//
// 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 is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "scalar-evolution"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Streams.h"
#include "llvm/ADT/Statistic.h"
#include <ostream>
#include <cmath>
using namespace llvm;
+STATISTIC(NumBruteForceEvaluations,
+ "Number of brute force evaluations needed to "
+ "calculate high-order polynomial exit values");
+STATISTIC(NumArrayLenItCounts,
+ "Number of trip counts computed with array length");
+STATISTIC(NumTripCountsComputed,
+ "Number of loops with predictable loop counts");
+STATISTIC(NumTripCountsNotComputed,
+ "Number of loops without predictable loop counts");
+STATISTIC(NumBruteForceTripCountsComputed,
+ "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));
+
namespace {
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");
- 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));
}
+char ScalarEvolution::ID = 0;
//===----------------------------------------------------------------------===//
// SCEV class definitions
//
SCEV::~SCEV() {}
void SCEV::dump() const {
- print(llvm_cerr);
+ print(cerr);
}
/// getValueRange - Return the tightest constant bounds that this value is
ConstantRange SCEV::getValueRange() const {
const Type *Ty = getType();
assert(Ty->isInteger() && "Can't get range for a non-integer SCEV!");
- Ty = Ty->getUnsignedVersion();
// Default to a full range if no better information is available.
- return ConstantRange(getType());
+ return ConstantRange(getBitWidth());
+}
+
+uint32_t SCEV::getBitWidth() const {
+ if (const IntegerType* ITy = dyn_cast<IntegerType>(getType()))
+ return ITy->getBitWidth();
+ return 0;
}
SCEVHandle SCEVCouldNotCompute::
replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
- const SCEVHandle &Conc) const {
+ const SCEVHandle &Conc,
+ ScalarEvolution &SE) const {
return this;
}
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::getBitCast(V, NewTy));
- }
-
+SCEVHandle ScalarEvolution::getConstant(ConstantInt *V) {
SCEVConstant *&R = (*SCEVConstants)[V];
if (R == 0) R = new SCEVConstant(V);
return R;
}
+SCEVHandle ScalarEvolution::getConstant(const APInt& Val) {
+ return getConstant(ConstantInt::get(Val));
+}
+
ConstantRange SCEVConstant::getValueRange() const {
- return ConstantRange(V);
+ return ConstantRange(V->getValue());
}
const Type *SCEVConstant::getType() const { return V->getType(); }
: SCEV(scTruncate), Op(op), Ty(ty) {
assert(Op->getType()->isInteger() && Ty->isInteger() &&
"Cannot truncate non-integer value!");
- assert(Op->getType()->getPrimitiveSize() > Ty->getPrimitiveSize() &&
- "This is not a truncating conversion!");
+ assert(Op->getType()->getPrimitiveSizeInBits() > Ty->getPrimitiveSizeInBits()
+ && "This is not a truncating conversion!");
}
SCEVTruncateExpr::~SCEVTruncateExpr() {
}
ConstantRange SCEVTruncateExpr::getValueRange() const {
- return getOperand()->getValueRange().truncate(getType());
+ return getOperand()->getValueRange().truncate(getBitWidth());
}
void SCEVTruncateExpr::print(std::ostream &OS) const {
: SCEV(scZeroExtend), Op(op), Ty(ty) {
assert(Op->getType()->isInteger() && Ty->isInteger() &&
"Cannot zero extend non-integer value!");
- assert(Op->getType()->getPrimitiveSize() < Ty->getPrimitiveSize() &&
- "This is not an extending conversion!");
+ assert(Op->getType()->getPrimitiveSizeInBits() < Ty->getPrimitiveSizeInBits()
+ && "This is not an extending conversion!");
}
SCEVZeroExtendExpr::~SCEVZeroExtendExpr() {
}
ConstantRange SCEVZeroExtendExpr::getValueRange() const {
- return getOperand()->getValueRange().zeroExtend(getType());
+ return getOperand()->getValueRange().zeroExtend(getBitWidth());
}
void SCEVZeroExtendExpr::print(std::ostream &OS) const {
OS << "(zeroextend " << *Op << " to " << *Ty << ")";
}
+// SCEVSignExtends - Only allow the creation of one SCEVSignExtendExpr 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*>,
+ SCEVSignExtendExpr*> > SCEVSignExtends;
+
+SCEVSignExtendExpr::SCEVSignExtendExpr(const SCEVHandle &op, const Type *ty)
+ : SCEV(scSignExtend), Op(op), Ty(ty) {
+ assert(Op->getType()->isInteger() && Ty->isInteger() &&
+ "Cannot sign extend non-integer value!");
+ assert(Op->getType()->getPrimitiveSizeInBits() < Ty->getPrimitiveSizeInBits()
+ && "This is not an extending conversion!");
+}
+
+SCEVSignExtendExpr::~SCEVSignExtendExpr() {
+ SCEVSignExtends->erase(std::make_pair(Op, Ty));
+}
+
+ConstantRange SCEVSignExtendExpr::getValueRange() const {
+ return getOperand()->getValueRange().signExtend(getBitWidth());
+}
+
+void SCEVSignExtendExpr::print(std::ostream &OS) const {
+ OS << "(signextend " << *Op << " to " << *Ty << ")";
+}
+
// 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!
SCEVHandle SCEVCommutativeExpr::
replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
- const SCEVHandle &Conc) const {
+ const SCEVHandle &Conc,
+ ScalarEvolution &SE) const {
for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
- SCEVHandle H = getOperand(i)->replaceSymbolicValuesWithConcrete(Sym, Conc);
+ SCEVHandle H =
+ getOperand(i)->replaceSymbolicValuesWithConcrete(Sym, Conc, SE);
if (H != getOperand(i)) {
std::vector<SCEVHandle> NewOps;
NewOps.reserve(getNumOperands());
NewOps.push_back(H);
for (++i; i != e; ++i)
NewOps.push_back(getOperand(i)->
- replaceSymbolicValuesWithConcrete(Sym, Conc));
+ replaceSymbolicValuesWithConcrete(Sym, Conc, SE));
if (isa<SCEVAddExpr>(this))
- return SCEVAddExpr::get(NewOps);
+ return SE.getAddExpr(NewOps);
else if (isa<SCEVMulExpr>(this))
- return SCEVMulExpr::get(NewOps);
+ return SE.getMulExpr(NewOps);
+ else if (isa<SCEVSMaxExpr>(this))
+ return SE.getSMaxExpr(NewOps);
else
assert(0 && "Unknown commutative expr!");
}
}
const Type *SCEVSDivExpr::getType() const {
- const Type *Ty = LHS->getType();
- if (Ty->isUnsigned()) Ty = Ty->getSignedVersion();
- return Ty;
+ return LHS->getType();
}
// SCEVAddRecExprs - Only allow the creation of one SCEVAddRecExpr for any
SCEVHandle SCEVAddRecExpr::
replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
- const SCEVHandle &Conc) const {
+ const SCEVHandle &Conc,
+ ScalarEvolution &SE) const {
for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
- SCEVHandle H = getOperand(i)->replaceSymbolicValuesWithConcrete(Sym, Conc);
+ SCEVHandle H =
+ getOperand(i)->replaceSymbolicValuesWithConcrete(Sym, Conc, SE);
if (H != getOperand(i)) {
std::vector<SCEVHandle> NewOps;
NewOps.reserve(getNumOperands());
NewOps.push_back(H);
for (++i; i != e; ++i)
NewOps.push_back(getOperand(i)->
- replaceSymbolicValuesWithConcrete(Sym, Conc));
+ replaceSymbolicValuesWithConcrete(Sym, Conc, SE));
- return get(NewOps, L);
+ return SE.getAddRecExpr(NewOps, L);
}
}
return this;
/// getIntegerSCEV - Given an integer or FP type, create a constant for the
/// specified signed integer value and return a SCEV for the constant.
-SCEVHandle SCEVUnknown::getIntegerSCEV(int Val, const Type *Ty) {
+SCEVHandle ScalarEvolution::getIntegerSCEV(int Val, const Type *Ty) {
Constant *C;
if (Val == 0)
C = Constant::getNullValue(Ty);
else if (Ty->isFloatingPoint())
- C = ConstantFP::get(Ty, Val);
- else if (Ty->isSigned())
+ C = ConstantFP::get(Ty, APFloat(Ty==Type::FloatTy ? APFloat::IEEEsingle :
+ APFloat::IEEEdouble, Val));
+ else
C = ConstantInt::get(Ty, Val);
- else {
- C = ConstantInt::get(Ty->getSignedVersion(), Val);
- C = ConstantExpr::getBitCast(C, Ty);
- }
- return SCEVUnknown::get(C);
+ return getUnknown(C);
}
/// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion of the
/// input value to the specified type. If the type must be extended, it is zero
/// extended.
-static SCEVHandle getTruncateOrZeroExtend(const SCEVHandle &V, const Type *Ty) {
+static SCEVHandle getTruncateOrZeroExtend(const SCEVHandle &V, const Type *Ty,
+ ScalarEvolution &SE) {
const Type *SrcTy = V->getType();
assert(SrcTy->isInteger() && Ty->isInteger() &&
"Cannot truncate or zero extend with non-integer arguments!");
- if (SrcTy->getPrimitiveSize() == Ty->getPrimitiveSize())
+ if (SrcTy->getPrimitiveSizeInBits() == Ty->getPrimitiveSizeInBits())
return V; // No conversion
- if (SrcTy->getPrimitiveSize() > Ty->getPrimitiveSize())
- return SCEVTruncateExpr::get(V, Ty);
- return SCEVZeroExtendExpr::get(V, Ty);
+ if (SrcTy->getPrimitiveSizeInBits() > Ty->getPrimitiveSizeInBits())
+ return SE.getTruncateExpr(V, Ty);
+ return SE.getZeroExtendExpr(V, Ty);
}
/// getNegativeSCEV - Return a SCEV corresponding to -V = -1*V
///
-SCEVHandle SCEV::getNegativeSCEV(const SCEVHandle &V) {
+SCEVHandle ScalarEvolution::getNegativeSCEV(const SCEVHandle &V) {
if (SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
- return SCEVUnknown::get(ConstantExpr::getNeg(VC->getValue()));
+ return getUnknown(ConstantExpr::getNeg(VC->getValue()));
- return SCEVMulExpr::get(V, SCEVUnknown::getIntegerSCEV(-1, V->getType()));
+ return getMulExpr(V, getIntegerSCEV(-1, V->getType()));
}
/// getMinusSCEV - Return a SCEV corresponding to LHS - RHS.
///
-SCEVHandle SCEV::getMinusSCEV(const SCEVHandle &LHS, const SCEVHandle &RHS) {
+SCEVHandle ScalarEvolution::getMinusSCEV(const SCEVHandle &LHS,
+ const SCEVHandle &RHS) {
// X - Y --> X + -Y
- return SCEVAddExpr::get(LHS, SCEV::getNegativeSCEV(RHS));
+ return getAddExpr(LHS, getNegativeSCEV(RHS));
}
/// PartialFact - Compute V!/(V-NumSteps)!
-static SCEVHandle PartialFact(SCEVHandle V, unsigned NumSteps) {
+static SCEVHandle PartialFact(SCEVHandle V, unsigned NumSteps,
+ ScalarEvolution &SE) {
// 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()->getZExtValue();
- uint64_t Result = 1;
+ const APInt& Val = SC->getValue()->getValue();
+ APInt Result(Val.getBitWidth(), 1);
for (; NumSteps; --NumSteps)
Result *= Val-(NumSteps-1);
- Constant *Res = ConstantInt::get(Type::ULongTy, Result);
- return SCEVUnknown::get(
- ConstantExpr::getTruncOrBitCast(Res, V->getType()));
+ return SE.getConstant(Result);
}
const Type *Ty = V->getType();
if (NumSteps == 0)
- return SCEVUnknown::getIntegerSCEV(1, Ty);
+ return SE.getIntegerSCEV(1, Ty);
SCEVHandle Result = V;
for (unsigned i = 1; i != NumSteps; ++i)
- Result = SCEVMulExpr::get(Result, SCEV::getMinusSCEV(V,
- SCEVUnknown::getIntegerSCEV(i, Ty)));
+ Result = SE.getMulExpr(Result, SE.getMinusSCEV(V,
+ SE.getIntegerSCEV(i, Ty)));
return Result;
}
/// FIXME/VERIFY: I don't trust that this is correct in the face of overflow.
/// Is the binomial equation safe using modular arithmetic??
///
-SCEVHandle SCEVAddRecExpr::evaluateAtIteration(SCEVHandle It) const {
+SCEVHandle SCEVAddRecExpr::evaluateAtIteration(SCEVHandle It,
+ ScalarEvolution &SE) const {
SCEVHandle Result = getStart();
int Divisor = 1;
const Type *Ty = It->getType();
for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
- SCEVHandle BC = PartialFact(It, i);
+ SCEVHandle BC = PartialFact(It, i, SE);
Divisor *= i;
- SCEVHandle Val = SCEVSDivExpr::get(SCEVMulExpr::get(BC, getOperand(i)),
- SCEVUnknown::getIntegerSCEV(Divisor,Ty));
- Result = SCEVAddExpr::get(Result, Val);
+ SCEVHandle Val = SE.getSDivExpr(SE.getMulExpr(BC, getOperand(i)),
+ SE.getIntegerSCEV(Divisor,Ty));
+ Result = SE.getAddExpr(Result, Val);
}
return Result;
}
// SCEV Expression folder implementations
//===----------------------------------------------------------------------===//
-SCEVHandle SCEVTruncateExpr::get(const SCEVHandle &Op, const Type *Ty) {
+SCEVHandle ScalarEvolution::getTruncateExpr(const SCEVHandle &Op, const Type *Ty) {
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
- return SCEVUnknown::get(
+ return getUnknown(
ConstantExpr::getTrunc(SC->getValue(), Ty));
// If the input value is a chrec scev made out of constants, truncate
for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
// FIXME: This should allow truncation of other expression types!
if (isa<SCEVConstant>(AddRec->getOperand(i)))
- Operands.push_back(get(AddRec->getOperand(i), Ty));
+ Operands.push_back(getTruncateExpr(AddRec->getOperand(i), Ty));
else
break;
if (Operands.size() == AddRec->getNumOperands())
- return SCEVAddRecExpr::get(Operands, AddRec->getLoop());
+ return getAddRecExpr(Operands, AddRec->getLoop());
}
SCEVTruncateExpr *&Result = (*SCEVTruncates)[std::make_pair(Op, Ty)];
return Result;
}
-SCEVHandle SCEVZeroExtendExpr::get(const SCEVHandle &Op, const Type *Ty) {
+SCEVHandle ScalarEvolution::getZeroExtendExpr(const SCEVHandle &Op, const Type *Ty) {
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
- return SCEVUnknown::get(
- ConstantExpr::getZeroExtend(SC->getValue(), Ty));
+ return getUnknown(
+ ConstantExpr::getZExt(SC->getValue(), Ty));
// FIXME: If the input value is a chrec scev, and we can prove that the value
// did not overflow the old, smaller, value, we can zero extend all of the
return Result;
}
+SCEVHandle ScalarEvolution::getSignExtendExpr(const SCEVHandle &Op, const Type *Ty) {
+ if (SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
+ return getUnknown(
+ ConstantExpr::getSExt(SC->getValue(), Ty));
+
+ // FIXME: If the input value is a chrec scev, and we can prove that the value
+ // did not overflow the old, smaller, value, we can sign extend all of the
+ // operands (often constants). This would allow analysis of something like
+ // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
+
+ SCEVSignExtendExpr *&Result = (*SCEVSignExtends)[std::make_pair(Op, Ty)];
+ if (Result == 0) Result = new SCEVSignExtendExpr(Op, Ty);
+ return Result;
+}
+
// get - Get a canonical add expression, or something simpler if possible.
-SCEVHandle SCEVAddExpr::get(std::vector<SCEVHandle> &Ops) {
+SCEVHandle ScalarEvolution::getAddExpr(std::vector<SCEVHandle> &Ops) {
assert(!Ops.empty() && "Cannot get empty add!");
if (Ops.size() == 1) return Ops[0];
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());
+ Constant *Fold = ConstantInt::get(LHSC->getValue()->getValue() +
+ RHSC->getValue()->getValue());
if (ConstantInt *CI = dyn_cast<ConstantInt>(Fold)) {
- Ops[0] = SCEVConstant::get(CI);
+ Ops[0] = getConstant(CI);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
LHSC = cast<SCEVConstant>(Ops[0]);
}
// If we are left with a constant zero being added, strip it off.
- if (cast<SCEVConstant>(Ops[0])->getValue()->isNullValue()) {
+ if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
Ops.erase(Ops.begin());
--Idx;
}
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 = SCEVUnknown::getIntegerSCEV(2, Ty);
- SCEVHandle Mul = SCEVMulExpr::get(Ops[i], Two);
+ SCEVHandle Two = getIntegerSCEV(2, Ty);
+ SCEVHandle Mul = getMulExpr(Ops[i], Two);
if (Ops.size() == 2)
return Mul;
Ops.erase(Ops.begin()+i, Ops.begin()+i+2);
Ops.push_back(Mul);
- return SCEVAddExpr::get(Ops);
+ return getAddExpr(Ops);
}
- // Okay, now we know the first non-constant operand. If there are add
- // operands they would be next.
+ // Now we know the first non-constant operand. Skip past any cast SCEVs.
+ while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
+ ++Idx;
+
+ // If there are add operands they would be next.
if (Idx < Ops.size()) {
bool DeletedAdd = false;
while (SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
// and they are not necessarily sorted. Recurse to resort and resimplify
// any operands we just aquired.
if (DeletedAdd)
- return get(Ops);
+ return getAddExpr(Ops);
}
// Skip over the add expression until we get to a multiply.
// Y*Z term.
std::vector<SCEVHandle> MulOps(Mul->op_begin(), Mul->op_end());
MulOps.erase(MulOps.begin()+MulOp);
- InnerMul = SCEVMulExpr::get(MulOps);
+ InnerMul = getMulExpr(MulOps);
}
- SCEVHandle One = SCEVUnknown::getIntegerSCEV(1, Ty);
- SCEVHandle AddOne = SCEVAddExpr::get(InnerMul, One);
- SCEVHandle OuterMul = SCEVMulExpr::get(AddOne, Ops[AddOp]);
+ SCEVHandle One = getIntegerSCEV(1, Ty);
+ SCEVHandle AddOne = getAddExpr(InnerMul, One);
+ SCEVHandle OuterMul = getMulExpr(AddOne, Ops[AddOp]);
if (Ops.size() == 2) return OuterMul;
if (AddOp < Idx) {
Ops.erase(Ops.begin()+AddOp);
Ops.erase(Ops.begin()+AddOp-1);
}
Ops.push_back(OuterMul);
- return SCEVAddExpr::get(Ops);
+ return getAddExpr(Ops);
}
// Check this multiply against other multiplies being added together.
if (Mul->getNumOperands() != 2) {
std::vector<SCEVHandle> MulOps(Mul->op_begin(), Mul->op_end());
MulOps.erase(MulOps.begin()+MulOp);
- InnerMul1 = SCEVMulExpr::get(MulOps);
+ InnerMul1 = getMulExpr(MulOps);
}
SCEVHandle InnerMul2 = OtherMul->getOperand(OMulOp == 0);
if (OtherMul->getNumOperands() != 2) {
std::vector<SCEVHandle> MulOps(OtherMul->op_begin(),
OtherMul->op_end());
MulOps.erase(MulOps.begin()+OMulOp);
- InnerMul2 = SCEVMulExpr::get(MulOps);
+ InnerMul2 = getMulExpr(MulOps);
}
- SCEVHandle InnerMulSum = SCEVAddExpr::get(InnerMul1,InnerMul2);
- SCEVHandle OuterMul = SCEVMulExpr::get(MulOpSCEV, InnerMulSum);
+ SCEVHandle InnerMulSum = getAddExpr(InnerMul1,InnerMul2);
+ SCEVHandle OuterMul = getMulExpr(MulOpSCEV, InnerMulSum);
if (Ops.size() == 2) return OuterMul;
Ops.erase(Ops.begin()+Idx);
Ops.erase(Ops.begin()+OtherMulIdx-1);
Ops.push_back(OuterMul);
- return SCEVAddExpr::get(Ops);
+ return getAddExpr(Ops);
}
}
}
LIOps.push_back(AddRec->getStart());
std::vector<SCEVHandle> AddRecOps(AddRec->op_begin(), AddRec->op_end());
- AddRecOps[0] = SCEVAddExpr::get(LIOps);
+ AddRecOps[0] = getAddExpr(LIOps);
- SCEVHandle NewRec = SCEVAddRecExpr::get(AddRecOps, AddRec->getLoop());
+ SCEVHandle NewRec = getAddRecExpr(AddRecOps, AddRec->getLoop());
// If all of the other operands were loop invariant, we are done.
if (Ops.size() == 1) return NewRec;
Ops[i] = NewRec;
break;
}
- return SCEVAddExpr::get(Ops);
+ return getAddExpr(Ops);
}
// Okay, if there weren't any loop invariants to be folded, check to see if
OtherAddRec->op_end());
break;
}
- NewOps[i] = SCEVAddExpr::get(NewOps[i], OtherAddRec->getOperand(i));
+ NewOps[i] = getAddExpr(NewOps[i], OtherAddRec->getOperand(i));
}
- SCEVHandle NewAddRec = SCEVAddRecExpr::get(NewOps, AddRec->getLoop());
+ SCEVHandle NewAddRec = getAddRecExpr(NewOps, AddRec->getLoop());
if (Ops.size() == 2) return NewAddRec;
Ops.erase(Ops.begin()+Idx);
Ops.erase(Ops.begin()+OtherIdx-1);
Ops.push_back(NewAddRec);
- return SCEVAddExpr::get(Ops);
+ return getAddExpr(Ops);
}
}
}
-SCEVHandle SCEVMulExpr::get(std::vector<SCEVHandle> &Ops) {
+SCEVHandle ScalarEvolution::getMulExpr(std::vector<SCEVHandle> &Ops) {
assert(!Ops.empty() && "Cannot get empty mul!");
// Sort by complexity, this groups all similar expression types together.
if (SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
if (Add->getNumOperands() == 2 &&
isa<SCEVConstant>(Add->getOperand(0)))
- return SCEVAddExpr::get(SCEVMulExpr::get(LHSC, Add->getOperand(0)),
- SCEVMulExpr::get(LHSC, Add->getOperand(1)));
+ return getAddExpr(getMulExpr(LHSC, Add->getOperand(0)),
+ getMulExpr(LHSC, Add->getOperand(1)));
++Idx;
while (SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
// We found two constants, fold them together!
- Constant *Fold = ConstantExpr::getMul(LHSC->getValue(), RHSC->getValue());
+ Constant *Fold = ConstantInt::get(LHSC->getValue()->getValue() *
+ RHSC->getValue()->getValue());
if (ConstantInt *CI = dyn_cast<ConstantInt>(Fold)) {
- Ops[0] = SCEVConstant::get(CI);
+ Ops[0] = getConstant(CI);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
LHSC = cast<SCEVConstant>(Ops[0]);
if (cast<SCEVConstant>(Ops[0])->getValue()->equalsInt(1)) {
Ops.erase(Ops.begin());
--Idx;
- } else if (cast<SCEVConstant>(Ops[0])->getValue()->isNullValue()) {
+ } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
// If we have a multiply of zero, it will always be zero.
return Ops[0];
}
// and they are not necessarily sorted. Recurse to resort and resimplify
// any operands we just aquired.
if (DeletedMul)
- return get(Ops);
+ return getMulExpr(Ops);
}
// If there are any add recurrences in the operands list, see if any other
if (LIOps.size() == 1) {
SCEV *Scale = LIOps[0];
for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
- NewOps.push_back(SCEVMulExpr::get(Scale, AddRec->getOperand(i)));
+ NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i)));
} else {
for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
std::vector<SCEVHandle> MulOps(LIOps);
MulOps.push_back(AddRec->getOperand(i));
- NewOps.push_back(SCEVMulExpr::get(MulOps));
+ NewOps.push_back(getMulExpr(MulOps));
}
}
- SCEVHandle NewRec = SCEVAddRecExpr::get(NewOps, AddRec->getLoop());
+ SCEVHandle NewRec = getAddRecExpr(NewOps, AddRec->getLoop());
// If all of the other operands were loop invariant, we are done.
if (Ops.size() == 1) return NewRec;
Ops[i] = NewRec;
break;
}
- return SCEVMulExpr::get(Ops);
+ return getMulExpr(Ops);
}
// Okay, if there weren't any loop invariants to be folded, check to see if
if (AddRec->getLoop() == OtherAddRec->getLoop()) {
// F * G --> {A,+,B} * {C,+,D} --> {A*C,+,F*D + G*B + B*D}
SCEVAddRecExpr *F = AddRec, *G = OtherAddRec;
- SCEVHandle NewStart = SCEVMulExpr::get(F->getStart(),
+ SCEVHandle NewStart = getMulExpr(F->getStart(),
G->getStart());
- SCEVHandle B = F->getStepRecurrence();
- SCEVHandle D = G->getStepRecurrence();
- SCEVHandle NewStep = SCEVAddExpr::get(SCEVMulExpr::get(F, D),
- SCEVMulExpr::get(G, B),
- SCEVMulExpr::get(B, D));
- SCEVHandle NewAddRec = SCEVAddRecExpr::get(NewStart, NewStep,
- F->getLoop());
+ SCEVHandle B = F->getStepRecurrence(*this);
+ SCEVHandle D = G->getStepRecurrence(*this);
+ SCEVHandle NewStep = getAddExpr(getMulExpr(F, D),
+ getMulExpr(G, B),
+ getMulExpr(B, D));
+ SCEVHandle NewAddRec = getAddRecExpr(NewStart, NewStep,
+ F->getLoop());
if (Ops.size() == 2) return NewAddRec;
Ops.erase(Ops.begin()+Idx);
Ops.erase(Ops.begin()+OtherIdx-1);
Ops.push_back(NewAddRec);
- return SCEVMulExpr::get(Ops);
+ return getMulExpr(Ops);
}
}
return Result;
}
-SCEVHandle SCEVSDivExpr::get(const SCEVHandle &LHS, const SCEVHandle &RHS) {
+SCEVHandle ScalarEvolution::getSDivExpr(const SCEVHandle &LHS, const SCEVHandle &RHS) {
if (SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
if (RHSC->getValue()->equalsInt(1))
return LHS; // X sdiv 1 --> x
if (RHSC->getValue()->isAllOnesValue())
- return SCEV::getNegativeSCEV(LHS); // X sdiv -1 --> -x
+ return getNegativeSCEV(LHS); // X sdiv -1 --> -x
if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
Constant *LHSCV = LHSC->getValue();
Constant *RHSCV = RHSC->getValue();
- return SCEVUnknown::get(ConstantExpr::getSDiv(LHSCV, RHSCV));
+ return getUnknown(ConstantExpr::getSDiv(LHSCV, RHSCV));
}
}
/// SCEVAddRecExpr::get - Get a add recurrence expression for the
/// specified loop. Simplify the expression as much as possible.
-SCEVHandle SCEVAddRecExpr::get(const SCEVHandle &Start,
+SCEVHandle ScalarEvolution::getAddRecExpr(const SCEVHandle &Start,
const SCEVHandle &Step, const Loop *L) {
std::vector<SCEVHandle> Operands;
Operands.push_back(Start);
if (StepChrec->getLoop() == L) {
Operands.insert(Operands.end(), StepChrec->op_begin(),
StepChrec->op_end());
- return get(Operands, L);
+ return getAddRecExpr(Operands, L);
}
Operands.push_back(Step);
- return get(Operands, L);
+ return getAddRecExpr(Operands, L);
}
/// SCEVAddRecExpr::get - Get a add recurrence expression for the
/// specified loop. Simplify the expression as much as possible.
-SCEVHandle SCEVAddRecExpr::get(std::vector<SCEVHandle> &Operands,
+SCEVHandle ScalarEvolution::getAddRecExpr(std::vector<SCEVHandle> &Operands,
const Loop *L) {
if (Operands.size() == 1) return Operands[0];
if (SCEVConstant *StepC = dyn_cast<SCEVConstant>(Operands.back()))
- if (StepC->getValue()->isNullValue()) {
+ if (StepC->getValue()->isZero()) {
Operands.pop_back();
- return get(Operands, L); // { X,+,0 } --> X
+ return getAddRecExpr(Operands, L); // { X,+,0 } --> X
}
SCEVAddRecExpr *&Result =
return Result;
}
-SCEVHandle SCEVUnknown::get(Value *V) {
+SCEVHandle ScalarEvolution::getSMaxExpr(const SCEVHandle &LHS,
+ const SCEVHandle &RHS) {
+ std::vector<SCEVHandle> Ops;
+ Ops.push_back(LHS);
+ Ops.push_back(RHS);
+ return getSMaxExpr(Ops);
+}
+
+SCEVHandle ScalarEvolution::getSMaxExpr(std::vector<SCEVHandle> Ops) {
+ assert(!Ops.empty() && "Cannot get empty smax!");
+ if (Ops.size() == 1) return Ops[0];
+
+ // Sort by complexity, this groups all similar expression types together.
+ 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 = ConstantInt::get(
+ APIntOps::smax(LHSC->getValue()->getValue(),
+ RHSC->getValue()->getValue()));
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Fold)) {
+ Ops[0] = getConstant(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
+ // constant fold constant ints to constant ints.
+ ++Idx;
+ }
+ }
+
+ // If we are left with a constant -inf, strip it off.
+ if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) {
+ Ops.erase(Ops.begin());
+ --Idx;
+ }
+ }
+
+ if (Ops.size() == 1) return Ops[0];
+
+ // Find the first SMax
+ while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scSMaxExpr)
+ ++Idx;
+
+ // Check to see if one of the operands is an SMax. If so, expand its operands
+ // onto our operand list, and recurse to simplify.
+ if (Idx < Ops.size()) {
+ bool DeletedSMax = false;
+ while (SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(Ops[Idx])) {
+ Ops.insert(Ops.end(), SMax->op_begin(), SMax->op_end());
+ Ops.erase(Ops.begin()+Idx);
+ DeletedSMax = true;
+ }
+
+ if (DeletedSMax)
+ return getSMaxExpr(Ops);
+ }
+
+ // Okay, check to see if the same value occurs in the operand list twice. If
+ // so, delete one. Since we sorted the list, these values are required to
+ // be adjacent.
+ for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
+ if (Ops[i] == Ops[i+1]) { // X smax Y smax Y --> X smax Y
+ Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
+ --i; --e;
+ }
+
+ if (Ops.size() == 1) return Ops[0];
+
+ assert(!Ops.empty() && "Reduced smax down to nothing!");
+
+ // 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(scSMaxExpr,
+ SCEVOps)];
+ if (Result == 0) Result = new SCEVSMaxExpr(Ops);
+ return Result;
+}
+
+SCEVHandle ScalarEvolution::getUnknown(Value *V) {
if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
- return SCEVConstant::get(CI);
+ return getConstant(CI);
SCEVUnknown *&Result = (*SCEVUnknowns)[V];
if (Result == 0) Result = new SCEVUnknown(V);
return Result;
///
namespace {
struct VISIBILITY_HIDDEN ScalarEvolutionsImpl {
+ /// SE - A reference to the public ScalarEvolution object.
+ ScalarEvolution &SE;
+
/// F - The function we are analyzing.
///
Function &F;
std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue;
public:
- ScalarEvolutionsImpl(Function &f, LoopInfo &li)
- : F(f), LI(li), UnknownValue(new SCEVCouldNotCompute()) {}
+ ScalarEvolutionsImpl(ScalarEvolution &se, Function &f, LoopInfo &li)
+ : SE(se), F(f), LI(li), UnknownValue(new SCEVCouldNotCompute()) {}
/// getSCEV - Return an existing SCEV if it exists, otherwise analyze the
/// expression and create a new one.
/// loop without a loop-invariant iteration count.
SCEVHandle getIterationCount(const Loop *L);
- /// deleteInstructionFromRecords - This method should be called by the
- /// client before it removes an instruction from the program, to make sure
+ /// deleteValueFromRecords - This method should be called by the
+ /// client before it removes a value from the program, to make sure
/// that no dangling references are left around.
- void deleteInstructionFromRecords(Instruction *I);
+ void deleteValueFromRecords(Value *V);
private:
/// createSCEV - We know that there is no SCEV for the specified value.
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.
+ /// 'icmp op load X, cst', try to see if we can compute the trip count.
SCEVHandle ComputeLoadConstantCompareIterationCount(LoadInst *LI,
Constant *RHS,
const Loop *L,
- unsigned SetCCOpcode);
+ ICmpInst::Predicate p);
/// ComputeIterationCountExhaustively - If the trip is known to execute a
/// constant number of times (the condition evolves only from constants),
/// 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);
+ /// UnknownValue. isSigned specifies whether the less-than is signed.
+ SCEVHandle HowManyLessThans(SCEV *LHS, SCEV *RHS, const Loop *L,
+ bool isSigned);
/// 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,
+ Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& Its,
const Loop *L);
};
}
// Basic SCEV Analysis and PHI Idiom Recognition Code
//
-/// deleteInstructionFromRecords - This method should be called by the
+/// deleteValueFromRecords - This method should be called by the
/// client before it removes an instruction from the program, to make sure
/// 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);
+void ScalarEvolutionsImpl::deleteValueFromRecords(Value *V) {
+ SmallVector<Value *, 16> Worklist;
+
+ if (Scalars.erase(V)) {
+ if (PHINode *PN = dyn_cast<PHINode>(V))
+ ConstantEvolutionLoopExitValue.erase(PN);
+ Worklist.push_back(V);
+ }
+
+ while (!Worklist.empty()) {
+ Value *VV = Worklist.back();
+ Worklist.pop_back();
+
+ for (Instruction::use_iterator UI = VV->use_begin(), UE = VV->use_end();
+ UI != UE; ++UI) {
+ Instruction *Inst = cast<Instruction>(*UI);
+ if (Scalars.erase(Inst)) {
+ if (PHINode *PN = dyn_cast<PHINode>(VV))
+ ConstantEvolutionLoopExitValue.erase(PN);
+ Worklist.push_back(Inst);
+ }
+ }
+ }
}
if (SI == Scalars.end()) return;
SCEVHandle NV =
- SI->second->replaceSymbolicValuesWithConcrete(SymName, NewVal);
+ SI->second->replaceSymbolicValuesWithConcrete(SymName, NewVal, SE);
if (NV == SI->second) return; // No change.
SI->second = NV; // Update the scalars map!
unsigned BackEdge = IncomingEdge^1;
// While we are analyzing this PHI node, handle its value symbolically.
- SCEVHandle SymbolicName = SCEVUnknown::get(PN);
+ SCEVHandle SymbolicName = SE.getUnknown(PN);
assert(Scalars.find(PN) == Scalars.end() &&
"PHI node already processed?");
Scalars.insert(std::make_pair(PN, SymbolicName));
for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
if (i != FoundIndex)
Ops.push_back(Add->getOperand(i));
- SCEVHandle Accum = SCEVAddExpr::get(Ops);
+ SCEVHandle Accum = SE.getAddExpr(Ops);
// This is not a valid addrec if the step amount is varying each
// loop iteration, but is not itself an addrec in this loop.
(isa<SCEVAddRecExpr>(Accum) &&
cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
SCEVHandle StartVal = getSCEV(PN->getIncomingValue(IncomingEdge));
- SCEVHandle PHISCEV = SCEVAddRecExpr::get(StartVal, Accum, L);
+ SCEVHandle PHISCEV = SE.getAddRecExpr(StartVal, Accum, 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
// 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))) {
+ if (StartVal == SE.getMinusSCEV(AddRec->getOperand(0),
+ AddRec->getOperand(1))) {
SCEVHandle PHISCEV =
- SCEVAddRecExpr::get(StartVal, AddRec->getOperand(1), L);
+ SE.getAddRecExpr(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
}
// If it's not a loop phi, we can't handle it yet.
- return SCEVUnknown::get(PN);
+ return SE.getUnknown(PN);
}
+/// GetMinTrailingZeros - Determine the minimum number of zero bits that S is
+/// guaranteed to end in (at every loop iteration). It is, at the same time,
+/// the minimum number of times S is divisible by 2. For example, given {4,+,8}
+/// it returns 2. If S is guaranteed to be 0, it returns the bitwidth of S.
+static uint32_t GetMinTrailingZeros(SCEVHandle S) {
+ if (SCEVConstant *C = dyn_cast<SCEVConstant>(S))
+ return C->getValue()->getValue().countTrailingZeros();
+
+ if (SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
+ return std::min(GetMinTrailingZeros(T->getOperand()), T->getBitWidth());
+
+ if (SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
+ uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
+ return OpRes == E->getOperand()->getBitWidth() ? E->getBitWidth() : OpRes;
+ }
+
+ if (SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
+ uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
+ return OpRes == E->getOperand()->getBitWidth() ? E->getBitWidth() : OpRes;
+ }
+
+ if (SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
+ // The result is the min of all operands results.
+ uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
+ for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
+ MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
+ return MinOpRes;
+ }
+
+ if (SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
+ // The result is the sum of all operands results.
+ uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
+ uint32_t BitWidth = M->getBitWidth();
+ for (unsigned i = 1, e = M->getNumOperands();
+ SumOpRes != BitWidth && i != e; ++i)
+ SumOpRes = std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)),
+ BitWidth);
+ return SumOpRes;
+ }
+
+ if (SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
+ // The result is the min of all operands results.
+ uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
+ for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
+ MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
+ return MinOpRes;
+ }
+
+ if (SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
+ // The result is the min of all operands results.
+ uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
+ for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
+ MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
+ return MinOpRes;
+ }
+
+ // SCEVSDivExpr, SCEVUnknown
+ return 0;
+}
/// createSCEV - We know that there is no SCEV for the specified value.
/// Analyze the expression.
///
SCEVHandle ScalarEvolutionsImpl::createSCEV(Value *V) {
+ if (!isa<IntegerType>(V->getType()))
+ return SE.getUnknown(V);
+
if (Instruction *I = dyn_cast<Instruction>(V)) {
switch (I->getOpcode()) {
case Instruction::Add:
- return SCEVAddExpr::get(getSCEV(I->getOperand(0)),
- getSCEV(I->getOperand(1)));
+ return SE.getAddExpr(getSCEV(I->getOperand(0)),
+ getSCEV(I->getOperand(1)));
case Instruction::Mul:
- return SCEVMulExpr::get(getSCEV(I->getOperand(0)),
- getSCEV(I->getOperand(1)));
+ return SE.getMulExpr(getSCEV(I->getOperand(0)),
+ getSCEV(I->getOperand(1)));
case Instruction::SDiv:
- return SCEVSDivExpr::get(getSCEV(I->getOperand(0)),
- getSCEV(I->getOperand(1)));
- break;
-
+ return SE.getSDivExpr(getSCEV(I->getOperand(0)),
+ getSCEV(I->getOperand(1)));
case Instruction::Sub:
- return SCEV::getMinusSCEV(getSCEV(I->getOperand(0)),
- getSCEV(I->getOperand(1)));
+ return SE.getMinusSCEV(getSCEV(I->getOperand(0)),
+ getSCEV(I->getOperand(1)));
+ case Instruction::Or:
+ // If the RHS of the Or is a constant, we may have something like:
+ // X*4+1 which got turned into X*4|1. Handle this as an Add so loop
+ // optimizations will transparently handle this case.
+ //
+ // In order for this transformation to be safe, the LHS must be of the
+ // form X*(2^n) and the Or constant must be less than 2^n.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ SCEVHandle LHS = getSCEV(I->getOperand(0));
+ const APInt &CIVal = CI->getValue();
+ if (GetMinTrailingZeros(LHS) >=
+ (CIVal.getBitWidth() - CIVal.countLeadingZeros()))
+ return SE.getAddExpr(LHS, getSCEV(I->getOperand(1)));
+ }
+ break;
+ case Instruction::Xor:
+ // If the RHS of the xor is a signbit, then this is just an add.
+ // Instcombine turns add of signbit into xor as a strength reduction step.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ if (CI->getValue().isSignBit())
+ return SE.getAddExpr(getSCEV(I->getOperand(0)),
+ getSCEV(I->getOperand(1)));
+ }
+ break;
case Instruction::Shl:
// Turn shift left of a constant amount into a multiply.
if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
- Constant *X = ConstantInt::get(V->getType(), 1);
- X = ConstantExpr::getShl(X, SA);
- return SCEVMulExpr::get(getSCEV(I->getOperand(0)), getSCEV(X));
+ uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
+ Constant *X = ConstantInt::get(
+ APInt(BitWidth, 1).shl(SA->getLimitedValue(BitWidth)));
+ return SE.getMulExpr(getSCEV(I->getOperand(0)), getSCEV(X));
}
break;
case Instruction::Trunc:
- // We must prevent boolean types such as setne, etc. from entering here
- // because we don't want to pass SCEVUnknown to the TruncateExpr.
- if (I->getType()->isInteger() && I->getOperand(0)->getType()->isInteger())
- return SCEVTruncateExpr::get(getSCEV(I->getOperand(0)),
- I->getType()->getUnsignedVersion());
- break;
+ return SE.getTruncateExpr(getSCEV(I->getOperand(0)), I->getType());
case Instruction::ZExt:
- // We must prevent boolean types such as setne, etc. from entering here
- // because we don't want to pass SCEVUnknown to the ZExtExpr.
- if (I->getType()->isInteger() && I->getOperand(0)->getType()->isInteger())
- return SCEVZeroExtendExpr::get(getSCEV(I->getOperand(0)),
- I->getType()->getUnsignedVersion());
- break;
+ return SE.getZeroExtendExpr(getSCEV(I->getOperand(0)), I->getType());
+
+ case Instruction::SExt:
+ return SE.getSignExtendExpr(getSCEV(I->getOperand(0)), I->getType());
case Instruction::BitCast:
// BitCasts are no-op casts so we just eliminate the cast.
- return getSCEV(I->getOperand(0));
+ if (I->getType()->isInteger() &&
+ I->getOperand(0)->getType()->isInteger())
+ return getSCEV(I->getOperand(0));
+ break;
case Instruction::PHI:
return createNodeForPHI(cast<PHINode>(I));
+ case Instruction::Select:
+ // This could be an SCEVSMax that was lowered earlier. Try to recover it.
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(I->getOperand(0))) {
+ Value *LHS = ICI->getOperand(0);
+ Value *RHS = ICI->getOperand(1);
+ switch (ICI->getPredicate()) {
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE:
+ std::swap(LHS, RHS);
+ // fall through
+ case ICmpInst::ICMP_SGT:
+ case ICmpInst::ICMP_SGE:
+ if (LHS == I->getOperand(1) && RHS == I->getOperand(2))
+ return SE.getSMaxExpr(getSCEV(LHS), getSCEV(RHS));
+ default:
+ break;
+ }
+ }
+
default: // We cannot analyze this expression.
break;
}
}
- return SCEVUnknown::get(V);
+ return SE.getUnknown(V);
}
/// will iterate.
SCEVHandle ScalarEvolutionsImpl::ComputeIterationCount(const Loop *L) {
// If the loop has a non-one exit block count, we can't analyze it.
- std::vector<BasicBlock*> ExitBlocks;
+ SmallVector<BasicBlock*, 8> ExitBlocks;
L->getExitBlocks(ExitBlocks);
if (ExitBlocks.size() != 1) return UnknownValue;
// exit.
//
// FIXME: we should be able to handle switch instructions (with a single exit)
- // FIXME: We should handle cast of int to bool as well
BranchInst *ExitBr = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
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) // Not a setcc
+
+ // At this point, we know we have a conditional branch that determines whether
+ // the loop is exited. However, we don't know if the branch is executed each
+ // time through the loop. If not, then the execution count of the branch will
+ // not be equal to the trip count of the loop.
+ //
+ // Currently we check for this by checking to see if the Exit branch goes to
+ // the loop header. If so, we know it will always execute the same number of
+ // times as the loop. We also handle the case where the exit block *is* the
+ // loop header. This is common for un-rotated loops. More extensive analysis
+ // could be done to handle more cases here.
+ if (ExitBr->getSuccessor(0) != L->getHeader() &&
+ ExitBr->getSuccessor(1) != L->getHeader() &&
+ ExitBr->getParent() != L->getHeader())
+ return UnknownValue;
+
+ ICmpInst *ExitCond = dyn_cast<ICmpInst>(ExitBr->getCondition());
+
+ // If its not an integer comparison then compute it the hard way.
+ // Note that ICmpInst deals with pointer comparisons too so we must check
+ // the type of the operand.
+ if (ExitCond == 0 || isa<PointerType>(ExitCond->getOperand(0)->getType()))
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 the condition was exit on true, convert the condition to exit on false
+ ICmpInst::Predicate Cond;
if (ExitBr->getSuccessor(1) == ExitBlock)
- Cond = ExitCond->getOpcode();
+ Cond = ExitCond->getPredicate();
else
- Cond = ExitCond->getInverseCondition();
+ Cond = ExitCond->getInversePredicate();
// Handle common loops like: for (X = "string"; *X; ++X)
if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
Tmp = getSCEVAtScope(RHS, L);
if (!isa<SCEVCouldNotCompute>(Tmp)) RHS = Tmp;
- // At this point, we would like to compute how many iterations of the loop the
- // predicate will return true for these inputs.
+ // 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 there is a constant, force it into the RHS.
std::swap(LHS, RHS);
- Cond = SetCondInst::getSwappedCondition(Cond);
+ Cond = ICmpInst::getSwappedPredicate(Cond);
}
// FIXME: think about handling pointer comparisons! i.e.:
// comparison.
ConstantInt *CompVal = RHSC->getValue();
const Type *RealTy = ExitCond->getOperand(0)->getType();
- CompVal = dyn_cast<ConstantInt>(ConstantExpr::getCast(CompVal, RealTy));
+ CompVal = dyn_cast<ConstantInt>(
+ ConstantExpr::getBitCast(CompVal, RealTy));
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()) {
- const Type *NewTy = RHSC->getValue()->getType();
- Constant *NewL = ConstantExpr::getCast(CompRange.getLower(), NewTy);
- Constant *NewU = ConstantExpr::getCast(CompRange.getUpper(), NewTy);
- CompRange = ConstantRange(NewL, NewU);
- }
+ ConstantRange CompRange(
+ ICmpInst::makeConstantRange(Cond, CompVal->getValue()));
- SCEVHandle Ret = AddRec->getNumIterationsInRange(CompRange);
+ SCEVHandle Ret = AddRec->getNumIterationsInRange(CompRange, SE);
if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
}
}
switch (Cond) {
- case Instruction::SetNE: // while (X != Y)
+ case ICmpInst::ICMP_NE: { // while (X != Y)
// Convert to: while (X-Y != 0)
- if (LHS->getType()->isInteger()) {
- SCEVHandle TC = HowFarToZero(SCEV::getMinusSCEV(LHS, RHS), L);
- if (!isa<SCEVCouldNotCompute>(TC)) return TC;
- }
+ SCEVHandle TC = HowFarToZero(SE.getMinusSCEV(LHS, RHS), L);
+ if (!isa<SCEVCouldNotCompute>(TC)) return TC;
break;
- case Instruction::SetEQ:
+ }
+ case ICmpInst::ICMP_EQ: {
// Convert to: while (X-Y == 0) // while (X == Y)
- if (LHS->getType()->isInteger()) {
- SCEVHandle TC = HowFarToNonZero(SCEV::getMinusSCEV(LHS, RHS), L);
- if (!isa<SCEVCouldNotCompute>(TC)) return TC;
- }
+ SCEVHandle TC = HowFarToNonZero(SE.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;
- }
+ }
+ case ICmpInst::ICMP_SLT: {
+ SCEVHandle TC = HowManyLessThans(LHS, RHS, L, true);
+ 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;
- }
+ }
+ case ICmpInst::ICMP_SGT: {
+ SCEVHandle TC = HowManyLessThans(SE.getNegativeSCEV(LHS),
+ SE.getNegativeSCEV(RHS), L, true);
+ if (!isa<SCEVCouldNotCompute>(TC)) return TC;
+ break;
+ }
+ case ICmpInst::ICMP_ULT: {
+ SCEVHandle TC = HowManyLessThans(LHS, RHS, L, false);
+ if (!isa<SCEVCouldNotCompute>(TC)) return TC;
+ break;
+ }
+ case ICmpInst::ICMP_UGT: {
+ SCEVHandle TC = HowManyLessThans(SE.getNegativeSCEV(LHS),
+ SE.getNegativeSCEV(RHS), L, false);
+ if (!isa<SCEVCouldNotCompute>(TC)) return TC;
break;
+ }
default:
#if 0
- llvm_cerr << "ComputeIterationCount ";
+ cerr << "ComputeIterationCount ";
if (ExitCond->getOperand(0)->getType()->isUnsigned())
- llvm_cerr << "[unsigned] ";
- llvm_cerr << *LHS << " "
- << Instruction::getOpcodeName(Cond) << " " << *RHS << "\n";
+ cerr << "[unsigned] ";
+ cerr << *LHS << " "
+ << Instruction::getOpcodeName(Instruction::ICmp)
+ << " " << *RHS << "\n";
#endif
break;
}
-
return ComputeIterationCountExhaustively(L, ExitCond,
- ExitBr->getSuccessor(0) == ExitBlock);
+ ExitBr->getSuccessor(0) == ExitBlock);
}
static ConstantInt *
-EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, Constant *C) {
- SCEVHandle InVal = SCEVConstant::get(cast<ConstantInt>(C));
- SCEVHandle Val = AddRec->evaluateAtIteration(InVal);
+EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
+ ScalarEvolution &SE) {
+ SCEVHandle InVal = SE.getConstant(C);
+ SCEVHandle Val = AddRec->evaluateAtIteration(InVal, SE);
assert(isa<SCEVConstant>(Val) &&
"Evaluation of SCEV at constant didn't fold correctly?");
return cast<SCEVConstant>(Val)->getValue();
}
/// ComputeLoadConstantCompareIterationCount - Given an exit condition of
-/// 'setcc load X, cst', try to se if we can compute the trip count.
+/// 'icmp op 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) {
+ const Loop *L,
+ ICmpInst::Predicate predicate) {
if (LI->isVolatile()) return UnknownValue;
// Check to see if the loaded pointer is a getelementptr of a global.
unsigned MaxSteps = MaxBruteForceIterations;
for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) {
ConstantInt *ItCst =
- ConstantInt::get(IdxExpr->getType()->getUnsignedVersion(), IterationNum);
- ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst);
+ ConstantInt::get(IdxExpr->getType(), IterationNum);
+ ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, SE);
// Form the GEP offset.
Indexes[VarIdxNum] = Val;
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) {
+ Result = ConstantExpr::getICmp(predicate, Result, RHS);
+ if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure
+ if (cast<ConstantInt>(Result)->getValue().isMinValue()) {
#if 0
- llvm_cerr << "\n***\n*** Computed loop count " << *ItCst
- << "\n*** From global " << *GV << "*** BB: " << *L->getHeader()
- << "***\n";
+ 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 SE.getConstant(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) ||
+ if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I))
return true;
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]);
-
- if (isa<CastInst>(I))
- return ConstantExpr::getCast(I->getOpcode(), Operands[0], I->getType());
-
- switch (I->getOpcode()) {
- 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
if (Operands[i] == 0) return 0;
}
- return ConstantFold(I, Operands);
+ if (const CmpInst *CI = dyn_cast<CmpInst>(I))
+ return ConstantFoldCompareInstOperands(CI->getPredicate(),
+ &Operands[0], Operands.size());
+ else
+ return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
+ &Operands[0], Operands.size());
}
/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
/// 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) {
+getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& Its, const Loop *L){
std::map<PHINode*, Constant*>::iterator I =
ConstantEvolutionLoopExitValue.find(PN);
if (I != ConstantEvolutionLoopExitValue.end())
return I->second;
- if (Its > MaxBruteForceIterations)
+ if (Its.ugt(APInt(Its.getBitWidth(),MaxBruteForceIterations)))
return ConstantEvolutionLoopExitValue[PN] = 0; // Not going to evaluate it.
Constant *&RetVal = ConstantEvolutionLoopExitValue[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??
+ if (Its.getActiveBits() >= 32)
+ return RetVal = 0; // More than 2^32-1 iterations?? Not doing it!
+ unsigned NumIterations = Its.getZExtValue(); // must be in range
+ unsigned IterationNum = 0;
for (Constant *PHIVal = StartCST; ; ++IterationNum) {
if (IterationNum == NumIterations)
return RetVal = PHIVal; // Got exit value!
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.
+ ConstantInt *CondVal =
+ dyn_cast_or_null<ConstantInt>(EvaluateExpression(Cond, PHIVal));
+
+ // Couldn't symbolically evaluate.
+ if (!CondVal) return UnknownValue;
- if (CondVal->getValue() == ExitWhen) {
+ if (CondVal->getValue() == uint64_t(ExitWhen)) {
ConstantEvolutionLoopExitValue[PN] = PHIVal;
++NumBruteForceTripCountsComputed;
- return SCEVConstant::get(ConstantInt::get(Type::UIntTy, IterationNum));
+ return SE.getConstant(ConstantInt::get(Type::Int32Ty, IterationNum));
}
// Compute the value of the PHI node for the next iteration.
// this is a constant evolving PHI node, get the final value at
// the specified iteration number.
Constant *RV = getConstantEvolutionLoopExitValue(PN,
- ICC->getValue()->getZExtValue(),
+ ICC->getValue()->getValue(),
LI);
- if (RV) return SCEVUnknown::get(RV);
+ if (RV) return SE.getUnknown(RV);
}
}
if (Constant *C = dyn_cast<Constant>(Op)) {
Operands.push_back(C);
} else {
+ // If any of the operands is non-constant and if they are
+ // non-integer, don't even try to analyze them with scev techniques.
+ if (!isa<IntegerType>(Op->getType()))
+ return V;
+
SCEVHandle OpV = getSCEVAtScope(getSCEV(Op), L);
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(OpV))
- Operands.push_back(ConstantExpr::getCast(SC->getValue(),
- Op->getType()));
+ Operands.push_back(ConstantExpr::getIntegerCast(SC->getValue(),
+ Op->getType(),
+ false));
else if (SCEVUnknown *SU = dyn_cast<SCEVUnknown>(OpV)) {
if (Constant *C = dyn_cast<Constant>(SU->getValue()))
- Operands.push_back(ConstantExpr::getCast(C, Op->getType()));
+ Operands.push_back(ConstantExpr::getIntegerCast(C,
+ Op->getType(),
+ false));
else
return V;
} else {
}
}
}
- return SCEVUnknown::get(ConstantFold(I, Operands));
+
+ Constant *C;
+ if (const CmpInst *CI = dyn_cast<CmpInst>(I))
+ C = ConstantFoldCompareInstOperands(CI->getPredicate(),
+ &Operands[0], Operands.size());
+ else
+ C = ConstantFoldInstOperands(I->getOpcode(), I->getType(),
+ &Operands[0], Operands.size());
+ return SE.getUnknown(C);
}
}
NewOps.push_back(OpAtScope);
}
if (isa<SCEVAddExpr>(Comm))
- return SCEVAddExpr::get(NewOps);
- assert(isa<SCEVMulExpr>(Comm) && "Only know about add and mul!");
- return SCEVMulExpr::get(NewOps);
+ return SE.getAddExpr(NewOps);
+ if (isa<SCEVMulExpr>(Comm))
+ return SE.getMulExpr(NewOps);
+ if (isa<SCEVSMaxExpr>(Comm))
+ return SE.getSMaxExpr(NewOps);
+ assert(0 && "Unknown commutative SCEV type!");
}
}
// If we got here, all operands are loop invariant.
if (RHS == UnknownValue) return RHS;
if (LHS == Div->getLHS() && RHS == Div->getRHS())
return Div; // must be loop invariant
- return SCEVSDivExpr::get(LHS, RHS);
+ return SE.getSDivExpr(LHS, RHS);
}
// If this is a loop recurrence for a loop that does not contain L, then we
SCEVHandle IterationCount = getIterationCount(AddRec->getLoop());
if (IterationCount == UnknownValue) return UnknownValue;
IterationCount = getTruncateOrZeroExtend(IterationCount,
- AddRec->getType());
+ AddRec->getType(), SE);
// If the value is affine, simplify the expression evaluation to just
// Start + Step*IterationCount.
if (AddRec->isAffine())
- return SCEVAddExpr::get(AddRec->getStart(),
- SCEVMulExpr::get(IterationCount,
- AddRec->getOperand(1)));
+ return SE.getAddExpr(AddRec->getStart(),
+ SE.getMulExpr(IterationCount,
+ AddRec->getOperand(1)));
// Otherwise, evaluate it the hard way.
- return AddRec->evaluateAtIteration(IterationCount);
+ return AddRec->evaluateAtIteration(IterationCount, SE);
}
return UnknownValue;
}
/// might be the same) or two SCEVCouldNotCompute objects.
///
static std::pair<SCEVHandle,SCEVHandle>
-SolveQuadraticEquation(const SCEVAddRecExpr *AddRec) {
+SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
assert(AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!");
- SCEVConstant *L = dyn_cast<SCEVConstant>(AddRec->getOperand(0));
- SCEVConstant *M = dyn_cast<SCEVConstant>(AddRec->getOperand(1));
- SCEVConstant *N = dyn_cast<SCEVConstant>(AddRec->getOperand(2));
+ SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0));
+ SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1));
+ SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2));
// We currently can only solve this if the coefficients are constants.
- if (!L || !M || !N) {
+ if (!LC || !MC || !NC) {
SCEV *CNC = new SCEVCouldNotCompute();
return std::make_pair(CNC, CNC);
}
- Constant *C = L->getValue();
- Constant *Two = ConstantInt::get(C->getType(), 2);
-
- // Convert from chrec coefficients to polynomial coefficients AX^2+BX+C
- // The B coefficient is M-N/2
- Constant *B = ConstantExpr::getSub(M->getValue(),
- ConstantExpr::getSDiv(N->getValue(),
- Two));
- // The A coefficient is N/2
- Constant *A = ConstantExpr::getSDiv(N->getValue(), Two);
-
- // Compute the B^2-4ac term.
- Constant *SqrtTerm =
- ConstantExpr::getMul(ConstantInt::get(C->getType(), 4),
- ConstantExpr::getMul(A, C));
- SqrtTerm = ConstantExpr::getSub(ConstantExpr::getMul(B, B), SqrtTerm);
-
- // Compute floor(sqrt(B^2-4ac))
- ConstantInt *SqrtVal =
- cast<ConstantInt>(ConstantExpr::getCast(SqrtTerm,
- SqrtTerm->getType()->getUnsignedVersion()));
- 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 ||
- (SqrtValV2+1)*(SqrtValV2+1) <= SqrtValV) {
- SCEV *CNC = new SCEVCouldNotCompute();
- return std::make_pair(CNC, CNC);
- }
-
- 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::getSDiv(ConstantExpr::getAdd(NegB, SqrtTerm), TwoA);
- Constant *Solution2 =
- ConstantExpr::getSDiv(ConstantExpr::getSub(NegB, SqrtTerm), TwoA);
- return std::make_pair(SCEVUnknown::get(Solution1),
- SCEVUnknown::get(Solution2));
+ uint32_t BitWidth = LC->getValue()->getValue().getBitWidth();
+ const APInt &L = LC->getValue()->getValue();
+ const APInt &M = MC->getValue()->getValue();
+ const APInt &N = NC->getValue()->getValue();
+ APInt Two(BitWidth, 2);
+ APInt Four(BitWidth, 4);
+
+ {
+ using namespace APIntOps;
+ const APInt& C = L;
+ // Convert from chrec coefficients to polynomial coefficients AX^2+BX+C
+ // The B coefficient is M-N/2
+ APInt B(M);
+ B -= sdiv(N,Two);
+
+ // The A coefficient is N/2
+ APInt A(N.sdiv(Two));
+
+ // Compute the B^2-4ac term.
+ APInt SqrtTerm(B);
+ SqrtTerm *= B;
+ SqrtTerm -= Four * (A * C);
+
+ // Compute sqrt(B^2-4ac). This is guaranteed to be the nearest
+ // integer value or else APInt::sqrt() will assert.
+ APInt SqrtVal(SqrtTerm.sqrt());
+
+ // Compute the two solutions for the quadratic formula.
+ // The divisions must be performed as signed divisions.
+ APInt NegB(-B);
+ APInt TwoA( A << 1 );
+ ConstantInt *Solution1 = ConstantInt::get((NegB + SqrtVal).sdiv(TwoA));
+ ConstantInt *Solution2 = ConstantInt::get((NegB - SqrtVal).sdiv(TwoA));
+
+ return std::make_pair(SE.getConstant(Solution1),
+ SE.getConstant(Solution2));
+ } // end APIntOps namespace
}
/// HowFarToZero - Return the number of times a backedge comparing the specified
// If the value is a constant
if (SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
// If the value is already zero, the branch will execute zero times.
- if (C->getValue()->isNullValue()) return C;
+ if (C->getValue()->isZero()) return C;
return UnknownValue; // Otherwise it will loop infinitely.
}
// 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 SCEV::getNegativeSCEV(Start); // 0 - Start/1 == -Start
+ return SE.getNegativeSCEV(Start); // 0 - Start/1 == -Start
if (StepC->getValue()->isAllOnesValue()) // N % -1 == 0
return Start; // 0 - Start/-1 == Start
Constant *Rem = ConstantExpr::getSRem(StartNegC, StepC->getValue());
if (Rem->isNullValue()) {
Constant *Result =ConstantExpr::getSDiv(StartNegC,StepC->getValue());
- return SCEVUnknown::get(Result);
+ return SE.getUnknown(Result);
}
}
}
} else if (AddRec->isQuadratic() && AddRec->getType()->isInteger()) {
// If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of
// the quadratic equation to solve it.
- std::pair<SCEVHandle,SCEVHandle> Roots = SolveQuadraticEquation(AddRec);
+ std::pair<SCEVHandle,SCEVHandle> Roots = SolveQuadraticEquation(AddRec, SE);
SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first);
SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second);
if (R1) {
#if 0
- llvm_cerr << "HFTZ: " << *V << " - sol#1: " << *R1
- << " sol#2: " << *R2 << "\n";
+ cerr << "HFTZ: " << *V << " - sol#1: " << *R1
+ << " sol#2: " << *R2 << "\n";
#endif
// Pick the smallest positive root value.
- assert(R1->getType()->isUnsigned()&&"Didn't canonicalize to unsigned?");
- if (ConstantBool *CB =
- dyn_cast<ConstantBool>(ConstantExpr::getSetLT(R1->getValue(),
- R2->getValue()))) {
- if (CB->getValue() == false)
+ if (ConstantInt *CB =
+ dyn_cast<ConstantInt>(ConstantExpr::getICmp(ICmpInst::ICMP_ULT,
+ R1->getValue(), R2->getValue()))) {
+ if (CB->getZExtValue() == 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.
- SCEVHandle Val = AddRec->evaluateAtIteration(R1);
+ SCEVHandle Val = AddRec->evaluateAtIteration(R1, SE);
if (SCEVConstant *EvalVal = dyn_cast<SCEVConstant>(Val))
- if (EvalVal->getValue()->isNullValue())
+ if (EvalVal->getValue()->isZero())
return R1; // We found a quadratic root!
}
}
// 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::getTrue())
+ Constant *NonZero =
+ ConstantExpr::getICmp(ICmpInst::ICMP_NE, C->getValue(), Zero);
+ if (NonZero == ConstantInt::getTrue())
return getSCEV(Zero);
return UnknownValue; // Otherwise it will loop infinitely.
}
/// specified less-than comparison will execute. If not computable, return
/// UnknownValue.
SCEVHandle ScalarEvolutionsImpl::
-HowManyLessThans(SCEV *LHS, SCEV *RHS, const Loop *L) {
+HowManyLessThans(SCEV *LHS, SCEV *RHS, const Loop *L, bool isSigned) {
// Only handle: "ADDREC < LoopInvariant".
if (!RHS->isLoopInvariant(L)) return UnknownValue;
return UnknownValue;
if (AddRec->isAffine()) {
+ // 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
+ // returns true zero times. To handle both cases, we return SMAX(0, m-n).
+
// FORNOW: We only support unit strides.
- SCEVHandle One = SCEVUnknown::getIntegerSCEV(1, RHS->getType());
+ SCEVHandle One = SE.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;
- }
+ SCEVHandle Iters = SE.getMinusSCEV(RHS, AddRec->getOperand(0));
- // 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();
+ if (isSigned)
+ return SE.getSMaxExpr(SE.getIntegerSCEV(0, RHS->getType()), Iters);
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;
- }
-
- //llvm_cerr << "Computed Loop Trip Count as: " <<
- // *SCEV::getMinusSCEV(RHS, AddRec->getOperand(0)) << "\n";
- return SCEV::getMinusSCEV(RHS, AddRec->getOperand(0));
+ return Iters;
}
return UnknownValue;
/// 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 SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range) const {
+SCEVHandle SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range,
+ ScalarEvolution &SE) const {
if (Range.isFullSet()) // Infinite loop.
return new SCEVCouldNotCompute();
// If the start is a non-zero constant, shift the range to simplify things.
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
- if (!SC->getValue()->isNullValue()) {
+ if (!SC->getValue()->isZero()) {
std::vector<SCEVHandle> Operands(op_begin(), op_end());
- Operands[0] = SCEVUnknown::getIntegerSCEV(0, SC->getType());
- SCEVHandle Shifted = SCEVAddRecExpr::get(Operands, getLoop());
+ Operands[0] = SE.getIntegerSCEV(0, SC->getType());
+ SCEVHandle Shifted = SE.getAddRecExpr(Operands, getLoop());
if (SCEVAddRecExpr *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted))
return ShiftedAddRec->getNumIterationsInRange(
- Range.subtract(SC->getValue()));
+ Range.subtract(SC->getValue()->getValue()), SE);
// This is strange and shouldn't happen.
return new SCEVCouldNotCompute();
}
// First check to see if the range contains zero. If not, the first
// iteration exits.
- ConstantInt *Zero = ConstantInt::get(getType(), 0);
- if (!Range.contains(Zero)) return SCEVConstant::get(Zero);
+ if (!Range.contains(APInt(getBitWidth(),0)))
+ return SE.getConstant(ConstantInt::get(getType(),0));
if (isAffine()) {
// If this is an affine expression then we have this situation:
// Solve {0,+,A} in Range === Ax in Range
- // Since we know that zero is in the range, we know that the upper value of
- // the range must be the first possible exit value. Also note that we
- // already checked for a full range.
- ConstantInt *Upper = cast<ConstantInt>(Range.getUpper());
- ConstantInt *A = cast<SCEVConstant>(getOperand(1))->getValue();
- ConstantInt *One = ConstantInt::get(getType(), 1);
-
- // The exit value should be (Upper+A-1)/A.
- Constant *ExitValue = Upper;
- if (A != One) {
- ExitValue = ConstantExpr::getSub(ConstantExpr::getAdd(Upper, A), One);
- ExitValue = ConstantExpr::getSDiv(ExitValue, A);
- }
- assert(isa<ConstantInt>(ExitValue) &&
- "Constant folding of integers not implemented?");
+ // We know that zero is in the range. If A is positive then we know that
+ // the upper value of the range must be the first possible exit value.
+ // If A is negative then the lower of the range is the last possible loop
+ // value. Also note that we already checked for a full range.
+ APInt One(getBitWidth(),1);
+ APInt A = cast<SCEVConstant>(getOperand(1))->getValue()->getValue();
+ APInt End = A.sge(One) ? (Range.getUpper() - One) : Range.getLower();
+
+ // The exit value should be (End+A)/A.
+ APInt ExitVal = (End + A).udiv(A);
+ ConstantInt *ExitValue = ConstantInt::get(ExitVal);
// Evaluate at the exit value. If we really did fall out of the valid
// range, then we computed our trip count, otherwise wrap around or other
// things must have happened.
- ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue);
- if (Range.contains(Val))
+ ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE);
+ if (Range.contains(Val->getValue()))
return new SCEVCouldNotCompute(); // Something strange happened
// Ensure that the previous value is in the range. This is a sanity check.
- assert(Range.contains(EvaluateConstantChrecAtConstant(this,
- ConstantExpr::getSub(ExitValue, One))) &&
+ assert(Range.contains(
+ EvaluateConstantChrecAtConstant(this,
+ ConstantInt::get(ExitVal - One), SE)->getValue()) &&
"Linear scev computation is off in a bad way!");
- return SCEVConstant::get(cast<ConstantInt>(ExitValue));
+ return SE.getConstant(ExitValue);
} else if (isQuadratic()) {
// If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of the
// quadratic equation to solve it. To do this, we must frame our problem in
// 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] = SCEV::getNegativeSCEV(SCEVUnknown::get(Range.getUpper()));
- SCEVHandle NewAddRec = SCEVAddRecExpr::get(NewOps, getLoop());
+ NewOps[0] = SE.getNegativeSCEV(SE.getConstant(Range.getUpper()));
+ SCEVHandle NewAddRec = SE.getAddRecExpr(NewOps, getLoop());
// Next, solve the constructed addrec
std::pair<SCEVHandle,SCEVHandle> Roots =
- SolveQuadraticEquation(cast<SCEVAddRecExpr>(NewAddRec));
+ SolveQuadraticEquation(cast<SCEVAddRecExpr>(NewAddRec), SE);
SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first);
SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second);
if (R1) {
// Pick the smallest positive root value.
- assert(R1->getType()->isUnsigned() && "Didn't canonicalize to unsigned?");
- if (ConstantBool *CB =
- dyn_cast<ConstantBool>(ConstantExpr::getSetLT(R1->getValue(),
- R2->getValue()))) {
- if (CB->getValue() == false)
+ if (ConstantInt *CB =
+ dyn_cast<ConstantInt>(ConstantExpr::getICmp(ICmpInst::ICMP_ULT,
+ R1->getValue(), R2->getValue()))) {
+ if (CB->getZExtValue() == 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.
ConstantInt *R1Val = EvaluateConstantChrecAtConstant(this,
- R1->getValue());
- if (Range.contains(R1Val)) {
+ R1->getValue(),
+ SE);
+ if (Range.contains(R1Val->getValue())) {
// The next iteration must be out of the range...
- Constant *NextVal =
- ConstantExpr::getAdd(R1->getValue(),
- ConstantInt::get(R1->getType(), 1));
+ ConstantInt *NextVal = ConstantInt::get(R1->getValue()->getValue()+1);
- R1Val = EvaluateConstantChrecAtConstant(this, NextVal);
- if (!Range.contains(R1Val))
- return SCEVUnknown::get(NextVal);
+ R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE);
+ if (!Range.contains(R1Val->getValue()))
+ return SE.getConstant(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 =
- ConstantExpr::getSub(R1->getValue(),
- ConstantInt::get(R1->getType(), 1));
- R1Val = EvaluateConstantChrecAtConstant(this, NextVal);
- if (Range.contains(R1Val))
+ ConstantInt *NextVal = ConstantInt::get(R1->getValue()->getValue()-1);
+ R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE);
+ if (Range.contains(R1Val->getValue()))
return R1;
return new SCEVCouldNotCompute(); // Something strange happened
}
// incredibly important, we will be able to simplify the exit test a lot, and
// we are almost guaranteed to get a trip count in this case.
ConstantInt *TestVal = ConstantInt::get(getType(), 0);
- ConstantInt *One = ConstantInt::get(getType(), 1);
ConstantInt *EndVal = TestVal; // Stop when we wrap around.
do {
++NumBruteForceEvaluations;
- SCEVHandle Val = evaluateAtIteration(SCEVConstant::get(TestVal));
+ SCEVHandle Val = evaluateAtIteration(SE.getConstant(TestVal), SE);
if (!isa<SCEVConstant>(Val)) // This shouldn't happen.
return new SCEVCouldNotCompute();
// Check to see if we found the value!
- if (!Range.contains(cast<SCEVConstant>(Val)->getValue()))
- return SCEVConstant::get(TestVal);
+ if (!Range.contains(cast<SCEVConstant>(Val)->getValue()->getValue()))
+ return SE.getConstant(TestVal);
// Increment to test the next index.
- TestVal = cast<ConstantInt>(ConstantExpr::getAdd(TestVal, One));
+ TestVal = ConstantInt::get(TestVal->getValue()+1);
} while (TestVal != EndVal);
return new SCEVCouldNotCompute();
//===----------------------------------------------------------------------===//
bool ScalarEvolution::runOnFunction(Function &F) {
- Impl = new ScalarEvolutionsImpl(F, getAnalysis<LoopInfo>());
+ Impl = new ScalarEvolutionsImpl(*this, F, getAnalysis<LoopInfo>());
return false;
}
return ((ScalarEvolutionsImpl*)Impl)->getSCEVAtScope(getSCEV(V), L);
}
-void ScalarEvolution::deleteInstructionFromRecords(Instruction *I) const {
- return ((ScalarEvolutionsImpl*)Impl)->deleteInstructionFromRecords(I);
+void ScalarEvolution::deleteValueFromRecords(Value *V) const {
+ return ((ScalarEvolutionsImpl*)Impl)->deleteValueFromRecords(V);
}
static void PrintLoopInfo(std::ostream &OS, const ScalarEvolution *SE,
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
PrintLoopInfo(OS, SE, *I);
- llvm_cerr << "Loop " << L->getHeader()->getName() << ": ";
+ cerr << "Loop " << L->getHeader()->getName() << ": ";
- std::vector<BasicBlock*> ExitBlocks;
+ SmallVector<BasicBlock*, 8> ExitBlocks;
L->getExitBlocks(ExitBlocks);
if (ExitBlocks.size() != 1)
- llvm_cerr << "<multiple exits> ";
+ cerr << "<multiple exits> ";
if (SE->hasLoopInvariantIterationCount(L)) {
- llvm_cerr << *SE->getIterationCount(L) << " iterations! ";
+ cerr << *SE->getIterationCount(L) << " iterations! ";
} else {
- llvm_cerr << "Unpredictable iteration count. ";
+ cerr << "Unpredictable iteration count. ";
}
- llvm_cerr << "\n";
+ cerr << "\n";
}
void ScalarEvolution::print(std::ostream &OS, const Module* ) const {
SV->print(OS);
OS << "\t\t";
- if ((*I).getType()->isIntegral()) {
+ if ((*I).getType()->isInteger()) {
ConstantRange Bounds = SV->getValueRange();
if (!Bounds.isFullSet())
OS << "Bounds: " << Bounds << " ";
for (LoopInfo::iterator I = LI.begin(), E = LI.end(); I != E; ++I)
PrintLoopInfo(OS, this, *I);
}
-
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