1 //===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the implementation of the scalar evolution expander,
11 // which is used to generate the code corresponding to a given scalar evolution
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Analysis/ScalarEvolutionExpander.h"
17 #include "llvm/Analysis/LoopInfo.h"
18 #include "llvm/Target/TargetData.h"
19 #include "llvm/ADT/STLExtras.h"
22 /// InsertCastOfTo - Insert a cast of V to the specified type, doing what
23 /// we can to share the casts.
24 Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V,
26 // Short-circuit unnecessary bitcasts.
27 if (opcode == Instruction::BitCast && V->getType() == Ty)
30 // Short-circuit unnecessary inttoptr<->ptrtoint casts.
31 if ((opcode == Instruction::PtrToInt || opcode == Instruction::IntToPtr) &&
32 SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) {
33 if (CastInst *CI = dyn_cast<CastInst>(V))
34 if ((CI->getOpcode() == Instruction::PtrToInt ||
35 CI->getOpcode() == Instruction::IntToPtr) &&
36 SE.getTypeSizeInBits(CI->getType()) ==
37 SE.getTypeSizeInBits(CI->getOperand(0)->getType()))
38 return CI->getOperand(0);
39 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
40 if ((CE->getOpcode() == Instruction::PtrToInt ||
41 CE->getOpcode() == Instruction::IntToPtr) &&
42 SE.getTypeSizeInBits(CE->getType()) ==
43 SE.getTypeSizeInBits(CE->getOperand(0)->getType()))
44 return CE->getOperand(0);
47 // FIXME: keep track of the cast instruction.
48 if (Constant *C = dyn_cast<Constant>(V))
49 return ConstantExpr::getCast(opcode, C, Ty);
51 if (Argument *A = dyn_cast<Argument>(V)) {
52 // Check to see if there is already a cast!
53 for (Value::use_iterator UI = A->use_begin(), E = A->use_end();
55 if ((*UI)->getType() == Ty)
56 if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI)))
57 if (CI->getOpcode() == opcode) {
58 // If the cast isn't the first instruction of the function, move it.
59 if (BasicBlock::iterator(CI) !=
60 A->getParent()->getEntryBlock().begin()) {
61 // Recreate the cast at the beginning of the entry block.
62 // The old cast is left in place in case it is being used
63 // as an insert point.
65 CastInst::Create(opcode, V, Ty, "",
66 A->getParent()->getEntryBlock().begin());
68 CI->replaceAllUsesWith(NewCI);
74 Instruction *I = CastInst::Create(opcode, V, Ty, V->getName(),
75 A->getParent()->getEntryBlock().begin());
76 InsertedValues.insert(I);
80 Instruction *I = cast<Instruction>(V);
82 // Check to see if there is already a cast. If there is, use it.
83 for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
85 if ((*UI)->getType() == Ty)
86 if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI)))
87 if (CI->getOpcode() == opcode) {
88 BasicBlock::iterator It = I; ++It;
89 if (isa<InvokeInst>(I))
90 It = cast<InvokeInst>(I)->getNormalDest()->begin();
91 while (isa<PHINode>(It)) ++It;
92 if (It != BasicBlock::iterator(CI)) {
93 // Recreate the cast at the beginning of the entry block.
94 // The old cast is left in place in case it is being used
95 // as an insert point.
96 Instruction *NewCI = CastInst::Create(opcode, V, Ty, "", It);
98 CI->replaceAllUsesWith(NewCI);
104 BasicBlock::iterator IP = I; ++IP;
105 if (InvokeInst *II = dyn_cast<InvokeInst>(I))
106 IP = II->getNormalDest()->begin();
107 while (isa<PHINode>(IP)) ++IP;
108 Instruction *CI = CastInst::Create(opcode, V, Ty, V->getName(), IP);
109 InsertedValues.insert(CI);
113 /// InsertNoopCastOfTo - Insert a cast of V to the specified type,
114 /// which must be possible with a noop cast.
115 Value *SCEVExpander::InsertNoopCastOfTo(Value *V, const Type *Ty) {
116 Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false);
117 assert((Op == Instruction::BitCast ||
118 Op == Instruction::PtrToInt ||
119 Op == Instruction::IntToPtr) &&
120 "InsertNoopCastOfTo cannot perform non-noop casts!");
121 assert(SE.getTypeSizeInBits(V->getType()) == SE.getTypeSizeInBits(Ty) &&
122 "InsertNoopCastOfTo cannot change sizes!");
123 return InsertCastOfTo(Op, V, Ty);
126 /// InsertBinop - Insert the specified binary operator, doing a small amount
127 /// of work to avoid inserting an obviously redundant operation.
128 Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, Value *LHS,
129 Value *RHS, BasicBlock::iterator InsertPt) {
130 // Fold a binop with constant operands.
131 if (Constant *CLHS = dyn_cast<Constant>(LHS))
132 if (Constant *CRHS = dyn_cast<Constant>(RHS))
133 return ConstantExpr::get(Opcode, CLHS, CRHS);
135 // Do a quick scan to see if we have this binop nearby. If so, reuse it.
136 unsigned ScanLimit = 6;
137 BasicBlock::iterator BlockBegin = InsertPt->getParent()->begin();
138 if (InsertPt != BlockBegin) {
139 // Scanning starts from the last instruction before InsertPt.
140 BasicBlock::iterator IP = InsertPt;
142 for (; ScanLimit; --IP, --ScanLimit) {
143 if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS &&
144 IP->getOperand(1) == RHS)
146 if (IP == BlockBegin) break;
150 // If we haven't found this binop, insert it.
151 Instruction *BO = BinaryOperator::Create(Opcode, LHS, RHS, "tmp", InsertPt);
152 InsertedValues.insert(BO);
156 /// FactorOutConstant - Test if S is divisible by Factor, using signed
157 /// division. If so, update S with Factor divided out and return true.
158 /// S need not be evenly divisble if a reasonable remainder can be
160 /// TODO: When ScalarEvolution gets a SCEVSDivExpr, this can be made
161 /// unnecessary; in its place, just signed-divide Ops[i] by the scale and
162 /// check to see if the divide was folded.
163 static bool FactorOutConstant(const SCEV* &S,
164 const SCEV* &Remainder,
166 ScalarEvolution &SE) {
167 // Everything is divisible by one.
171 // For a Constant, check for a multiple of the given factor.
172 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
174 ConstantInt::get(C->getValue()->getValue().sdiv(Factor));
175 // If the quotient is zero and the remainder is non-zero, reject
176 // the value at this scale. It will be considered for subsequent
178 if (C->isZero() || !CI->isZero()) {
179 const SCEV* Div = SE.getConstant(CI);
182 SE.getAddExpr(Remainder,
183 SE.getConstant(C->getValue()->getValue().srem(Factor)));
188 // In a Mul, check if there is a constant operand which is a multiple
189 // of the given factor.
190 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S))
191 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
192 if (!C->getValue()->getValue().srem(Factor)) {
193 const SmallVectorImpl<const SCEV*> &MOperands = M->getOperands();
194 SmallVector<const SCEV*, 4> NewMulOps(MOperands.begin(), MOperands.end());
196 SE.getConstant(C->getValue()->getValue().sdiv(Factor));
197 S = SE.getMulExpr(NewMulOps);
201 // In an AddRec, check if both start and step are divisible.
202 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
203 const SCEV* Step = A->getStepRecurrence(SE);
204 const SCEV* StepRem = SE.getIntegerSCEV(0, Step->getType());
205 if (!FactorOutConstant(Step, StepRem, Factor, SE))
207 if (!StepRem->isZero())
209 const SCEV* Start = A->getStart();
210 if (!FactorOutConstant(Start, Remainder, Factor, SE))
212 S = SE.getAddRecExpr(Start, Step, A->getLoop());
219 /// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
220 /// instead of using ptrtoint+arithmetic+inttoptr. This helps
221 /// BasicAliasAnalysis analyze the result. However, it suffers from the
222 /// underlying bug described in PR2831. Addition in LLVM currently always
223 /// has two's complement wrapping guaranteed. However, the semantics for
224 /// getelementptr overflow are ambiguous. In the common case though, this
225 /// expansion gets used when a GEP in the original code has been converted
226 /// into integer arithmetic, in which case the resulting code will be no
227 /// more undefined than it was originally.
229 /// Design note: It might seem desirable for this function to be more
230 /// loop-aware. If some of the indices are loop-invariant while others
231 /// aren't, it might seem desirable to emit multiple GEPs, keeping the
232 /// loop-invariant portions of the overall computation outside the loop.
233 /// However, there are a few reasons this is not done here. Hoisting simple
234 /// arithmetic is a low-level optimization that often isn't very
235 /// important until late in the optimization process. In fact, passes
236 /// like InstructionCombining will combine GEPs, even if it means
237 /// pushing loop-invariant computation down into loops, so even if the
238 /// GEPs were split here, the work would quickly be undone. The
239 /// LoopStrengthReduction pass, which is usually run quite late (and
240 /// after the last InstructionCombining pass), takes care of hoisting
241 /// loop-invariant portions of expressions, after considering what
242 /// can be folded using target addressing modes.
244 Value *SCEVExpander::expandAddToGEP(const SCEV* const *op_begin,
245 const SCEV* const *op_end,
246 const PointerType *PTy,
249 const Type *ElTy = PTy->getElementType();
250 SmallVector<Value *, 4> GepIndices;
251 SmallVector<const SCEV*, 8> Ops(op_begin, op_end);
252 bool AnyNonZeroIndices = false;
254 // Decend down the pointer's type and attempt to convert the other
255 // operands into GEP indices, at each level. The first index in a GEP
256 // indexes into the array implied by the pointer operand; the rest of
257 // the indices index into the element or field type selected by the
260 APInt ElSize = APInt(SE.getTypeSizeInBits(Ty),
261 ElTy->isSized() ? SE.TD->getTypeAllocSize(ElTy) : 0);
262 SmallVector<const SCEV*, 8> NewOps;
263 SmallVector<const SCEV*, 8> ScaledOps;
264 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
265 // Split AddRecs up into parts as either of the parts may be usable
266 // without the other.
267 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i]))
268 if (!A->getStart()->isZero()) {
269 const SCEV* Start = A->getStart();
270 Ops.push_back(SE.getAddRecExpr(SE.getIntegerSCEV(0, A->getType()),
271 A->getStepRecurrence(SE),
276 // If the scale size is not 0, attempt to factor out a scale.
278 const SCEV* Op = Ops[i];
279 const SCEV* Remainder = SE.getIntegerSCEV(0, Op->getType());
280 if (FactorOutConstant(Op, Remainder, ElSize, SE)) {
281 ScaledOps.push_back(Op); // Op now has ElSize factored out.
282 NewOps.push_back(Remainder);
286 // If the operand was not divisible, add it to the list of operands
287 // we'll scan next iteration.
288 NewOps.push_back(Ops[i]);
291 AnyNonZeroIndices |= !ScaledOps.empty();
292 Value *Scaled = ScaledOps.empty() ?
293 Constant::getNullValue(Ty) :
294 expandCodeFor(SE.getAddExpr(ScaledOps), Ty);
295 GepIndices.push_back(Scaled);
297 // Collect struct field index operands.
299 while (const StructType *STy = dyn_cast<StructType>(ElTy)) {
300 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0]))
301 if (SE.getTypeSizeInBits(C->getType()) <= 64) {
302 const StructLayout &SL = *SE.TD->getStructLayout(STy);
303 uint64_t FullOffset = C->getValue()->getZExtValue();
304 if (FullOffset < SL.getSizeInBytes()) {
305 unsigned ElIdx = SL.getElementContainingOffset(FullOffset);
306 GepIndices.push_back(ConstantInt::get(Type::Int32Ty, ElIdx));
307 ElTy = STy->getTypeAtIndex(ElIdx);
309 SE.getConstant(Ty, FullOffset - SL.getElementOffset(ElIdx));
310 AnyNonZeroIndices = true;
317 if (const ArrayType *ATy = dyn_cast<ArrayType>(ElTy)) {
318 ElTy = ATy->getElementType();
324 // If none of the operands were convertable to proper GEP indices, cast
325 // the base to i8* and do an ugly getelementptr with that. It's still
326 // better than ptrtoint+arithmetic+inttoptr at least.
327 if (!AnyNonZeroIndices) {
328 V = InsertNoopCastOfTo(V,
329 Type::Int8Ty->getPointerTo(PTy->getAddressSpace()));
330 Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
332 // Fold a GEP with constant operands.
333 if (Constant *CLHS = dyn_cast<Constant>(V))
334 if (Constant *CRHS = dyn_cast<Constant>(Idx))
335 return ConstantExpr::getGetElementPtr(CLHS, &CRHS, 1);
337 // Do a quick scan to see if we have this GEP nearby. If so, reuse it.
338 unsigned ScanLimit = 6;
339 BasicBlock::iterator BlockBegin = InsertPt->getParent()->begin();
340 if (InsertPt != BlockBegin) {
341 // Scanning starts from the last instruction before InsertPt.
342 BasicBlock::iterator IP = InsertPt;
344 for (; ScanLimit; --IP, --ScanLimit) {
345 if (IP->getOpcode() == Instruction::GetElementPtr &&
346 IP->getOperand(0) == V && IP->getOperand(1) == Idx)
348 if (IP == BlockBegin) break;
352 Value *GEP = GetElementPtrInst::Create(V, Idx, "scevgep", InsertPt);
353 InsertedValues.insert(GEP);
357 // Insert a pretty getelementptr.
358 Value *GEP = GetElementPtrInst::Create(V,
361 "scevgep", InsertPt);
362 Ops.push_back(SE.getUnknown(GEP));
363 InsertedValues.insert(GEP);
364 return expand(SE.getAddExpr(Ops));
367 Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
368 const Type *Ty = SE.getEffectiveSCEVType(S->getType());
369 Value *V = expand(S->getOperand(S->getNumOperands()-1));
371 // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
372 // comments on expandAddToGEP for details.
374 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType())) {
375 const SmallVectorImpl<const SCEV*> &Ops = S->getOperands();
376 return expandAddToGEP(&Ops[0], &Ops[Ops.size() - 1],
380 V = InsertNoopCastOfTo(V, Ty);
382 // Emit a bunch of add instructions
383 for (int i = S->getNumOperands()-2; i >= 0; --i) {
384 Value *W = expandCodeFor(S->getOperand(i), Ty);
385 V = InsertBinop(Instruction::Add, V, W, InsertPt);
390 Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
391 const Type *Ty = SE.getEffectiveSCEVType(S->getType());
392 int FirstOp = 0; // Set if we should emit a subtract.
393 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0)))
394 if (SC->getValue()->isAllOnesValue())
397 int i = S->getNumOperands()-2;
398 Value *V = expandCodeFor(S->getOperand(i+1), Ty);
400 // Emit a bunch of multiply instructions
401 for (; i >= FirstOp; --i) {
402 Value *W = expandCodeFor(S->getOperand(i), Ty);
403 V = InsertBinop(Instruction::Mul, V, W, InsertPt);
406 // -1 * ... ---> 0 - ...
408 V = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), V, InsertPt);
412 Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) {
413 const Type *Ty = SE.getEffectiveSCEVType(S->getType());
415 Value *LHS = expandCodeFor(S->getLHS(), Ty);
416 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) {
417 const APInt &RHS = SC->getValue()->getValue();
418 if (RHS.isPowerOf2())
419 return InsertBinop(Instruction::LShr, LHS,
420 ConstantInt::get(Ty, RHS.logBase2()),
424 Value *RHS = expandCodeFor(S->getRHS(), Ty);
425 return InsertBinop(Instruction::UDiv, LHS, RHS, InsertPt);
428 /// Move parts of Base into Rest to leave Base with the minimal
429 /// expression that provides a pointer operand suitable for a
431 static void ExposePointerBase(const SCEV* &Base, const SCEV* &Rest,
432 ScalarEvolution &SE) {
433 while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Base)) {
434 Base = A->getStart();
435 Rest = SE.getAddExpr(Rest,
436 SE.getAddRecExpr(SE.getIntegerSCEV(0, A->getType()),
437 A->getStepRecurrence(SE),
440 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) {
441 Base = A->getOperand(A->getNumOperands()-1);
442 SmallVector<const SCEV*, 8> NewAddOps(A->op_begin(), A->op_end());
443 NewAddOps.back() = Rest;
444 Rest = SE.getAddExpr(NewAddOps);
445 ExposePointerBase(Base, Rest, SE);
449 Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
450 const Type *Ty = SE.getEffectiveSCEVType(S->getType());
451 const Loop *L = S->getLoop();
453 // First check for an existing canonical IV in a suitable type.
454 PHINode *CanonicalIV = 0;
455 if (PHINode *PN = L->getCanonicalInductionVariable())
456 if (SE.isSCEVable(PN->getType()) &&
457 isa<IntegerType>(SE.getEffectiveSCEVType(PN->getType())) &&
458 SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty))
461 // Rewrite an AddRec in terms of the canonical induction variable, if
462 // its type is more narrow.
464 SE.getTypeSizeInBits(CanonicalIV->getType()) >
465 SE.getTypeSizeInBits(Ty)) {
466 const SCEV* Start = SE.getAnyExtendExpr(S->getStart(),
467 CanonicalIV->getType());
468 const SCEV* Step = SE.getAnyExtendExpr(S->getStepRecurrence(SE),
469 CanonicalIV->getType());
470 Value *V = expand(SE.getAddRecExpr(Start, Step, S->getLoop()));
471 BasicBlock::iterator SaveInsertPt = InsertPt;
472 BasicBlock::iterator NewInsertPt =
473 next(BasicBlock::iterator(cast<Instruction>(V)));
474 while (isa<PHINode>(NewInsertPt)) ++NewInsertPt;
475 V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), 0,
477 InsertPt = SaveInsertPt;
481 // {X,+,F} --> X + {0,+,F}
482 if (!S->getStart()->isZero()) {
483 const SmallVectorImpl<const SCEV*> &SOperands = S->getOperands();
484 SmallVector<const SCEV*, 4> NewOps(SOperands.begin(), SOperands.end());
485 NewOps[0] = SE.getIntegerSCEV(0, Ty);
486 const SCEV* Rest = SE.getAddRecExpr(NewOps, L);
488 // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
489 // comments on expandAddToGEP for details.
491 const SCEV* Base = S->getStart();
492 const SCEV* RestArray[1] = { Rest };
493 // Dig into the expression to find the pointer base for a GEP.
494 ExposePointerBase(Base, RestArray[0], SE);
495 // If we found a pointer, expand the AddRec with a GEP.
496 if (const PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
497 // Make sure the Base isn't something exotic, such as a multiplied
498 // or divided pointer value. In those cases, the result type isn't
499 // actually a pointer type.
500 if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) {
501 Value *StartV = expand(Base);
502 assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!");
503 return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV);
508 // Just do a normal add. Pre-expand the operands to suppress folding.
509 return expand(SE.getAddExpr(SE.getUnknown(expand(S->getStart())),
510 SE.getUnknown(expand(Rest))));
513 // {0,+,1} --> Insert a canonical induction variable into the loop!
515 S->getOperand(1) == SE.getIntegerSCEV(1, Ty)) {
516 // If there's a canonical IV, just use it.
518 assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) &&
519 "IVs with types different from the canonical IV should "
520 "already have been handled!");
524 // Create and insert the PHI node for the induction variable in the
526 BasicBlock *Header = L->getHeader();
527 PHINode *PN = PHINode::Create(Ty, "indvar", Header->begin());
528 InsertedValues.insert(PN);
529 PN->addIncoming(Constant::getNullValue(Ty), L->getLoopPreheader());
531 pred_iterator HPI = pred_begin(Header);
532 assert(HPI != pred_end(Header) && "Loop with zero preds???");
533 if (!L->contains(*HPI)) ++HPI;
534 assert(HPI != pred_end(Header) && L->contains(*HPI) &&
535 "No backedge in loop?");
537 // Insert a unit add instruction right before the terminator corresponding
539 Constant *One = ConstantInt::get(Ty, 1);
540 Instruction *Add = BinaryOperator::CreateAdd(PN, One, "indvar.next",
541 (*HPI)->getTerminator());
542 InsertedValues.insert(Add);
544 pred_iterator PI = pred_begin(Header);
545 if (*PI == L->getLoopPreheader())
547 PN->addIncoming(Add, *PI);
551 // {0,+,F} --> {0,+,1} * F
552 // Get the canonical induction variable I for this loop.
553 Value *I = CanonicalIV ?
555 getOrInsertCanonicalInductionVariable(L, Ty);
557 // If this is a simple linear addrec, emit it now as a special case.
558 if (S->isAffine()) // {0,+,F} --> i*F
560 expand(SE.getTruncateOrNoop(
561 SE.getMulExpr(SE.getUnknown(I),
562 SE.getNoopOrAnyExtend(S->getOperand(1),
566 // If this is a chain of recurrences, turn it into a closed form, using the
567 // folders, then expandCodeFor the closed form. This allows the folders to
568 // simplify the expression without having to build a bunch of special code
570 const SCEV* IH = SE.getUnknown(I); // Get I as a "symbolic" SCEV.
572 // Promote S up to the canonical IV type, if the cast is foldable.
573 const SCEV* NewS = S;
574 const SCEV* Ext = SE.getNoopOrAnyExtend(S, I->getType());
575 if (isa<SCEVAddRecExpr>(Ext))
578 const SCEV* V = cast<SCEVAddRecExpr>(NewS)->evaluateAtIteration(IH, SE);
579 //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
581 // Truncate the result down to the original type, if needed.
582 const SCEV* T = SE.getTruncateOrNoop(V, Ty);
586 Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) {
587 const Type *Ty = SE.getEffectiveSCEVType(S->getType());
588 Value *V = expandCodeFor(S->getOperand(),
589 SE.getEffectiveSCEVType(S->getOperand()->getType()));
590 Instruction *I = new TruncInst(V, Ty, "tmp.", InsertPt);
591 InsertedValues.insert(I);
595 Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) {
596 const Type *Ty = SE.getEffectiveSCEVType(S->getType());
597 Value *V = expandCodeFor(S->getOperand(),
598 SE.getEffectiveSCEVType(S->getOperand()->getType()));
599 Instruction *I = new ZExtInst(V, Ty, "tmp.", InsertPt);
600 InsertedValues.insert(I);
604 Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) {
605 const Type *Ty = SE.getEffectiveSCEVType(S->getType());
606 Value *V = expandCodeFor(S->getOperand(),
607 SE.getEffectiveSCEVType(S->getOperand()->getType()));
608 Instruction *I = new SExtInst(V, Ty, "tmp.", InsertPt);
609 InsertedValues.insert(I);
613 Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) {
614 const Type *Ty = SE.getEffectiveSCEVType(S->getType());
615 Value *LHS = expandCodeFor(S->getOperand(0), Ty);
616 for (unsigned i = 1; i < S->getNumOperands(); ++i) {
617 Value *RHS = expandCodeFor(S->getOperand(i), Ty);
619 new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS, "tmp", InsertPt);
620 InsertedValues.insert(ICmp);
621 Instruction *Sel = SelectInst::Create(ICmp, LHS, RHS, "smax", InsertPt);
622 InsertedValues.insert(Sel);
628 Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
629 const Type *Ty = SE.getEffectiveSCEVType(S->getType());
630 Value *LHS = expandCodeFor(S->getOperand(0), Ty);
631 for (unsigned i = 1; i < S->getNumOperands(); ++i) {
632 Value *RHS = expandCodeFor(S->getOperand(i), Ty);
634 new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS, "tmp", InsertPt);
635 InsertedValues.insert(ICmp);
636 Instruction *Sel = SelectInst::Create(ICmp, LHS, RHS, "umax", InsertPt);
637 InsertedValues.insert(Sel);
643 Value *SCEVExpander::expandCodeFor(const SCEV* SH, const Type *Ty) {
644 // Expand the code for this SCEV.
645 Value *V = expand(SH);
647 assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) &&
648 "non-trivial casts should be done with the SCEVs directly!");
649 V = InsertNoopCastOfTo(V, Ty);
654 Value *SCEVExpander::expand(const SCEV *S) {
655 BasicBlock::iterator SaveInsertPt = InsertPt;
657 // Compute an insertion point for this SCEV object. Hoist the instructions
658 // as far out in the loop nest as possible.
659 for (Loop *L = SE.LI->getLoopFor(InsertPt->getParent()); ;
660 L = L->getParentLoop())
661 if (S->isLoopInvariant(L)) {
663 if (BasicBlock *Preheader = L->getLoopPreheader())
664 InsertPt = Preheader->getTerminator();
666 // If the SCEV is computable at this level, insert it into the header
667 // after the PHIs (and after any other instructions that we've inserted
668 // there) so that it is guaranteed to dominate any user inside the loop.
669 if (L && S->hasComputableLoopEvolution(L))
670 InsertPt = L->getHeader()->getFirstNonPHI();
671 while (isInsertedInstruction(InsertPt)) ++InsertPt;
675 // Check to see if we already expanded this here.
676 std::map<std::pair<const SCEV *, Instruction *>,
677 AssertingVH<Value> >::iterator I =
678 InsertedExpressions.find(std::make_pair(S, InsertPt));
679 if (I != InsertedExpressions.end()) {
680 InsertPt = SaveInsertPt;
684 // Expand the expression into instructions.
687 // Remember the expanded value for this SCEV at this location.
688 InsertedExpressions[std::make_pair(S, InsertPt)] = V;
690 InsertPt = SaveInsertPt;
694 /// getOrInsertCanonicalInductionVariable - This method returns the
695 /// canonical induction variable of the specified type for the specified
696 /// loop (inserting one if there is none). A canonical induction variable
697 /// starts at zero and steps by one on each iteration.
699 SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L,
701 assert(Ty->isInteger() && "Can only insert integer induction variables!");
702 const SCEV* H = SE.getAddRecExpr(SE.getIntegerSCEV(0, Ty),
703 SE.getIntegerSCEV(1, Ty), L);
704 BasicBlock::iterator SaveInsertPt = InsertPt;
705 Value *V = expandCodeFor(H, 0, L->getHeader()->begin());
706 InsertPt = SaveInsertPt;