#include "llvm/Operator.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Assembly/Writer.h"
"derived loop"),
cl::init(100));
-static RegisterPass<ScalarEvolution>
-R("scalar-evolution", "Scalar Evolution Analysis", false, true);
+INITIALIZE_PASS_BEGIN(ScalarEvolution, "scalar-evolution",
+ "Scalar Evolution Analysis", false, true)
+INITIALIZE_PASS_DEPENDENCY(LoopInfo)
+INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_END(ScalarEvolution, "scalar-evolution",
+ "Scalar Evolution Analysis", false, true)
char ScalarEvolution::ID = 0;
//===----------------------------------------------------------------------===//
// Implementation of the SCEV class.
//
-SCEV::~SCEV() {}
-
void SCEV::dump() const {
print(dbgs());
dbgs() << '\n';
}
+void SCEV::print(raw_ostream &OS) const {
+ switch (getSCEVType()) {
+ case scConstant:
+ WriteAsOperand(OS, cast<SCEVConstant>(this)->getValue(), false);
+ return;
+ case scTruncate: {
+ const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this);
+ const SCEV *Op = Trunc->getOperand();
+ OS << "(trunc " << *Op->getType() << " " << *Op << " to "
+ << *Trunc->getType() << ")";
+ return;
+ }
+ case scZeroExtend: {
+ const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this);
+ const SCEV *Op = ZExt->getOperand();
+ OS << "(zext " << *Op->getType() << " " << *Op << " to "
+ << *ZExt->getType() << ")";
+ return;
+ }
+ case scSignExtend: {
+ const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this);
+ const SCEV *Op = SExt->getOperand();
+ OS << "(sext " << *Op->getType() << " " << *Op << " to "
+ << *SExt->getType() << ")";
+ return;
+ }
+ case scAddRecExpr: {
+ const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this);
+ OS << "{" << *AR->getOperand(0);
+ for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i)
+ OS << ",+," << *AR->getOperand(i);
+ OS << "}<";
+ if (AR->getNoWrapFlags(FlagNUW))
+ OS << "nuw><";
+ if (AR->getNoWrapFlags(FlagNSW))
+ OS << "nsw><";
+ if (AR->getNoWrapFlags(FlagNW) &&
+ !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW)))
+ OS << "nw><";
+ WriteAsOperand(OS, AR->getLoop()->getHeader(), /*PrintType=*/false);
+ OS << ">";
+ return;
+ }
+ case scAddExpr:
+ case scMulExpr:
+ case scUMaxExpr:
+ case scSMaxExpr: {
+ const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this);
+ const char *OpStr = 0;
+ switch (NAry->getSCEVType()) {
+ case scAddExpr: OpStr = " + "; break;
+ case scMulExpr: OpStr = " * "; break;
+ case scUMaxExpr: OpStr = " umax "; break;
+ case scSMaxExpr: OpStr = " smax "; break;
+ }
+ OS << "(";
+ for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
+ I != E; ++I) {
+ OS << **I;
+ if (llvm::next(I) != E)
+ OS << OpStr;
+ }
+ OS << ")";
+ return;
+ }
+ case scUDivExpr: {
+ const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this);
+ OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")";
+ return;
+ }
+ case scUnknown: {
+ const SCEVUnknown *U = cast<SCEVUnknown>(this);
+ Type *AllocTy;
+ if (U->isSizeOf(AllocTy)) {
+ OS << "sizeof(" << *AllocTy << ")";
+ return;
+ }
+ if (U->isAlignOf(AllocTy)) {
+ OS << "alignof(" << *AllocTy << ")";
+ return;
+ }
+
+ Type *CTy;
+ Constant *FieldNo;
+ if (U->isOffsetOf(CTy, FieldNo)) {
+ OS << "offsetof(" << *CTy << ", ";
+ WriteAsOperand(OS, FieldNo, false);
+ OS << ")";
+ return;
+ }
+
+ // Otherwise just print it normally.
+ WriteAsOperand(OS, U->getValue(), false);
+ return;
+ }
+ case scCouldNotCompute:
+ OS << "***COULDNOTCOMPUTE***";
+ return;
+ default: break;
+ }
+ llvm_unreachable("Unknown SCEV kind!");
+}
+
+Type *SCEV::getType() const {
+ switch (getSCEVType()) {
+ case scConstant:
+ return cast<SCEVConstant>(this)->getType();
+ case scTruncate:
+ case scZeroExtend:
+ case scSignExtend:
+ return cast<SCEVCastExpr>(this)->getType();
+ case scAddRecExpr:
+ case scMulExpr:
+ case scUMaxExpr:
+ case scSMaxExpr:
+ return cast<SCEVNAryExpr>(this)->getType();
+ case scAddExpr:
+ return cast<SCEVAddExpr>(this)->getType();
+ case scUDivExpr:
+ return cast<SCEVUDivExpr>(this)->getType();
+ case scUnknown:
+ return cast<SCEVUnknown>(this)->getType();
+ case scCouldNotCompute:
+ llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
+ return 0;
+ default: break;
+ }
+ llvm_unreachable("Unknown SCEV kind!");
+ return 0;
+}
+
bool SCEV::isZero() const {
if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
return SC->getValue()->isZero();
SCEVCouldNotCompute::SCEVCouldNotCompute() :
SCEV(FoldingSetNodeIDRef(), scCouldNotCompute) {}
-bool SCEVCouldNotCompute::isLoopInvariant(const Loop *L) const {
- llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
- return false;
-}
-
-const Type *SCEVCouldNotCompute::getType() const {
- llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
- return 0;
-}
-
-bool SCEVCouldNotCompute::hasComputableLoopEvolution(const Loop *L) const {
- llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
- return false;
-}
-
-bool SCEVCouldNotCompute::hasOperand(const SCEV *) const {
- llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
- return false;
-}
-
-void SCEVCouldNotCompute::print(raw_ostream &OS) const {
- OS << "***COULDNOTCOMPUTE***";
-}
-
bool SCEVCouldNotCompute::classof(const SCEV *S) {
return S->getSCEVType() == scCouldNotCompute;
}
}
const SCEV *
-ScalarEvolution::getConstant(const Type *Ty, uint64_t V, bool isSigned) {
- return getConstant(
- ConstantInt::get(cast<IntegerType>(Ty), V, isSigned));
-}
-
-const Type *SCEVConstant::getType() const { return V->getType(); }
-
-void SCEVConstant::print(raw_ostream &OS) const {
- WriteAsOperand(OS, V, false);
+ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) {
+ IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
+ return getConstant(ConstantInt::get(ITy, V, isSigned));
}
SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID,
- unsigned SCEVTy, const SCEV *op, const Type *ty)
+ unsigned SCEVTy, const SCEV *op, Type *ty)
: SCEV(ID, SCEVTy), Op(op), Ty(ty) {}
-bool SCEVCastExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
- return Op->dominates(BB, DT);
-}
-
-bool SCEVCastExpr::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- return Op->properlyDominates(BB, DT);
-}
-
SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
- const SCEV *op, const Type *ty)
+ const SCEV *op, Type *ty)
: SCEVCastExpr(ID, scTruncate, op, ty) {
assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) &&
"Cannot truncate non-integer value!");
}
-void SCEVTruncateExpr::print(raw_ostream &OS) const {
- OS << "(trunc " << *Op->getType() << " " << *Op << " to " << *Ty << ")";
-}
-
SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
- const SCEV *op, const Type *ty)
+ const SCEV *op, Type *ty)
: SCEVCastExpr(ID, scZeroExtend, op, ty) {
assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) &&
"Cannot zero extend non-integer value!");
}
-void SCEVZeroExtendExpr::print(raw_ostream &OS) const {
- OS << "(zext " << *Op->getType() << " " << *Op << " to " << *Ty << ")";
-}
-
SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
- const SCEV *op, const Type *ty)
+ const SCEV *op, Type *ty)
: SCEVCastExpr(ID, scSignExtend, op, ty) {
assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) &&
"Cannot sign extend non-integer value!");
}
-void SCEVSignExtendExpr::print(raw_ostream &OS) const {
- OS << "(sext " << *Op->getType() << " " << *Op << " to " << *Ty << ")";
-}
-
-void SCEVCommutativeExpr::print(raw_ostream &OS) const {
- assert(NumOperands > 1 && "This plus expr shouldn't exist!");
- const char *OpStr = getOperationStr();
- OS << "(" << *Operands[0];
- for (unsigned i = 1, e = NumOperands; i != e; ++i)
- OS << OpStr << *Operands[i];
- OS << ")";
-}
-
-bool SCEVNAryExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
- if (!getOperand(i)->dominates(BB, DT))
- return false;
- }
- return true;
-}
-
-bool SCEVNAryExpr::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
- if (!getOperand(i)->properlyDominates(BB, DT))
- return false;
- }
- return true;
-}
-
-bool SCEVUDivExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
- return LHS->dominates(BB, DT) && RHS->dominates(BB, DT);
-}
-
-bool SCEVUDivExpr::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- return LHS->properlyDominates(BB, DT) && RHS->properlyDominates(BB, DT);
-}
-
-void SCEVUDivExpr::print(raw_ostream &OS) const {
- OS << "(" << *LHS << " /u " << *RHS << ")";
-}
-
-const Type *SCEVUDivExpr::getType() const {
- // In most cases the types of LHS and RHS will be the same, but in some
- // crazy cases one or the other may be a pointer. ScalarEvolution doesn't
- // depend on the type for correctness, but handling types carefully can
- // avoid extra casts in the SCEVExpander. The LHS is more likely to be
- // a pointer type than the RHS, so use the RHS' type here.
- return RHS->getType();
-}
-
-bool SCEVAddRecExpr::isLoopInvariant(const Loop *QueryLoop) const {
- // Add recurrences are never invariant in the function-body (null loop).
- if (!QueryLoop)
- return false;
-
- // This recurrence is variant w.r.t. QueryLoop if QueryLoop contains L.
- if (QueryLoop->contains(L))
- return false;
-
- // This recurrence is variant w.r.t. QueryLoop if any of its operands
- // are variant.
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
- if (!getOperand(i)->isLoopInvariant(QueryLoop))
- return false;
-
- // Otherwise it's loop-invariant.
- return true;
-}
-
-bool
-SCEVAddRecExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
- return DT->dominates(L->getHeader(), BB) &&
- SCEVNAryExpr::dominates(BB, DT);
-}
+void SCEVUnknown::deleted() {
+ // Clear this SCEVUnknown from various maps.
+ SE->forgetMemoizedResults(this);
-bool
-SCEVAddRecExpr::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- // This uses a "dominates" query instead of "properly dominates" query because
- // the instruction which produces the addrec's value is a PHI, and a PHI
- // effectively properly dominates its entire containing block.
- return DT->dominates(L->getHeader(), BB) &&
- SCEVNAryExpr::properlyDominates(BB, DT);
-}
-
-void SCEVAddRecExpr::print(raw_ostream &OS) const {
- OS << "{" << *Operands[0];
- for (unsigned i = 1, e = NumOperands; i != e; ++i)
- OS << ",+," << *Operands[i];
- OS << "}<";
- WriteAsOperand(OS, L->getHeader(), /*PrintType=*/false);
- OS << ">";
-}
+ // Remove this SCEVUnknown from the uniquing map.
+ SE->UniqueSCEVs.RemoveNode(this);
-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.
- // Instructions are never considered invariant in the function body
- // (null loop) because they are defined within the "loop".
- if (Instruction *I = dyn_cast<Instruction>(V))
- return L && !L->contains(I);
- return true;
+ // Release the value.
+ setValPtr(0);
}
-bool SCEVUnknown::dominates(BasicBlock *BB, DominatorTree *DT) const {
- if (Instruction *I = dyn_cast<Instruction>(getValue()))
- return DT->dominates(I->getParent(), BB);
- return true;
-}
+void SCEVUnknown::allUsesReplacedWith(Value *New) {
+ // Clear this SCEVUnknown from various maps.
+ SE->forgetMemoizedResults(this);
-bool SCEVUnknown::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- if (Instruction *I = dyn_cast<Instruction>(getValue()))
- return DT->properlyDominates(I->getParent(), BB);
- return true;
-}
+ // Remove this SCEVUnknown from the uniquing map.
+ SE->UniqueSCEVs.RemoveNode(this);
-const Type *SCEVUnknown::getType() const {
- return V->getType();
+ // Update this SCEVUnknown to point to the new value. This is needed
+ // because there may still be outstanding SCEVs which still point to
+ // this SCEVUnknown.
+ setValPtr(New);
}
-bool SCEVUnknown::isSizeOf(const Type *&AllocTy) const {
- if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(V))
+bool SCEVUnknown::isSizeOf(Type *&AllocTy) const {
+ if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
if (VCE->getOpcode() == Instruction::PtrToInt)
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
if (CE->getOpcode() == Instruction::GetElementPtr &&
return false;
}
-bool SCEVUnknown::isAlignOf(const Type *&AllocTy) const {
- if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(V))
+bool SCEVUnknown::isAlignOf(Type *&AllocTy) const {
+ if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
if (VCE->getOpcode() == Instruction::PtrToInt)
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
if (CE->getOpcode() == Instruction::GetElementPtr &&
CE->getOperand(0)->isNullValue()) {
- const Type *Ty =
+ Type *Ty =
cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
- if (const StructType *STy = dyn_cast<StructType>(Ty))
+ if (StructType *STy = dyn_cast<StructType>(Ty))
if (!STy->isPacked() &&
CE->getNumOperands() == 3 &&
CE->getOperand(1)->isNullValue()) {
return false;
}
-bool SCEVUnknown::isOffsetOf(const Type *&CTy, Constant *&FieldNo) const {
- if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(V))
+bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
+ if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
if (VCE->getOpcode() == Instruction::PtrToInt)
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
if (CE->getOpcode() == Instruction::GetElementPtr &&
CE->getNumOperands() == 3 &&
CE->getOperand(0)->isNullValue() &&
CE->getOperand(1)->isNullValue()) {
- const Type *Ty =
+ Type *Ty =
cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
// Ignore vector types here so that ScalarEvolutionExpander doesn't
// emit getelementptrs that index into vectors.
return false;
}
-void SCEVUnknown::print(raw_ostream &OS) const {
- const Type *AllocTy;
- if (isSizeOf(AllocTy)) {
- OS << "sizeof(" << *AllocTy << ")";
- return;
- }
- if (isAlignOf(AllocTy)) {
- OS << "alignof(" << *AllocTy << ")";
- return;
- }
-
- const Type *CTy;
- Constant *FieldNo;
- if (isOffsetOf(CTy, FieldNo)) {
- OS << "offsetof(" << *CTy << ", ";
- WriteAsOperand(OS, FieldNo, false);
- OS << ")";
- return;
- }
-
- // Otherwise just print it normally.
- WriteAsOperand(OS, V, false);
-}
-
//===----------------------------------------------------------------------===//
// SCEV Utilities
//===----------------------------------------------------------------------===//
-static bool CompareTypes(const Type *A, const Type *B) {
- if (A->getTypeID() != B->getTypeID())
- return A->getTypeID() < B->getTypeID();
- if (const IntegerType *AI = dyn_cast<IntegerType>(A)) {
- const IntegerType *BI = cast<IntegerType>(B);
- return AI->getBitWidth() < BI->getBitWidth();
- }
- if (const PointerType *AI = dyn_cast<PointerType>(A)) {
- const PointerType *BI = cast<PointerType>(B);
- return CompareTypes(AI->getElementType(), BI->getElementType());
- }
- if (const ArrayType *AI = dyn_cast<ArrayType>(A)) {
- const ArrayType *BI = cast<ArrayType>(B);
- if (AI->getNumElements() != BI->getNumElements())
- return AI->getNumElements() < BI->getNumElements();
- return CompareTypes(AI->getElementType(), BI->getElementType());
- }
- if (const VectorType *AI = dyn_cast<VectorType>(A)) {
- const VectorType *BI = cast<VectorType>(B);
- if (AI->getNumElements() != BI->getNumElements())
- return AI->getNumElements() < BI->getNumElements();
- return CompareTypes(AI->getElementType(), BI->getElementType());
- }
- if (const StructType *AI = dyn_cast<StructType>(A)) {
- const StructType *BI = cast<StructType>(B);
- if (AI->getNumElements() != BI->getNumElements())
- return AI->getNumElements() < BI->getNumElements();
- for (unsigned i = 0, e = AI->getNumElements(); i != e; ++i)
- if (CompareTypes(AI->getElementType(i), BI->getElementType(i)) ||
- CompareTypes(BI->getElementType(i), AI->getElementType(i)))
- return CompareTypes(AI->getElementType(i), BI->getElementType(i));
- }
- return false;
-}
-
namespace {
/// SCEVComplexityCompare - Return true if the complexity of the LHS is less
/// than the complexity of the RHS. This comparator is used to canonicalize
/// expressions.
class SCEVComplexityCompare {
- LoopInfo *LI;
+ const LoopInfo *const LI;
public:
- explicit SCEVComplexityCompare(LoopInfo *li) : LI(li) {}
+ explicit SCEVComplexityCompare(const LoopInfo *li) : LI(li) {}
+ // Return true or false if LHS is less than, or at least RHS, respectively.
bool operator()(const SCEV *LHS, const SCEV *RHS) const {
+ return compare(LHS, RHS) < 0;
+ }
+
+ // Return negative, zero, or positive, if LHS is less than, equal to, or
+ // greater than RHS, respectively. A three-way result allows recursive
+ // comparisons to be more efficient.
+ int compare(const SCEV *LHS, const SCEV *RHS) const {
// Fast-path: SCEVs are uniqued so we can do a quick equality check.
if (LHS == RHS)
- return false;
+ return 0;
// Primarily, sort the SCEVs by their getSCEVType().
- if (LHS->getSCEVType() != RHS->getSCEVType())
- return LHS->getSCEVType() < RHS->getSCEVType();
+ unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
+ if (LType != RType)
+ return (int)LType - (int)RType;
// Aside from the getSCEVType() ordering, the particular ordering
// isn't very important except that it's beneficial to be consistent,
// so that (a + b) and (b + a) don't end up as different expressions.
-
- // Sort SCEVUnknown values with some loose heuristics. TODO: This is
- // not as complete as it could be.
- if (const SCEVUnknown *LU = dyn_cast<SCEVUnknown>(LHS)) {
+ switch (LType) {
+ case scUnknown: {
+ const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
+ // Sort SCEVUnknown values with some loose heuristics. TODO: This is
+ // not as complete as it could be.
+ const Value *LV = LU->getValue(), *RV = RU->getValue();
+
// Order pointer values after integer values. This helps SCEVExpander
// form GEPs.
- if (LU->getType()->isPointerTy() && !RU->getType()->isPointerTy())
- return false;
- if (RU->getType()->isPointerTy() && !LU->getType()->isPointerTy())
- return true;
+ bool LIsPointer = LV->getType()->isPointerTy(),
+ RIsPointer = RV->getType()->isPointerTy();
+ if (LIsPointer != RIsPointer)
+ return (int)LIsPointer - (int)RIsPointer;
// Compare getValueID values.
- if (LU->getValue()->getValueID() != RU->getValue()->getValueID())
- return LU->getValue()->getValueID() < RU->getValue()->getValueID();
+ unsigned LID = LV->getValueID(),
+ RID = RV->getValueID();
+ if (LID != RID)
+ return (int)LID - (int)RID;
// Sort arguments by their position.
- if (const Argument *LA = dyn_cast<Argument>(LU->getValue())) {
- const Argument *RA = cast<Argument>(RU->getValue());
- return LA->getArgNo() < RA->getArgNo();
+ if (const Argument *LA = dyn_cast<Argument>(LV)) {
+ const Argument *RA = cast<Argument>(RV);
+ unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo();
+ return (int)LArgNo - (int)RArgNo;
}
- // For instructions, compare their loop depth, and their opcode.
- // This is pretty loose.
- if (Instruction *LV = dyn_cast<Instruction>(LU->getValue())) {
- Instruction *RV = cast<Instruction>(RU->getValue());
+ // For instructions, compare their loop depth, and their operand
+ // count. This is pretty loose.
+ if (const Instruction *LInst = dyn_cast<Instruction>(LV)) {
+ const Instruction *RInst = cast<Instruction>(RV);
// Compare loop depths.
- if (LI->getLoopDepth(LV->getParent()) !=
- LI->getLoopDepth(RV->getParent()))
- return LI->getLoopDepth(LV->getParent()) <
- LI->getLoopDepth(RV->getParent());
-
- // Compare opcodes.
- if (LV->getOpcode() != RV->getOpcode())
- return LV->getOpcode() < RV->getOpcode();
+ const BasicBlock *LParent = LInst->getParent(),
+ *RParent = RInst->getParent();
+ if (LParent != RParent) {
+ unsigned LDepth = LI->getLoopDepth(LParent),
+ RDepth = LI->getLoopDepth(RParent);
+ if (LDepth != RDepth)
+ return (int)LDepth - (int)RDepth;
+ }
// Compare the number of operands.
- if (LV->getNumOperands() != RV->getNumOperands())
- return LV->getNumOperands() < RV->getNumOperands();
+ unsigned LNumOps = LInst->getNumOperands(),
+ RNumOps = RInst->getNumOperands();
+ return (int)LNumOps - (int)RNumOps;
}
- return false;
+ return 0;
}
- // Compare constant values.
- if (const SCEVConstant *LC = dyn_cast<SCEVConstant>(LHS)) {
+ case scConstant: {
+ const SCEVConstant *LC = cast<SCEVConstant>(LHS);
const SCEVConstant *RC = cast<SCEVConstant>(RHS);
- if (LC->getValue()->getBitWidth() != RC->getValue()->getBitWidth())
- return LC->getValue()->getBitWidth() < RC->getValue()->getBitWidth();
- return LC->getValue()->getValue().ult(RC->getValue()->getValue());
+
+ // Compare constant values.
+ const APInt &LA = LC->getValue()->getValue();
+ const APInt &RA = RC->getValue()->getValue();
+ unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth();
+ if (LBitWidth != RBitWidth)
+ return (int)LBitWidth - (int)RBitWidth;
+ return LA.ult(RA) ? -1 : 1;
}
- // Compare addrec loop depths.
- if (const SCEVAddRecExpr *LA = dyn_cast<SCEVAddRecExpr>(LHS)) {
+ case scAddRecExpr: {
+ const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS);
const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
- if (LA->getLoop()->getLoopDepth() != RA->getLoop()->getLoopDepth())
- return LA->getLoop()->getLoopDepth() < RA->getLoop()->getLoopDepth();
+
+ // Compare addrec loop depths.
+ const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop();
+ if (LLoop != RLoop) {
+ unsigned LDepth = LLoop->getLoopDepth(),
+ RDepth = RLoop->getLoopDepth();
+ if (LDepth != RDepth)
+ return (int)LDepth - (int)RDepth;
+ }
+
+ // Addrec complexity grows with operand count.
+ unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands();
+ if (LNumOps != RNumOps)
+ return (int)LNumOps - (int)RNumOps;
+
+ // Lexicographically compare.
+ for (unsigned i = 0; i != LNumOps; ++i) {
+ long X = compare(LA->getOperand(i), RA->getOperand(i));
+ if (X != 0)
+ return X;
+ }
+
+ return 0;
}
- // Lexicographically compare n-ary expressions.
- if (const SCEVNAryExpr *LC = dyn_cast<SCEVNAryExpr>(LHS)) {
+ case scAddExpr:
+ case scMulExpr:
+ case scSMaxExpr:
+ case scUMaxExpr: {
+ const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS);
const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
- for (unsigned i = 0, e = LC->getNumOperands(); i != e; ++i) {
- if (i >= RC->getNumOperands())
- return false;
- if (operator()(LC->getOperand(i), RC->getOperand(i)))
- return true;
- if (operator()(RC->getOperand(i), LC->getOperand(i)))
- return false;
+
+ // Lexicographically compare n-ary expressions.
+ unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
+ for (unsigned i = 0; i != LNumOps; ++i) {
+ if (i >= RNumOps)
+ return 1;
+ long X = compare(LC->getOperand(i), RC->getOperand(i));
+ if (X != 0)
+ return X;
}
- return LC->getNumOperands() < RC->getNumOperands();
+ return (int)LNumOps - (int)RNumOps;
}
- // Lexicographically compare udiv expressions.
- if (const SCEVUDivExpr *LC = dyn_cast<SCEVUDivExpr>(LHS)) {
+ case scUDivExpr: {
+ const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS);
const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
- if (operator()(LC->getLHS(), RC->getLHS()))
- return true;
- if (operator()(RC->getLHS(), LC->getLHS()))
- return false;
- if (operator()(LC->getRHS(), RC->getRHS()))
- return true;
- if (operator()(RC->getRHS(), LC->getRHS()))
- return false;
- return false;
+
+ // Lexicographically compare udiv expressions.
+ long X = compare(LC->getLHS(), RC->getLHS());
+ if (X != 0)
+ return X;
+ return compare(LC->getRHS(), RC->getRHS());
}
- // Compare cast expressions by operand.
- if (const SCEVCastExpr *LC = dyn_cast<SCEVCastExpr>(LHS)) {
+ case scTruncate:
+ case scZeroExtend:
+ case scSignExtend: {
+ const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS);
const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
- return operator()(LC->getOperand(), RC->getOperand());
+
+ // Compare cast expressions by operand.
+ return compare(LC->getOperand(), RC->getOperand());
+ }
+
+ default:
+ break;
}
llvm_unreachable("Unknown SCEV kind!");
- return false;
+ return 0;
}
};
}
if (Ops.size() == 2) {
// This is the common case, which also happens to be trivially simple.
// Special case it.
- if (SCEVComplexityCompare(LI)(Ops[1], Ops[0]))
- std::swap(Ops[0], Ops[1]);
+ const SCEV *&LHS = Ops[0], *&RHS = Ops[1];
+ if (SCEVComplexityCompare(LI)(RHS, LHS))
+ std::swap(LHS, RHS);
return;
}
/// Assume, K > 0.
static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
ScalarEvolution &SE,
- const Type* ResultTy) {
+ Type* ResultTy) {
// Handle the simplest case efficiently.
if (K == 1)
return SE.getTruncateOrZeroExtend(It, ResultTy);
MultiplyFactor = MultiplyFactor.trunc(W);
// Calculate the product, at width T+W
- const IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
+ IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
CalculationBits);
const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
for (unsigned i = 1; i != K; ++i) {
- const SCEV *S = SE.getMinusSCEV(It, SE.getIntegerSCEV(i, It->getType()));
+ const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
Dividend = SE.getMulExpr(Dividend,
SE.getTruncateOrZeroExtend(S, CalculationTy));
}
//===----------------------------------------------------------------------===//
const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op,
- const Type *Ty) {
+ Type *Ty) {
assert(getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) &&
"This is not a truncating conversion!");
assert(isSCEVable(Ty) &&
// Fold if the operand is constant.
if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
return getConstant(
- cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty)));
+ cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(),
+ getEffectiveSCEVType(Ty))));
// trunc(trunc(x)) --> trunc(x)
if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
return getTruncateOrZeroExtend(SZ->getOperand(), Ty);
+ // trunc(x1+x2+...+xN) --> trunc(x1)+trunc(x2)+...+trunc(xN) if we can
+ // eliminate all the truncates.
+ if (const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Op)) {
+ SmallVector<const SCEV *, 4> Operands;
+ bool hasTrunc = false;
+ for (unsigned i = 0, e = SA->getNumOperands(); i != e && !hasTrunc; ++i) {
+ const SCEV *S = getTruncateExpr(SA->getOperand(i), Ty);
+ hasTrunc = isa<SCEVTruncateExpr>(S);
+ Operands.push_back(S);
+ }
+ if (!hasTrunc)
+ return getAddExpr(Operands);
+ UniqueSCEVs.FindNodeOrInsertPos(ID, IP); // Mutates IP, returns NULL.
+ }
+
+ // trunc(x1*x2*...*xN) --> trunc(x1)*trunc(x2)*...*trunc(xN) if we can
+ // eliminate all the truncates.
+ if (const SCEVMulExpr *SM = dyn_cast<SCEVMulExpr>(Op)) {
+ SmallVector<const SCEV *, 4> Operands;
+ bool hasTrunc = false;
+ for (unsigned i = 0, e = SM->getNumOperands(); i != e && !hasTrunc; ++i) {
+ const SCEV *S = getTruncateExpr(SM->getOperand(i), Ty);
+ hasTrunc = isa<SCEVTruncateExpr>(S);
+ Operands.push_back(S);
+ }
+ if (!hasTrunc)
+ return getMulExpr(Operands);
+ UniqueSCEVs.FindNodeOrInsertPos(ID, IP); // Mutates IP, returns NULL.
+ }
+
// If the input value is a chrec scev, truncate the chrec's operands.
if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
SmallVector<const SCEV *, 4> Operands;
for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
Operands.push_back(getTruncateExpr(AddRec->getOperand(i), Ty));
- return getAddRecExpr(Operands, AddRec->getLoop());
+ return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
}
- // The cast wasn't folded; create an explicit cast node.
- // Recompute the insert position, as it may have been invalidated.
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
+ // As a special case, fold trunc(undef) to undef. We don't want to
+ // know too much about SCEVUnknowns, but this special case is handy
+ // and harmless.
+ if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Op))
+ if (isa<UndefValue>(U->getValue()))
+ return getSCEV(UndefValue::get(Ty));
+
+ // The cast wasn't folded; create an explicit cast node. We can reuse
+ // the existing insert position since if we get here, we won't have
+ // made any changes which would invalidate it.
SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
Op, Ty);
UniqueSCEVs.InsertNode(S, IP);
}
const SCEV *ScalarEvolution::getZeroExtendExpr(const SCEV *Op,
- const Type *Ty) {
+ Type *Ty) {
assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&
"This is not an extending conversion!");
assert(isSCEVable(Ty) &&
Ty = getEffectiveSCEVType(Ty);
// Fold if the operand is constant.
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) {
- const Type *IntTy = getEffectiveSCEVType(Ty);
- Constant *C = ConstantExpr::getZExt(SC->getValue(), IntTy);
- if (IntTy != Ty) C = ConstantExpr::getIntToPtr(C, Ty);
- return getConstant(cast<ConstantInt>(C));
- }
+ if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
+ return getConstant(
+ cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(),
+ getEffectiveSCEVType(Ty))));
// zext(zext(x)) --> zext(x)
if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
void *IP = 0;
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
+ // zext(trunc(x)) --> zext(x) or x or trunc(x)
+ if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
+ // It's possible the bits taken off by the truncate were all zero bits. If
+ // so, we should be able to simplify this further.
+ const SCEV *X = ST->getOperand();
+ ConstantRange CR = getUnsignedRange(X);
+ unsigned TruncBits = getTypeSizeInBits(ST->getType());
+ unsigned NewBits = getTypeSizeInBits(Ty);
+ if (CR.truncate(TruncBits).zeroExtend(NewBits).contains(
+ CR.zextOrTrunc(NewBits)))
+ return getTruncateOrZeroExtend(X, Ty);
+ }
+
// 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
// operands (often constants). This allows analysis of something like
// If we have special knowledge that this addrec won't overflow,
// we don't need to do any further analysis.
- if (AR->hasNoUnsignedWrap())
+ if (AR->getNoWrapFlags(SCEV::FlagNUW))
return getAddRecExpr(getZeroExtendExpr(Start, Ty),
getZeroExtendExpr(Step, Ty),
- L);
+ L, AR->getNoWrapFlags());
// Check whether the backedge-taken count is SCEVCouldNotCompute.
// Note that this serves two purposes: It filters out loops that are
const SCEV *RecastedMaxBECount =
getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
if (MaxBECount == RecastedMaxBECount) {
- const Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
+ Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
// Check whether Start+Step*MaxBECount has no unsigned overflow.
const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step);
const SCEV *Add = getAddExpr(Start, ZMul);
getAddExpr(getZeroExtendExpr(Start, WideTy),
getMulExpr(getZeroExtendExpr(CastedMaxBECount, WideTy),
getZeroExtendExpr(Step, WideTy)));
- if (getZeroExtendExpr(Add, WideTy) == OperandExtendedAdd)
+ if (getZeroExtendExpr(Add, WideTy) == OperandExtendedAdd) {
+ // Cache knowledge of AR NUW, which is propagated to this AddRec.
+ const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
// Return the expression with the addrec on the outside.
return getAddRecExpr(getZeroExtendExpr(Start, Ty),
getZeroExtendExpr(Step, Ty),
- L);
-
+ L, AR->getNoWrapFlags());
+ }
// Similar to above, only this time treat the step value as signed.
// This covers loops that count down.
const SCEV *SMul = getMulExpr(CastedMaxBECount, Step);
getAddExpr(getZeroExtendExpr(Start, WideTy),
getMulExpr(getZeroExtendExpr(CastedMaxBECount, WideTy),
getSignExtendExpr(Step, WideTy)));
- if (getZeroExtendExpr(Add, WideTy) == OperandExtendedAdd)
+ if (getZeroExtendExpr(Add, WideTy) == OperandExtendedAdd) {
+ // Cache knowledge of AR NW, which is propagated to this AddRec.
+ // Negative step causes unsigned wrap, but it still can't self-wrap.
+ const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
// Return the expression with the addrec on the outside.
return getAddRecExpr(getZeroExtendExpr(Start, Ty),
getSignExtendExpr(Step, Ty),
- L);
+ L, AR->getNoWrapFlags());
+ }
}
// If the backedge is guarded by a comparison with the pre-inc value
if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
(isLoopEntryGuardedByCond(L, ICmpInst::ICMP_ULT, Start, N) &&
isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT,
- AR->getPostIncExpr(*this), N)))
+ AR->getPostIncExpr(*this), N))) {
+ // Cache knowledge of AR NUW, which is propagated to this AddRec.
+ const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
// Return the expression with the addrec on the outside.
return getAddRecExpr(getZeroExtendExpr(Start, Ty),
getZeroExtendExpr(Step, Ty),
- L);
+ L, AR->getNoWrapFlags());
+ }
} else if (isKnownNegative(Step)) {
const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
getSignedRange(Step).getSignedMin());
- if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) &&
- (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_UGT, Start, N) ||
+ if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
+ (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_UGT, Start, N) &&
isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT,
- AR->getPostIncExpr(*this), N)))
+ AR->getPostIncExpr(*this), N))) {
+ // Cache knowledge of AR NW, which is propagated to this AddRec.
+ // Negative step causes unsigned wrap, but it still can't self-wrap.
+ const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
// Return the expression with the addrec on the outside.
return getAddRecExpr(getZeroExtendExpr(Start, Ty),
getSignExtendExpr(Step, Ty),
- L);
+ L, AR->getNoWrapFlags());
+ }
}
}
}
return S;
}
+// Get the limit of a recurrence such that incrementing by Step cannot cause
+// signed overflow as long as the value of the recurrence within the loop does
+// not exceed this limit before incrementing.
+static const SCEV *getOverflowLimitForStep(const SCEV *Step,
+ ICmpInst::Predicate *Pred,
+ ScalarEvolution *SE) {
+ unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
+ if (SE->isKnownPositive(Step)) {
+ *Pred = ICmpInst::ICMP_SLT;
+ return SE->getConstant(APInt::getSignedMinValue(BitWidth) -
+ SE->getSignedRange(Step).getSignedMax());
+ }
+ if (SE->isKnownNegative(Step)) {
+ *Pred = ICmpInst::ICMP_SGT;
+ return SE->getConstant(APInt::getSignedMaxValue(BitWidth) -
+ SE->getSignedRange(Step).getSignedMin());
+ }
+ return 0;
+}
+
+// The recurrence AR has been shown to have no signed wrap. Typically, if we can
+// prove NSW for AR, then we can just as easily prove NSW for its preincrement
+// or postincrement sibling. This allows normalizing a sign extended AddRec as
+// such: {sext(Step + Start),+,Step} => {(Step + sext(Start),+,Step} As a
+// result, the expression "Step + sext(PreIncAR)" is congruent with
+// "sext(PostIncAR)"
+static const SCEV *getPreStartForSignExtend(const SCEVAddRecExpr *AR,
+ Type *Ty,
+ ScalarEvolution *SE) {
+ const Loop *L = AR->getLoop();
+ const SCEV *Start = AR->getStart();
+ const SCEV *Step = AR->getStepRecurrence(*SE);
+
+ // Check for a simple looking step prior to loop entry.
+ const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start);
+ if (!SA || SA->getNumOperands() != 2 || SA->getOperand(0) != Step)
+ return 0;
+
+ // This is a postinc AR. Check for overflow on the preinc recurrence using the
+ // same three conditions that getSignExtendedExpr checks.
+
+ // 1. NSW flags on the step increment.
+ const SCEV *PreStart = SA->getOperand(1);
+ const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
+ SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
+
+ if (PreAR && PreAR->getNoWrapFlags(SCEV::FlagNSW))
+ return PreStart;
+
+ // 2. Direct overflow check on the step operation's expression.
+ unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
+ Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
+ const SCEV *OperandExtendedStart =
+ SE->getAddExpr(SE->getSignExtendExpr(PreStart, WideTy),
+ SE->getSignExtendExpr(Step, WideTy));
+ if (SE->getSignExtendExpr(Start, WideTy) == OperandExtendedStart) {
+ // Cache knowledge of PreAR NSW.
+ if (PreAR)
+ const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(SCEV::FlagNSW);
+ // FIXME: this optimization needs a unit test
+ DEBUG(dbgs() << "SCEV: untested prestart overflow check\n");
+ return PreStart;
+ }
+
+ // 3. Loop precondition.
+ ICmpInst::Predicate Pred;
+ const SCEV *OverflowLimit = getOverflowLimitForStep(Step, &Pred, SE);
+
+ if (OverflowLimit &&
+ SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit)) {
+ return PreStart;
+ }
+ return 0;
+}
+
+// Get the normalized sign-extended expression for this AddRec's Start.
+static const SCEV *getSignExtendAddRecStart(const SCEVAddRecExpr *AR,
+ Type *Ty,
+ ScalarEvolution *SE) {
+ const SCEV *PreStart = getPreStartForSignExtend(AR, Ty, SE);
+ if (!PreStart)
+ return SE->getSignExtendExpr(AR->getStart(), Ty);
+
+ return SE->getAddExpr(SE->getSignExtendExpr(AR->getStepRecurrence(*SE), Ty),
+ SE->getSignExtendExpr(PreStart, Ty));
+}
+
const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
- const Type *Ty) {
+ Type *Ty) {
assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&
"This is not an extending conversion!");
assert(isSCEVable(Ty) &&
Ty = getEffectiveSCEVType(Ty);
// Fold if the operand is constant.
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) {
- const Type *IntTy = getEffectiveSCEVType(Ty);
- Constant *C = ConstantExpr::getSExt(SC->getValue(), IntTy);
- if (IntTy != Ty) C = ConstantExpr::getIntToPtr(C, Ty);
- return getConstant(cast<ConstantInt>(C));
- }
+ if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
+ return getConstant(
+ cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(),
+ getEffectiveSCEVType(Ty))));
// sext(sext(x)) --> sext(x)
if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
return getSignExtendExpr(SS->getOperand(), Ty);
+ // sext(zext(x)) --> zext(x)
+ if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
+ return getZeroExtendExpr(SZ->getOperand(), Ty);
+
// Before doing any expensive analysis, check to see if we've already
// computed a SCEV for this Op and Ty.
FoldingSetNodeID ID;
void *IP = 0;
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
+ // If the input value is provably positive, build a zext instead.
+ if (isKnownNonNegative(Op))
+ return getZeroExtendExpr(Op, Ty);
+
+ // sext(trunc(x)) --> sext(x) or x or trunc(x)
+ if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
+ // It's possible the bits taken off by the truncate were all sign bits. If
+ // so, we should be able to simplify this further.
+ const SCEV *X = ST->getOperand();
+ ConstantRange CR = getSignedRange(X);
+ unsigned TruncBits = getTypeSizeInBits(ST->getType());
+ unsigned NewBits = getTypeSizeInBits(Ty);
+ if (CR.truncate(TruncBits).signExtend(NewBits).contains(
+ CR.sextOrTrunc(NewBits)))
+ return getTruncateOrSignExtend(X, Ty);
+ }
+
// 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 allows analysis of something like
// If we have special knowledge that this addrec won't overflow,
// we don't need to do any further analysis.
- if (AR->hasNoSignedWrap())
- return getAddRecExpr(getSignExtendExpr(Start, Ty),
+ if (AR->getNoWrapFlags(SCEV::FlagNSW))
+ return getAddRecExpr(getSignExtendAddRecStart(AR, Ty, this),
getSignExtendExpr(Step, Ty),
- L);
+ L, SCEV::FlagNSW);
// Check whether the backedge-taken count is SCEVCouldNotCompute.
// Note that this serves two purposes: It filters out loops that are
const SCEV *RecastedMaxBECount =
getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
if (MaxBECount == RecastedMaxBECount) {
- const Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
+ Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
// Check whether Start+Step*MaxBECount has no signed overflow.
const SCEV *SMul = getMulExpr(CastedMaxBECount, Step);
const SCEV *Add = getAddExpr(Start, SMul);
getAddExpr(getSignExtendExpr(Start, WideTy),
getMulExpr(getZeroExtendExpr(CastedMaxBECount, WideTy),
getSignExtendExpr(Step, WideTy)));
- if (getSignExtendExpr(Add, WideTy) == OperandExtendedAdd)
+ if (getSignExtendExpr(Add, WideTy) == OperandExtendedAdd) {
+ // Cache knowledge of AR NSW, which is propagated to this AddRec.
+ const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
// Return the expression with the addrec on the outside.
- return getAddRecExpr(getSignExtendExpr(Start, Ty),
+ return getAddRecExpr(getSignExtendAddRecStart(AR, Ty, this),
getSignExtendExpr(Step, Ty),
- L);
-
+ L, AR->getNoWrapFlags());
+ }
// Similar to above, only this time treat the step value as unsigned.
// This covers loops that count up with an unsigned step.
const SCEV *UMul = getMulExpr(CastedMaxBECount, Step);
getAddExpr(getSignExtendExpr(Start, WideTy),
getMulExpr(getZeroExtendExpr(CastedMaxBECount, WideTy),
getZeroExtendExpr(Step, WideTy)));
- if (getSignExtendExpr(Add, WideTy) == OperandExtendedAdd)
+ if (getSignExtendExpr(Add, WideTy) == OperandExtendedAdd) {
+ // Cache knowledge of AR NSW, which is propagated to this AddRec.
+ const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
// Return the expression with the addrec on the outside.
- return getAddRecExpr(getSignExtendExpr(Start, Ty),
+ return getAddRecExpr(getSignExtendAddRecStart(AR, Ty, this),
getZeroExtendExpr(Step, Ty),
- L);
+ L, AR->getNoWrapFlags());
+ }
}
// If the backedge is guarded by a comparison with the pre-inc value
// the addrec is safe. Also, if the entry is guarded by a comparison
// with the start value and the backedge is guarded by a comparison
// with the post-inc value, the addrec is safe.
- if (isKnownPositive(Step)) {
- const SCEV *N = getConstant(APInt::getSignedMinValue(BitWidth) -
- getSignedRange(Step).getSignedMax());
- if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SLT, AR, N) ||
- (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_SLT, Start, N) &&
- isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SLT,
- AR->getPostIncExpr(*this), N)))
- // Return the expression with the addrec on the outside.
- return getAddRecExpr(getSignExtendExpr(Start, Ty),
- getSignExtendExpr(Step, Ty),
- L);
- } else if (isKnownNegative(Step)) {
- const SCEV *N = getConstant(APInt::getSignedMaxValue(BitWidth) -
- getSignedRange(Step).getSignedMin());
- if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SGT, AR, N) ||
- (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_SGT, Start, N) &&
- isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SGT,
- AR->getPostIncExpr(*this), N)))
- // Return the expression with the addrec on the outside.
- return getAddRecExpr(getSignExtendExpr(Start, Ty),
- getSignExtendExpr(Step, Ty),
- L);
+ ICmpInst::Predicate Pred;
+ const SCEV *OverflowLimit = getOverflowLimitForStep(Step, &Pred, this);
+ if (OverflowLimit &&
+ (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
+ (isLoopEntryGuardedByCond(L, Pred, Start, OverflowLimit) &&
+ isLoopBackedgeGuardedByCond(L, Pred, AR->getPostIncExpr(*this),
+ OverflowLimit)))) {
+ // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec.
+ const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
+ return getAddRecExpr(getSignExtendAddRecStart(AR, Ty, this),
+ getSignExtendExpr(Step, Ty),
+ L, AR->getNoWrapFlags());
}
}
}
/// unspecified bits out to the given type.
///
const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
- const Type *Ty) {
+ Type *Ty) {
assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&
"This is not an extending conversion!");
assert(isSCEVable(Ty) &&
for (SCEVAddRecExpr::op_iterator I = AR->op_begin(), E = AR->op_end();
I != E; ++I)
Ops.push_back(getAnyExtendExpr(*I, Ty));
- return getAddRecExpr(Ops, AR->getLoop());
+ return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
}
+ // As a special case, fold anyext(undef) to undef. We don't want to
+ // know too much about SCEVUnknowns, but this special case is handy
+ // and harmless.
+ if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Op))
+ if (isa<UndefValue>(U->getValue()))
+ return getSCEV(UndefValue::get(Ty));
+
// If the expression is obviously signed, use the sext cast value.
if (isa<SCEVSMaxExpr>(Op))
return SExt;
ScalarEvolution &SE) {
bool Interesting = false;
- // Iterate over the add operands.
- for (unsigned i = 0, e = NumOperands; i != e; ++i) {
+ // Iterate over the add operands. They are sorted, with constants first.
+ unsigned i = 0;
+ while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
+ ++i;
+ // Pull a buried constant out to the outside.
+ if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
+ Interesting = true;
+ AccumulatedConstant += Scale * C->getValue()->getValue();
+ }
+
+ // Next comes everything else. We're especially interested in multiplies
+ // here, but they're in the middle, so just visit the rest with one loop.
+ for (; i != NumOperands; ++i) {
const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
APInt NewScale =
Interesting = true;
}
}
- } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
- // Pull a buried constant out to the outside.
- if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
- Interesting = true;
- AccumulatedConstant += Scale * C->getValue()->getValue();
} else {
// An ordinary operand. Update the map.
std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
/// getAddExpr - Get a canonical add expression, or something simpler if
/// possible.
const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
- bool HasNUW, bool HasNSW) {
+ SCEV::NoWrapFlags Flags) {
+ assert(!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&
+ "only nuw or nsw allowed");
assert(!Ops.empty() && "Cannot get empty add!");
if (Ops.size() == 1) return Ops[0];
#ifndef NDEBUG
+ Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
for (unsigned i = 1, e = Ops.size(); i != e; ++i)
- assert(getEffectiveSCEVType(Ops[i]->getType()) ==
- getEffectiveSCEVType(Ops[0]->getType()) &&
+ assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVAddExpr operand types don't match!");
#endif
- // If HasNSW is true and all the operands are non-negative, infer HasNUW.
- if (!HasNUW && HasNSW) {
+ // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
+ // And vice-versa.
+ int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
+ SCEV::NoWrapFlags SignOrUnsignWrap = maskFlags(Flags, SignOrUnsignMask);
+ if (SignOrUnsignWrap && (SignOrUnsignWrap != SignOrUnsignMask)) {
bool All = true;
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (!isKnownNonNegative(Ops[i])) {
+ for (SmallVectorImpl<const SCEV *>::const_iterator I = Ops.begin(),
+ E = Ops.end(); I != E; ++I)
+ if (!isKnownNonNegative(*I)) {
All = false;
break;
}
- if (All) HasNUW = true;
+ if (All) Flags = setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
}
// Sort by complexity, this groups all similar expression types together.
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.
- const Type *Ty = Ops[0]->getType();
- for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
+ // Okay, check to see if the same value occurs in the operand list more than
+ // once. If so, merge them together into an multiply expression. Since we
+ // sorted the list, these values are required to be adjacent.
+ Type *Ty = Ops[0]->getType();
+ bool FoundMatch = false;
+ for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
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.
- const SCEV *Two = getIntegerSCEV(2, Ty);
- const SCEV *Mul = getMulExpr(Ops[i], Two);
- if (Ops.size() == 2)
+ // Scan ahead to count how many equal operands there are.
+ unsigned Count = 2;
+ while (i+Count != e && Ops[i+Count] == Ops[i])
+ ++Count;
+ // Merge the values into a multiply.
+ const SCEV *Scale = getConstant(Ty, Count);
+ const SCEV *Mul = getMulExpr(Scale, Ops[i]);
+ if (Ops.size() == Count)
return Mul;
- Ops.erase(Ops.begin()+i, Ops.begin()+i+2);
- Ops.push_back(Mul);
- return getAddExpr(Ops, HasNUW, HasNSW);
+ Ops[i] = Mul;
+ Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
+ --i; e -= Count - 1;
+ FoundMatch = true;
}
+ if (FoundMatch)
+ return getAddExpr(Ops, Flags);
// Check for truncates. If all the operands are truncated from the same
// type, see if factoring out the truncate would permit the result to be
// if the contents of the resulting outer trunc fold to something simple.
for (; Idx < Ops.size() && isa<SCEVTruncateExpr>(Ops[Idx]); ++Idx) {
const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(Ops[Idx]);
- const Type *DstType = Trunc->getType();
- const Type *SrcType = Trunc->getOperand()->getType();
+ Type *DstType = Trunc->getType();
+ Type *SrcType = Trunc->getOperand()->getType();
SmallVector<const SCEV *, 8> LargeOps;
bool Ok = true;
// Check all the operands to see if they can be represented in the
}
LargeOps.push_back(T->getOperand());
} else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
- // This could be either sign or zero extension, but sign extension
- // is much more likely to be foldable here.
- LargeOps.push_back(getSignExtendExpr(C, SrcType));
+ LargeOps.push_back(getAnyExtendExpr(C, SrcType));
} else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
SmallVector<const SCEV *, 8> LargeMulOps;
for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
LargeMulOps.push_back(T->getOperand());
} else if (const SCEVConstant *C =
dyn_cast<SCEVConstant>(M->getOperand(j))) {
- // This could be either sign or zero extension, but sign extension
- // is much more likely to be foldable here.
- LargeMulOps.push_back(getSignExtendExpr(C, SrcType));
+ LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
} else {
Ok = false;
break;
}
if (Ok) {
// Evaluate the expression in the larger type.
- const SCEV *Fold = getAddExpr(LargeOps, HasNUW, HasNSW);
+ const SCEV *Fold = getAddExpr(LargeOps, Flags);
// If it folds to something simple, use it. Otherwise, don't.
if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
return getTruncateExpr(Fold, DstType);
while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
// If we have an add, expand the add operands onto the end of the operands
// list.
- Ops.insert(Ops.end(), Add->op_begin(), Add->op_end());
Ops.erase(Ops.begin()+Idx);
+ Ops.append(Add->op_begin(), Add->op_end());
DeletedAdd = true;
}
// re-generate the operands list. Group the operands by constant scale,
// to avoid multiplying by the same constant scale multiple times.
std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
- for (SmallVector<const SCEV *, 8>::iterator I = NewOps.begin(),
+ for (SmallVector<const SCEV *, 8>::const_iterator I = NewOps.begin(),
E = NewOps.end(); I != E; ++I)
MulOpLists[M.find(*I)->second].push_back(*I);
// Re-generate the operands list.
Ops.push_back(getMulExpr(getConstant(I->first),
getAddExpr(I->second)));
if (Ops.empty())
- return getIntegerSCEV(0, Ty);
+ return getConstant(Ty, 0);
if (Ops.size() == 1)
return Ops[0];
return getAddExpr(Ops);
const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
+ if (isa<SCEVConstant>(MulOpSCEV))
+ continue;
for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
- if (MulOpSCEV == Ops[AddOp] && !isa<SCEVConstant>(Ops[AddOp])) {
+ if (MulOpSCEV == Ops[AddOp]) {
// Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
if (Mul->getNumOperands() != 2) {
// If the multiply has more than two operands, we must get the
// Y*Z term.
- SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), Mul->op_end());
- MulOps.erase(MulOps.begin()+MulOp);
+ SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
+ Mul->op_begin()+MulOp);
+ MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
InnerMul = getMulExpr(MulOps);
}
- const SCEV *One = getIntegerSCEV(1, Ty);
- const SCEV *AddOne = getAddExpr(InnerMul, One);
- const SCEV *OuterMul = getMulExpr(AddOne, Ops[AddOp]);
+ const SCEV *One = getConstant(Ty, 1);
+ const SCEV *AddOne = getAddExpr(One, InnerMul);
+ const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV);
if (Ops.size() == 2) return OuterMul;
if (AddOp < Idx) {
Ops.erase(Ops.begin()+AddOp);
const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
if (Mul->getNumOperands() != 2) {
SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
- Mul->op_end());
- MulOps.erase(MulOps.begin()+MulOp);
+ Mul->op_begin()+MulOp);
+ MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
InnerMul1 = getMulExpr(MulOps);
}
const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
if (OtherMul->getNumOperands() != 2) {
SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
- OtherMul->op_end());
- MulOps.erase(MulOps.begin()+OMulOp);
+ OtherMul->op_begin()+OMulOp);
+ MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
InnerMul2 = getMulExpr(MulOps);
}
const SCEV *InnerMulSum = getAddExpr(InnerMul1,InnerMul2);
const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
const Loop *AddRecLoop = AddRec->getLoop();
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (Ops[i]->isLoopInvariant(AddRecLoop)) {
+ if (isLoopInvariant(Ops[i], AddRecLoop)) {
LIOps.push_back(Ops[i]);
Ops.erase(Ops.begin()+i);
--i; --e;
AddRec->op_end());
AddRecOps[0] = getAddExpr(LIOps);
- // It's tempting to propagate NUW/NSW flags here, but nuw/nsw addition
- // is not associative so this isn't necessarily safe.
- const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop);
+ // Build the new addrec. Propagate the NUW and NSW flags if both the
+ // outer add and the inner addrec are guaranteed to have no overflow.
+ // Always propagate NW.
+ Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
+ const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
// If all of the other operands were loop invariant, we are done.
if (Ops.size() == 1) return NewRec;
// there are multiple AddRec's with the same loop induction variable being
// added together. If so, we can fold them.
for (unsigned OtherIdx = Idx+1;
- OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);++OtherIdx)
- if (OtherIdx != Idx) {
- const SCEVAddRecExpr *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
- if (AddRecLoop == OtherAddRec->getLoop()) {
- // Other + {A,+,B} + {C,+,D} --> Other + {A+C,+,B+D}
- SmallVector<const SCEV *, 4> NewOps(AddRec->op_begin(),
- AddRec->op_end());
- for (unsigned i = 0, e = OtherAddRec->getNumOperands(); i != e; ++i) {
- if (i >= NewOps.size()) {
- NewOps.insert(NewOps.end(), OtherAddRec->op_begin()+i,
- OtherAddRec->op_end());
- break;
+ OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
+ ++OtherIdx)
+ if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
+ // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
+ SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
+ AddRec->op_end());
+ for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
+ ++OtherIdx)
+ if (const SCEVAddRecExpr *OtherAddRec =
+ dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]))
+ if (OtherAddRec->getLoop() == AddRecLoop) {
+ for (unsigned i = 0, e = OtherAddRec->getNumOperands();
+ i != e; ++i) {
+ if (i >= AddRecOps.size()) {
+ AddRecOps.append(OtherAddRec->op_begin()+i,
+ OtherAddRec->op_end());
+ break;
+ }
+ AddRecOps[i] = getAddExpr(AddRecOps[i],
+ OtherAddRec->getOperand(i));
+ }
+ Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
}
- NewOps[i] = getAddExpr(NewOps[i], OtherAddRec->getOperand(i));
- }
- const SCEV *NewAddRec = getAddRecExpr(NewOps, AddRecLoop);
-
- if (Ops.size() == 2) return NewAddRec;
-
- Ops.erase(Ops.begin()+Idx);
- Ops.erase(Ops.begin()+OtherIdx-1);
- Ops.push_back(NewAddRec);
- return getAddExpr(Ops);
- }
+ // Step size has changed, so we cannot guarantee no self-wraparound.
+ Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
+ return getAddExpr(Ops);
}
// Otherwise couldn't fold anything into this recurrence. Move onto the
// already have one, otherwise create a new one.
FoldingSetNodeID ID;
ID.AddInteger(scAddExpr);
- ID.AddInteger(Ops.size());
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
ID.AddPointer(Ops[i]);
void *IP = 0;
O, Ops.size());
UniqueSCEVs.InsertNode(S, IP);
}
- if (HasNUW) S->setHasNoUnsignedWrap(true);
- if (HasNSW) S->setHasNoSignedWrap(true);
+ S->setNoWrapFlags(Flags);
return S;
}
/// getMulExpr - Get a canonical multiply expression, or something simpler if
/// possible.
const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
- bool HasNUW, bool HasNSW) {
+ SCEV::NoWrapFlags Flags) {
+ assert(Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&
+ "only nuw or nsw allowed");
assert(!Ops.empty() && "Cannot get empty mul!");
if (Ops.size() == 1) return Ops[0];
#ifndef NDEBUG
+ Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
for (unsigned i = 1, e = Ops.size(); i != e; ++i)
- assert(getEffectiveSCEVType(Ops[i]->getType()) ==
- getEffectiveSCEVType(Ops[0]->getType()) &&
+ assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVMulExpr operand types don't match!");
#endif
- // If HasNSW is true and all the operands are non-negative, infer HasNUW.
- if (!HasNUW && HasNSW) {
+ // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
+ // And vice-versa.
+ int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
+ SCEV::NoWrapFlags SignOrUnsignWrap = maskFlags(Flags, SignOrUnsignMask);
+ if (SignOrUnsignWrap && (SignOrUnsignWrap != SignOrUnsignMask)) {
bool All = true;
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (!isKnownNonNegative(Ops[i])) {
+ for (SmallVectorImpl<const SCEV *>::const_iterator I = Ops.begin(),
+ E = Ops.end(); I != E; ++I)
+ if (!isKnownNonNegative(*I)) {
All = false;
break;
}
- if (All) HasNUW = true;
+ if (All) Flags = setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
}
// Sort by complexity, this groups all similar expression types together.
} else if (Ops[0]->isAllOnesValue()) {
// If we have a mul by -1 of an add, try distributing the -1 among the
// add operands.
- if (Ops.size() == 2)
+ if (Ops.size() == 2) {
if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
SmallVector<const SCEV *, 4> NewOps;
bool AnyFolded = false;
- for (SCEVAddRecExpr::op_iterator I = Add->op_begin(), E = Add->op_end();
- I != E; ++I) {
+ for (SCEVAddRecExpr::op_iterator I = Add->op_begin(),
+ E = Add->op_end(); I != E; ++I) {
const SCEV *Mul = getMulExpr(Ops[0], *I);
if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
NewOps.push_back(Mul);
if (AnyFolded)
return getAddExpr(NewOps);
}
+ else if (const SCEVAddRecExpr *
+ AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
+ // Negation preserves a recurrence's no self-wrap property.
+ SmallVector<const SCEV *, 4> Operands;
+ for (SCEVAddRecExpr::op_iterator I = AddRec->op_begin(),
+ E = AddRec->op_end(); I != E; ++I) {
+ Operands.push_back(getMulExpr(Ops[0], *I));
+ }
+ return getAddRecExpr(Operands, AddRec->getLoop(),
+ AddRec->getNoWrapFlags(SCEV::FlagNW));
+ }
+ }
}
if (Ops.size() == 1)
while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
// If we have an mul, expand the mul operands onto the end of the operands
// list.
- Ops.insert(Ops.end(), Mul->op_begin(), Mul->op_end());
Ops.erase(Ops.begin()+Idx);
+ Ops.append(Mul->op_begin(), Mul->op_end());
DeletedMul = true;
}
// they are loop invariant w.r.t. the recurrence.
SmallVector<const SCEV *, 8> LIOps;
const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
+ const Loop *AddRecLoop = AddRec->getLoop();
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (Ops[i]->isLoopInvariant(AddRec->getLoop())) {
+ if (isLoopInvariant(Ops[i], AddRecLoop)) {
LIOps.push_back(Ops[i]);
Ops.erase(Ops.begin()+i);
--i; --e;
// NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
SmallVector<const SCEV *, 4> NewOps;
NewOps.reserve(AddRec->getNumOperands());
- if (LIOps.size() == 1) {
- const SCEV *Scale = LIOps[0];
- for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
- NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i)));
- } else {
- for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
- SmallVector<const SCEV *, 4> MulOps(LIOps.begin(), LIOps.end());
- MulOps.push_back(AddRec->getOperand(i));
- NewOps.push_back(getMulExpr(MulOps));
- }
- }
-
- // It's tempting to propagate the NSW flag here, but nsw multiplication
- // is not associative so this isn't necessarily safe.
- const SCEV *NewRec = getAddRecExpr(NewOps, AddRec->getLoop(),
- HasNUW && AddRec->hasNoUnsignedWrap(),
- /*HasNSW=*/false);
+ const SCEV *Scale = getMulExpr(LIOps);
+ for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
+ NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i)));
+
+ // Build the new addrec. Propagate the NUW and NSW flags if both the
+ // outer mul and the inner addrec are guaranteed to have no overflow.
+ //
+ // No self-wrap cannot be guaranteed after changing the step size, but
+ // will be inferred if either NUW or NSW is true.
+ Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW));
+ const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags);
// If all of the other operands were loop invariant, we are done.
if (Ops.size() == 1) return NewRec;
// there are multiple AddRec's with the same loop induction variable being
// multiplied together. If so, we can fold them.
for (unsigned OtherIdx = Idx+1;
- OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);++OtherIdx)
- if (OtherIdx != Idx) {
- const SCEVAddRecExpr *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
- if (AddRec->getLoop() == OtherAddRec->getLoop()) {
- // F * G --> {A,+,B} * {C,+,D} --> {A*C,+,F*D + G*B + B*D}
- const SCEVAddRecExpr *F = AddRec, *G = OtherAddRec;
- const SCEV *NewStart = getMulExpr(F->getStart(),
- G->getStart());
- const SCEV *B = F->getStepRecurrence(*this);
- const SCEV *D = G->getStepRecurrence(*this);
- const SCEV *NewStep = getAddExpr(getMulExpr(F, D),
- getMulExpr(G, B),
- getMulExpr(B, D));
- const SCEV *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 getMulExpr(Ops);
- }
+ OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
+ ++OtherIdx)
+ if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
+ // F * G, where F = {A,+,B}<L> and G = {C,+,D}<L> -->
+ // {A*C,+,F*D + G*B + B*D}<L>
+ for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
+ ++OtherIdx)
+ if (const SCEVAddRecExpr *OtherAddRec =
+ dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]))
+ if (OtherAddRec->getLoop() == AddRecLoop) {
+ const SCEVAddRecExpr *F = AddRec, *G = OtherAddRec;
+ const SCEV *NewStart = getMulExpr(F->getStart(), G->getStart());
+ const SCEV *B = F->getStepRecurrence(*this);
+ const SCEV *D = G->getStepRecurrence(*this);
+ const SCEV *NewStep = getAddExpr(getMulExpr(F, D),
+ getMulExpr(G, B),
+ getMulExpr(B, D));
+ const SCEV *NewAddRec = getAddRecExpr(NewStart, NewStep,
+ F->getLoop(),
+ SCEV::FlagAnyWrap);
+ if (Ops.size() == 2) return NewAddRec;
+ Ops[Idx] = AddRec = cast<SCEVAddRecExpr>(NewAddRec);
+ Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
+ }
+ return getMulExpr(Ops);
}
// Otherwise couldn't fold anything into this recurrence. Move onto the
// already have one, otherwise create a new one.
FoldingSetNodeID ID;
ID.AddInteger(scMulExpr);
- ID.AddInteger(Ops.size());
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
ID.AddPointer(Ops[i]);
void *IP = 0;
O, Ops.size());
UniqueSCEVs.InsertNode(S, IP);
}
- if (HasNUW) S->setHasNoUnsignedWrap(true);
- if (HasNSW) S->setHasNoSignedWrap(true);
+ S->setNoWrapFlags(Flags);
return S;
}
if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
if (RHSC->getValue()->equalsInt(1))
return LHS; // X udiv 1 --> x
- if (RHSC->getValue()->isZero())
- return getIntegerSCEV(0, LHS->getType()); // value is undefined
-
- // Determine if the division can be folded into the operands of
- // its operands.
- // TODO: Generalize this to non-constants by using known-bits information.
- const Type *Ty = LHS->getType();
- unsigned LZ = RHSC->getValue()->getValue().countLeadingZeros();
- unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ;
- // For non-power-of-two values, effectively round the value up to the
- // nearest power of two.
- if (!RHSC->getValue()->getValue().isPowerOf2())
- ++MaxShiftAmt;
- const IntegerType *ExtTy =
- IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
- // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
- if (const SCEVConstant *Step =
- dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this)))
- if (!Step->getValue()->getValue()
- .urem(RHSC->getValue()->getValue()) &&
- getZeroExtendExpr(AR, ExtTy) ==
- getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
- getZeroExtendExpr(Step, ExtTy),
- AR->getLoop())) {
- SmallVector<const SCEV *, 4> Operands;
- for (unsigned i = 0, e = AR->getNumOperands(); i != e; ++i)
- Operands.push_back(getUDivExpr(AR->getOperand(i), RHS));
- return getAddRecExpr(Operands, AR->getLoop());
- }
- // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
- if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
- SmallVector<const SCEV *, 4> Operands;
- for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i)
- Operands.push_back(getZeroExtendExpr(M->getOperand(i), ExtTy));
- if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
- // Find an operand that's safely divisible.
- for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
- const SCEV *Op = M->getOperand(i);
- const SCEV *Div = getUDivExpr(Op, RHSC);
- if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
- Operands = SmallVector<const SCEV *, 4>(M->op_begin(), M->op_end());
- Operands[i] = Div;
- return getMulExpr(Operands);
+ // If the denominator is zero, the result of the udiv is undefined. Don't
+ // try to analyze it, because the resolution chosen here may differ from
+ // the resolution chosen in other parts of the compiler.
+ if (!RHSC->getValue()->isZero()) {
+ // Determine if the division can be folded into the operands of
+ // its operands.
+ // TODO: Generalize this to non-constants by using known-bits information.
+ Type *Ty = LHS->getType();
+ unsigned LZ = RHSC->getValue()->getValue().countLeadingZeros();
+ unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
+ // For non-power-of-two values, effectively round the value up to the
+ // nearest power of two.
+ if (!RHSC->getValue()->getValue().isPowerOf2())
+ ++MaxShiftAmt;
+ IntegerType *ExtTy =
+ IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
+ // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
+ if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
+ if (const SCEVConstant *Step =
+ dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this)))
+ if (!Step->getValue()->getValue()
+ .urem(RHSC->getValue()->getValue()) &&
+ getZeroExtendExpr(AR, ExtTy) ==
+ getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
+ getZeroExtendExpr(Step, ExtTy),
+ AR->getLoop(), SCEV::FlagAnyWrap)) {
+ SmallVector<const SCEV *, 4> Operands;
+ for (unsigned i = 0, e = AR->getNumOperands(); i != e; ++i)
+ Operands.push_back(getUDivExpr(AR->getOperand(i), RHS));
+ return getAddRecExpr(Operands, AR->getLoop(),
+ SCEV::FlagNW);
}
+ // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
+ if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
+ SmallVector<const SCEV *, 4> Operands;
+ for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i)
+ Operands.push_back(getZeroExtendExpr(M->getOperand(i), ExtTy));
+ if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
+ // Find an operand that's safely divisible.
+ for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
+ const SCEV *Op = M->getOperand(i);
+ const SCEV *Div = getUDivExpr(Op, RHSC);
+ if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
+ Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
+ M->op_end());
+ Operands[i] = Div;
+ return getMulExpr(Operands);
+ }
+ }
+ }
+ // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
+ if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
+ SmallVector<const SCEV *, 4> Operands;
+ for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i)
+ Operands.push_back(getZeroExtendExpr(A->getOperand(i), ExtTy));
+ if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
+ Operands.clear();
+ for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
+ const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
+ if (isa<SCEVUDivExpr>(Op) ||
+ getMulExpr(Op, RHS) != A->getOperand(i))
+ break;
+ Operands.push_back(Op);
+ }
+ if (Operands.size() == A->getNumOperands())
+ return getAddExpr(Operands);
}
- }
- // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
- if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(LHS)) {
- SmallVector<const SCEV *, 4> Operands;
- for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i)
- Operands.push_back(getZeroExtendExpr(A->getOperand(i), ExtTy));
- if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
- Operands.clear();
- for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
- const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
- if (isa<SCEVUDivExpr>(Op) || getMulExpr(Op, RHS) != A->getOperand(i))
- break;
- Operands.push_back(Op);
- }
- if (Operands.size() == A->getNumOperands())
- return getAddExpr(Operands);
}
- }
- // Fold if both operands are constant.
- if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
- Constant *LHSCV = LHSC->getValue();
- Constant *RHSCV = RHSC->getValue();
- return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
- RHSCV)));
+ // Fold if both operands are constant.
+ if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
+ Constant *LHSCV = LHSC->getValue();
+ Constant *RHSCV = RHSC->getValue();
+ return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
+ RHSCV)));
+ }
}
}
/// getAddRecExpr - Get an add recurrence expression for the specified loop.
/// Simplify the expression as much as possible.
-const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start,
- const SCEV *Step, const Loop *L,
- bool HasNUW, bool HasNSW) {
+const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
+ const Loop *L,
+ SCEV::NoWrapFlags Flags) {
SmallVector<const SCEV *, 4> Operands;
Operands.push_back(Start);
if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
if (StepChrec->getLoop() == L) {
- Operands.insert(Operands.end(), StepChrec->op_begin(),
- StepChrec->op_end());
- return getAddRecExpr(Operands, L);
+ Operands.append(StepChrec->op_begin(), StepChrec->op_end());
+ return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
}
Operands.push_back(Step);
- return getAddRecExpr(Operands, L, HasNUW, HasNSW);
+ return getAddRecExpr(Operands, L, Flags);
}
/// getAddRecExpr - Get an add recurrence expression for the specified loop.
/// Simplify the expression as much as possible.
const SCEV *
ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
- const Loop *L,
- bool HasNUW, bool HasNSW) {
+ const Loop *L, SCEV::NoWrapFlags Flags) {
if (Operands.size() == 1) return Operands[0];
#ifndef NDEBUG
+ Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
for (unsigned i = 1, e = Operands.size(); i != e; ++i)
- assert(getEffectiveSCEVType(Operands[i]->getType()) ==
- getEffectiveSCEVType(Operands[0]->getType()) &&
+ assert(getEffectiveSCEVType(Operands[i]->getType()) == ETy &&
"SCEVAddRecExpr operand types don't match!");
+ for (unsigned i = 0, e = Operands.size(); i != e; ++i)
+ assert(isLoopInvariant(Operands[i], L) &&
+ "SCEVAddRecExpr operand is not loop-invariant!");
#endif
if (Operands.back()->isZero()) {
Operands.pop_back();
- return getAddRecExpr(Operands, L, HasNUW, HasNSW); // {X,+,0} --> X
+ return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
}
// It's tempting to want to call getMaxBackedgeTakenCount count here and
// meaningful BE count at this point (and if we don't, we'd be stuck
// with a SCEVCouldNotCompute as the cached BE count).
- // If HasNSW is true and all the operands are non-negative, infer HasNUW.
- if (!HasNUW && HasNSW) {
+ // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
+ // And vice-versa.
+ int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
+ SCEV::NoWrapFlags SignOrUnsignWrap = maskFlags(Flags, SignOrUnsignMask);
+ if (SignOrUnsignWrap && (SignOrUnsignWrap != SignOrUnsignMask)) {
bool All = true;
- for (unsigned i = 0, e = Operands.size(); i != e; ++i)
- if (!isKnownNonNegative(Operands[i])) {
+ for (SmallVectorImpl<const SCEV *>::const_iterator I = Operands.begin(),
+ E = Operands.end(); I != E; ++I)
+ if (!isKnownNonNegative(*I)) {
All = false;
break;
}
- if (All) HasNUW = true;
+ if (All) Flags = setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
}
// Canonicalize nested AddRecs in by nesting them in order of loop depth.
if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
const Loop *NestedLoop = NestedAR->getLoop();
- if (L->contains(NestedLoop->getHeader()) ?
+ if (L->contains(NestedLoop) ?
(L->getLoopDepth() < NestedLoop->getLoopDepth()) :
- (!NestedLoop->contains(L->getHeader()) &&
+ (!NestedLoop->contains(L) &&
DT->dominates(L->getHeader(), NestedLoop->getHeader()))) {
SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(),
NestedAR->op_end());
// requirement.
bool AllInvariant = true;
for (unsigned i = 0, e = Operands.size(); i != e; ++i)
- if (!Operands[i]->isLoopInvariant(L)) {
+ if (!isLoopInvariant(Operands[i], L)) {
AllInvariant = false;
break;
}
if (AllInvariant) {
- NestedOperands[0] = getAddRecExpr(Operands, L);
+ // Create a recurrence for the outer loop with the same step size.
+ //
+ // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
+ // inner recurrence has the same property.
+ SCEV::NoWrapFlags OuterFlags =
+ maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
+
+ NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
AllInvariant = true;
for (unsigned i = 0, e = NestedOperands.size(); i != e; ++i)
- if (!NestedOperands[i]->isLoopInvariant(NestedLoop)) {
+ if (!isLoopInvariant(NestedOperands[i], NestedLoop)) {
AllInvariant = false;
break;
}
- if (AllInvariant)
+ if (AllInvariant) {
// Ok, both add recurrences are valid after the transformation.
- return getAddRecExpr(NestedOperands, NestedLoop, HasNUW, HasNSW);
+ //
+ // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
+ // the outer recurrence has the same property.
+ SCEV::NoWrapFlags InnerFlags =
+ maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
+ return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
+ }
}
// Reset Operands to its original state.
Operands[0] = NestedAR;
// already have one, otherwise create a new one.
FoldingSetNodeID ID;
ID.AddInteger(scAddRecExpr);
- ID.AddInteger(Operands.size());
for (unsigned i = 0, e = Operands.size(); i != e; ++i)
ID.AddPointer(Operands[i]);
ID.AddPointer(L);
O, Operands.size(), L);
UniqueSCEVs.InsertNode(S, IP);
}
- if (HasNUW) S->setHasNoUnsignedWrap(true);
- if (HasNSW) S->setHasNoSignedWrap(true);
+ S->setNoWrapFlags(Flags);
return S;
}
assert(!Ops.empty() && "Cannot get empty smax!");
if (Ops.size() == 1) return Ops[0];
#ifndef NDEBUG
+ Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
for (unsigned i = 1, e = Ops.size(); i != e; ++i)
- assert(getEffectiveSCEVType(Ops[i]->getType()) ==
- getEffectiveSCEVType(Ops[0]->getType()) &&
+ assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVSMaxExpr operand types don't match!");
#endif
if (Idx < Ops.size()) {
bool DeletedSMax = false;
while (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(Ops[Idx])) {
- Ops.insert(Ops.end(), SMax->op_begin(), SMax->op_end());
Ops.erase(Ops.begin()+Idx);
+ Ops.append(SMax->op_begin(), SMax->op_end());
DeletedSMax = true;
}
// already have one, otherwise create a new one.
FoldingSetNodeID ID;
ID.AddInteger(scSMaxExpr);
- ID.AddInteger(Ops.size());
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
ID.AddPointer(Ops[i]);
void *IP = 0;
assert(!Ops.empty() && "Cannot get empty umax!");
if (Ops.size() == 1) return Ops[0];
#ifndef NDEBUG
+ Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
for (unsigned i = 1, e = Ops.size(); i != e; ++i)
- assert(getEffectiveSCEVType(Ops[i]->getType()) ==
- getEffectiveSCEVType(Ops[0]->getType()) &&
+ assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVUMaxExpr operand types don't match!");
#endif
if (Idx < Ops.size()) {
bool DeletedUMax = false;
while (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(Ops[Idx])) {
- Ops.insert(Ops.end(), UMax->op_begin(), UMax->op_end());
Ops.erase(Ops.begin()+Idx);
+ Ops.append(UMax->op_begin(), UMax->op_end());
DeletedUMax = true;
}
// already have one, otherwise create a new one.
FoldingSetNodeID ID;
ID.AddInteger(scUMaxExpr);
- ID.AddInteger(Ops.size());
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
ID.AddPointer(Ops[i]);
void *IP = 0;
return getNotSCEV(getUMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
}
-const SCEV *ScalarEvolution::getSizeOfExpr(const Type *AllocTy) {
+const SCEV *ScalarEvolution::getSizeOfExpr(Type *AllocTy) {
// If we have TargetData, we can bypass creating a target-independent
// constant expression and then folding it back into a ConstantInt.
// This is just a compile-time optimization.
Constant *C = ConstantExpr::getSizeOf(AllocTy);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
- C = ConstantFoldConstantExpression(CE, TD);
- const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(AllocTy));
+ if (Constant *Folded = ConstantFoldConstantExpression(CE, TD))
+ C = Folded;
+ Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(AllocTy));
return getTruncateOrZeroExtend(getSCEV(C), Ty);
}
-const SCEV *ScalarEvolution::getAlignOfExpr(const Type *AllocTy) {
+const SCEV *ScalarEvolution::getAlignOfExpr(Type *AllocTy) {
Constant *C = ConstantExpr::getAlignOf(AllocTy);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
- C = ConstantFoldConstantExpression(CE, TD);
- const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(AllocTy));
+ if (Constant *Folded = ConstantFoldConstantExpression(CE, TD))
+ C = Folded;
+ Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(AllocTy));
return getTruncateOrZeroExtend(getSCEV(C), Ty);
}
-const SCEV *ScalarEvolution::getOffsetOfExpr(const StructType *STy,
+const SCEV *ScalarEvolution::getOffsetOfExpr(StructType *STy,
unsigned FieldNo) {
// If we have TargetData, we can bypass creating a target-independent
// constant expression and then folding it back into a ConstantInt.
Constant *C = ConstantExpr::getOffsetOf(STy, FieldNo);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
- C = ConstantFoldConstantExpression(CE, TD);
- const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(STy));
+ if (Constant *Folded = ConstantFoldConstantExpression(CE, TD))
+ C = Folded;
+ Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(STy));
return getTruncateOrZeroExtend(getSCEV(C), Ty);
}
-const SCEV *ScalarEvolution::getOffsetOfExpr(const Type *CTy,
+const SCEV *ScalarEvolution::getOffsetOfExpr(Type *CTy,
Constant *FieldNo) {
Constant *C = ConstantExpr::getOffsetOf(CTy, FieldNo);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
- C = ConstantFoldConstantExpression(CE, TD);
- const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(CTy));
+ if (Constant *Folded = ConstantFoldConstantExpression(CE, TD))
+ C = Folded;
+ Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(CTy));
return getTruncateOrZeroExtend(getSCEV(C), Ty);
}
ID.AddInteger(scUnknown);
ID.AddPointer(V);
void *IP = 0;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
- SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V);
+ if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
+ assert(cast<SCEVUnknown>(S)->getValue() == V &&
+ "Stale SCEVUnknown in uniquing map!");
+ return S;
+ }
+ SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
+ FirstUnknown);
+ FirstUnknown = cast<SCEVUnknown>(S);
UniqueSCEVs.InsertNode(S, IP);
return S;
}
/// the SCEV framework. This primarily includes integer types, and it
/// can optionally include pointer types if the ScalarEvolution class
/// has access to target-specific information.
-bool ScalarEvolution::isSCEVable(const Type *Ty) const {
+bool ScalarEvolution::isSCEVable(Type *Ty) const {
// Integers and pointers are always SCEVable.
return Ty->isIntegerTy() || Ty->isPointerTy();
}
/// getTypeSizeInBits - Return the size in bits of the specified type,
/// for which isSCEVable must return true.
-uint64_t ScalarEvolution::getTypeSizeInBits(const Type *Ty) const {
+uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
assert(isSCEVable(Ty) && "Type is not SCEVable!");
// If we have a TargetData, use it!
/// the given type and which represents how SCEV will treat the given
/// type, for which isSCEVable must return true. For pointer types,
/// this is the pointer-sized integer type.
-const Type *ScalarEvolution::getEffectiveSCEVType(const Type *Ty) const {
+Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
assert(isSCEVable(Ty) && "Type is not SCEVable!");
if (Ty->isIntegerTy())
const SCEV *ScalarEvolution::getSCEV(Value *V) {
assert(isSCEVable(V->getType()) && "Value is not SCEVable!");
- std::map<SCEVCallbackVH, const SCEV *>::iterator I = Scalars.find(V);
- if (I != Scalars.end()) return I->second;
+ ValueExprMapType::const_iterator I = ValueExprMap.find(V);
+ if (I != ValueExprMap.end()) return I->second;
const SCEV *S = createSCEV(V);
- Scalars.insert(std::make_pair(SCEVCallbackVH(V, this), S));
- return S;
-}
-/// getIntegerSCEV - Given a SCEVable type, create a constant for the
-/// specified signed integer value and return a SCEV for the constant.
-const SCEV *ScalarEvolution::getIntegerSCEV(int64_t Val, const Type *Ty) {
- const IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
- return getConstant(ConstantInt::get(ITy, Val));
+ // The process of creating a SCEV for V may have caused other SCEVs
+ // to have been created, so it's necessary to insert the new entry
+ // from scratch, rather than trying to remember the insert position
+ // above.
+ ValueExprMap.insert(std::make_pair(SCEVCallbackVH(V, this), S));
+ return S;
}
/// getNegativeSCEV - Return a SCEV corresponding to -V = -1*V
return getConstant(
cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
- const Type *Ty = V->getType();
+ Type *Ty = V->getType();
Ty = getEffectiveSCEVType(Ty);
return getMulExpr(V,
getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))));
return getConstant(
cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
- const Type *Ty = V->getType();
+ Type *Ty = V->getType();
Ty = getEffectiveSCEVType(Ty);
const SCEV *AllOnes =
getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)));
return getMinusSCEV(AllOnes, V);
}
-/// getMinusSCEV - Return a SCEV corresponding to LHS - RHS.
-///
-const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS,
- const SCEV *RHS) {
+/// getMinusSCEV - Return LHS-RHS. Minus is represented in SCEV as A+B*-1.
+const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
+ SCEV::NoWrapFlags Flags) {
+ assert(!maskFlags(Flags, SCEV::FlagNUW) && "subtraction does not have NUW");
+
+ // Fast path: X - X --> 0.
+ if (LHS == RHS)
+ return getConstant(LHS->getType(), 0);
+
// X - Y --> X + -Y
- return getAddExpr(LHS, getNegativeSCEV(RHS));
+ return getAddExpr(LHS, getNegativeSCEV(RHS), Flags);
}
/// 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.
const SCEV *
-ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V,
- const Type *Ty) {
- const Type *SrcTy = V->getType();
+ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty) {
+ Type *SrcTy = V->getType();
assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) &&
"Cannot truncate or zero extend with non-integer arguments!");
/// extended.
const SCEV *
ScalarEvolution::getTruncateOrSignExtend(const SCEV *V,
- const Type *Ty) {
- const Type *SrcTy = V->getType();
+ Type *Ty) {
+ Type *SrcTy = V->getType();
assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) &&
"Cannot truncate or zero extend with non-integer arguments!");
/// input value to the specified type. If the type must be extended, it is zero
/// extended. The conversion must not be narrowing.
const SCEV *
-ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, const Type *Ty) {
- const Type *SrcTy = V->getType();
+ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
+ Type *SrcTy = V->getType();
assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) &&
"Cannot noop or zero extend with non-integer arguments!");
/// input value to the specified type. If the type must be extended, it is sign
/// extended. The conversion must not be narrowing.
const SCEV *
-ScalarEvolution::getNoopOrSignExtend(const SCEV *V, const Type *Ty) {
- const Type *SrcTy = V->getType();
+ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
+ Type *SrcTy = V->getType();
assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) &&
"Cannot noop or sign extend with non-integer arguments!");
/// it is extended with unspecified bits. The conversion must not be
/// narrowing.
const SCEV *
-ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, const Type *Ty) {
- const Type *SrcTy = V->getType();
+ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
+ Type *SrcTy = V->getType();
assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) &&
"Cannot noop or any extend with non-integer arguments!");
/// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
/// input value to the specified type. The conversion must not be widening.
const SCEV *
-ScalarEvolution::getTruncateOrNoop(const SCEV *V, const Type *Ty) {
- const Type *SrcTy = V->getType();
+ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
+ Type *SrcTy = V->getType();
assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) &&
"Cannot truncate or noop with non-integer arguments!");
return getUMinExpr(PromotedLHS, PromotedRHS);
}
+/// getPointerBase - Transitively follow the chain of pointer-type operands
+/// until reaching a SCEV that does not have a single pointer operand. This
+/// returns a SCEVUnknown pointer for well-formed pointer-type expressions,
+/// but corner cases do exist.
+const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
+ // A pointer operand may evaluate to a nonpointer expression, such as null.
+ if (!V->getType()->isPointerTy())
+ return V;
+
+ if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) {
+ return getPointerBase(Cast->getOperand());
+ }
+ else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) {
+ const SCEV *PtrOp = 0;
+ for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
+ I != E; ++I) {
+ if ((*I)->getType()->isPointerTy()) {
+ // Cannot find the base of an expression with multiple pointer operands.
+ if (PtrOp)
+ return V;
+ PtrOp = *I;
+ }
+ }
+ if (!PtrOp)
+ return V;
+ return getPointerBase(PtrOp);
+ }
+ return V;
+}
+
/// PushDefUseChildren - Push users of the given Instruction
/// onto the given Worklist.
static void
// Push the def-use children onto the Worklist stack.
for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
UI != UE; ++UI)
- Worklist.push_back(cast<Instruction>(UI));
+ Worklist.push_back(cast<Instruction>(*UI));
}
/// ForgetSymbolicValue - This looks up computed SCEV values for all
/// instructions that depend on the given instruction and removes them from
-/// the Scalars map if they reference SymName. This is used during PHI
+/// the ValueExprMapType map if they reference SymName. This is used during PHI
/// resolution.
void
ScalarEvolution::ForgetSymbolicName(Instruction *PN, const SCEV *SymName) {
Instruction *I = Worklist.pop_back_val();
if (!Visited.insert(I)) continue;
- std::map<SCEVCallbackVH, const SCEV *>::iterator It =
- Scalars.find(static_cast<Value *>(I));
- if (It != Scalars.end()) {
+ ValueExprMapType::iterator It =
+ ValueExprMap.find(static_cast<Value *>(I));
+ if (It != ValueExprMap.end()) {
+ const SCEV *Old = It->second;
+
// Short-circuit the def-use traversal if the symbolic name
// ceases to appear in expressions.
- if (It->second != SymName && !It->second->hasOperand(SymName))
+ if (Old != SymName && !hasOperand(Old, SymName))
continue;
// SCEVUnknown for a PHI either means that it has an unrecognized
// updates on its own when it gets to that point. In the third, we do
// want to forget the SCEVUnknown.
if (!isa<PHINode>(I) ||
- !isa<SCEVUnknown>(It->second) ||
- (I != PN && It->second == SymName)) {
- ValuesAtScopes.erase(It->second);
- Scalars.erase(It);
+ !isa<SCEVUnknown>(Old) ||
+ (I != PN && Old == SymName)) {
+ forgetMemoizedResults(Old);
+ ValueExprMap.erase(It);
}
}
if (BEValueV && StartValueV) {
// While we are analyzing this PHI node, handle its value symbolically.
const SCEV *SymbolicName = getUnknown(PN);
- assert(Scalars.find(PN) == Scalars.end() &&
+ assert(ValueExprMap.find(PN) == ValueExprMap.end() &&
"PHI node already processed?");
- Scalars.insert(std::make_pair(SCEVCallbackVH(PN, this), SymbolicName));
+ ValueExprMap.insert(std::make_pair(SCEVCallbackVH(PN, this), SymbolicName));
// Using this symbolic name for the PHI, analyze the value coming around
// the back-edge.
// This is not a valid addrec if the step amount is varying each
// loop iteration, but is not itself an addrec in this loop.
- if (Accum->isLoopInvariant(L) ||
+ if (isLoopInvariant(Accum, L) ||
(isa<SCEVAddRecExpr>(Accum) &&
cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
- bool HasNUW = false;
- bool HasNSW = false;
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
// If the increment doesn't overflow, then neither the addrec nor
// the post-increment will overflow.
if (const AddOperator *OBO = dyn_cast<AddOperator>(BEValueV)) {
if (OBO->hasNoUnsignedWrap())
- HasNUW = true;
+ Flags = setFlags(Flags, SCEV::FlagNUW);
if (OBO->hasNoSignedWrap())
- HasNSW = true;
+ Flags = setFlags(Flags, SCEV::FlagNSW);
+ } else if (const GEPOperator *GEP =
+ dyn_cast<GEPOperator>(BEValueV)) {
+ // If the increment is an inbounds GEP, then we know the address
+ // space cannot be wrapped around. We cannot make any guarantee
+ // about signed or unsigned overflow because pointers are
+ // unsigned but we may have a negative index from the base
+ // pointer.
+ if (GEP->isInBounds())
+ Flags = setFlags(Flags, SCEV::FlagNW);
}
const SCEV *StartVal = getSCEV(StartValueV);
- const SCEV *PHISCEV =
- getAddRecExpr(StartVal, Accum, L, HasNUW, HasNSW);
+ const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
// Since the no-wrap flags are on the increment, they apply to the
// post-incremented value as well.
- if (Accum->isLoopInvariant(L))
+ if (isLoopInvariant(Accum, L))
(void)getAddRecExpr(getAddExpr(StartVal, Accum),
- Accum, L, HasNUW, HasNSW);
+ Accum, L, Flags);
// Okay, for the entire analysis of this edge we assumed the PHI
// to be symbolic. We now need to go back and purge all of the
// entries for the scalars that use the symbolic expression.
ForgetSymbolicName(PN, SymbolicName);
- Scalars[SCEVCallbackVH(PN, this)] = PHISCEV;
+ ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
return PHISCEV;
}
}
// initial step of the addrec evolution.
if (StartVal == getMinusSCEV(AddRec->getOperand(0),
AddRec->getOperand(1))) {
+ // FIXME: For constant StartVal, we should be able to infer
+ // no-wrap flags.
const SCEV *PHISCEV =
- getAddRecExpr(StartVal, AddRec->getOperand(1), L);
+ getAddRecExpr(StartVal, AddRec->getOperand(1), L,
+ SCEV::FlagAnyWrap);
// Okay, for the entire analysis of this edge we assumed the PHI
// to be symbolic. We now need to go back and purge all of the
// entries for the scalars that use the symbolic expression.
ForgetSymbolicName(PN, SymbolicName);
- Scalars[SCEVCallbackVH(PN, this)] = PHISCEV;
+ ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
return PHISCEV;
}
}
// PHI's incoming blocks are in a different loop, in which case doing so
// risks breaking LCSSA form. Instcombine would normally zap these, but
// it doesn't have DominatorTree information, so it may miss cases.
- if (Value *V = PN->hasConstantValue(DT)) {
- bool AllSameLoop = true;
- Loop *PNLoop = LI->getLoopFor(PN->getParent());
- for (size_t i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
- if (LI->getLoopFor(PN->getIncomingBlock(i)) != PNLoop) {
- AllSameLoop = false;
- break;
- }
- if (AllSameLoop)
+ if (Value *V = SimplifyInstruction(PN, TD, DT))
+ if (LI->replacementPreservesLCSSAForm(PN, V))
return getSCEV(V);
- }
// If it's not a loop phi, we can't handle it yet.
return getUnknown(PN);
///
const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
- bool InBounds = GEP->isInBounds();
- const Type *IntPtrTy = getEffectiveSCEVType(GEP->getType());
+ // Don't blindly transfer the inbounds flag from the GEP instruction to the
+ // Add expression, because the Instruction may be guarded by control flow
+ // and the no-overflow bits may not be valid for the expression in any
+ // context.
+ bool isInBounds = GEP->isInBounds();
+
+ Type *IntPtrTy = getEffectiveSCEVType(GEP->getType());
Value *Base = GEP->getOperand(0);
// Don't attempt to analyze GEPs over unsized objects.
if (!cast<PointerType>(Base->getType())->getElementType()->isSized())
return getUnknown(GEP);
- const SCEV *TotalOffset = getIntegerSCEV(0, IntPtrTy);
+ const SCEV *TotalOffset = getConstant(IntPtrTy, 0);
gep_type_iterator GTI = gep_type_begin(GEP);
- for (GetElementPtrInst::op_iterator I = next(GEP->op_begin()),
+ for (GetElementPtrInst::op_iterator I = llvm::next(GEP->op_begin()),
E = GEP->op_end();
I != E; ++I) {
Value *Index = *I;
// Compute the (potentially symbolic) offset in bytes for this index.
- if (const StructType *STy = dyn_cast<StructType>(*GTI++)) {
+ if (StructType *STy = dyn_cast<StructType>(*GTI++)) {
// For a struct, add the member offset.
unsigned FieldNo = cast<ConstantInt>(Index)->getZExtValue();
- TotalOffset = getAddExpr(TotalOffset,
- getOffsetOfExpr(STy, FieldNo),
- /*HasNUW=*/false, /*HasNSW=*/InBounds);
+ const SCEV *FieldOffset = getOffsetOfExpr(STy, FieldNo);
+
+ // Add the field offset to the running total offset.
+ TotalOffset = getAddExpr(TotalOffset, FieldOffset);
} else {
// For an array, add the element offset, explicitly scaled.
- const SCEV *LocalOffset = getSCEV(Index);
+ const SCEV *ElementSize = getSizeOfExpr(*GTI);
+ const SCEV *IndexS = getSCEV(Index);
// Getelementptr indices are signed.
- LocalOffset = getTruncateOrSignExtend(LocalOffset, IntPtrTy);
- // Lower "inbounds" GEPs to NSW arithmetic.
- LocalOffset = getMulExpr(LocalOffset, getSizeOfExpr(*GTI),
- /*HasNUW=*/false, /*HasNSW=*/InBounds);
- TotalOffset = getAddExpr(TotalOffset, LocalOffset,
- /*HasNUW=*/false, /*HasNSW=*/InBounds);
+ IndexS = getTruncateOrSignExtend(IndexS, IntPtrTy);
+
+ // Multiply the index by the element size to compute the element offset.
+ const SCEV *LocalOffset = getMulExpr(IndexS, ElementSize,
+ isInBounds ? SCEV::FlagNSW :
+ SCEV::FlagAnyWrap);
+
+ // Add the element offset to the running total offset.
+ TotalOffset = getAddExpr(TotalOffset, LocalOffset);
}
}
- return getAddExpr(getSCEV(Base), TotalOffset,
- /*HasNUW=*/false, /*HasNSW=*/InBounds);
+
+ // Get the SCEV for the GEP base.
+ const SCEV *BaseS = getSCEV(Base);
+
+ // Add the total offset from all the GEP indices to the base.
+ return getAddExpr(BaseS, TotalOffset,
+ isInBounds ? SCEV::FlagNSW : SCEV::FlagAnyWrap);
}
/// GetMinTrailingZeros - Determine the minimum number of zero bits that S is
///
ConstantRange
ScalarEvolution::getUnsignedRange(const SCEV *S) {
+ // See if we've computed this range already.
+ DenseMap<const SCEV *, ConstantRange>::iterator I = UnsignedRanges.find(S);
+ if (I != UnsignedRanges.end())
+ return I->second;
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
- return ConstantRange(C->getValue()->getValue());
+ return setUnsignedRange(C, ConstantRange(C->getValue()->getValue()));
unsigned BitWidth = getTypeSizeInBits(S->getType());
ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
ConstantRange X = getUnsignedRange(Add->getOperand(0));
for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
X = X.add(getUnsignedRange(Add->getOperand(i)));
- return ConservativeResult.intersectWith(X);
+ return setUnsignedRange(Add, ConservativeResult.intersectWith(X));
}
if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
ConstantRange X = getUnsignedRange(Mul->getOperand(0));
for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
X = X.multiply(getUnsignedRange(Mul->getOperand(i)));
- return ConservativeResult.intersectWith(X);
+ return setUnsignedRange(Mul, ConservativeResult.intersectWith(X));
}
if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
ConstantRange X = getUnsignedRange(SMax->getOperand(0));
for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
X = X.smax(getUnsignedRange(SMax->getOperand(i)));
- return ConservativeResult.intersectWith(X);
+ return setUnsignedRange(SMax, ConservativeResult.intersectWith(X));
}
if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
ConstantRange X = getUnsignedRange(UMax->getOperand(0));
for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
X = X.umax(getUnsignedRange(UMax->getOperand(i)));
- return ConservativeResult.intersectWith(X);
+ return setUnsignedRange(UMax, ConservativeResult.intersectWith(X));
}
if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
ConstantRange X = getUnsignedRange(UDiv->getLHS());
ConstantRange Y = getUnsignedRange(UDiv->getRHS());
- return ConservativeResult.intersectWith(X.udiv(Y));
+ return setUnsignedRange(UDiv, ConservativeResult.intersectWith(X.udiv(Y)));
}
if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
ConstantRange X = getUnsignedRange(ZExt->getOperand());
- return ConservativeResult.intersectWith(X.zeroExtend(BitWidth));
+ return setUnsignedRange(ZExt,
+ ConservativeResult.intersectWith(X.zeroExtend(BitWidth)));
}
if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
ConstantRange X = getUnsignedRange(SExt->getOperand());
- return ConservativeResult.intersectWith(X.signExtend(BitWidth));
+ return setUnsignedRange(SExt,
+ ConservativeResult.intersectWith(X.signExtend(BitWidth)));
}
if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
ConstantRange X = getUnsignedRange(Trunc->getOperand());
- return ConservativeResult.intersectWith(X.truncate(BitWidth));
+ return setUnsignedRange(Trunc,
+ ConservativeResult.intersectWith(X.truncate(BitWidth)));
}
if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
// If there's no unsigned wrap, the value will never be less than its
// initial value.
- if (AddRec->hasNoUnsignedWrap())
+ if (AddRec->getNoWrapFlags(SCEV::FlagNUW))
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart()))
if (!C->getValue()->isZero())
ConservativeResult =
- ConstantRange(C->getValue()->getValue(), APInt(BitWidth, 0));
+ ConservativeResult.intersectWith(
+ ConstantRange(C->getValue()->getValue(), APInt(BitWidth, 0)));
// TODO: non-affine addrec
if (AddRec->isAffine()) {
- const Type *Ty = AddRec->getType();
+ Type *Ty = AddRec->getType();
const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
ConstantRange ExtEndRange = EndRange.zextOrTrunc(BitWidth*2+1);
if (ExtStartRange.add(ExtMaxBECountRange.multiply(ExtStepRange)) !=
ExtEndRange)
- return ConservativeResult;
+ return setUnsignedRange(AddRec, ConservativeResult);
APInt Min = APIntOps::umin(StartRange.getUnsignedMin(),
EndRange.getUnsignedMin());
APInt Max = APIntOps::umax(StartRange.getUnsignedMax(),
EndRange.getUnsignedMax());
if (Min.isMinValue() && Max.isMaxValue())
- return ConservativeResult;
- return ConservativeResult.intersectWith(ConstantRange(Min, Max+1));
+ return setUnsignedRange(AddRec, ConservativeResult);
+ return setUnsignedRange(AddRec,
+ ConservativeResult.intersectWith(ConstantRange(Min, Max+1)));
}
}
- return ConservativeResult;
+ return setUnsignedRange(AddRec, ConservativeResult);
}
if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
APInt Zeros(BitWidth, 0), Ones(BitWidth, 0);
ComputeMaskedBits(U->getValue(), Mask, Zeros, Ones, TD);
if (Ones == ~Zeros + 1)
- return ConservativeResult;
- return ConservativeResult.intersectWith(ConstantRange(Ones, ~Zeros + 1));
+ return setUnsignedRange(U, ConservativeResult);
+ return setUnsignedRange(U,
+ ConservativeResult.intersectWith(ConstantRange(Ones, ~Zeros + 1)));
}
- return ConservativeResult;
+ return setUnsignedRange(S, ConservativeResult);
}
/// getSignedRange - Determine the signed range for a particular SCEV.
///
ConstantRange
ScalarEvolution::getSignedRange(const SCEV *S) {
+ // See if we've computed this range already.
+ DenseMap<const SCEV *, ConstantRange>::iterator I = SignedRanges.find(S);
+ if (I != SignedRanges.end())
+ return I->second;
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
- return ConstantRange(C->getValue()->getValue());
+ return setSignedRange(C, ConstantRange(C->getValue()->getValue()));
unsigned BitWidth = getTypeSizeInBits(S->getType());
ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
ConstantRange X = getSignedRange(Add->getOperand(0));
for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
X = X.add(getSignedRange(Add->getOperand(i)));
- return ConservativeResult.intersectWith(X);
+ return setSignedRange(Add, ConservativeResult.intersectWith(X));
}
if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
ConstantRange X = getSignedRange(Mul->getOperand(0));
for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
X = X.multiply(getSignedRange(Mul->getOperand(i)));
- return ConservativeResult.intersectWith(X);
+ return setSignedRange(Mul, ConservativeResult.intersectWith(X));
}
if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
ConstantRange X = getSignedRange(SMax->getOperand(0));
for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
X = X.smax(getSignedRange(SMax->getOperand(i)));
- return ConservativeResult.intersectWith(X);
+ return setSignedRange(SMax, ConservativeResult.intersectWith(X));
}
if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
ConstantRange X = getSignedRange(UMax->getOperand(0));
for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
X = X.umax(getSignedRange(UMax->getOperand(i)));
- return ConservativeResult.intersectWith(X);
+ return setSignedRange(UMax, ConservativeResult.intersectWith(X));
}
if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
ConstantRange X = getSignedRange(UDiv->getLHS());
ConstantRange Y = getSignedRange(UDiv->getRHS());
- return ConservativeResult.intersectWith(X.udiv(Y));
+ return setSignedRange(UDiv, ConservativeResult.intersectWith(X.udiv(Y)));
}
if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
ConstantRange X = getSignedRange(ZExt->getOperand());
- return ConservativeResult.intersectWith(X.zeroExtend(BitWidth));
+ return setSignedRange(ZExt,
+ ConservativeResult.intersectWith(X.zeroExtend(BitWidth)));
}
if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
ConstantRange X = getSignedRange(SExt->getOperand());
- return ConservativeResult.intersectWith(X.signExtend(BitWidth));
+ return setSignedRange(SExt,
+ ConservativeResult.intersectWith(X.signExtend(BitWidth)));
}
if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
ConstantRange X = getSignedRange(Trunc->getOperand());
- return ConservativeResult.intersectWith(X.truncate(BitWidth));
+ return setSignedRange(Trunc,
+ ConservativeResult.intersectWith(X.truncate(BitWidth)));
}
if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
// If there's no signed wrap, and all the operands have the same sign or
// zero, the value won't ever change sign.
- if (AddRec->hasNoSignedWrap()) {
+ if (AddRec->getNoWrapFlags(SCEV::FlagNSW)) {
bool AllNonNeg = true;
bool AllNonPos = true;
for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
// TODO: non-affine addrec
if (AddRec->isAffine()) {
- const Type *Ty = AddRec->getType();
+ Type *Ty = AddRec->getType();
const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
ConstantRange ExtEndRange = EndRange.sextOrTrunc(BitWidth*2+1);
if (ExtStartRange.add(ExtMaxBECountRange.multiply(ExtStepRange)) !=
ExtEndRange)
- return ConservativeResult;
+ return setSignedRange(AddRec, ConservativeResult);
APInt Min = APIntOps::smin(StartRange.getSignedMin(),
EndRange.getSignedMin());
APInt Max = APIntOps::smax(StartRange.getSignedMax(),
EndRange.getSignedMax());
if (Min.isMinSignedValue() && Max.isMaxSignedValue())
- return ConservativeResult;
- return ConservativeResult.intersectWith(ConstantRange(Min, Max+1));
+ return setSignedRange(AddRec, ConservativeResult);
+ return setSignedRange(AddRec,
+ ConservativeResult.intersectWith(ConstantRange(Min, Max+1)));
}
}
- return ConservativeResult;
+ return setSignedRange(AddRec, ConservativeResult);
}
if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
// For a SCEVUnknown, ask ValueTracking.
if (!U->getValue()->getType()->isIntegerTy() && !TD)
- return ConservativeResult;
+ return setSignedRange(U, ConservativeResult);
unsigned NS = ComputeNumSignBits(U->getValue(), TD);
if (NS == 1)
- return ConservativeResult;
- return ConservativeResult.intersectWith(
+ return setSignedRange(U, ConservativeResult);
+ return setSignedRange(U, ConservativeResult.intersectWith(
ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
- APInt::getSignedMaxValue(BitWidth).ashr(NS - 1)+1));
+ APInt::getSignedMaxValue(BitWidth).ashr(NS - 1)+1)));
}
- return ConservativeResult;
+ return setSignedRange(S, ConservativeResult);
}
/// createSCEV - We know that there is no SCEV for the specified value.
else if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
return getConstant(CI);
else if (isa<ConstantPointerNull>(V))
- return getIntegerSCEV(0, V->getType());
+ return getConstant(V->getType(), 0);
else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
return GA->mayBeOverridden() ? getUnknown(V) : getSCEV(GA->getAliasee());
else
Operator *U = cast<Operator>(V);
switch (Opcode) {
- case Instruction::Add:
- // Don't transfer the NSW and NUW bits from the Add instruction to the
- // Add expression, because the Instruction may be guarded by control
- // flow and the no-overflow bits may not be valid for the expression in
- // any context.
- return getAddExpr(getSCEV(U->getOperand(0)),
- getSCEV(U->getOperand(1)));
- case Instruction::Mul:
- // Don't transfer the NSW and NUW bits from the Mul instruction to the
- // Mul expression, as with Add.
- return getMulExpr(getSCEV(U->getOperand(0)),
- getSCEV(U->getOperand(1)));
+ case Instruction::Add: {
+ // The simple thing to do would be to just call getSCEV on both operands
+ // and call getAddExpr with the result. However if we're looking at a
+ // bunch of things all added together, this can be quite inefficient,
+ // because it leads to N-1 getAddExpr calls for N ultimate operands.
+ // Instead, gather up all the operands and make a single getAddExpr call.
+ // LLVM IR canonical form means we need only traverse the left operands.
+ SmallVector<const SCEV *, 4> AddOps;
+ AddOps.push_back(getSCEV(U->getOperand(1)));
+ for (Value *Op = U->getOperand(0); ; Op = U->getOperand(0)) {
+ unsigned Opcode = Op->getValueID() - Value::InstructionVal;
+ if (Opcode != Instruction::Add && Opcode != Instruction::Sub)
+ break;
+ U = cast<Operator>(Op);
+ const SCEV *Op1 = getSCEV(U->getOperand(1));
+ if (Opcode == Instruction::Sub)
+ AddOps.push_back(getNegativeSCEV(Op1));
+ else
+ AddOps.push_back(Op1);
+ }
+ AddOps.push_back(getSCEV(U->getOperand(0)));
+ return getAddExpr(AddOps);
+ }
+ case Instruction::Mul: {
+ // See the Add code above.
+ SmallVector<const SCEV *, 4> MulOps;
+ MulOps.push_back(getSCEV(U->getOperand(1)));
+ for (Value *Op = U->getOperand(0);
+ Op->getValueID() == Instruction::Mul + Value::InstructionVal;
+ Op = U->getOperand(0)) {
+ U = cast<Operator>(Op);
+ MulOps.push_back(getSCEV(U->getOperand(1)));
+ }
+ MulOps.push_back(getSCEV(U->getOperand(0)));
+ return getMulExpr(MulOps);
+ }
case Instruction::UDiv:
return getUDivExpr(getSCEV(U->getOperand(0)),
getSCEV(U->getOperand(1)));
// transfer the no-wrap flags, since an or won't introduce a wrap.
if (const SCEVAddRecExpr *NewAR = dyn_cast<SCEVAddRecExpr>(S)) {
const SCEVAddRecExpr *OldAR = cast<SCEVAddRecExpr>(LHS);
- if (OldAR->hasNoUnsignedWrap())
- const_cast<SCEVAddRecExpr *>(NewAR)->setHasNoUnsignedWrap(true);
- if (OldAR->hasNoSignedWrap())
- const_cast<SCEVAddRecExpr *>(NewAR)->setHasNoSignedWrap(true);
+ const_cast<SCEVAddRecExpr *>(NewAR)->setNoWrapFlags(
+ OldAR->getNoWrapFlags());
}
return S;
}
LCI->getValue() == CI->getValue())
if (const SCEVZeroExtendExpr *Z =
dyn_cast<SCEVZeroExtendExpr>(getSCEV(U->getOperand(0)))) {
- const Type *UTy = U->getType();
+ Type *UTy = U->getType();
const SCEV *Z0 = Z->getOperand();
- const Type *Z0Ty = Z0->getType();
+ Type *Z0Ty = Z0->getType();
unsigned Z0TySize = getTypeSizeInBits(Z0Ty);
// If C is a low-bits mask, the zero extend is serving to
// If C is a single bit, it may be in the sign-bit position
// before the zero-extend. In this case, represent the xor
// using an add, which is equivalent, and re-apply the zext.
- APInt Trunc = APInt(CI->getValue()).trunc(Z0TySize);
- if (APInt(Trunc).zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
+ APInt Trunc = CI->getValue().trunc(Z0TySize);
+ if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
Trunc.isSignBit())
return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
UTy);
// Turn shift left of a constant amount into a multiply.
if (ConstantInt *SA = dyn_cast<ConstantInt>(U->getOperand(1))) {
uint32_t BitWidth = cast<IntegerType>(U->getType())->getBitWidth();
+
+ // If the shift count is not less than the bitwidth, the result of
+ // the shift is undefined. Don't try to analyze it, because the
+ // resolution chosen here may differ from the resolution chosen in
+ // other parts of the compiler.
+ if (SA->getValue().uge(BitWidth))
+ break;
+
Constant *X = ConstantInt::get(getContext(),
- APInt(BitWidth, 1).shl(SA->getLimitedValue(BitWidth)));
+ APInt(BitWidth, 1).shl(SA->getZExtValue()));
return getMulExpr(getSCEV(U->getOperand(0)), getSCEV(X));
}
break;
// Turn logical shift right of a constant into a unsigned divide.
if (ConstantInt *SA = dyn_cast<ConstantInt>(U->getOperand(1))) {
uint32_t BitWidth = cast<IntegerType>(U->getType())->getBitWidth();
+
+ // If the shift count is not less than the bitwidth, the result of
+ // the shift is undefined. Don't try to analyze it, because the
+ // resolution chosen here may differ from the resolution chosen in
+ // other parts of the compiler.
+ if (SA->getValue().uge(BitWidth))
+ break;
+
Constant *X = ConstantInt::get(getContext(),
- APInt(BitWidth, 1).shl(SA->getLimitedValue(BitWidth)));
+ APInt(BitWidth, 1).shl(SA->getZExtValue()));
return getUDivExpr(getSCEV(U->getOperand(0)), getSCEV(X));
}
break;
case Instruction::AShr:
// For a two-shift sext-inreg, use sext(trunc(x)) as the SCEV expression.
if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1)))
- if (Instruction *L = dyn_cast<Instruction>(U->getOperand(0)))
+ if (Operator *L = dyn_cast<Operator>(U->getOperand(0)))
if (L->getOpcode() == Instruction::Shl &&
L->getOperand(1) == U->getOperand(1)) {
- unsigned BitWidth = getTypeSizeInBits(U->getType());
+ uint64_t BitWidth = getTypeSizeInBits(U->getType());
+
+ // If the shift count is not less than the bitwidth, the result of
+ // the shift is undefined. Don't try to analyze it, because the
+ // resolution chosen here may differ from the resolution chosen in
+ // other parts of the compiler.
+ if (CI->getValue().uge(BitWidth))
+ break;
+
uint64_t Amt = BitWidth - CI->getZExtValue();
if (Amt == BitWidth)
return getSCEV(L->getOperand(0)); // shift by zero --> noop
- if (Amt > BitWidth)
- return getIntegerSCEV(0, U->getType()); // value is undefined
return
getSignExtendExpr(getTruncateExpr(getSCEV(L->getOperand(0)),
- IntegerType::get(getContext(), Amt)),
- U->getType());
+ IntegerType::get(getContext(),
+ Amt)),
+ U->getType());
}
break;
// fall through
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
- if (LHS == U->getOperand(1) && RHS == U->getOperand(2))
- return getSMaxExpr(getSCEV(LHS), getSCEV(RHS));
- else if (LHS == U->getOperand(2) && RHS == U->getOperand(1))
- return getSMinExpr(getSCEV(LHS), getSCEV(RHS));
+ // a >s b ? a+x : b+x -> smax(a, b)+x
+ // a >s b ? b+x : a+x -> smin(a, b)+x
+ if (LHS->getType() == U->getType()) {
+ const SCEV *LS = getSCEV(LHS);
+ const SCEV *RS = getSCEV(RHS);
+ const SCEV *LA = getSCEV(U->getOperand(1));
+ const SCEV *RA = getSCEV(U->getOperand(2));
+ const SCEV *LDiff = getMinusSCEV(LA, LS);
+ const SCEV *RDiff = getMinusSCEV(RA, RS);
+ if (LDiff == RDiff)
+ return getAddExpr(getSMaxExpr(LS, RS), LDiff);
+ LDiff = getMinusSCEV(LA, RS);
+ RDiff = getMinusSCEV(RA, LS);
+ if (LDiff == RDiff)
+ return getAddExpr(getSMinExpr(LS, RS), LDiff);
+ }
break;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
// fall through
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
- if (LHS == U->getOperand(1) && RHS == U->getOperand(2))
- return getUMaxExpr(getSCEV(LHS), getSCEV(RHS));
- else if (LHS == U->getOperand(2) && RHS == U->getOperand(1))
- return getUMinExpr(getSCEV(LHS), getSCEV(RHS));
+ // a >u b ? a+x : b+x -> umax(a, b)+x
+ // a >u b ? b+x : a+x -> umin(a, b)+x
+ if (LHS->getType() == U->getType()) {
+ const SCEV *LS = getSCEV(LHS);
+ const SCEV *RS = getSCEV(RHS);
+ const SCEV *LA = getSCEV(U->getOperand(1));
+ const SCEV *RA = getSCEV(U->getOperand(2));
+ const SCEV *LDiff = getMinusSCEV(LA, LS);
+ const SCEV *RDiff = getMinusSCEV(RA, RS);
+ if (LDiff == RDiff)
+ return getAddExpr(getUMaxExpr(LS, RS), LDiff);
+ LDiff = getMinusSCEV(LA, RS);
+ RDiff = getMinusSCEV(RA, LS);
+ if (LDiff == RDiff)
+ return getAddExpr(getUMinExpr(LS, RS), LDiff);
+ }
break;
case ICmpInst::ICMP_NE:
- // n != 0 ? n : 1 -> umax(n, 1)
- if (LHS == U->getOperand(1) &&
- isa<ConstantInt>(U->getOperand(2)) &&
- cast<ConstantInt>(U->getOperand(2))->isOne() &&
+ // n != 0 ? n+x : 1+x -> umax(n, 1)+x
+ if (LHS->getType() == U->getType() &&
isa<ConstantInt>(RHS) &&
- cast<ConstantInt>(RHS)->isZero())
- return getUMaxExpr(getSCEV(LHS), getSCEV(U->getOperand(2)));
+ cast<ConstantInt>(RHS)->isZero()) {
+ const SCEV *One = getConstant(LHS->getType(), 1);
+ const SCEV *LS = getSCEV(LHS);
+ const SCEV *LA = getSCEV(U->getOperand(1));
+ const SCEV *RA = getSCEV(U->getOperand(2));
+ const SCEV *LDiff = getMinusSCEV(LA, LS);
+ const SCEV *RDiff = getMinusSCEV(RA, One);
+ if (LDiff == RDiff)
+ return getAddExpr(getUMaxExpr(One, LS), LDiff);
+ }
break;
case ICmpInst::ICMP_EQ:
- // n == 0 ? 1 : n -> umax(n, 1)
- if (LHS == U->getOperand(2) &&
- isa<ConstantInt>(U->getOperand(1)) &&
- cast<ConstantInt>(U->getOperand(1))->isOne() &&
+ // n == 0 ? 1+x : n+x -> umax(n, 1)+x
+ if (LHS->getType() == U->getType() &&
isa<ConstantInt>(RHS) &&
- cast<ConstantInt>(RHS)->isZero())
- return getUMaxExpr(getSCEV(LHS), getSCEV(U->getOperand(1)));
+ cast<ConstantInt>(RHS)->isZero()) {
+ const SCEV *One = getConstant(LHS->getType(), 1);
+ const SCEV *LS = getSCEV(LHS);
+ const SCEV *LA = getSCEV(U->getOperand(1));
+ const SCEV *RA = getSCEV(U->getOperand(2));
+ const SCEV *LDiff = getMinusSCEV(LA, One);
+ const SCEV *RDiff = getMinusSCEV(RA, LS);
+ if (LDiff == RDiff)
+ return getAddExpr(getUMaxExpr(One, LS), LDiff);
+ }
break;
default:
break;
// Iteration Count Computation Code
//
+// getExitCount - Get the expression for the number of loop iterations for which
+// this loop is guaranteed not to exit via ExitintBlock. Otherwise return
+// SCEVCouldNotCompute.
+const SCEV *ScalarEvolution::getExitCount(Loop *L, BasicBlock *ExitingBlock) {
+ return getBackedgeTakenInfo(L).getExact(ExitingBlock, this);
+}
+
/// getBackedgeTakenCount - If the specified loop has a predictable
/// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
/// object. The backedge-taken count is the number of times the loop header
/// hasLoopInvariantBackedgeTakenCount).
///
const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L) {
- return getBackedgeTakenInfo(L).Exact;
+ return getBackedgeTakenInfo(L).getExact(this);
}
/// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
/// return the least SCEV value that is known never to be less than the
/// actual backedge taken count.
const SCEV *ScalarEvolution::getMaxBackedgeTakenCount(const Loop *L) {
- return getBackedgeTakenInfo(L).Max;
+ return getBackedgeTakenInfo(L).getMax(this);
}
/// PushLoopPHIs - Push PHI nodes in the header of the given loop
const ScalarEvolution::BackedgeTakenInfo &
ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
- // Initially insert a CouldNotCompute for this loop. If the insertion
+ // Initially insert an invalid entry for this loop. If the insertion
// succeeds, proceed to actually compute a backedge-taken count and
// update the value. The temporary CouldNotCompute value tells SCEV
// code elsewhere that it shouldn't attempt to request a new
// backedge-taken count, which could result in infinite recursion.
- std::pair<std::map<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
- BackedgeTakenCounts.insert(std::make_pair(L, getCouldNotCompute()));
- if (Pair.second) {
- BackedgeTakenInfo BECount = ComputeBackedgeTakenCount(L);
- if (BECount.Exact != getCouldNotCompute()) {
- assert(BECount.Exact->isLoopInvariant(L) &&
- BECount.Max->isLoopInvariant(L) &&
- "Computed backedge-taken count isn't loop invariant for loop!");
- ++NumTripCountsComputed;
-
- // Update the value in the map.
- Pair.first->second = BECount;
- } else {
- if (BECount.Max != getCouldNotCompute())
- // Update the value in the map.
- Pair.first->second = BECount;
- if (isa<PHINode>(L->getHeader()->begin()))
- // Only count loops that have phi nodes as not being computable.
- ++NumTripCountsNotComputed;
- }
-
- // Now that we know more about the trip count for this loop, forget any
- // existing SCEV values for PHI nodes in this loop since they are only
- // conservative estimates made without the benefit of trip count
- // information. This is similar to the code in forgetLoop, except that
- // it handles SCEVUnknown PHI nodes specially.
- if (BECount.hasAnyInfo()) {
- SmallVector<Instruction *, 16> Worklist;
- PushLoopPHIs(L, Worklist);
-
- SmallPtrSet<Instruction *, 8> Visited;
- while (!Worklist.empty()) {
- Instruction *I = Worklist.pop_back_val();
- if (!Visited.insert(I)) continue;
-
- std::map<SCEVCallbackVH, const SCEV *>::iterator It =
- Scalars.find(static_cast<Value *>(I));
- if (It != Scalars.end()) {
- // SCEVUnknown for a PHI either means that it has an unrecognized
- // structure, or it's a PHI that's in the progress of being computed
- // by createNodeForPHI. In the former case, additional loop trip
- // count information isn't going to change anything. In the later
- // case, createNodeForPHI will perform the necessary updates on its
- // own when it gets to that point.
- if (!isa<PHINode>(I) || !isa<SCEVUnknown>(It->second)) {
- ValuesAtScopes.erase(It->second);
- Scalars.erase(It);
- }
- if (PHINode *PN = dyn_cast<PHINode>(I))
- ConstantEvolutionLoopExitValue.erase(PN);
+ std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
+ BackedgeTakenCounts.insert(std::make_pair(L, BackedgeTakenInfo()));
+ if (!Pair.second)
+ return Pair.first->second;
+
+ // ComputeBackedgeTakenCount may allocate memory for its result. Inserting it
+ // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result
+ // must be cleared in this scope.
+ BackedgeTakenInfo Result = ComputeBackedgeTakenCount(L);
+
+ if (Result.getExact(this) != getCouldNotCompute()) {
+ assert(isLoopInvariant(Result.getExact(this), L) &&
+ isLoopInvariant(Result.getMax(this), L) &&
+ "Computed backedge-taken count isn't loop invariant for loop!");
+ ++NumTripCountsComputed;
+ }
+ else if (Result.getMax(this) == getCouldNotCompute() &&
+ isa<PHINode>(L->getHeader()->begin())) {
+ // Only count loops that have phi nodes as not being computable.
+ ++NumTripCountsNotComputed;
+ }
+
+ // Now that we know more about the trip count for this loop, forget any
+ // existing SCEV values for PHI nodes in this loop since they are only
+ // conservative estimates made without the benefit of trip count
+ // information. This is similar to the code in forgetLoop, except that
+ // it handles SCEVUnknown PHI nodes specially.
+ if (Result.hasAnyInfo()) {
+ SmallVector<Instruction *, 16> Worklist;
+ PushLoopPHIs(L, Worklist);
+
+ SmallPtrSet<Instruction *, 8> Visited;
+ while (!Worklist.empty()) {
+ Instruction *I = Worklist.pop_back_val();
+ if (!Visited.insert(I)) continue;
+
+ ValueExprMapType::iterator It =
+ ValueExprMap.find(static_cast<Value *>(I));
+ if (It != ValueExprMap.end()) {
+ const SCEV *Old = It->second;
+
+ // SCEVUnknown for a PHI either means that it has an unrecognized
+ // structure, or it's a PHI that's in the progress of being computed
+ // by createNodeForPHI. In the former case, additional loop trip
+ // count information isn't going to change anything. In the later
+ // case, createNodeForPHI will perform the necessary updates on its
+ // own when it gets to that point.
+ if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) {
+ forgetMemoizedResults(Old);
+ ValueExprMap.erase(It);
}
-
- PushDefUseChildren(I, Worklist);
+ if (PHINode *PN = dyn_cast<PHINode>(I))
+ ConstantEvolutionLoopExitValue.erase(PN);
}
+
+ PushDefUseChildren(I, Worklist);
}
}
- return Pair.first->second;
+
+ // Re-lookup the insert position, since the call to
+ // ComputeBackedgeTakenCount above could result in a
+ // recusive call to getBackedgeTakenInfo (on a different
+ // loop), which would invalidate the iterator computed
+ // earlier.
+ return BackedgeTakenCounts.find(L)->second = Result;
}
/// forgetLoop - This method should be called by the client when it has
/// compute a trip count, or if the loop is deleted.
void ScalarEvolution::forgetLoop(const Loop *L) {
// Drop any stored trip count value.
- BackedgeTakenCounts.erase(L);
+ DenseMap<const Loop*, BackedgeTakenInfo>::iterator BTCPos =
+ BackedgeTakenCounts.find(L);
+ if (BTCPos != BackedgeTakenCounts.end()) {
+ BTCPos->second.clear();
+ BackedgeTakenCounts.erase(BTCPos);
+ }
// Drop information about expressions based on loop-header PHIs.
SmallVector<Instruction *, 16> Worklist;
Instruction *I = Worklist.pop_back_val();
if (!Visited.insert(I)) continue;
- std::map<SCEVCallbackVH, const SCEV *>::iterator It =
- Scalars.find(static_cast<Value *>(I));
- if (It != Scalars.end()) {
- ValuesAtScopes.erase(It->second);
- Scalars.erase(It);
+ ValueExprMapType::iterator It = ValueExprMap.find(static_cast<Value *>(I));
+ if (It != ValueExprMap.end()) {
+ forgetMemoizedResults(It->second);
+ ValueExprMap.erase(It);
if (PHINode *PN = dyn_cast<PHINode>(I))
ConstantEvolutionLoopExitValue.erase(PN);
}
PushDefUseChildren(I, Worklist);
}
+
+ // Forget all contained loops too, to avoid dangling entries in the
+ // ValuesAtScopes map.
+ for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
+ forgetLoop(*I);
}
/// forgetValue - This method should be called by the client when it has
I = Worklist.pop_back_val();
if (!Visited.insert(I)) continue;
- std::map<SCEVCallbackVH, const SCEV *>::iterator It =
- Scalars.find(static_cast<Value *>(I));
- if (It != Scalars.end()) {
- ValuesAtScopes.erase(It->second);
- Scalars.erase(It);
+ ValueExprMapType::iterator It = ValueExprMap.find(static_cast<Value *>(I));
+ if (It != ValueExprMap.end()) {
+ forgetMemoizedResults(It->second);
+ ValueExprMap.erase(It);
if (PHINode *PN = dyn_cast<PHINode>(I))
ConstantEvolutionLoopExitValue.erase(PN);
}
}
}
+/// getExact - Get the exact loop backedge taken count considering all loop
+/// exits. If all exits are computable, this is the minimum computed count.
+const SCEV *
+ScalarEvolution::BackedgeTakenInfo::getExact(ScalarEvolution *SE) const {
+ // If any exits were not computable, the loop is not computable.
+ if (!ExitNotTaken.isCompleteList()) return SE->getCouldNotCompute();
+
+ // We need at least one computable exit.
+ if (!ExitNotTaken.ExitingBlock) return SE->getCouldNotCompute();
+ assert(ExitNotTaken.ExactNotTaken && "uninitialized not-taken info");
+
+ const SCEV *BECount = 0;
+ for (const ExitNotTakenInfo *ENT = &ExitNotTaken;
+ ENT != 0; ENT = ENT->getNextExit()) {
+
+ assert(ENT->ExactNotTaken != SE->getCouldNotCompute() && "bad exit SCEV");
+
+ if (!BECount)
+ BECount = ENT->ExactNotTaken;
+ else
+ BECount = SE->getUMinFromMismatchedTypes(BECount, ENT->ExactNotTaken);
+ }
+ return BECount;
+}
+
+/// getExact - Get the exact not taken count for this loop exit.
+const SCEV *
+ScalarEvolution::BackedgeTakenInfo::getExact(BasicBlock *ExitingBlock,
+ ScalarEvolution *SE) const {
+ for (const ExitNotTakenInfo *ENT = &ExitNotTaken;
+ ENT != 0; ENT = ENT->getNextExit()) {
+
+ if (ENT->ExitingBlock == ExitingBlock)
+ return ENT->ExactNotTaken;
+ }
+ return SE->getCouldNotCompute();
+}
+
+/// getMax - Get the max backedge taken count for the loop.
+const SCEV *
+ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const {
+ return Max ? Max : SE->getCouldNotCompute();
+}
+
+/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
+/// computable exit into a persistent ExitNotTakenInfo array.
+ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
+ SmallVectorImpl< std::pair<BasicBlock *, const SCEV *> > &ExitCounts,
+ bool Complete, const SCEV *MaxCount) : Max(MaxCount) {
+
+ if (!Complete)
+ ExitNotTaken.setIncomplete();
+
+ unsigned NumExits = ExitCounts.size();
+ if (NumExits == 0) return;
+
+ ExitNotTaken.ExitingBlock = ExitCounts[0].first;
+ ExitNotTaken.ExactNotTaken = ExitCounts[0].second;
+ if (NumExits == 1) return;
+
+ // Handle the rare case of multiple computable exits.
+ ExitNotTakenInfo *ENT = new ExitNotTakenInfo[NumExits-1];
+
+ ExitNotTakenInfo *PrevENT = &ExitNotTaken;
+ for (unsigned i = 1; i < NumExits; ++i, PrevENT = ENT, ++ENT) {
+ PrevENT->setNextExit(ENT);
+ ENT->ExitingBlock = ExitCounts[i].first;
+ ENT->ExactNotTaken = ExitCounts[i].second;
+ }
+}
+
+/// clear - Invalidate this result and free the ExitNotTakenInfo array.
+void ScalarEvolution::BackedgeTakenInfo::clear() {
+ ExitNotTaken.ExitingBlock = 0;
+ ExitNotTaken.ExactNotTaken = 0;
+ delete[] ExitNotTaken.getNextExit();
+}
+
/// ComputeBackedgeTakenCount - Compute the number of times the backedge
/// of the specified loop will execute.
ScalarEvolution::BackedgeTakenInfo
L->getExitingBlocks(ExitingBlocks);
// Examine all exits and pick the most conservative values.
- const SCEV *BECount = getCouldNotCompute();
const SCEV *MaxBECount = getCouldNotCompute();
- bool CouldNotComputeBECount = false;
+ bool CouldComputeBECount = true;
+ SmallVector<std::pair<BasicBlock *, const SCEV *>, 4> ExitCounts;
for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
- BackedgeTakenInfo NewBTI =
- ComputeBackedgeTakenCountFromExit(L, ExitingBlocks[i]);
-
- if (NewBTI.Exact == getCouldNotCompute()) {
+ ExitLimit EL = ComputeExitLimit(L, ExitingBlocks[i]);
+ if (EL.Exact == getCouldNotCompute())
// We couldn't compute an exact value for this exit, so
// we won't be able to compute an exact value for the loop.
- CouldNotComputeBECount = true;
- BECount = getCouldNotCompute();
- } else if (!CouldNotComputeBECount) {
- if (BECount == getCouldNotCompute())
- BECount = NewBTI.Exact;
- else
- BECount = getUMinFromMismatchedTypes(BECount, NewBTI.Exact);
- }
+ CouldComputeBECount = false;
+ else
+ ExitCounts.push_back(std::make_pair(ExitingBlocks[i], EL.Exact));
+
if (MaxBECount == getCouldNotCompute())
- MaxBECount = NewBTI.Max;
- else if (NewBTI.Max != getCouldNotCompute())
- MaxBECount = getUMinFromMismatchedTypes(MaxBECount, NewBTI.Max);
+ MaxBECount = EL.Max;
+ else if (EL.Max != getCouldNotCompute())
+ MaxBECount = getUMinFromMismatchedTypes(MaxBECount, EL.Max);
}
- return BackedgeTakenInfo(BECount, MaxBECount);
+ return BackedgeTakenInfo(ExitCounts, CouldComputeBECount, MaxBECount);
}
-/// ComputeBackedgeTakenCountFromExit - Compute the number of times the backedge
-/// of the specified loop will execute if it exits via the specified block.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeBackedgeTakenCountFromExit(const Loop *L,
- BasicBlock *ExitingBlock) {
+/// ComputeExitLimit - Compute the number of times the backedge of the specified
+/// loop will execute if it exits via the specified block.
+ScalarEvolution::ExitLimit
+ScalarEvolution::ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock) {
// Okay, we've chosen an exiting block. See what condition causes us to
// exit at this block.
}
// Proceed to the next level to examine the exit condition expression.
- return ComputeBackedgeTakenCountFromExitCond(L, ExitBr->getCondition(),
- ExitBr->getSuccessor(0),
- ExitBr->getSuccessor(1));
+ return ComputeExitLimitFromCond(L, ExitBr->getCondition(),
+ ExitBr->getSuccessor(0),
+ ExitBr->getSuccessor(1));
}
-/// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the
+/// ComputeExitLimitFromCond - Compute the number of times the
/// backedge of the specified loop will execute if its exit condition
/// were a conditional branch of ExitCond, TBB, and FBB.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeBackedgeTakenCountFromExitCond(const Loop *L,
- Value *ExitCond,
- BasicBlock *TBB,
- BasicBlock *FBB) {
+ScalarEvolution::ExitLimit
+ScalarEvolution::ComputeExitLimitFromCond(const Loop *L,
+ Value *ExitCond,
+ BasicBlock *TBB,
+ BasicBlock *FBB) {
// Check if the controlling expression for this loop is an And or Or.
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) {
if (BO->getOpcode() == Instruction::And) {
// Recurse on the operands of the and.
- BackedgeTakenInfo BTI0 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(0), TBB, FBB);
- BackedgeTakenInfo BTI1 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(1), TBB, FBB);
+ ExitLimit EL0 = ComputeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB);
+ ExitLimit EL1 = ComputeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB);
const SCEV *BECount = getCouldNotCompute();
const SCEV *MaxBECount = getCouldNotCompute();
if (L->contains(TBB)) {
// Both conditions must be true for the loop to continue executing.
// Choose the less conservative count.
- if (BTI0.Exact == getCouldNotCompute() ||
- BTI1.Exact == getCouldNotCompute())
+ if (EL0.Exact == getCouldNotCompute() ||
+ EL1.Exact == getCouldNotCompute())
BECount = getCouldNotCompute();
else
- BECount = getUMinFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max == getCouldNotCompute())
- MaxBECount = BTI1.Max;
- else if (BTI1.Max == getCouldNotCompute())
- MaxBECount = BTI0.Max;
+ BECount = getUMinFromMismatchedTypes(EL0.Exact, EL1.Exact);
+ if (EL0.Max == getCouldNotCompute())
+ MaxBECount = EL1.Max;
+ else if (EL1.Max == getCouldNotCompute())
+ MaxBECount = EL0.Max;
else
- MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max);
+ MaxBECount = getUMinFromMismatchedTypes(EL0.Max, EL1.Max);
} else {
- // Both conditions must be true for the loop to exit.
+ // Both conditions must be true at the same time for the loop to exit.
+ // For now, be conservative.
assert(L->contains(FBB) && "Loop block has no successor in loop!");
- if (BTI0.Exact != getCouldNotCompute() &&
- BTI1.Exact != getCouldNotCompute())
- BECount = getUMaxFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max != getCouldNotCompute() &&
- BTI1.Max != getCouldNotCompute())
- MaxBECount = getUMaxFromMismatchedTypes(BTI0.Max, BTI1.Max);
+ if (EL0.Max == EL1.Max)
+ MaxBECount = EL0.Max;
+ if (EL0.Exact == EL1.Exact)
+ BECount = EL0.Exact;
}
- return BackedgeTakenInfo(BECount, MaxBECount);
+ return ExitLimit(BECount, MaxBECount);
}
if (BO->getOpcode() == Instruction::Or) {
// Recurse on the operands of the or.
- BackedgeTakenInfo BTI0 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(0), TBB, FBB);
- BackedgeTakenInfo BTI1 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(1), TBB, FBB);
+ ExitLimit EL0 = ComputeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB);
+ ExitLimit EL1 = ComputeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB);
const SCEV *BECount = getCouldNotCompute();
const SCEV *MaxBECount = getCouldNotCompute();
if (L->contains(FBB)) {
// Both conditions must be false for the loop to continue executing.
// Choose the less conservative count.
- if (BTI0.Exact == getCouldNotCompute() ||
- BTI1.Exact == getCouldNotCompute())
+ if (EL0.Exact == getCouldNotCompute() ||
+ EL1.Exact == getCouldNotCompute())
BECount = getCouldNotCompute();
else
- BECount = getUMinFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max == getCouldNotCompute())
- MaxBECount = BTI1.Max;
- else if (BTI1.Max == getCouldNotCompute())
- MaxBECount = BTI0.Max;
+ BECount = getUMinFromMismatchedTypes(EL0.Exact, EL1.Exact);
+ if (EL0.Max == getCouldNotCompute())
+ MaxBECount = EL1.Max;
+ else if (EL1.Max == getCouldNotCompute())
+ MaxBECount = EL0.Max;
else
- MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max);
+ MaxBECount = getUMinFromMismatchedTypes(EL0.Max, EL1.Max);
} else {
- // Both conditions must be false for the loop to exit.
+ // Both conditions must be false at the same time for the loop to exit.
+ // For now, be conservative.
assert(L->contains(TBB) && "Loop block has no successor in loop!");
- if (BTI0.Exact != getCouldNotCompute() &&
- BTI1.Exact != getCouldNotCompute())
- BECount = getUMaxFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max != getCouldNotCompute() &&
- BTI1.Max != getCouldNotCompute())
- MaxBECount = getUMaxFromMismatchedTypes(BTI0.Max, BTI1.Max);
+ if (EL0.Max == EL1.Max)
+ MaxBECount = EL0.Max;
+ if (EL0.Exact == EL1.Exact)
+ BECount = EL0.Exact;
}
- return BackedgeTakenInfo(BECount, MaxBECount);
+ return ExitLimit(BECount, MaxBECount);
}
}
// With an icmp, it may be feasible to compute an exact backedge-taken count.
// Proceed to the next level to examine the icmp.
if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond))
- return ComputeBackedgeTakenCountFromExitCondICmp(L, ExitCondICmp, TBB, FBB);
+ return ComputeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB);
// Check for a constant condition. These are normally stripped out by
// SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
return getCouldNotCompute();
else
// The backedge is never taken.
- return getIntegerSCEV(0, CI->getType());
+ return getConstant(CI->getType(), 0);
}
// If it's not an integer or pointer comparison then compute it the hard way.
- return ComputeBackedgeTakenCountExhaustively(L, ExitCond, !L->contains(TBB));
+ return ComputeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
}
-/// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of times the
+/// ComputeExitLimitFromICmp - Compute the number of times the
/// backedge of the specified loop will execute if its exit condition
/// were a conditional branch of the ICmpInst ExitCond, TBB, and FBB.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
- ICmpInst *ExitCond,
- BasicBlock *TBB,
- BasicBlock *FBB) {
+ScalarEvolution::ExitLimit
+ScalarEvolution::ComputeExitLimitFromICmp(const Loop *L,
+ ICmpInst *ExitCond,
+ BasicBlock *TBB,
+ BasicBlock *FBB) {
// If the condition was exit on true, convert the condition to exit on false
ICmpInst::Predicate Cond;
// 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))) {
- BackedgeTakenInfo ItCnt =
- ComputeLoadConstantCompareBackedgeTakenCount(LI, RHS, L, Cond);
+ ExitLimit ItCnt =
+ ComputeLoadConstantCompareExitLimit(LI, RHS, L, Cond);
if (ItCnt.hasAnyInfo())
return ItCnt;
}
// At this point, we would like to compute how many iterations of the
// loop the predicate will return true for these inputs.
- if (LHS->isLoopInvariant(L) && !RHS->isLoopInvariant(L)) {
+ if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) {
// If there is a loop-invariant, force it into the RHS.
std::swap(LHS, RHS);
Cond = ICmpInst::getSwappedPredicate(Cond);
}
+ // Simplify the operands before analyzing them.
+ (void)SimplifyICmpOperands(Cond, LHS, RHS);
+
// If we have a comparison of a chrec against a constant, try to use value
// ranges to answer this query.
if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
switch (Cond) {
case ICmpInst::ICMP_NE: { // while (X != Y)
// Convert to: while (X-Y != 0)
- BackedgeTakenInfo BTI = HowFarToZero(getMinusSCEV(LHS, RHS), L);
- if (BTI.hasAnyInfo()) return BTI;
+ ExitLimit EL = HowFarToZero(getMinusSCEV(LHS, RHS), L);
+ if (EL.hasAnyInfo()) return EL;
break;
}
case ICmpInst::ICMP_EQ: { // while (X == Y)
// Convert to: while (X-Y == 0)
- BackedgeTakenInfo BTI = HowFarToNonZero(getMinusSCEV(LHS, RHS), L);
- if (BTI.hasAnyInfo()) return BTI;
+ ExitLimit EL = HowFarToNonZero(getMinusSCEV(LHS, RHS), L);
+ if (EL.hasAnyInfo()) return EL;
break;
}
case ICmpInst::ICMP_SLT: {
- BackedgeTakenInfo BTI = HowManyLessThans(LHS, RHS, L, true);
- if (BTI.hasAnyInfo()) return BTI;
+ ExitLimit EL = HowManyLessThans(LHS, RHS, L, true);
+ if (EL.hasAnyInfo()) return EL;
break;
}
case ICmpInst::ICMP_SGT: {
- BackedgeTakenInfo BTI = HowManyLessThans(getNotSCEV(LHS),
+ ExitLimit EL = HowManyLessThans(getNotSCEV(LHS),
getNotSCEV(RHS), L, true);
- if (BTI.hasAnyInfo()) return BTI;
+ if (EL.hasAnyInfo()) return EL;
break;
}
case ICmpInst::ICMP_ULT: {
- BackedgeTakenInfo BTI = HowManyLessThans(LHS, RHS, L, false);
- if (BTI.hasAnyInfo()) return BTI;
+ ExitLimit EL = HowManyLessThans(LHS, RHS, L, false);
+ if (EL.hasAnyInfo()) return EL;
break;
}
case ICmpInst::ICMP_UGT: {
- BackedgeTakenInfo BTI = HowManyLessThans(getNotSCEV(LHS),
+ ExitLimit EL = HowManyLessThans(getNotSCEV(LHS),
getNotSCEV(RHS), L, false);
- if (BTI.hasAnyInfo()) return BTI;
+ if (EL.hasAnyInfo()) return EL;
break;
}
default:
#endif
break;
}
- return
- ComputeBackedgeTakenCountExhaustively(L, ExitCond, !L->contains(TBB));
+ return ComputeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
}
static ConstantInt *
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())) {
+ if (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())) {
+ } else if (ArrayType *ATy = dyn_cast<ArrayType>(Init->getType())) {
if (Idx >= ATy->getNumElements()) return 0; // Bogus program
Init = Constant::getNullValue(ATy->getElementType());
} else {
return Init;
}
-/// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition of
+/// ComputeLoadConstantCompareExitLimit - Given an exit condition of
/// 'icmp op load X, cst', try to see if we can compute the backedge
/// execution count.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeLoadConstantCompareBackedgeTakenCount(
- LoadInst *LI,
- Constant *RHS,
- const Loop *L,
- ICmpInst::Predicate predicate) {
+ScalarEvolution::ExitLimit
+ScalarEvolution::ComputeLoadConstantCompareExitLimit(
+ LoadInst *LI,
+ Constant *RHS,
+ const Loop *L,
+ ICmpInst::Predicate predicate) {
+
if (LI->isVolatile()) return getCouldNotCompute();
// Check to see if the loaded pointer is a getelementptr of a global.
// We can only recognize very limited forms of loop index expressions, in
// particular, only affine AddRec's like {C1,+,C2}.
const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
- if (!IdxExpr || !IdxExpr->isAffine() || IdxExpr->isLoopInvariant(L) ||
+ if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) ||
!isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
!isa<SCEVConstant>(IdxExpr->getOperand(1)))
return getCouldNotCompute();
// 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)))) {
+ if (!isa<Constant>(I->getOperand(Op))) {
PHINode *P = getConstantEvolvingPHI(I->getOperand(Op), L);
if (P == 0) return 0; // Not evolving from PHI
if (PHI == 0)
const TargetData *TD) {
if (isa<PHINode>(V)) return PHIVal;
if (Constant *C = dyn_cast<Constant>(V)) return C;
- if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) return GV;
Instruction *I = cast<Instruction>(V);
- std::vector<Constant*> Operands;
- Operands.resize(I->getNumOperands());
+ std::vector<Constant*> Operands(I->getNumOperands());
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
Operands[i] = EvaluateExpression(I->getOperand(i), PHIVal, TD);
if (const CmpInst *CI = dyn_cast<CmpInst>(I))
return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
Operands[1], TD);
- return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
- &Operands[0], Operands.size(), TD);
+ return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Operands, TD);
}
/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
const APInt &BEs,
const Loop *L) {
- std::map<PHINode*, Constant*>::iterator I =
+ DenseMap<PHINode*, Constant*>::const_iterator I =
ConstantEvolutionLoopExitValue.find(PN);
if (I != ConstantEvolutionLoopExitValue.end())
return I->second;
return RetVal = 0; // Must be a constant.
Value *BEValue = PN->getIncomingValue(SecondIsBackedge);
- PHINode *PN2 = getConstantEvolvingPHI(BEValue, L);
- if (PN2 != PN)
+ if (getConstantEvolvingPHI(BEValue, L) != PN &&
+ !isa<Constant>(BEValue))
return RetVal = 0; // Not derived from same PHI.
// Execute the loop symbolically to determine the exit value.
}
}
-/// ComputeBackedgeTakenCountExhaustively - If the loop is known to execute a
+/// ComputeExitCountExhaustively - If the loop 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 getCouldNotCompute().
-const SCEV *
-ScalarEvolution::ComputeBackedgeTakenCountExhaustively(const Loop *L,
- Value *Cond,
- bool ExitWhen) {
+const SCEV * ScalarEvolution::ComputeExitCountExhaustively(const Loop *L,
+ Value *Cond,
+ bool ExitWhen) {
PHINode *PN = getConstantEvolvingPHI(Cond, L);
if (PN == 0) return getCouldNotCompute();
- // 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
+ // If the loop is canonicalized, the PHI will have exactly two entries.
+ // That's the only form we support here.
+ if (PN->getNumIncomingValues() != 2) return getCouldNotCompute();
+
+ // 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 =
if (StartCST == 0) return getCouldNotCompute(); // Must be a constant.
Value *BEValue = PN->getIncomingValue(SecondIsBackedge);
- PHINode *PN2 = getConstantEvolvingPHI(BEValue, L);
- if (PN2 != PN) return getCouldNotCompute(); // Not derived from same PHI.
+ if (getConstantEvolvingPHI(BEValue, L) != PN &&
+ !isa<Constant>(BEValue))
+ return getCouldNotCompute(); // 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
// the arguments into constants, and if so, 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());
+ SmallVector<Constant *, 4> Operands;
+ bool MadeImprovement = false;
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 {
- // If any of the operands is non-constant and if they are
- // non-integer and non-pointer, don't even try to analyze them
- // with scev techniques.
- if (!isSCEVable(Op->getType()))
- return V;
-
- const SCEV *OpV = getSCEVAtScope(Op, L);
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(OpV)) {
- Constant *C = SC->getValue();
- if (C->getType() != Op->getType())
- C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
- Op->getType(),
- false),
- C, Op->getType());
- Operands.push_back(C);
- } else if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(OpV)) {
- if (Constant *C = dyn_cast<Constant>(SU->getValue())) {
- if (C->getType() != Op->getType())
- C =
- ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
- Op->getType(),
- false),
- C, Op->getType());
- Operands.push_back(C);
- } else
- return V;
- } else {
- return V;
- }
+ continue;
}
+
+ // If any of the operands is non-constant and if they are
+ // non-integer and non-pointer, don't even try to analyze them
+ // with scev techniques.
+ if (!isSCEVable(Op->getType()))
+ return V;
+
+ const SCEV *OrigV = getSCEV(Op);
+ const SCEV *OpV = getSCEVAtScope(OrigV, L);
+ MadeImprovement |= OrigV != OpV;
+
+ Constant *C = 0;
+ if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(OpV))
+ C = SC->getValue();
+ if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(OpV))
+ C = dyn_cast<Constant>(SU->getValue());
+ if (!C) return V;
+ if (C->getType() != Op->getType())
+ C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
+ Op->getType(),
+ false),
+ C, Op->getType());
+ Operands.push_back(C);
}
- Constant *C = 0;
- if (const CmpInst *CI = dyn_cast<CmpInst>(I))
- C = ConstantFoldCompareInstOperands(CI->getPredicate(),
- Operands[0], Operands[1], TD);
- else
- C = ConstantFoldInstOperands(I->getOpcode(), I->getType(),
- &Operands[0], Operands.size(), TD);
- if (C)
+ // Check to see if getSCEVAtScope actually made an improvement.
+ if (MadeImprovement) {
+ Constant *C = 0;
+ if (const CmpInst *CI = dyn_cast<CmpInst>(I))
+ C = ConstantFoldCompareInstOperands(CI->getPredicate(),
+ Operands[0], Operands[1], TD);
+ else
+ C = ConstantFoldInstOperands(I->getOpcode(), I->getType(),
+ Operands, TD);
+ if (!C) return V;
return getSCEV(C);
+ }
}
}
// If this is a loop recurrence for a loop that does not contain L, then we
// are dealing with the final value computed by the loop.
if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) {
- if (!L || !AddRec->getLoop()->contains(L)) {
+ // First, attempt to evaluate each operand.
+ // Avoid performing the look-up in the common case where the specified
+ // expression has no loop-variant portions.
+ for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
+ const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L);
+ if (OpAtScope == AddRec->getOperand(i))
+ continue;
+
+ // Okay, at least one of these operands is loop variant but might be
+ // foldable. Build a new instance of the folded commutative expression.
+ SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(),
+ AddRec->op_begin()+i);
+ NewOps.push_back(OpAtScope);
+ for (++i; i != e; ++i)
+ NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L));
+
+ const SCEV *FoldedRec =
+ getAddRecExpr(NewOps, AddRec->getLoop(),
+ AddRec->getNoWrapFlags(SCEV::FlagNW));
+ AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec);
+ // The addrec may be folded to a nonrecurrence, for example, if the
+ // induction variable is multiplied by zero after constant folding. Go
+ // ahead and return the folded value.
+ if (!AddRec)
+ return FoldedRec;
+ break;
+ }
+
+ // If the scope is outside the addrec's loop, evaluate it by using the
+ // loop exit value of the addrec.
+ if (!AddRec->getLoop()->contains(L)) {
// To evaluate this recurrence, we need to know how many times the AddRec
// loop iterates. Compute this now.
const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop());
// Then, evaluate the AddRec.
return AddRec->evaluateAtIteration(BackedgeTakenCount, *this);
}
+
return AddRec;
}
// bit width during computations.
APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D
APInt Mod(BW + 1, 0);
- Mod.set(BW - Mult2); // Mod = N / D
+ Mod.setBit(BW - Mult2); // Mod = N / D
APInt I = AD.multiplicativeInverse(Mod);
// 4. Compute the minimum unsigned root of the equation:
/// HowFarToZero - Return the number of times a backedge comparing the specified
/// value to zero will execute. If not computable, return CouldNotCompute.
-ScalarEvolution::BackedgeTakenInfo
+///
+/// This is only used for loops with a "x != y" exit test. The exit condition is
+/// now expressed as a single expression, V = x-y. So the exit test is
+/// effectively V != 0. We know and take advantage of the fact that this
+/// expression only being used in a comparison by zero context.
+ScalarEvolution::ExitLimit
ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L) {
// If the value is a constant
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
if (!AddRec || AddRec->getLoop() != L)
return getCouldNotCompute();
- if (AddRec->isAffine()) {
- // If this is an affine expression, the execution count of this branch is
- // the minimum unsigned root of the following equation:
- //
- // Start + Step*N = 0 (mod 2^BW)
- //
- // equivalent to:
- //
- // Step*N = -Start (mod 2^BW)
- //
- // where BW is the common bit width of Start and Step.
-
- // Get the initial value for the loop.
- const SCEV *Start = getSCEVAtScope(AddRec->getStart(),
- L->getParentLoop());
- const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1),
- L->getParentLoop());
-
- if (const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step)) {
- // For now we handle only constant steps.
-
- // First, handle unitary steps.
- if (StepC->getValue()->equalsInt(1)) // 1*N = -Start (mod 2^BW), so:
- return getNegativeSCEV(Start); // N = -Start (as unsigned)
- if (StepC->getValue()->isAllOnesValue()) // -1*N = -Start (mod 2^BW), so:
- return Start; // N = Start (as unsigned)
-
- // Then, try to solve the above equation provided that Start is constant.
- if (const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start))
- return SolveLinEquationWithOverflow(StepC->getValue()->getValue(),
- -StartC->getValue()->getValue(),
- *this);
- }
- } else if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) {
- // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of
- // the quadratic equation to solve it.
- std::pair<const SCEV *,const SCEV *> Roots = SolveQuadraticEquation(AddRec,
- *this);
+ // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of
+ // the quadratic equation to solve it.
+ if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) {
+ std::pair<const SCEV *,const SCEV *> Roots =
+ SolveQuadraticEquation(AddRec, *this);
const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first);
const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second);
- if (R1) {
+ if (R1 && R2) {
#if 0
dbgs() << "HFTZ: " << *V << " - sol#1: " << *R1
<< " sol#2: " << *R2 << "\n";
#endif
// Pick the smallest positive root value.
if (ConstantInt *CB =
- dyn_cast<ConstantInt>(ConstantExpr::getICmp(ICmpInst::ICMP_ULT,
- R1->getValue(), R2->getValue()))) {
+ dyn_cast<ConstantInt>(ConstantExpr::getICmp(CmpInst::ICMP_ULT,
+ R1->getValue(),
+ R2->getValue()))) {
if (CB->getZExtValue() == false)
std::swap(R1, R2); // R1 is the minimum root now.
return R1; // We found a quadratic root!
}
}
+ return getCouldNotCompute();
}
+ // Otherwise we can only handle this if it is affine.
+ if (!AddRec->isAffine())
+ return getCouldNotCompute();
+
+ // If this is an affine expression, the execution count of this branch is
+ // the minimum unsigned root of the following equation:
+ //
+ // Start + Step*N = 0 (mod 2^BW)
+ //
+ // equivalent to:
+ //
+ // Step*N = -Start (mod 2^BW)
+ //
+ // where BW is the common bit width of Start and Step.
+
+ // Get the initial value for the loop.
+ const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop());
+ const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop());
+
+ // For now we handle only constant steps.
+ //
+ // TODO: Handle a nonconstant Step given AddRec<NUW>. If the
+ // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap
+ // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step.
+ // We have not yet seen any such cases.
+ const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step);
+ if (StepC == 0)
+ return getCouldNotCompute();
+
+ // For positive steps (counting up until unsigned overflow):
+ // N = -Start/Step (as unsigned)
+ // For negative steps (counting down to zero):
+ // N = Start/-Step
+ // First compute the unsigned distance from zero in the direction of Step.
+ bool CountDown = StepC->getValue()->getValue().isNegative();
+ const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start);
+
+ // Handle unitary steps, which cannot wraparound.
+ // 1*N = -Start; -1*N = Start (mod 2^BW), so:
+ // N = Distance (as unsigned)
+ if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue())
+ return Distance;
+
+ // If the recurrence is known not to wraparound, unsigned divide computes the
+ // back edge count. We know that the value will either become zero (and thus
+ // the loop terminates), that the loop will terminate through some other exit
+ // condition first, or that the loop has undefined behavior. This means
+ // we can't "miss" the exit value, even with nonunit stride.
+ //
+ // FIXME: Prove that loops always exhibits *acceptable* undefined
+ // behavior. Loops must exhibit defined behavior until a wrapped value is
+ // actually used. So the trip count computed by udiv could be smaller than the
+ // number of well-defined iterations.
+ if (AddRec->getNoWrapFlags(SCEV::FlagNW))
+ // FIXME: We really want an "isexact" bit for udiv.
+ return getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step);
+
+ // Then, try to solve the above equation provided that Start is constant.
+ if (const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start))
+ return SolveLinEquationWithOverflow(StepC->getValue()->getValue(),
+ -StartC->getValue()->getValue(),
+ *this);
return getCouldNotCompute();
}
/// HowFarToNonZero - Return the number of times a backedge checking the
/// specified value for nonzero will execute. If not computable, return
/// CouldNotCompute
-ScalarEvolution::BackedgeTakenInfo
+ScalarEvolution::ExitLimit
ScalarEvolution::HowFarToNonZero(const SCEV *V, const Loop *L) {
// 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
// already. If so, the backedge will execute zero times.
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
if (!C->getValue()->isNullValue())
- return getIntegerSCEV(0, C->getType());
+ return getConstant(C->getType(), 0);
return getCouldNotCompute(); // Otherwise it will loop infinitely.
}
return getCouldNotCompute();
}
-/// getLoopPredecessor - If the given loop's header has exactly one unique
-/// predecessor outside the loop, return it. Otherwise return null.
-/// This is less strict that the loop "preheader" concept, which requires
-/// the predecessor to have only one single successor.
-///
-BasicBlock *ScalarEvolution::getLoopPredecessor(const Loop *L) {
- BasicBlock *Header = L->getHeader();
- BasicBlock *Pred = 0;
- for (pred_iterator PI = pred_begin(Header), E = pred_end(Header);
- PI != E; ++PI)
- if (!L->contains(*PI)) {
- if (Pred && Pred != *PI) return 0; // Multiple predecessors.
- Pred = *PI;
- }
- return Pred;
-}
-
/// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
/// (which may not be an immediate predecessor) which has exactly one
/// successor from which BB is reachable, or null if no such block is
// If the header has a unique predecessor outside the loop, it must be
// a block that has exactly one successor that can reach the loop.
if (Loop *L = LI->getLoopFor(BB))
- return std::make_pair(getLoopPredecessor(L), L->getHeader());
+ return std::make_pair(L->getLoopPredecessor(), L->getHeader());
return std::pair<BasicBlock *, BasicBlock *>();
}
return false;
}
+/// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with
+/// predicate Pred. Return true iff any changes were made.
+///
+bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
+ const SCEV *&LHS, const SCEV *&RHS) {
+ bool Changed = false;
+
+ // Canonicalize a constant to the right side.
+ if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
+ // Check for both operands constant.
+ if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
+ if (ConstantExpr::getICmp(Pred,
+ LHSC->getValue(),
+ RHSC->getValue())->isNullValue())
+ goto trivially_false;
+ else
+ goto trivially_true;
+ }
+ // Otherwise swap the operands to put the constant on the right.
+ std::swap(LHS, RHS);
+ Pred = ICmpInst::getSwappedPredicate(Pred);
+ Changed = true;
+ }
+
+ // If we're comparing an addrec with a value which is loop-invariant in the
+ // addrec's loop, put the addrec on the left. Also make a dominance check,
+ // as both operands could be addrecs loop-invariant in each other's loop.
+ if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) {
+ const Loop *L = AR->getLoop();
+ if (isLoopInvariant(LHS, L) && properlyDominates(LHS, L->getHeader())) {
+ std::swap(LHS, RHS);
+ Pred = ICmpInst::getSwappedPredicate(Pred);
+ Changed = true;
+ }
+ }
+
+ // If there's a constant operand, canonicalize comparisons with boundary
+ // cases, and canonicalize *-or-equal comparisons to regular comparisons.
+ if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) {
+ const APInt &RA = RC->getValue()->getValue();
+ switch (Pred) {
+ default: llvm_unreachable("Unexpected ICmpInst::Predicate value!");
+ case ICmpInst::ICMP_EQ:
+ case ICmpInst::ICMP_NE:
+ break;
+ case ICmpInst::ICMP_UGE:
+ if ((RA - 1).isMinValue()) {
+ Pred = ICmpInst::ICMP_NE;
+ RHS = getConstant(RA - 1);
+ Changed = true;
+ break;
+ }
+ if (RA.isMaxValue()) {
+ Pred = ICmpInst::ICMP_EQ;
+ Changed = true;
+ break;
+ }
+ if (RA.isMinValue()) goto trivially_true;
+
+ Pred = ICmpInst::ICMP_UGT;
+ RHS = getConstant(RA - 1);
+ Changed = true;
+ break;
+ case ICmpInst::ICMP_ULE:
+ if ((RA + 1).isMaxValue()) {
+ Pred = ICmpInst::ICMP_NE;
+ RHS = getConstant(RA + 1);
+ Changed = true;
+ break;
+ }
+ if (RA.isMinValue()) {
+ Pred = ICmpInst::ICMP_EQ;
+ Changed = true;
+ break;
+ }
+ if (RA.isMaxValue()) goto trivially_true;
+
+ Pred = ICmpInst::ICMP_ULT;
+ RHS = getConstant(RA + 1);
+ Changed = true;
+ break;
+ case ICmpInst::ICMP_SGE:
+ if ((RA - 1).isMinSignedValue()) {
+ Pred = ICmpInst::ICMP_NE;
+ RHS = getConstant(RA - 1);
+ Changed = true;
+ break;
+ }
+ if (RA.isMaxSignedValue()) {
+ Pred = ICmpInst::ICMP_EQ;
+ Changed = true;
+ break;
+ }
+ if (RA.isMinSignedValue()) goto trivially_true;
+
+ Pred = ICmpInst::ICMP_SGT;
+ RHS = getConstant(RA - 1);
+ Changed = true;
+ break;
+ case ICmpInst::ICMP_SLE:
+ if ((RA + 1).isMaxSignedValue()) {
+ Pred = ICmpInst::ICMP_NE;
+ RHS = getConstant(RA + 1);
+ Changed = true;
+ break;
+ }
+ if (RA.isMinSignedValue()) {
+ Pred = ICmpInst::ICMP_EQ;
+ Changed = true;
+ break;
+ }
+ if (RA.isMaxSignedValue()) goto trivially_true;
+
+ Pred = ICmpInst::ICMP_SLT;
+ RHS = getConstant(RA + 1);
+ Changed = true;
+ break;
+ case ICmpInst::ICMP_UGT:
+ if (RA.isMinValue()) {
+ Pred = ICmpInst::ICMP_NE;
+ Changed = true;
+ break;
+ }
+ if ((RA + 1).isMaxValue()) {
+ Pred = ICmpInst::ICMP_EQ;
+ RHS = getConstant(RA + 1);
+ Changed = true;
+ break;
+ }
+ if (RA.isMaxValue()) goto trivially_false;
+ break;
+ case ICmpInst::ICMP_ULT:
+ if (RA.isMaxValue()) {
+ Pred = ICmpInst::ICMP_NE;
+ Changed = true;
+ break;
+ }
+ if ((RA - 1).isMinValue()) {
+ Pred = ICmpInst::ICMP_EQ;
+ RHS = getConstant(RA - 1);
+ Changed = true;
+ break;
+ }
+ if (RA.isMinValue()) goto trivially_false;
+ break;
+ case ICmpInst::ICMP_SGT:
+ if (RA.isMinSignedValue()) {
+ Pred = ICmpInst::ICMP_NE;
+ Changed = true;
+ break;
+ }
+ if ((RA + 1).isMaxSignedValue()) {
+ Pred = ICmpInst::ICMP_EQ;
+ RHS = getConstant(RA + 1);
+ Changed = true;
+ break;
+ }
+ if (RA.isMaxSignedValue()) goto trivially_false;
+ break;
+ case ICmpInst::ICMP_SLT:
+ if (RA.isMaxSignedValue()) {
+ Pred = ICmpInst::ICMP_NE;
+ Changed = true;
+ break;
+ }
+ if ((RA - 1).isMinSignedValue()) {
+ Pred = ICmpInst::ICMP_EQ;
+ RHS = getConstant(RA - 1);
+ Changed = true;
+ break;
+ }
+ if (RA.isMinSignedValue()) goto trivially_false;
+ break;
+ }
+ }
+
+ // Check for obvious equality.
+ if (HasSameValue(LHS, RHS)) {
+ if (ICmpInst::isTrueWhenEqual(Pred))
+ goto trivially_true;
+ if (ICmpInst::isFalseWhenEqual(Pred))
+ goto trivially_false;
+ }
+
+ // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by
+ // adding or subtracting 1 from one of the operands.
+ switch (Pred) {
+ case ICmpInst::ICMP_SLE:
+ if (!getSignedRange(RHS).getSignedMax().isMaxSignedValue()) {
+ RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
+ SCEV::FlagNSW);
+ Pred = ICmpInst::ICMP_SLT;
+ Changed = true;
+ } else if (!getSignedRange(LHS).getSignedMin().isMinSignedValue()) {
+ LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
+ SCEV::FlagNSW);
+ Pred = ICmpInst::ICMP_SLT;
+ Changed = true;
+ }
+ break;
+ case ICmpInst::ICMP_SGE:
+ if (!getSignedRange(RHS).getSignedMin().isMinSignedValue()) {
+ RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
+ SCEV::FlagNSW);
+ Pred = ICmpInst::ICMP_SGT;
+ Changed = true;
+ } else if (!getSignedRange(LHS).getSignedMax().isMaxSignedValue()) {
+ LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
+ SCEV::FlagNSW);
+ Pred = ICmpInst::ICMP_SGT;
+ Changed = true;
+ }
+ break;
+ case ICmpInst::ICMP_ULE:
+ if (!getUnsignedRange(RHS).getUnsignedMax().isMaxValue()) {
+ RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
+ SCEV::FlagNUW);
+ Pred = ICmpInst::ICMP_ULT;
+ Changed = true;
+ } else if (!getUnsignedRange(LHS).getUnsignedMin().isMinValue()) {
+ LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
+ SCEV::FlagNUW);
+ Pred = ICmpInst::ICMP_ULT;
+ Changed = true;
+ }
+ break;
+ case ICmpInst::ICMP_UGE:
+ if (!getUnsignedRange(RHS).getUnsignedMin().isMinValue()) {
+ RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
+ SCEV::FlagNUW);
+ Pred = ICmpInst::ICMP_UGT;
+ Changed = true;
+ } else if (!getUnsignedRange(LHS).getUnsignedMax().isMaxValue()) {
+ LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
+ SCEV::FlagNUW);
+ Pred = ICmpInst::ICMP_UGT;
+ Changed = true;
+ }
+ break;
+ default:
+ break;
+ }
+
+ // TODO: More simplifications are possible here.
+
+ return Changed;
+
+trivially_true:
+ // Return 0 == 0.
+ LHS = RHS = getConstant(ConstantInt::getFalse(getContext()));
+ Pred = ICmpInst::ICMP_EQ;
+ return true;
+
+trivially_false:
+ // Return 0 != 0.
+ LHS = RHS = getConstant(ConstantInt::getFalse(getContext()));
+ Pred = ICmpInst::ICMP_NE;
+ return true;
+}
+
bool ScalarEvolution::isKnownNegative(const SCEV *S) {
return getSignedRange(S).getSignedMax().isNegative();
}
bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS) {
+ // Canonicalize the inputs first.
+ (void)SimplifyICmpOperands(Pred, LHS, RHS);
+
// If LHS or RHS is an addrec, check to see if the condition is true in
// every iteration of the loop.
if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
if (isLoopEntryGuardedByCond(
AR->getLoop(), Pred, AR->getStart(), RHS) &&
isLoopBackedgeGuardedByCond(
- AR->getLoop(), Pred,
- getAddExpr(AR, AR->getStepRecurrence(*this)), RHS))
+ AR->getLoop(), Pred, AR->getPostIncExpr(*this), RHS))
return true;
if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS))
if (isLoopEntryGuardedByCond(
AR->getLoop(), Pred, LHS, AR->getStart()) &&
isLoopBackedgeGuardedByCond(
- AR->getLoop(), Pred,
- LHS, getAddExpr(AR, AR->getStepRecurrence(*this))))
+ AR->getLoop(), Pred, LHS, AR->getPostIncExpr(*this)))
return true;
// Otherwise see what can be done with known constant ranges.
LoopContinuePredicate->isUnconditional())
return false;
- return isImpliedCond(LoopContinuePredicate->getCondition(), Pred, LHS, RHS,
+ return isImpliedCond(Pred, LHS, RHS,
+ LoopContinuePredicate->getCondition(),
LoopContinuePredicate->getSuccessor(0) != L->getHeader());
}
// as there are predecessors that can be found that have unique successors
// leading to the original header.
for (std::pair<BasicBlock *, BasicBlock *>
- Pair(getLoopPredecessor(L), L->getHeader());
+ Pair(L->getLoopPredecessor(), L->getHeader());
Pair.first;
Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
LoopEntryPredicate->isUnconditional())
continue;
- if (isImpliedCond(LoopEntryPredicate->getCondition(), Pred, LHS, RHS,
+ if (isImpliedCond(Pred, LHS, RHS,
+ LoopEntryPredicate->getCondition(),
LoopEntryPredicate->getSuccessor(0) != Pair.second))
return true;
}
/// isImpliedCond - Test whether the condition described by Pred, LHS,
/// and RHS is true whenever the given Cond value evaluates to true.
-bool ScalarEvolution::isImpliedCond(Value *CondValue,
- ICmpInst::Predicate Pred,
+bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
+ Value *FoundCondValue,
bool Inverse) {
// Recursively handle And and Or conditions.
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(CondValue)) {
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FoundCondValue)) {
if (BO->getOpcode() == Instruction::And) {
if (!Inverse)
- return isImpliedCond(BO->getOperand(0), Pred, LHS, RHS, Inverse) ||
- isImpliedCond(BO->getOperand(1), Pred, LHS, RHS, Inverse);
+ return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) ||
+ isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse);
} else if (BO->getOpcode() == Instruction::Or) {
if (Inverse)
- return isImpliedCond(BO->getOperand(0), Pred, LHS, RHS, Inverse) ||
- isImpliedCond(BO->getOperand(1), Pred, LHS, RHS, Inverse);
+ return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) ||
+ isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse);
}
}
- ICmpInst *ICI = dyn_cast<ICmpInst>(CondValue);
+ ICmpInst *ICI = dyn_cast<ICmpInst>(FoundCondValue);
if (!ICI) return false;
// Bail if the ICmp's operands' types are wider than the needed type
// Canonicalize the query to match the way instcombine will have
// canonicalized the comparison.
- // First, put a constant operand on the right.
- if (isa<SCEVConstant>(LHS)) {
- std::swap(LHS, RHS);
- Pred = ICmpInst::getSwappedPredicate(Pred);
- }
- // Then, canonicalize comparisons with boundary cases.
- if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) {
- const APInt &RA = RC->getValue()->getValue();
- switch (Pred) {
- default: llvm_unreachable("Unexpected ICmpInst::Predicate value!");
- case ICmpInst::ICMP_EQ:
- case ICmpInst::ICMP_NE:
- break;
- case ICmpInst::ICMP_UGE:
- if ((RA - 1).isMinValue()) {
- Pred = ICmpInst::ICMP_NE;
- RHS = getConstant(RA - 1);
- break;
- }
- if (RA.isMaxValue()) {
- Pred = ICmpInst::ICMP_EQ;
- break;
- }
- if (RA.isMinValue()) return true;
- break;
- case ICmpInst::ICMP_ULE:
- if ((RA + 1).isMaxValue()) {
- Pred = ICmpInst::ICMP_NE;
- RHS = getConstant(RA + 1);
- break;
- }
- if (RA.isMinValue()) {
- Pred = ICmpInst::ICMP_EQ;
- break;
- }
- if (RA.isMaxValue()) return true;
- break;
- case ICmpInst::ICMP_SGE:
- if ((RA - 1).isMinSignedValue()) {
- Pred = ICmpInst::ICMP_NE;
- RHS = getConstant(RA - 1);
- break;
- }
- if (RA.isMaxSignedValue()) {
- Pred = ICmpInst::ICMP_EQ;
- break;
- }
- if (RA.isMinSignedValue()) return true;
- break;
- case ICmpInst::ICMP_SLE:
- if ((RA + 1).isMaxSignedValue()) {
- Pred = ICmpInst::ICMP_NE;
- RHS = getConstant(RA + 1);
- break;
- }
- if (RA.isMinSignedValue()) {
- Pred = ICmpInst::ICMP_EQ;
- break;
- }
- if (RA.isMaxSignedValue()) return true;
- break;
- case ICmpInst::ICMP_UGT:
- if (RA.isMinValue()) {
- Pred = ICmpInst::ICMP_NE;
- break;
- }
- if ((RA + 1).isMaxValue()) {
- Pred = ICmpInst::ICMP_EQ;
- RHS = getConstant(RA + 1);
- break;
- }
- if (RA.isMaxValue()) return false;
- break;
- case ICmpInst::ICMP_ULT:
- if (RA.isMaxValue()) {
- Pred = ICmpInst::ICMP_NE;
- break;
- }
- if ((RA - 1).isMinValue()) {
- Pred = ICmpInst::ICMP_EQ;
- RHS = getConstant(RA - 1);
- break;
- }
- if (RA.isMinValue()) return false;
- break;
- case ICmpInst::ICMP_SGT:
- if (RA.isMinSignedValue()) {
- Pred = ICmpInst::ICMP_NE;
- break;
- }
- if ((RA + 1).isMaxSignedValue()) {
- Pred = ICmpInst::ICMP_EQ;
- RHS = getConstant(RA + 1);
- break;
- }
- if (RA.isMaxSignedValue()) return false;
- break;
- case ICmpInst::ICMP_SLT:
- if (RA.isMaxSignedValue()) {
- Pred = ICmpInst::ICMP_NE;
- break;
- }
- if ((RA - 1).isMinSignedValue()) {
- Pred = ICmpInst::ICMP_EQ;
- RHS = getConstant(RA - 1);
- break;
- }
- if (RA.isMinSignedValue()) return false;
- break;
- }
- }
+ if (SimplifyICmpOperands(Pred, LHS, RHS))
+ if (LHS == RHS)
+ return CmpInst::isTrueWhenEqual(Pred);
+ if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS))
+ if (FoundLHS == FoundRHS)
+ return CmpInst::isFalseWhenEqual(Pred);
// Check to see if we can make the LHS or RHS match.
if (LHS == FoundRHS || RHS == FoundLHS) {
assert(!isKnownNegative(Step) &&
"This code doesn't handle negative strides yet!");
- const Type *Ty = Start->getType();
- const SCEV *NegOne = getIntegerSCEV(-1, Ty);
+ Type *Ty = Start->getType();
+
+ // When Start == End, we have an exact BECount == 0. Short-circuit this case
+ // here because SCEV may not be able to determine that the unsigned division
+ // after rounding is zero.
+ if (Start == End)
+ return getConstant(Ty, 0);
+
+ const SCEV *NegOne = getConstant(Ty, (uint64_t)-1);
const SCEV *Diff = getMinusSCEV(End, Start);
const SCEV *RoundUp = getAddExpr(Step, NegOne);
if (!NoWrap) {
// Check Add for unsigned overflow.
// TODO: More sophisticated things could be done here.
- const Type *WideTy = IntegerType::get(getContext(),
+ Type *WideTy = IntegerType::get(getContext(),
getTypeSizeInBits(Ty) + 1);
const SCEV *EDiff = getZeroExtendExpr(Diff, WideTy);
const SCEV *ERoundUp = getZeroExtendExpr(RoundUp, WideTy);
/// HowManyLessThans - Return the number of times a backedge containing the
/// specified less-than comparison will execute. If not computable, return
/// CouldNotCompute.
-ScalarEvolution::BackedgeTakenInfo
+ScalarEvolution::ExitLimit
ScalarEvolution::HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
const Loop *L, bool isSigned) {
// Only handle: "ADDREC < LoopInvariant".
- if (!RHS->isLoopInvariant(L)) return getCouldNotCompute();
+ if (!isLoopInvariant(RHS, L)) return getCouldNotCompute();
const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS);
if (!AddRec || AddRec->getLoop() != L)
return getCouldNotCompute();
// Check to see if we have a flag which makes analysis easy.
- bool NoWrap = isSigned ? AddRec->hasNoSignedWrap() :
- AddRec->hasNoUnsignedWrap();
+ bool NoWrap = isSigned ? AddRec->getNoWrapFlags(SCEV::FlagNSW) :
+ AddRec->getNoWrapFlags(SCEV::FlagNUW);
if (AddRec->isAffine()) {
unsigned BitWidth = getTypeSizeInBits(AddRec->getType());
// behavior, so if wrap does occur, the loop could either terminate or
// loop infinitely, but in either case, the loop is guaranteed to
// iterate at least until the iteration where the wrapping occurs.
- const SCEV *One = getIntegerSCEV(1, Step->getType());
+ const SCEV *One = getConstant(Step->getType(), 1);
if (isSigned) {
APInt Max = APInt::getSignedMaxValue(BitWidth);
if ((Max - getSignedRange(getMinusSCEV(Step, One)).getSignedMax())
// This allows the subsequent ceiling division of (N+(step-1))/step to
// compute the correct value.
const SCEV *StepMinusOne = getMinusSCEV(Step,
- getIntegerSCEV(1, Step->getType()));
+ getConstant(Step->getType(), 1));
MaxEnd = isSigned ?
getSMinExpr(MaxEnd,
getMinusSCEV(getConstant(APInt::getSignedMaxValue(BitWidth)),
// The maximum backedge count is similar, except using the minimum start
// value and the maximum end value.
- const SCEV *MaxBECount = getBECount(MinStart, MaxEnd, Step, NoWrap);
+ // If we already have an exact constant BECount, use it instead.
+ const SCEV *MaxBECount = isa<SCEVConstant>(BECount) ? BECount
+ : getBECount(MinStart, MaxEnd, Step, NoWrap);
+
+ // If the stride is nonconstant, and NoWrap == true, then
+ // getBECount(MinStart, MaxEnd) may not compute. This would result in an
+ // exact BECount and invalid MaxBECount, which should be avoided to catch
+ // more optimization opportunities.
+ if (isa<SCEVCouldNotCompute>(MaxBECount))
+ MaxBECount = BECount;
- return BackedgeTakenInfo(BECount, MaxBECount);
+ return ExitLimit(BECount, MaxBECount);
}
return getCouldNotCompute();
if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
if (!SC->getValue()->isZero()) {
SmallVector<const SCEV *, 4> Operands(op_begin(), op_end());
- Operands[0] = SE.getIntegerSCEV(0, SC->getType());
- const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop());
+ Operands[0] = SE.getConstant(SC->getType(), 0);
+ const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(),
+ getNoWrapFlags(FlagNW));
if (const SCEVAddRecExpr *ShiftedAddRec =
dyn_cast<SCEVAddRecExpr>(Shifted))
return ShiftedAddRec->getNumIterationsInRange(
// iteration exits.
unsigned BitWidth = SE.getTypeSizeInBits(getType());
if (!Range.contains(APInt(BitWidth, 0)))
- return SE.getIntegerSCEV(0, getType());
+ return SE.getConstant(getType(), 0);
if (isAffine()) {
// If this is an affine expression then we have this situation:
// Range.getUpper() is crossed.
SmallVector<const SCEV *, 4> NewOps(op_begin(), op_end());
NewOps[0] = SE.getNegativeSCEV(SE.getConstant(Range.getUpper()));
- const SCEV *NewAddRec = SE.getAddRecExpr(NewOps, getLoop());
+ const SCEV *NewAddRec = SE.getAddRecExpr(NewOps, getLoop(),
+ // getNoWrapFlags(FlagNW)
+ FlagAnyWrap);
// Next, solve the constructed addrec
std::pair<const SCEV *,const SCEV *> Roots =
assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!");
if (PHINode *PN = dyn_cast<PHINode>(getValPtr()))
SE->ConstantEvolutionLoopExitValue.erase(PN);
- SE->Scalars.erase(getValPtr());
+ SE->ValueExprMap.erase(getValPtr());
// this now dangles!
}
-void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *) {
+void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) {
assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!");
// Forget all the expressions associated with users of the old value,
// so that future queries will recompute the expressions using the new
// value.
+ Value *Old = getValPtr();
SmallVector<User *, 16> Worklist;
SmallPtrSet<User *, 8> Visited;
- Value *Old = getValPtr();
- bool DeleteOld = false;
for (Value::use_iterator UI = Old->use_begin(), UE = Old->use_end();
UI != UE; ++UI)
Worklist.push_back(*UI);
User *U = Worklist.pop_back_val();
// Deleting the Old value will cause this to dangle. Postpone
// that until everything else is done.
- if (U == Old) {
- DeleteOld = true;
+ if (U == Old)
continue;
- }
if (!Visited.insert(U))
continue;
if (PHINode *PN = dyn_cast<PHINode>(U))
SE->ConstantEvolutionLoopExitValue.erase(PN);
- SE->Scalars.erase(U);
+ SE->ValueExprMap.erase(U);
for (Value::use_iterator UI = U->use_begin(), UE = U->use_end();
UI != UE; ++UI)
Worklist.push_back(*UI);
}
- // Delete the Old value if it (indirectly) references itself.
- if (DeleteOld) {
- if (PHINode *PN = dyn_cast<PHINode>(Old))
- SE->ConstantEvolutionLoopExitValue.erase(PN);
- SE->Scalars.erase(Old);
- // this now dangles!
- }
- // this may dangle!
+ // Delete the Old value.
+ if (PHINode *PN = dyn_cast<PHINode>(Old))
+ SE->ConstantEvolutionLoopExitValue.erase(PN);
+ SE->ValueExprMap.erase(Old);
+ // this now dangles!
}
ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se)
//===----------------------------------------------------------------------===//
ScalarEvolution::ScalarEvolution()
- : FunctionPass(&ID) {
+ : FunctionPass(ID), FirstUnknown(0) {
+ initializeScalarEvolutionPass(*PassRegistry::getPassRegistry());
}
bool ScalarEvolution::runOnFunction(Function &F) {
}
void ScalarEvolution::releaseMemory() {
- Scalars.clear();
+ // Iterate through all the SCEVUnknown instances and call their
+ // destructors, so that they release their references to their values.
+ for (SCEVUnknown *U = FirstUnknown; U; U = U->Next)
+ U->~SCEVUnknown();
+ FirstUnknown = 0;
+
+ ValueExprMap.clear();
+
+ // Free any extra memory created for ExitNotTakenInfo in the unlikely event
+ // that a loop had multiple computable exits.
+ for (DenseMap<const Loop*, BackedgeTakenInfo>::iterator I =
+ BackedgeTakenCounts.begin(), E = BackedgeTakenCounts.end();
+ I != E; ++I) {
+ I->second.clear();
+ }
+
BackedgeTakenCounts.clear();
ConstantEvolutionLoopExitValue.clear();
ValuesAtScopes.clear();
+ LoopDispositions.clear();
+ BlockDispositions.clear();
+ UnsignedRanges.clear();
+ SignedRanges.clear();
UniqueSCEVs.clear();
SCEVAllocator.Reset();
}
WriteAsOperand(OS, F, /*PrintType=*/false);
OS << "\n";
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
- if (isSCEVable(I->getType())) {
+ if (isSCEVable(I->getType()) && !isa<CmpInst>(*I)) {
OS << *I << '\n';
OS << " --> ";
const SCEV *SV = SE.getSCEV(&*I);
if (L) {
OS << "\t\t" "Exits: ";
const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop());
- if (!ExitValue->isLoopInvariant(L)) {
+ if (!SE.isLoopInvariant(ExitValue, L)) {
OS << "<<Unknown>>";
} else {
OS << *ExitValue;
PrintLoopInfo(OS, &SE, *I);
}
+ScalarEvolution::LoopDisposition
+ScalarEvolution::getLoopDisposition(const SCEV *S, const Loop *L) {
+ std::map<const Loop *, LoopDisposition> &Values = LoopDispositions[S];
+ std::pair<std::map<const Loop *, LoopDisposition>::iterator, bool> Pair =
+ Values.insert(std::make_pair(L, LoopVariant));
+ if (!Pair.second)
+ return Pair.first->second;
+
+ LoopDisposition D = computeLoopDisposition(S, L);
+ return LoopDispositions[S][L] = D;
+}
+
+ScalarEvolution::LoopDisposition
+ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) {
+ switch (S->getSCEVType()) {
+ case scConstant:
+ return LoopInvariant;
+ case scTruncate:
+ case scZeroExtend:
+ case scSignExtend:
+ return getLoopDisposition(cast<SCEVCastExpr>(S)->getOperand(), L);
+ case scAddRecExpr: {
+ const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
+
+ // If L is the addrec's loop, it's computable.
+ if (AR->getLoop() == L)
+ return LoopComputable;
+
+ // Add recurrences are never invariant in the function-body (null loop).
+ if (!L)
+ return LoopVariant;
+
+ // This recurrence is variant w.r.t. L if L contains AR's loop.
+ if (L->contains(AR->getLoop()))
+ return LoopVariant;
+
+ // This recurrence is invariant w.r.t. L if AR's loop contains L.
+ if (AR->getLoop()->contains(L))
+ return LoopInvariant;
+
+ // This recurrence is variant w.r.t. L if any of its operands
+ // are variant.
+ for (SCEVAddRecExpr::op_iterator I = AR->op_begin(), E = AR->op_end();
+ I != E; ++I)
+ if (!isLoopInvariant(*I, L))
+ return LoopVariant;
+
+ // Otherwise it's loop-invariant.
+ return LoopInvariant;
+ }
+ case scAddExpr:
+ case scMulExpr:
+ case scUMaxExpr:
+ case scSMaxExpr: {
+ const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S);
+ bool HasVarying = false;
+ for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
+ I != E; ++I) {
+ LoopDisposition D = getLoopDisposition(*I, L);
+ if (D == LoopVariant)
+ return LoopVariant;
+ if (D == LoopComputable)
+ HasVarying = true;
+ }
+ return HasVarying ? LoopComputable : LoopInvariant;
+ }
+ case scUDivExpr: {
+ const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
+ LoopDisposition LD = getLoopDisposition(UDiv->getLHS(), L);
+ if (LD == LoopVariant)
+ return LoopVariant;
+ LoopDisposition RD = getLoopDisposition(UDiv->getRHS(), L);
+ if (RD == LoopVariant)
+ return LoopVariant;
+ return (LD == LoopInvariant && RD == LoopInvariant) ?
+ LoopInvariant : LoopComputable;
+ }
+ case scUnknown:
+ // All non-instruction values are loop invariant. All instructions are loop
+ // invariant if they are not contained in the specified loop.
+ // Instructions are never considered invariant in the function body
+ // (null loop) because they are defined within the "loop".
+ if (Instruction *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue()))
+ return (L && !L->contains(I)) ? LoopInvariant : LoopVariant;
+ return LoopInvariant;
+ case scCouldNotCompute:
+ llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
+ return LoopVariant;
+ default: break;
+ }
+ llvm_unreachable("Unknown SCEV kind!");
+ return LoopVariant;
+}
+
+bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) {
+ return getLoopDisposition(S, L) == LoopInvariant;
+}
+
+bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) {
+ return getLoopDisposition(S, L) == LoopComputable;
+}
+
+ScalarEvolution::BlockDisposition
+ScalarEvolution::getBlockDisposition(const SCEV *S, const BasicBlock *BB) {
+ std::map<const BasicBlock *, BlockDisposition> &Values = BlockDispositions[S];
+ std::pair<std::map<const BasicBlock *, BlockDisposition>::iterator, bool>
+ Pair = Values.insert(std::make_pair(BB, DoesNotDominateBlock));
+ if (!Pair.second)
+ return Pair.first->second;
+
+ BlockDisposition D = computeBlockDisposition(S, BB);
+ return BlockDispositions[S][BB] = D;
+}
+
+ScalarEvolution::BlockDisposition
+ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) {
+ switch (S->getSCEVType()) {
+ case scConstant:
+ return ProperlyDominatesBlock;
+ case scTruncate:
+ case scZeroExtend:
+ case scSignExtend:
+ return getBlockDisposition(cast<SCEVCastExpr>(S)->getOperand(), BB);
+ case scAddRecExpr: {
+ // This uses a "dominates" query instead of "properly dominates" query
+ // to test for proper dominance too, because the instruction which
+ // produces the addrec's value is a PHI, and a PHI effectively properly
+ // dominates its entire containing block.
+ const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
+ if (!DT->dominates(AR->getLoop()->getHeader(), BB))
+ return DoesNotDominateBlock;
+ }
+ // FALL THROUGH into SCEVNAryExpr handling.
+ case scAddExpr:
+ case scMulExpr:
+ case scUMaxExpr:
+ case scSMaxExpr: {
+ const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S);
+ bool Proper = true;
+ for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
+ I != E; ++I) {
+ BlockDisposition D = getBlockDisposition(*I, BB);
+ if (D == DoesNotDominateBlock)
+ return DoesNotDominateBlock;
+ if (D == DominatesBlock)
+ Proper = false;
+ }
+ return Proper ? ProperlyDominatesBlock : DominatesBlock;
+ }
+ case scUDivExpr: {
+ const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
+ const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS();
+ BlockDisposition LD = getBlockDisposition(LHS, BB);
+ if (LD == DoesNotDominateBlock)
+ return DoesNotDominateBlock;
+ BlockDisposition RD = getBlockDisposition(RHS, BB);
+ if (RD == DoesNotDominateBlock)
+ return DoesNotDominateBlock;
+ return (LD == ProperlyDominatesBlock && RD == ProperlyDominatesBlock) ?
+ ProperlyDominatesBlock : DominatesBlock;
+ }
+ case scUnknown:
+ if (Instruction *I =
+ dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) {
+ if (I->getParent() == BB)
+ return DominatesBlock;
+ if (DT->properlyDominates(I->getParent(), BB))
+ return ProperlyDominatesBlock;
+ return DoesNotDominateBlock;
+ }
+ return ProperlyDominatesBlock;
+ case scCouldNotCompute:
+ llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
+ return DoesNotDominateBlock;
+ default: break;
+ }
+ llvm_unreachable("Unknown SCEV kind!");
+ return DoesNotDominateBlock;
+}
+
+bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) {
+ return getBlockDisposition(S, BB) >= DominatesBlock;
+}
+
+bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) {
+ return getBlockDisposition(S, BB) == ProperlyDominatesBlock;
+}
+
+bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const {
+ switch (S->getSCEVType()) {
+ case scConstant:
+ return false;
+ case scTruncate:
+ case scZeroExtend:
+ case scSignExtend: {
+ const SCEVCastExpr *Cast = cast<SCEVCastExpr>(S);
+ const SCEV *CastOp = Cast->getOperand();
+ return Op == CastOp || hasOperand(CastOp, Op);
+ }
+ case scAddRecExpr:
+ case scAddExpr:
+ case scMulExpr:
+ case scUMaxExpr:
+ case scSMaxExpr: {
+ const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S);
+ for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
+ I != E; ++I) {
+ const SCEV *NAryOp = *I;
+ if (NAryOp == Op || hasOperand(NAryOp, Op))
+ return true;
+ }
+ return false;
+ }
+ case scUDivExpr: {
+ const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
+ const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS();
+ return LHS == Op || hasOperand(LHS, Op) ||
+ RHS == Op || hasOperand(RHS, Op);
+ }
+ case scUnknown:
+ return false;
+ case scCouldNotCompute:
+ llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
+ return false;
+ default: break;
+ }
+ llvm_unreachable("Unknown SCEV kind!");
+ return false;
+}
+
+void ScalarEvolution::forgetMemoizedResults(const SCEV *S) {
+ ValuesAtScopes.erase(S);
+ LoopDispositions.erase(S);
+ BlockDispositions.erase(S);
+ UnsignedRanges.erase(S);
+ SignedRanges.erase(S);
+}
projects / oota-llvm.git / blobdiff