandle ScalarEvolutionsImpl::
+ComputeLoadConstantCompareIterationCount(LoadInst *LI, Constant *RHS,
+ const Loop *L, unsigned SetCCOpcode) {
+ if (LI->isVolatile()) return UnknownValue;
+
+ // Check to see if the loaded pointer is a getelementptr of a global.
+ GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0));
+ if (!GEP) return UnknownValue;
+
+ // Make sure that it is really a constant global we are gepping, with an
+ // initializer, and make sure the first IDX is really 0.
+ GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
+ if (!GV || !GV->isConstant() || !GV->hasInitializer() ||
+ GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) ||
+ !cast<Constant>(GEP->getOperand(1))->isNullValue())
+ return UnknownValue;
+
+ // Okay, we allow one non-constant index into the GEP instruction.
+ Value *VarIdx = 0;
+ std::vector<ConstantInt*> Indexes;
+ unsigned VarIdxNum = 0;
+ for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i)
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
+ Indexes.push_back(CI);
+ } else if (!isa<ConstantInt>(GEP->getOperand(i))) {
+ if (VarIdx) return UnknownValue; // Multiple non-constant idx's.
+ VarIdx = GEP->getOperand(i);
+ VarIdxNum = i-2;
+ Indexes.push_back(0);
+ }
+
+ // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant.
+ // Check to see if X is a loop variant variable value now.
+ SCEVHandle Idx = getSCEV(VarIdx);
+ SCEVHandle Tmp = getSCEVAtScope(Idx, L);
+ if (!isa<SCEVCouldNotCompute>(Tmp)) Idx = Tmp;
+
+ // We can only recognize very limited forms of loop index expressions, in
+ // particular, only affine AddRec's like {C1,+,C2}.
+ SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
+ if (!IdxExpr || !IdxExpr->isAffine() || IdxExpr->isLoopInvariant(L) ||
+ !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
+ !isa<SCEVConstant>(IdxExpr->getOperand(1)))
+ return UnknownValue;
+
+ unsigned MaxSteps = MaxBruteForceIterations;
+ for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) {
+ ConstantInt *ItCst =
+ ConstantInt::get(IdxExpr->getType()->getUnsignedVersion(), IterationNum);
+ ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst);
+
+ // Form the GEP offset.
+ Indexes[VarIdxNum] = Val;
+
+ Constant *Result = GetAddressedElementFromGlobal(GV, Indexes);
+ if (Result == 0) break; // Cannot compute!
+
+ // Evaluate the condition for this iteration.
+ Result = ConstantExpr::get(SetCCOpcode, Result, RHS);
+ if (!isa<ConstantBool>(Result)) break; // Couldn't decide for sure
+ if (cast<ConstantBool>(Result)->getValue() == false) {
+#if 0
+ std::cerr << "\n***\n*** Computed loop count " << *ItCst
+ << "\n*** From global " << *GV << "*** BB: " << *L->getHeader()
+ << "***\n";
+#endif
+ ++NumArrayLenItCounts;
+ return SCEVConstant::get(ItCst); // Found terminating iteration!
+ }
+ }
+ return UnknownValue;
+}
+
+
+/// CanConstantFold - Return true if we can constant fold an instruction of the
+/// specified type, assuming that all operands were constants.
+static bool CanConstantFold(const Instruction *I) {
+ if (isa<BinaryOperator>(I) || isa<ShiftInst>(I) ||
+ isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I))
+ return true;
+
+ if (const CallInst *CI = dyn_cast<CallInst>(I))
+ if (const Function *F = CI->getCalledFunction())
+ return canConstantFoldCallTo((Function*)F); // FIXME: elim cast
+ return false;
+}
+
+/// ConstantFold - Constant fold an instruction of the specified type with the
+/// specified constant operands. This function may modify the operands vector.
+static Constant *ConstantFold(const Instruction *I,
+ std::vector<Constant*> &Operands) {
+ if (isa<BinaryOperator>(I) || isa<ShiftInst>(I))
+ return ConstantExpr::get(I->getOpcode(), Operands[0], Operands[1]);
+
+ switch (I->getOpcode()) {
+ case Instruction::Cast:
+ return ConstantExpr::getCast(Operands[0], I->getType());
+ case Instruction::Select:
+ return ConstantExpr::getSelect(Operands[0], Operands[1], Operands[2]);
+ case Instruction::Call:
+ if (Function *GV = dyn_cast<Function>(Operands[0])) {
+ Operands.erase(Operands.begin());
+ return ConstantFoldCall(cast<Function>(GV), Operands);
+ }
+
+ return 0;
+ case Instruction::GetElementPtr:
+ Constant *Base = Operands[0];
+ Operands.erase(Operands.begin());
+ return ConstantExpr::getGetElementPtr(Base, Operands);
+ }
+ return 0;
+}
+
+
+/// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node
+/// in the loop that V is derived from. We allow arbitrary operations along the
+/// way, but the operands of an operation must either be constants or a value
+/// derived from a constant PHI. If this expression does not fit with these
+/// constraints, return null.
+static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) {
+ // If this is not an instruction, or if this is an instruction outside of the
+ // loop, it can't be derived from a loop PHI.
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (I == 0 || !L->contains(I->getParent())) return 0;
+
+ if (PHINode *PN = dyn_cast<PHINode>(I))
+ if (L->getHeader() == I->getParent())
+ return PN;
+ else
+ // We don't currently keep track of the control flow needed to evaluate
+ // PHIs, so we cannot handle PHIs inside of loops.
+ return 0;
+
+ // If we won't be able to constant fold this expression even if the operands
+ // are constants, return early.
+ if (!CanConstantFold(I)) return 0;
+
+ // Otherwise, we can evaluate this instruction if all of its operands are
+ // constant or derived from a PHI node themselves.
+ PHINode *PHI = 0;
+ for (unsigned Op = 0, e = I->getNumOperands(); Op != e; ++Op)
+ if (!(isa<Constant>(I->getOperand(Op)) ||
+ isa<GlobalValue>(I->getOperand(Op)))) {
+ PHINode *P = getConstantEvolvingPHI(I->getOperand(Op), L);
+ if (P == 0) return 0; // Not evolving from PHI
+ if (PHI == 0)
+ PHI = P;
+ else if (PHI != P)
+ return 0; // Evolving from multiple different PHIs.
+ }
+
+ // This is a expression evolving from a constant PHI!
+ return PHI;
+}
+
+/// EvaluateExpression - Given an expression that passes the
+/// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node
+/// in the loop has the value PHIVal. If we can't fold this expression for some
+/// reason, return null.
+static Constant *EvaluateExpression(Value *V, Constant *PHIVal) {
+ if (isa<PHINode>(V)) return PHIVal;
+ if (GlobalValue *GV = dyn_cast<GlobalValue>(V))
+ return GV;
+ if (Constant *C = dyn_cast<Constant>(V)) return C;
+ Instruction *I = cast<Instruction>(V);
+
+ std::vector<Constant*> Operands;
+ Operands.resize(I->getNumOperands());
+
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
+ Operands[i] = EvaluateExpression(I->getOperand(i), PHIVal);
+ if (Operands[i] == 0) return 0;
+ }
+
+ return ConstantFold(I, Operands);
+}
+
+/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
+/// in the header of its containing loop, we know the loop executes a
+/// constant number of times, and the PHI node is just a recurrence
+/// involving constants, fold it.
+Constant *ScalarEvolutionsImpl::
+getConstantEvolutionLoopExitValue(PHINode *PN, uint64_t Its, const Loop *L) {
+ std::map<PHINode*, Constant*>::iterator I =
+ ConstantEvolutionLoopExitValue.find(PN);
+ if (I != ConstantEvolutionLoopExitValue.end())
+ return I->second;
+
+ if (Its > MaxBruteForceIterations)
+ return ConstantEvolutionLoopExitValue[PN] = 0; // Not going to evaluate it.
+
+ Constant *&RetVal = ConstantEvolutionLoopExitValue[PN];
+
+ // Since the loop is canonicalized, the PHI node must have two entries. One
+ // entry must be a constant (coming in from outside of the loop), and the
+ // second must be derived from the same PHI.
+ bool SecondIsBackedge = L->contains(PN->getIncomingBlock(1));
+ Constant *StartCST =
+ dyn_cast<Constant>(PN->getIncomingValue(!SecondIsBackedge));
+ if (StartCST == 0)
+ return RetVal = 0; // Must be a constant.
+
+ Value *BEValue = PN->getIncomingValue(SecondIsBackedge);
+ PHINode *PN2 = getConstantEvolvingPHI(BEValue, L);
+ if (PN2 != PN)
+ return RetVal = 0; // Not derived from same PHI.
+
+ // Execute the loop symbolically to determine the exit value.
+ unsigned IterationNum = 0;
+ unsigned NumIterations = Its;
+ if (NumIterations != Its)
+ return RetVal = 0; // More than 2^32 iterations??
+
+ for (Constant *PHIVal = StartCST; ; ++IterationNum) {
+ if (IterationNum == NumIterations)
+ return RetVal = PHIVal; // Got exit value!
+
+ // Compute the value of the PHI node for the next iteration.
+ Constant *NextPHI = EvaluateExpression(BEValue, PHIVal);
+ if (NextPHI == PHIVal)
+ return RetVal = NextPHI; // Stopped evolving!
+ if (NextPHI == 0)
+ return 0; // Couldn't evaluate!
+ PHIVal = NextPHI;
+ }
+}
+
+/// ComputeIterationCountExhaustively - If the trip is known to execute a
+/// constant number of times (the condition evolves only from constants),
+/// try to evaluate a few iterations of the loop until we get the exit
+/// condition gets a value of ExitWhen (true or false). If we cannot
+/// evaluate the trip count of the loop, return UnknownValue.
+SCEVHandle ScalarEvolutionsImpl::
+ComputeIterationCountExhaustively(const Loop *L, Value *Cond, bool ExitWhen) {
+ PHINode *PN = getConstantEvolvingPHI(Cond, L);
+ if (PN == 0) return UnknownValue;
+
+ // Since the loop is canonicalized, the PHI node must have two entries. One
+ // entry must be a constant (coming in from outside of the loop), and the
+ // second must be derived from the same PHI.
+ bool SecondIsBackedge = L->contains(PN->getIncomingBlock(1));
+ Constant *StartCST =
+ dyn_cast<Constant>(PN->getIncomingValue(!SecondIsBackedge));
+ if (StartCST == 0) return UnknownValue; // Must be a constant.
+
+ Value *BEValue = PN->getIncomingValue(SecondIsBackedge);
+ PHINode *PN2 = getConstantEvolvingPHI(BEValue, L);
+ if (PN2 != PN) return UnknownValue; // Not derived from same PHI.
+
+ // Okay, we find a PHI node that defines the trip count of this loop. Execute
+ // the loop symbolically to determine when the condition gets a value of
+ // "ExitWhen".
+ unsigned IterationNum = 0;
+ unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis.
+ for (Constant *PHIVal = StartCST;
+ IterationNum != MaxIterations; ++IterationNum) {
+ ConstantBool *CondVal =
+ dyn_cast_or_null<ConstantBool>(EvaluateExpression(Cond, PHIVal));
+ if (!CondVal) return UnknownValue; // Couldn't symbolically evaluate.
+
+ if (CondVal->getValue() == ExitWhen) {
+ ConstantEvolutionLoopExitValue[PN] = PHIVal;
+ ++NumBruteForceTripCountsComputed;
+ return SCEVConstant::get(ConstantInt::get(Type::UIntTy, IterationNum));
+ }
+
+ // Compute the value of the PHI node for the next iteration.
+ Constant *NextPHI = EvaluateExpression(BEValue, PHIVal);
+ if (NextPHI == 0 || NextPHI == PHIVal)
+ return UnknownValue; // Couldn't evaluate or not making progress...
+ PHIVal = NextPHI;
+ }
+
+ // Too many iterations were needed to evaluate.
return UnknownValue;
}
SCEVHandle ScalarEvolutionsImpl::getSCEVAtScope(SCEV *V, const Loop *L) {
// FIXME: this should be turned into a virtual method on SCEV!
- if (isa<SCEVConstant>(V) || isa<SCEVUnknown>(V)) return V;
+ if (isa<SCEVConstant>(V)) return V;
+
+ // If this instruction is evolves from a constant-evolving PHI, compute the
+ // exit value from the loop without using SCEVs.
+ if (SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) {
+ if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
+ const Loop *LI = this->LI[I->getParent()];
+ if (LI && LI->getParentLoop() == L) // Looking for loop exit value.
+ if (PHINode *PN = dyn_cast<PHINode>(I))
+ if (PN->getParent() == LI->getHeader()) {
+ // Okay, there is no closed form solution for the PHI node. Check
+ // to see if the loop that contains it has a known iteration count.
+ // If so, we may be able to force computation of the exit value.
+ SCEVHandle IterationCount = getIterationCount(LI);
+ if (SCEVConstant *ICC = dyn_cast<SCEVConstant>(IterationCount)) {
+ // Okay, we know how many times the containing loop executes. If
+ // this is a constant evolving PHI node, get the final value at
+ // the specified iteration number.
+ Constant *RV = getConstantEvolutionLoopExitValue(PN,
+ ICC->getValue()->getZExtValue(),
+ LI);
+ if (RV) return SCEVUnknown::get(RV);
+ }
+ }
+
+ // Okay, this is a some expression that we cannot symbolically evaluate
+ // into a SCEV. Check to see if it's possible to symbolically evaluate
+ // the arguments into constants, and if see, try to constant propagate the
+ // result. This is particularly useful for computing loop exit values.
+ if (CanConstantFold(I)) {
+ std::vector<Constant*> Operands;
+ Operands.reserve(I->getNumOperands());
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
+ Value *Op = I->getOperand(i);
+ if (Constant *C = dyn_cast<Constant>(Op)) {
+ Operands.push_back(C);
+ } else {
+ SCEVHandle OpV = getSCEVAtScope(getSCEV(Op), L);
+ if (SCEVConstant *SC = dyn_cast<SCEVConstant>(OpV))
+ Operands.push_back(ConstantExpr::getCast(SC->getValue(),
+ Op->getType()));
+ else if (SCEVUnknown *SU = dyn_cast<SCEVUnknown>(OpV)) {
+ if (Constant *C = dyn_cast<Constant>(SU->getValue()))
+ Operands.push_back(ConstantExpr::getCast(C, Op->getType()));
+ else
+ return V;
+ } else {
+ return V;
+ }
+ }
+ }
+ return SCEVUnknown::get(ConstantFold(I, Operands));
+ }
+ }
+
+ // This is some other type of SCEVUnknown, just return it.
+ return V;
+ }
+
if (SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) {
// Avoid performing the look-up in the common case where the specified
// expression has no loop-variant portions.
if (OpAtScope == UnknownValue) return UnknownValue;
// Okay, at least one of these operands is loop variant but might be
// foldable. Build a new instance of the folded commutative expression.
- std::vector<SCEVHandle> NewOps(Comm->op_begin(), Comm->op_begin()+i-1);
+ std::vector<SCEVHandle> NewOps(Comm->op_begin(), Comm->op_begin()+i);
NewOps.push_back(OpAtScope);
for (++i; i != e; ++i) {
return Comm;
}
- if (SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(V)) {
- SCEVHandle LHS = getSCEVAtScope(UDiv->getLHS(), L);
+ if (SCEVSDivExpr *Div = dyn_cast<SCEVSDivExpr>(V)) {
+ SCEVHandle LHS = getSCEVAtScope(Div->getLHS(), L);
if (LHS == UnknownValue) return LHS;
- SCEVHandle RHS = getSCEVAtScope(UDiv->getRHS(), L);
+ SCEVHandle RHS = getSCEVAtScope(Div->getRHS(), L);
if (RHS == UnknownValue) return RHS;
- if (LHS == UDiv->getLHS() && RHS == UDiv->getRHS())
- return UDiv; // must be loop invariant
- return SCEVUDivExpr::get(LHS, RHS);
+ if (LHS == Div->getLHS() && RHS == Div->getRHS())
+ return Div; // must be loop invariant
+ return SCEVSDivExpr::get(LHS, RHS);
}
// If this is a loop recurrence for a loop that does not contain L, then we
if (IterationCount == UnknownValue) return UnknownValue;
IterationCount = getTruncateOrZeroExtend(IterationCount,
AddRec->getType());
-
+
// If the value is affine, simplify the expression evaluation to just
// Start + Step*IterationCount.
if (AddRec->isAffine())
SCEVConstant *L = dyn_cast<SCEVConstant>(AddRec->getOperand(0));
SCEVConstant *M = dyn_cast<SCEVConstant>(AddRec->getOperand(1));
SCEVConstant *N = dyn_cast<SCEVConstant>(AddRec->getOperand(2));
-
+
// We currently can only solve this if the coefficients are constants.
if (!L || !M || !N) {
SCEV *CNC = new SCEVCouldNotCompute();
}
Constant *Two = ConstantInt::get(L->getValue()->getType(), 2);
-
+
// Convert from chrec coefficients to polynomial coefficients AX^2+BX+C
Constant *C = L->getValue();
// The B coefficient is M-N/2
Two));
// The A coefficient is N/2
Constant *A = ConstantExpr::getDiv(N->getValue(), Two);
-
+
// Compute the B^2-4ac term.
Constant *SqrtTerm =
ConstantExpr::getMul(ConstantInt::get(C->getType(), 4),
SqrtTerm = ConstantExpr::getSub(ConstantExpr::getMul(B, B), SqrtTerm);
// Compute floor(sqrt(B^2-4ac))
- ConstantUInt *SqrtVal =
- cast<ConstantUInt>(ConstantExpr::getCast(SqrtTerm,
+ ConstantInt *SqrtVal =
+ cast<ConstantInt>(ConstantExpr::getCast(SqrtTerm,
SqrtTerm->getType()->getUnsignedVersion()));
- uint64_t SqrtValV = SqrtVal->getValue();
- uint64_t SqrtValV2 = (uint64_t)sqrtl(SqrtValV);
+ uint64_t SqrtValV = SqrtVal->getZExtValue();
+ uint64_t SqrtValV2 = (uint64_t)sqrt((double)SqrtValV);
// The square root might not be precise for arbitrary 64-bit integer
// values. Do some sanity checks to ensure it's correct.
if (SqrtValV2*SqrtValV2 > SqrtValV ||
return std::make_pair(CNC, CNC);
}
- SqrtVal = ConstantUInt::get(Type::ULongTy, SqrtValV2);
+ SqrtVal = ConstantInt::get(Type::ULongTy, SqrtValV2);
SqrtTerm = ConstantExpr::getCast(SqrtVal, SqrtTerm->getType());
-
+
Constant *NegB = ConstantExpr::getNeg(B);
Constant *TwoA = ConstantExpr::getMul(A, Two);
-
+
// The divisions must be performed as signed divisions.
const Type *SignedTy = NegB->getType()->getSignedVersion();
NegB = ConstantExpr::getCast(NegB, SignedTy);
TwoA = ConstantExpr::getCast(TwoA, SignedTy);
SqrtTerm = ConstantExpr::getCast(SqrtTerm, SignedTy);
-
+
Constant *Solution1 =
ConstantExpr::getDiv(ConstantExpr::getAdd(NegB, SqrtTerm), TwoA);
Constant *Solution2 =
//
// Get the initial value for the loop.
SCEVHandle Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop());
+ if (isa<SCEVCouldNotCompute>(Start)) return UnknownValue;
SCEVHandle Step = AddRec->getOperand(1);
Step = getSCEVAtScope(Step, L->getParentLoop());
// FIXME: We should add DivExpr and RemExpr operations to our AST.
if (SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step)) {
if (StepC->getValue()->equalsInt(1)) // N % 1 == 0
- return getNegativeSCEV(Start); // 0 - Start/1 == -Start
+ return SCEV::getNegativeSCEV(Start); // 0 - Start/1 == -Start
if (StepC->getValue()->isAllOnesValue()) // N % -1 == 0
return Start; // 0 - Start/-1 == Start
if (ConstantBool *CB =
dyn_cast<ConstantBool>(ConstantExpr::getSetLT(R1->getValue(),
R2->getValue()))) {
- if (CB != ConstantBool::True)
+ if (CB->getValue() == false)
std::swap(R1, R2); // R1 is the minimum root now.
-
+
// We can only use this value if the chrec ends up with an exact zero
// value at this index. When solving for "X*X != 5", for example, we
// should not accept a root of 2.
}
}
}
-
+
return UnknownValue;
}
// Loops that look like: while (X == 0) are very strange indeed. We don't
// handle them yet except for the trivial case. This could be expanded in the
// future as needed.
-
+
// If the value is a constant, check to see if it is known to be non-zero
// already. If so, the backedge will execute zero times.
if (SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
Constant *Zero = Constant::getNullValue(C->getValue()->getType());
Constant *NonZero = ConstantExpr::getSetNE(C->getValue(), Zero);
- if (NonZero == ConstantBool::True)
+ if (NonZero == ConstantBool::getTrue())
return getSCEV(Zero);
return UnknownValue; // Otherwise it will loop infinitely.
}
-
+
// We could implement others, but I really doubt anyone writes loops like
// this, and if they did, they would already be constant folded.
return UnknownValue;
}
-static ConstantInt *
-EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, Constant *C) {
- SCEVHandle InVal = SCEVConstant::get(cast<ConstantInt>(C));
- SCEVHandle Val = AddRec->evaluateAtIteration(InVal);
- assert(isa<SCEVConstant>(Val) &&
- "Evaluation of SCEV at constant didn't fold correctly?");
- return cast<SCEVConstant>(Val)->getValue();
-}
+/// HowManyLessThans - Return the number of times a backedge containing the
+/// specified less-than comparison will execute. If not computable, return
+/// UnknownValue.
+SCEVHandle ScalarEvolutionsImpl::
+HowManyLessThans(SCEV *LHS, SCEV *RHS, const Loop *L) {
+ // Only handle: "ADDREC < LoopInvariant".
+ if (!RHS->isLoopInvariant(L)) return UnknownValue;
+
+ SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS);
+ if (!AddRec || AddRec->getLoop() != L)
+ return UnknownValue;
+
+ if (AddRec->isAffine()) {
+ // FORNOW: We only support unit strides.
+ SCEVHandle One = SCEVUnknown::getIntegerSCEV(1, RHS->getType());
+ if (AddRec->getOperand(1) != One)
+ return UnknownValue;
+
+ // The number of iterations for "[n,+,1] < m", is m-n. However, we don't
+ // know that m is >= n on input to the loop. If it is, the condition return
+ // true zero times. What we really should return, for full generality, is
+ // SMAX(0, m-n). Since we cannot check this, we will instead check for a
+ // canonical loop form: most do-loops will have a check that dominates the
+ // loop, that only enters the loop if [n-1]<m. If we can find this check,
+ // we know that the SMAX will evaluate to m-n, because we know that m >= n.
+
+ // Search for the check.
+ BasicBlock *Preheader = L->getLoopPreheader();
+ BasicBlock *PreheaderDest = L->getHeader();
+ if (Preheader == 0) return UnknownValue;
+
+ BranchInst *LoopEntryPredicate =
+ dyn_cast<BranchInst>(Preheader->getTerminator());
+ if (!LoopEntryPredicate) return UnknownValue;
+
+ // This might be a critical edge broken out. If the loop preheader ends in
+ // an unconditional branch to the loop, check to see if the preheader has a
+ // single predecessor, and if so, look for its terminator.
+ while (LoopEntryPredicate->isUnconditional()) {
+ PreheaderDest = Preheader;
+ Preheader = Preheader->getSinglePredecessor();
+ if (!Preheader) return UnknownValue; // Multiple preds.
+
+ LoopEntryPredicate =
+ dyn_cast<BranchInst>(Preheader->getTerminator());
+ if (!LoopEntryPredicate) return UnknownValue;
+ }
+
+ // Now that we found a conditional branch that dominates the loop, check to
+ // see if it is the comparison we are looking for.
+ SetCondInst *SCI =dyn_cast<SetCondInst>(LoopEntryPredicate->getCondition());
+ if (!SCI) return UnknownValue;
+ Value *PreCondLHS = SCI->getOperand(0);
+ Value *PreCondRHS = SCI->getOperand(1);
+ Instruction::BinaryOps Cond;
+ if (LoopEntryPredicate->getSuccessor(0) == PreheaderDest)
+ Cond = SCI->getOpcode();
+ else
+ Cond = SCI->getInverseCondition();
+
+ switch (Cond) {
+ case Instruction::SetGT:
+ std::swap(PreCondLHS, PreCondRHS);
+ Cond = Instruction::SetLT;
+ // Fall Through.
+ case Instruction::SetLT:
+ if (PreCondLHS->getType()->isInteger() &&
+ PreCondLHS->getType()->isSigned()) {
+ if (RHS != getSCEV(PreCondRHS))
+ return UnknownValue; // Not a comparison against 'm'.
+
+ if (SCEV::getMinusSCEV(AddRec->getOperand(0), One)
+ != getSCEV(PreCondLHS))
+ return UnknownValue; // Not a comparison against 'n-1'.
+ break;
+ } else {
+ return UnknownValue;
+ }
+ default: break;
+ }
+ //std::cerr << "Computed Loop Trip Count as: " <<
+ // *SCEV::getMinusSCEV(RHS, AddRec->getOperand(0)) << "\n";
+ return SCEV::getMinusSCEV(RHS, AddRec->getOperand(0));
+ }
+
+ return UnknownValue;
+}
/// getNumIterationsInRange - Return the number of iterations of this loop that
/// produce values in the specified constant range. Another way of looking at
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
if (!SC->getValue()->isNullValue()) {
std::vector<SCEVHandle> Operands(op_begin(), op_end());
- Operands[0] = getIntegerSCEV(0, SC->getType());
+ Operands[0] = SCEVUnknown::getIntegerSCEV(0, SC->getType());
SCEVHandle Shifted = SCEVAddRecExpr::get(Operands, getLoop());
if (SCEVAddRecExpr *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted))
return ShiftedAddRec->getNumIterationsInRange(
// iteration exits.
ConstantInt *Zero = ConstantInt::get(getType(), 0);
if (!Range.contains(Zero)) return SCEVConstant::get(Zero);
-
+
if (isAffine()) {
// If this is an affine expression then we have this situation:
// Solve {0,+,A} in Range === Ax in Range
// terms of figuring out when zero is crossed, instead of when
// Range.getUpper() is crossed.
std::vector<SCEVHandle> NewOps(op_begin(), op_end());
- NewOps[0] = getNegativeSCEV(SCEVUnknown::get(Range.getUpper()));
+ NewOps[0] = SCEV::getNegativeSCEV(SCEVUnknown::get(Range.getUpper()));
SCEVHandle NewAddRec = SCEVAddRecExpr::get(NewOps, getLoop());
// Next, solve the constructed addrec
if (ConstantBool *CB =
dyn_cast<ConstantBool>(ConstantExpr::getSetLT(R1->getValue(),
R2->getValue()))) {
- if (CB != ConstantBool::True)
+ if (CB->getValue() == false)
std::swap(R1, R2); // R1 is the minimum root now.
-
+
// Make sure the root is not off by one. The returned iteration should
// not be in the range, but the previous one should be. When solving
// for "X*X < 5", for example, we should not return a root of 2.
Constant *NextVal =
ConstantExpr::getAdd(R1->getValue(),
ConstantInt::get(R1->getType(), 1));
-
+
R1Val = EvaluateConstantChrecAtConstant(this, NextVal);
if (!Range.contains(R1Val))
return SCEVUnknown::get(NextVal);
return new SCEVCouldNotCompute(); // Something strange happened
}
-
+
// If R1 was not in the range, then it is a good return value. Make
// sure that R1-1 WAS in the range though, just in case.
Constant *NextVal =
// Increment to test the next index.
TestVal = cast<ConstantInt>(ConstantExpr::getAdd(TestVal, One));
} while (TestVal != EndVal);
-
+
return new SCEVCouldNotCompute();
}
void ScalarEvolution::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
- AU.addRequiredID(LoopSimplifyID);
AU.addRequiredTransitive<LoopInfo>();
}
return ((ScalarEvolutionsImpl*)Impl)->getSCEV(V);
}
+/// hasSCEV - Return true if the SCEV for this value has already been
+/// computed.
+bool ScalarEvolution::hasSCEV(Value *V) const {
+ return ((ScalarEvolutionsImpl*)Impl)->hasSCEV(V);
+}
+
+
+/// setSCEV - Insert the specified SCEV into the map of current SCEVs for
+/// the specified value.
+void ScalarEvolution::setSCEV(Value *V, const SCEVHandle &H) {
+ ((ScalarEvolutionsImpl*)Impl)->setSCEV(V, H);
+}
+
+
SCEVHandle ScalarEvolution::getIterationCount(const Loop *L) const {
return ((ScalarEvolutionsImpl*)Impl)->getIterationCount(L);
}
return ((ScalarEvolutionsImpl*)Impl)->deleteInstructionFromRecords(I);
}
-
-/// shouldSubstituteIndVar - Return true if we should perform induction variable
-/// substitution for this variable. This is a hack because we don't have a
-/// strength reduction pass yet. When we do we will promote all vars, because
-/// we can strength reduce them later as desired.
-bool ScalarEvolution::shouldSubstituteIndVar(const SCEV *S) const {
- // Don't substitute high degree polynomials.
- if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S))
- if (AddRec->getNumOperands() > 3) return false;
- return true;
-}
-
-
-static void PrintLoopInfo(std::ostream &OS, const ScalarEvolution *SE,
+static void PrintLoopInfo(std::ostream &OS, const ScalarEvolution *SE,
const Loop *L) {
// Print all inner loops first
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
PrintLoopInfo(OS, SE, *I);
-
+
std::cerr << "Loop " << L->getHeader()->getName() << ": ";
- if (L->getExitBlocks().size() != 1)
+
+ std::vector<BasicBlock*> ExitBlocks;
+ L->getExitBlocks(ExitBlocks);
+ if (ExitBlocks.size() != 1)
std::cerr << "<multiple exits> ";
if (SE->hasLoopInvariantIterationCount(L)) {
std::cerr << "\n";
}
-void ScalarEvolution::print(std::ostream &OS) const {
+void ScalarEvolution::print(std::ostream &OS, const Module* ) const {
Function &F = ((ScalarEvolutionsImpl*)Impl)->F;
LoopInfo &LI = ((ScalarEvolutionsImpl*)Impl)->LI;
OS << "Classifying expressions for: " << F.getName() << "\n";
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
- if ((*I)->getType()->isInteger()) {
- OS << **I;
+ if (I->getType()->isInteger()) {
+ OS << *I;
OS << " --> ";
- SCEVHandle SV = getSCEV(*I);
+ SCEVHandle SV = getSCEV(&*I);
SV->print(OS);
OS << "\t\t";
-
- if ((*I)->getType()->isIntegral()) {
+
+ if ((*I).getType()->isIntegral()) {
ConstantRange Bounds = SV->getValueRange();
if (!Bounds.isFullSet())
OS << "Bounds: " << Bounds << " ";
}
- if (const Loop *L = LI.getLoopFor((*I)->getParent())) {
+ if (const Loop *L = LI.getLoopFor((*I).getParent())) {
OS << "Exits: ";
- SCEVHandle ExitValue = getSCEVAtScope(*I, L->getParentLoop());
+ SCEVHandle ExitValue = getSCEVAtScope(&*I, L->getParentLoop());
if (isa<SCEVCouldNotCompute>(ExitValue)) {
OS << "<<Unknown>>";
} else {
PrintLoopInfo(OS, this, *I);
}
-//===----------------------------------------------------------------------===//
-// ScalarEvolutionRewriter Class Implementation
-//===----------------------------------------------------------------------===//
-
-Value *ScalarEvolutionRewriter::
-GetOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty) {
- assert((Ty->isInteger() || Ty->isFloatingPoint()) &&
- "Can only insert integer or floating point induction variables!");
-
- // Check to see if we already inserted one.
- SCEVHandle H = SCEVAddRecExpr::get(getIntegerSCEV(0, Ty),
- getIntegerSCEV(1, Ty), L);
- return ExpandCodeFor(H, 0, Ty);
-}
-
-/// ExpandCodeFor - Insert code to directly compute the specified SCEV
-/// expression into the program. The inserted code is inserted into the
-/// specified block.
-Value *ScalarEvolutionRewriter::ExpandCodeFor(SCEVHandle SH,
- Instruction *InsertPt,
- const Type *Ty) {
- std::map<SCEVHandle, Value*>::iterator ExistVal =InsertedExpressions.find(SH);
- Value *V;
- if (ExistVal != InsertedExpressions.end()) {
- V = ExistVal->second;
- } else {
- // Ask the recurrence object to expand the code for itself.
- V = SH->expandCodeFor(*this, InsertPt);
- // Cache the generated result.
- InsertedExpressions.insert(std::make_pair(SH, V));
- }
-
- if (Ty == 0 || V->getType() == Ty)
- return V;
- if (Constant *C = dyn_cast<Constant>(V))
- return ConstantExpr::getCast(C, Ty);
- else if (Instruction *I = dyn_cast<Instruction>(V)) {
- // FIXME: check to see if there is already a cast!
- BasicBlock::iterator IP = I; ++IP;
- if (InvokeInst *II = dyn_cast<InvokeInst>(I))
- IP = II->getNormalDest()->begin();
- while (isa<PHINode>(IP)) ++IP;
- return new CastInst(V, Ty, V->getName(), IP);
- } else {
- // FIXME: check to see if there is already a cast!
- return new CastInst(V, Ty, V->getName(), InsertPt);
- }
-}
projects / oota-llvm.git / blobdiff