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llvm-mirror/lib/Analysis/ScalarEvolutionExpander.cpp
Dan Gohman dd7f97c496 Change all SCEV* to SCEV *. 
llvm-svn: 74918
2009-07-07 17:06:11 +00:00

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//===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the implementation of the scalar evolution expander,
// which is used to generate the code corresponding to a given scalar evolution
// expression.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/LLVMContext.h"
#include "llvm/Target/TargetData.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
/// InsertNoopCastOfTo - Insert a cast of V to the specified type,
/// which must be possible with a noop cast, doing what we can to share
/// the casts.
Value *SCEVExpander::InsertNoopCastOfTo(Value *V, const Type *Ty) {
Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false);
assert((Op == Instruction::BitCast ||
Op == Instruction::PtrToInt ||
Op == Instruction::IntToPtr) &&
"InsertNoopCastOfTo cannot perform non-noop casts!");
assert(SE.getTypeSizeInBits(V->getType()) == SE.getTypeSizeInBits(Ty) &&
"InsertNoopCastOfTo cannot change sizes!");
// Short-circuit unnecessary bitcasts.
if (Op == Instruction::BitCast && V->getType() == Ty)
return V;
// Short-circuit unnecessary inttoptr<->ptrtoint casts.
if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) &&
SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) {
if (CastInst *CI = dyn_cast<CastInst>(V))
if ((CI->getOpcode() == Instruction::PtrToInt ||
CI->getOpcode() == Instruction::IntToPtr) &&
SE.getTypeSizeInBits(CI->getType()) ==
SE.getTypeSizeInBits(CI->getOperand(0)->getType()))
return CI->getOperand(0);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
if ((CE->getOpcode() == Instruction::PtrToInt ||
CE->getOpcode() == Instruction::IntToPtr) &&
SE.getTypeSizeInBits(CE->getType()) ==
SE.getTypeSizeInBits(CE->getOperand(0)->getType()))
return CE->getOperand(0);
}
// FIXME: keep track of the cast instruction.
if (Constant *C = dyn_cast<Constant>(V))
return getContext()->getConstantExprCast(Op, C, Ty);
if (Argument *A = dyn_cast<Argument>(V)) {
// Check to see if there is already a cast!
for (Value::use_iterator UI = A->use_begin(), E = A->use_end();
UI != E; ++UI)
if ((*UI)->getType() == Ty)
if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI)))
if (CI->getOpcode() == Op) {
// If the cast isn't the first instruction of the function, move it.
if (BasicBlock::iterator(CI) !=
A->getParent()->getEntryBlock().begin()) {
// Recreate the cast at the beginning of the entry block.
// The old cast is left in place in case it is being used
// as an insert point.
Instruction *NewCI =
CastInst::Create(Op, V, Ty, "",
A->getParent()->getEntryBlock().begin());
NewCI->takeName(CI);
CI->replaceAllUsesWith(NewCI);
return NewCI;
}
return CI;
}
Instruction *I = CastInst::Create(Op, V, Ty, V->getName(),
A->getParent()->getEntryBlock().begin());
InsertedValues.insert(I);
return I;
}
Instruction *I = cast<Instruction>(V);
// Check to see if there is already a cast. If there is, use it.
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI) {
if ((*UI)->getType() == Ty)
if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI)))
if (CI->getOpcode() == Op) {
BasicBlock::iterator It = I; ++It;
if (isa<InvokeInst>(I))
It = cast<InvokeInst>(I)->getNormalDest()->begin();
while (isa<PHINode>(It)) ++It;
if (It != BasicBlock::iterator(CI)) {
// Recreate the cast at the beginning of the entry block.
// The old cast is left in place in case it is being used
// as an insert point.
Instruction *NewCI = CastInst::Create(Op, V, Ty, "", It);
NewCI->takeName(CI);
CI->replaceAllUsesWith(NewCI);
return NewCI;
}
return CI;
}
}
BasicBlock::iterator IP = I; ++IP;
if (InvokeInst *II = dyn_cast<InvokeInst>(I))
IP = II->getNormalDest()->begin();
while (isa<PHINode>(IP)) ++IP;
Instruction *CI = CastInst::Create(Op, V, Ty, V->getName(), IP);
InsertedValues.insert(CI);
return CI;
}
/// InsertBinop - Insert the specified binary operator, doing a small amount
/// of work to avoid inserting an obviously redundant operation.
Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
Value *LHS, Value *RHS) {
// Fold a binop with constant operands.
if (Constant *CLHS = dyn_cast<Constant>(LHS))
if (Constant *CRHS = dyn_cast<Constant>(RHS))
return getContext()->getConstantExpr(Opcode, CLHS, CRHS);
// Do a quick scan to see if we have this binop nearby. If so, reuse it.
unsigned ScanLimit = 6;
BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
// Scanning starts from the last instruction before the insertion point.
BasicBlock::iterator IP = Builder.GetInsertPoint();
if (IP != BlockBegin) {
--IP;
for (; ScanLimit; --IP, --ScanLimit) {
if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS &&
IP->getOperand(1) == RHS)
return IP;
if (IP == BlockBegin) break;
}
}
// If we haven't found this binop, insert it.
Value *BO = Builder.CreateBinOp(Opcode, LHS, RHS, "tmp");
InsertedValues.insert(BO);
return BO;
}
/// FactorOutConstant - Test if S is divisible by Factor, using signed
/// division. If so, update S with Factor divided out and return true.
/// S need not be evenly divisble if a reasonable remainder can be
/// computed.
/// TODO: When ScalarEvolution gets a SCEVSDivExpr, this can be made
/// unnecessary; in its place, just signed-divide Ops[i] by the scale and
/// check to see if the divide was folded.
static bool FactorOutConstant(const SCEV *&S,
const SCEV *&Remainder,
const APInt &Factor,
ScalarEvolution &SE) {
// Everything is divisible by one.
if (Factor == 1)
return true;
// For a Constant, check for a multiple of the given factor.
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
ConstantInt *CI =
SE.getContext()->getConstantInt(C->getValue()->getValue().sdiv(Factor));
// If the quotient is zero and the remainder is non-zero, reject
// the value at this scale. It will be considered for subsequent
// smaller scales.
if (C->isZero() || !CI->isZero()) {
const SCEV *Div = SE.getConstant(CI);
S = Div;
Remainder =
SE.getAddExpr(Remainder,
SE.getConstant(C->getValue()->getValue().srem(Factor)));
return true;
}
}
// In a Mul, check if there is a constant operand which is a multiple
// of the given factor.
if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S))
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
if (!C->getValue()->getValue().srem(Factor)) {
const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands();
SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(),
MOperands.end());
NewMulOps[0] =
SE.getConstant(C->getValue()->getValue().sdiv(Factor));
S = SE.getMulExpr(NewMulOps);
return true;
}
// In an AddRec, check if both start and step are divisible.
if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
const SCEV *Step = A->getStepRecurrence(SE);
const SCEV *StepRem = SE.getIntegerSCEV(0, Step->getType());
if (!FactorOutConstant(Step, StepRem, Factor, SE))
return false;
if (!StepRem->isZero())
return false;
const SCEV *Start = A->getStart();
if (!FactorOutConstant(Start, Remainder, Factor, SE))
return false;
S = SE.getAddRecExpr(Start, Step, A->getLoop());
return true;
}
return false;
}
/// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
/// instead of using ptrtoint+arithmetic+inttoptr. This helps
/// BasicAliasAnalysis analyze the result. However, it suffers from the
/// underlying bug described in PR2831. Addition in LLVM currently always
/// has two's complement wrapping guaranteed. However, the semantics for
/// getelementptr overflow are ambiguous. In the common case though, this
/// expansion gets used when a GEP in the original code has been converted
/// into integer arithmetic, in which case the resulting code will be no
/// more undefined than it was originally.
///
/// Design note: It might seem desirable for this function to be more
/// loop-aware. If some of the indices are loop-invariant while others
/// aren't, it might seem desirable to emit multiple GEPs, keeping the
/// loop-invariant portions of the overall computation outside the loop.
/// However, there are a few reasons this is not done here. Hoisting simple
/// arithmetic is a low-level optimization that often isn't very
/// important until late in the optimization process. In fact, passes
/// like InstructionCombining will combine GEPs, even if it means
/// pushing loop-invariant computation down into loops, so even if the
/// GEPs were split here, the work would quickly be undone. The
/// LoopStrengthReduction pass, which is usually run quite late (and
/// after the last InstructionCombining pass), takes care of hoisting
/// loop-invariant portions of expressions, after considering what
/// can be folded using target addressing modes.
///
Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
const SCEV *const *op_end,
const PointerType *PTy,
const Type *Ty,
Value *V) {
const Type *ElTy = PTy->getElementType();
SmallVector<Value *, 4> GepIndices;
SmallVector<const SCEV *, 8> Ops(op_begin, op_end);
bool AnyNonZeroIndices = false;
// Decend down the pointer's type and attempt to convert the other
// operands into GEP indices, at each level. The first index in a GEP
// indexes into the array implied by the pointer operand; the rest of
// the indices index into the element or field type selected by the
// preceding index.
for (;;) {
APInt ElSize = APInt(SE.getTypeSizeInBits(Ty),
ElTy->isSized() ? SE.TD->getTypeAllocSize(ElTy) : 0);
SmallVector<const SCEV *, 8> NewOps;
SmallVector<const SCEV *, 8> ScaledOps;
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
// Split AddRecs up into parts as either of the parts may be usable
// without the other.
if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i]))
if (!A->getStart()->isZero()) {
const SCEV *Start = A->getStart();
Ops.push_back(SE.getAddRecExpr(SE.getIntegerSCEV(0, A->getType()),
A->getStepRecurrence(SE),
A->getLoop()));
Ops[i] = Start;
++e;
}
// If the scale size is not 0, attempt to factor out a scale.
if (ElSize != 0) {
const SCEV *Op = Ops[i];
const SCEV *Remainder = SE.getIntegerSCEV(0, Op->getType());
if (FactorOutConstant(Op, Remainder, ElSize, SE)) {
ScaledOps.push_back(Op); // Op now has ElSize factored out.
NewOps.push_back(Remainder);
continue;
}
}
// If the operand was not divisible, add it to the list of operands
// we'll scan next iteration.
NewOps.push_back(Ops[i]);
}
Ops = NewOps;
AnyNonZeroIndices |= !ScaledOps.empty();
Value *Scaled = ScaledOps.empty() ?
getContext()->getNullValue(Ty) :
expandCodeFor(SE.getAddExpr(ScaledOps), Ty);
GepIndices.push_back(Scaled);
// Collect struct field index operands.
if (!Ops.empty())
while (const StructType *STy = dyn_cast<StructType>(ElTy)) {
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0]))
if (SE.getTypeSizeInBits(C->getType()) <= 64) {
const StructLayout &SL = *SE.TD->getStructLayout(STy);
uint64_t FullOffset = C->getValue()->getZExtValue();
if (FullOffset < SL.getSizeInBytes()) {
unsigned ElIdx = SL.getElementContainingOffset(FullOffset);
GepIndices.push_back(
getContext()->getConstantInt(Type::Int32Ty, ElIdx));
ElTy = STy->getTypeAtIndex(ElIdx);
Ops[0] =
SE.getConstant(Ty, FullOffset - SL.getElementOffset(ElIdx));
AnyNonZeroIndices = true;
continue;
}
}
break;
}
if (const ArrayType *ATy = dyn_cast<ArrayType>(ElTy)) {
ElTy = ATy->getElementType();
continue;
}
break;
}
// If none of the operands were convertable to proper GEP indices, cast
// the base to i8* and do an ugly getelementptr with that. It's still
// better than ptrtoint+arithmetic+inttoptr at least.
if (!AnyNonZeroIndices) {
V = InsertNoopCastOfTo(V,
Type::Int8Ty->getPointerTo(PTy->getAddressSpace()));
Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
// Fold a GEP with constant operands.
if (Constant *CLHS = dyn_cast<Constant>(V))
if (Constant *CRHS = dyn_cast<Constant>(Idx))
return getContext()->getConstantExprGetElementPtr(CLHS, &CRHS, 1);
// Do a quick scan to see if we have this GEP nearby. If so, reuse it.
unsigned ScanLimit = 6;
BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
// Scanning starts from the last instruction before the insertion point.
BasicBlock::iterator IP = Builder.GetInsertPoint();
if (IP != BlockBegin) {
--IP;
for (; ScanLimit; --IP, --ScanLimit) {
if (IP->getOpcode() == Instruction::GetElementPtr &&
IP->getOperand(0) == V && IP->getOperand(1) == Idx)
return IP;
if (IP == BlockBegin) break;
}
}
Value *GEP = Builder.CreateGEP(V, Idx, "scevgep");
InsertedValues.insert(GEP);
return GEP;
}
// Insert a pretty getelementptr.
Value *GEP = Builder.CreateGEP(V,
GepIndices.begin(),
GepIndices.end(),
"scevgep");
Ops.push_back(SE.getUnknown(GEP));
InsertedValues.insert(GEP);
return expand(SE.getAddExpr(Ops));
}
Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *V = expand(S->getOperand(S->getNumOperands()-1));
// Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
// comments on expandAddToGEP for details.
if (SE.TD)
if (const PointerType *PTy = dyn_cast<PointerType>(V->getType())) {
const SmallVectorImpl<const SCEV *> &Ops = S->getOperands();
return expandAddToGEP(&Ops[0], &Ops[Ops.size() - 1], PTy, Ty, V);
}
V = InsertNoopCastOfTo(V, Ty);
// Emit a bunch of add instructions
for (int i = S->getNumOperands()-2; i >= 0; --i) {
Value *W = expandCodeFor(S->getOperand(i), Ty);
V = InsertBinop(Instruction::Add, V, W);
}
return V;
}
Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
int FirstOp = 0; // Set if we should emit a subtract.
if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0)))
if (SC->getValue()->isAllOnesValue())
FirstOp = 1;
int i = S->getNumOperands()-2;
Value *V = expandCodeFor(S->getOperand(i+1), Ty);
// Emit a bunch of multiply instructions
for (; i >= FirstOp; --i) {
Value *W = expandCodeFor(S->getOperand(i), Ty);
V = InsertBinop(Instruction::Mul, V, W);
}
// -1 * ... ---> 0 - ...
if (FirstOp == 1)
V = InsertBinop(Instruction::Sub, getContext()->getNullValue(Ty), V);
return V;
}
Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) {
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *LHS = expandCodeFor(S->getLHS(), Ty);
if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) {
const APInt &RHS = SC->getValue()->getValue();
if (RHS.isPowerOf2())
return InsertBinop(Instruction::LShr, LHS,
getContext()->getConstantInt(Ty, RHS.logBase2()));
}
Value *RHS = expandCodeFor(S->getRHS(), Ty);
return InsertBinop(Instruction::UDiv, LHS, RHS);
}
/// Move parts of Base into Rest to leave Base with the minimal
/// expression that provides a pointer operand suitable for a
/// GEP expansion.
static void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest,
ScalarEvolution &SE) {
while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Base)) {
Base = A->getStart();
Rest = SE.getAddExpr(Rest,
SE.getAddRecExpr(SE.getIntegerSCEV(0, A->getType()),
A->getStepRecurrence(SE),
A->getLoop()));
}
if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) {
Base = A->getOperand(A->getNumOperands()-1);
SmallVector<const SCEV *, 8> NewAddOps(A->op_begin(), A->op_end());
NewAddOps.back() = Rest;
Rest = SE.getAddExpr(NewAddOps);
ExposePointerBase(Base, Rest, SE);
}
}
Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
const Loop *L = S->getLoop();
// First check for an existing canonical IV in a suitable type.
PHINode *CanonicalIV = 0;
if (PHINode *PN = L->getCanonicalInductionVariable())
if (SE.isSCEVable(PN->getType()) &&
isa<IntegerType>(SE.getEffectiveSCEVType(PN->getType())) &&
SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty))
CanonicalIV = PN;
// Rewrite an AddRec in terms of the canonical induction variable, if
// its type is more narrow.
if (CanonicalIV &&
SE.getTypeSizeInBits(CanonicalIV->getType()) >
SE.getTypeSizeInBits(Ty)) {
const SCEV *Start = SE.getAnyExtendExpr(S->getStart(),
CanonicalIV->getType());
const SCEV *Step = SE.getAnyExtendExpr(S->getStepRecurrence(SE),
CanonicalIV->getType());
Value *V = expand(SE.getAddRecExpr(Start, Step, S->getLoop()));
BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
BasicBlock::iterator NewInsertPt =
next(BasicBlock::iterator(cast<Instruction>(V)));
while (isa<PHINode>(NewInsertPt)) ++NewInsertPt;
V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), 0,
NewInsertPt);
Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
return V;
}
// {X,+,F} --> X + {0,+,F}
if (!S->getStart()->isZero()) {
const SmallVectorImpl<const SCEV *> &SOperands = S->getOperands();
SmallVector<const SCEV *, 4> NewOps(SOperands.begin(), SOperands.end());
NewOps[0] = SE.getIntegerSCEV(0, Ty);
const SCEV *Rest = SE.getAddRecExpr(NewOps, L);
// Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
// comments on expandAddToGEP for details.
if (SE.TD) {
const SCEV *Base = S->getStart();
const SCEV *RestArray[1] = { Rest };
// Dig into the expression to find the pointer base for a GEP.
ExposePointerBase(Base, RestArray[0], SE);
// If we found a pointer, expand the AddRec with a GEP.
if (const PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
// Make sure the Base isn't something exotic, such as a multiplied
// or divided pointer value. In those cases, the result type isn't
// actually a pointer type.
if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) {
Value *StartV = expand(Base);
assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!");
return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV);
}
}
}
// Just do a normal add. Pre-expand the operands to suppress folding.
return expand(SE.getAddExpr(SE.getUnknown(expand(S->getStart())),
SE.getUnknown(expand(Rest))));
}
// {0,+,1} --> Insert a canonical induction variable into the loop!
if (S->isAffine() &&
S->getOperand(1) == SE.getIntegerSCEV(1, Ty)) {
// If there's a canonical IV, just use it.
if (CanonicalIV) {
assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) &&
"IVs with types different from the canonical IV should "
"already have been handled!");
return CanonicalIV;
}
// Create and insert the PHI node for the induction variable in the
// specified loop.
BasicBlock *Header = L->getHeader();
BasicBlock *Preheader = L->getLoopPreheader();
PHINode *PN = PHINode::Create(Ty, "indvar", Header->begin());
InsertedValues.insert(PN);
PN->addIncoming(getContext()->getNullValue(Ty), Preheader);
pred_iterator HPI = pred_begin(Header);
assert(HPI != pred_end(Header) && "Loop with zero preds???");
if (!L->contains(*HPI)) ++HPI;
assert(HPI != pred_end(Header) && L->contains(*HPI) &&
"No backedge in loop?");
// Insert a unit add instruction right before the terminator corresponding
// to the back-edge.
Constant *One = getContext()->getConstantInt(Ty, 1);
Instruction *Add = BinaryOperator::CreateAdd(PN, One, "indvar.next",
(*HPI)->getTerminator());
InsertedValues.insert(Add);
pred_iterator PI = pred_begin(Header);
if (*PI == Preheader)
++PI;
PN->addIncoming(Add, *PI);
return PN;
}
// {0,+,F} --> {0,+,1} * F
// Get the canonical induction variable I for this loop.
Value *I = CanonicalIV ?
CanonicalIV :
getOrInsertCanonicalInductionVariable(L, Ty);
// If this is a simple linear addrec, emit it now as a special case.
if (S->isAffine()) // {0,+,F} --> i*F
return
expand(SE.getTruncateOrNoop(
SE.getMulExpr(SE.getUnknown(I),
SE.getNoopOrAnyExtend(S->getOperand(1),
I->getType())),
Ty));
// If this is a chain of recurrences, turn it into a closed form, using the
// folders, then expandCodeFor the closed form. This allows the folders to
// simplify the expression without having to build a bunch of special code
// into this folder.
const SCEV *IH = SE.getUnknown(I); // Get I as a "symbolic" SCEV.
// Promote S up to the canonical IV type, if the cast is foldable.
const SCEV *NewS = S;
const SCEV *Ext = SE.getNoopOrAnyExtend(S, I->getType());
if (isa<SCEVAddRecExpr>(Ext))
NewS = Ext;
const SCEV *V = cast<SCEVAddRecExpr>(NewS)->evaluateAtIteration(IH, SE);
//cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
// Truncate the result down to the original type, if needed.
const SCEV *T = SE.getTruncateOrNoop(V, Ty);
return expand(T);
}
Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) {
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *V = expandCodeFor(S->getOperand(),
SE.getEffectiveSCEVType(S->getOperand()->getType()));
Value *I = Builder.CreateTrunc(V, Ty, "tmp");
InsertedValues.insert(I);
return I;
}
Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) {
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *V = expandCodeFor(S->getOperand(),
SE.getEffectiveSCEVType(S->getOperand()->getType()));
Value *I = Builder.CreateZExt(V, Ty, "tmp");
InsertedValues.insert(I);
return I;
}
Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) {
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *V = expandCodeFor(S->getOperand(),
SE.getEffectiveSCEVType(S->getOperand()->getType()));
Value *I = Builder.CreateSExt(V, Ty, "tmp");
InsertedValues.insert(I);
return I;
}
Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) {
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *LHS = expandCodeFor(S->getOperand(0), Ty);
for (unsigned i = 1; i < S->getNumOperands(); ++i) {
Value *RHS = expandCodeFor(S->getOperand(i), Ty);
Value *ICmp = Builder.CreateICmpSGT(LHS, RHS, "tmp");
InsertedValues.insert(ICmp);
Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax");
InsertedValues.insert(Sel);
LHS = Sel;
}
return LHS;
}
Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
Value *LHS = expandCodeFor(S->getOperand(0), Ty);
for (unsigned i = 1; i < S->getNumOperands(); ++i) {
Value *RHS = expandCodeFor(S->getOperand(i), Ty);
Value *ICmp = Builder.CreateICmpUGT(LHS, RHS, "tmp");
InsertedValues.insert(ICmp);
Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax");
InsertedValues.insert(Sel);
LHS = Sel;
}
return LHS;
}
Value *SCEVExpander::expandCodeFor(const SCEV *SH, const Type *Ty) {
// Expand the code for this SCEV.
Value *V = expand(SH);
if (Ty) {
assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) &&
"non-trivial casts should be done with the SCEVs directly!");
V = InsertNoopCastOfTo(V, Ty);
}
return V;
}
Value *SCEVExpander::expand(const SCEV *S) {
// Compute an insertion point for this SCEV object. Hoist the instructions
// as far out in the loop nest as possible.
Instruction *InsertPt = Builder.GetInsertPoint();
for (Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock()); ;
L = L->getParentLoop())
if (S->isLoopInvariant(L)) {
if (!L) break;
if (BasicBlock *Preheader = L->getLoopPreheader())
InsertPt = Preheader->getTerminator();
} else {
// If the SCEV is computable at this level, insert it into the header
// after the PHIs (and after any other instructions that we've inserted
// there) so that it is guaranteed to dominate any user inside the loop.
if (L && S->hasComputableLoopEvolution(L))
InsertPt = L->getHeader()->getFirstNonPHI();
while (isInsertedInstruction(InsertPt))
InsertPt = next(BasicBlock::iterator(InsertPt));
break;
}
// Check to see if we already expanded this here.
std::map<std::pair<const SCEV *, Instruction *>,
AssertingVH<Value> >::iterator I =
InsertedExpressions.find(std::make_pair(S, InsertPt));
if (I != InsertedExpressions.end())
return I->second;
BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
Builder.SetInsertPoint(InsertPt->getParent(), InsertPt);
// Expand the expression into instructions.
Value *V = visit(S);
// Remember the expanded value for this SCEV at this location.
InsertedExpressions[std::make_pair(S, InsertPt)] = V;
Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
return V;
}
/// getOrInsertCanonicalInductionVariable - This method returns the
/// canonical induction variable of the specified type for the specified
/// loop (inserting one if there is none). A canonical induction variable
/// starts at zero and steps by one on each iteration.
Value *
SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L,
const Type *Ty) {
assert(Ty->isInteger() && "Can only insert integer induction variables!");
const SCEV *H = SE.getAddRecExpr(SE.getIntegerSCEV(0, Ty),
SE.getIntegerSCEV(1, Ty), L);
BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
Value *V = expandCodeFor(H, 0, L->getHeader()->begin());
if (SaveInsertBB)
Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
return V;
}
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