1 //===- ConstantFold.cpp - LLVM constant folder ----------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements folding of constants for LLVM. This implements the
11 // (internal) ConstantFold.h interface, which is used by the
12 // ConstantExpr::get* methods to automatically fold constants when possible.
14 // The current constant folding implementation is implemented in two pieces: the
15 // template-based folder for simple primitive constants like ConstantInt, and
16 // the special case hackery that we use to symbolically evaluate expressions
17 // that use ConstantExprs.
19 //===----------------------------------------------------------------------===//
21 #include "ConstantFold.h"
22 #include "llvm/Constants.h"
23 #include "llvm/Instructions.h"
24 #include "llvm/DerivedTypes.h"
25 #include "llvm/Function.h"
26 #include "llvm/GlobalAlias.h"
27 #include "llvm/ADT/SmallVector.h"
28 #include "llvm/Support/Compiler.h"
29 #include "llvm/Support/GetElementPtrTypeIterator.h"
30 #include "llvm/Support/ManagedStatic.h"
31 #include "llvm/Support/MathExtras.h"
35 //===----------------------------------------------------------------------===//
36 // ConstantFold*Instruction Implementations
37 //===----------------------------------------------------------------------===//
39 /// CastConstantVector - Convert the specified ConstantVector node to the
40 /// specified vector type. At this point, we know that the elements of the
41 /// input vector constant are all simple integer or FP values.
42 static Constant *CastConstantVector(ConstantVector *CV,
43 const VectorType *DstTy) {
44 unsigned SrcNumElts = CV->getType()->getNumElements();
45 unsigned DstNumElts = DstTy->getNumElements();
46 const Type *SrcEltTy = CV->getType()->getElementType();
47 const Type *DstEltTy = DstTy->getElementType();
49 // If both vectors have the same number of elements (thus, the elements
50 // are the same size), perform the conversion now.
51 if (SrcNumElts == DstNumElts) {
52 std::vector<Constant*> Result;
54 // If the src and dest elements are both integers, or both floats, we can
55 // just BitCast each element because the elements are the same size.
56 if ((SrcEltTy->isInteger() && DstEltTy->isInteger()) ||
57 (SrcEltTy->isFloatingPoint() && DstEltTy->isFloatingPoint())) {
58 for (unsigned i = 0; i != SrcNumElts; ++i)
60 ConstantExpr::getBitCast(CV->getOperand(i), DstEltTy));
61 return ConstantVector::get(Result);
64 // If this is an int-to-fp cast ..
65 if (SrcEltTy->isInteger()) {
66 // Ensure that it is int-to-fp cast
67 assert(DstEltTy->isFloatingPoint());
68 if (DstEltTy->getTypeID() == Type::DoubleTyID) {
69 for (unsigned i = 0; i != SrcNumElts; ++i) {
70 ConstantInt *CI = cast<ConstantInt>(CV->getOperand(i));
71 double V = CI->getValue().bitsToDouble();
72 Result.push_back(ConstantFP::get(Type::DoubleTy, APFloat(V)));
74 return ConstantVector::get(Result);
76 assert(DstEltTy == Type::FloatTy && "Unknown fp type!");
77 for (unsigned i = 0; i != SrcNumElts; ++i) {
78 ConstantInt *CI = cast<ConstantInt>(CV->getOperand(i));
79 float V = CI->getValue().bitsToFloat();
80 Result.push_back(ConstantFP::get(Type::FloatTy, APFloat(V)));
82 return ConstantVector::get(Result);
85 // Otherwise, this is an fp-to-int cast.
86 assert(SrcEltTy->isFloatingPoint() && DstEltTy->isInteger());
88 if (SrcEltTy->getTypeID() == Type::DoubleTyID) {
89 for (unsigned i = 0; i != SrcNumElts; ++i) {
90 uint64_t V = cast<ConstantFP>(CV->getOperand(i))->
91 getValueAPF().convertToAPInt().getZExtValue();
92 Constant *C = ConstantInt::get(Type::Int64Ty, V);
93 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy ));
95 return ConstantVector::get(Result);
98 assert(SrcEltTy->getTypeID() == Type::FloatTyID);
99 for (unsigned i = 0; i != SrcNumElts; ++i) {
100 uint32_t V = (uint32_t)cast<ConstantFP>(CV->getOperand(i))->
101 getValueAPF().convertToAPInt().getZExtValue();
102 Constant *C = ConstantInt::get(Type::Int32Ty, V);
103 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy));
105 return ConstantVector::get(Result);
108 // Otherwise, this is a cast that changes element count and size. Handle
109 // casts which shrink the elements here.
111 // FIXME: We need to know endianness to do this!
116 /// This function determines which opcode to use to fold two constant cast
117 /// expressions together. It uses CastInst::isEliminableCastPair to determine
118 /// the opcode. Consequently its just a wrapper around that function.
119 /// @brief Determine if it is valid to fold a cast of a cast
121 foldConstantCastPair(
122 unsigned opc, ///< opcode of the second cast constant expression
123 const ConstantExpr*Op, ///< the first cast constant expression
124 const Type *DstTy ///< desintation type of the first cast
126 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
127 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
128 assert(CastInst::isCast(opc) && "Invalid cast opcode");
130 // The the types and opcodes for the two Cast constant expressions
131 const Type *SrcTy = Op->getOperand(0)->getType();
132 const Type *MidTy = Op->getType();
133 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
134 Instruction::CastOps secondOp = Instruction::CastOps(opc);
136 // Let CastInst::isEliminableCastPair do the heavy lifting.
137 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
141 Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
142 const Type *DestTy) {
143 const Type *SrcTy = V->getType();
145 if (isa<UndefValue>(V)) {
146 // zext(undef) = 0, because the top bits will be zero.
147 // sext(undef) = 0, because the top bits will all be the same.
148 if (opc == Instruction::ZExt || opc == Instruction::SExt)
149 return Constant::getNullValue(DestTy);
150 return UndefValue::get(DestTy);
153 // If the cast operand is a constant expression, there's a few things we can
154 // do to try to simplify it.
155 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
157 // Try hard to fold cast of cast because they are often eliminable.
158 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
159 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
160 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
161 // If all of the indexes in the GEP are null values, there is no pointer
162 // adjustment going on. We might as well cast the source pointer.
163 bool isAllNull = true;
164 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
165 if (!CE->getOperand(i)->isNullValue()) {
170 // This is casting one pointer type to another, always BitCast
171 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
175 // We actually have to do a cast now. Perform the cast according to the
178 case Instruction::FPTrunc:
179 case Instruction::FPExt:
180 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
181 APFloat Val = FPC->getValueAPF();
182 Val.convert(DestTy == Type::FloatTy ? APFloat::IEEEsingle :
183 DestTy == Type::DoubleTy ? APFloat::IEEEdouble :
184 DestTy == Type::X86_FP80Ty ? APFloat::x87DoubleExtended :
185 DestTy == Type::FP128Ty ? APFloat::IEEEquad :
187 APFloat::rmNearestTiesToEven);
188 return ConstantFP::get(DestTy, Val);
190 return 0; // Can't fold.
191 case Instruction::FPToUI:
192 case Instruction::FPToSI:
193 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
194 APFloat V = FPC->getValueAPF();
196 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
197 (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI,
198 APFloat::rmTowardZero);
199 APInt Val(DestBitWidth, 2, x);
200 return ConstantInt::get(Val);
202 return 0; // Can't fold.
203 case Instruction::IntToPtr: //always treated as unsigned
204 if (V->isNullValue()) // Is it an integral null value?
205 return ConstantPointerNull::get(cast<PointerType>(DestTy));
206 return 0; // Other pointer types cannot be casted
207 case Instruction::PtrToInt: // always treated as unsigned
208 if (V->isNullValue()) // is it a null pointer value?
209 return ConstantInt::get(DestTy, 0);
210 return 0; // Other pointer types cannot be casted
211 case Instruction::UIToFP:
212 case Instruction::SIToFP:
213 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
214 APInt api = CI->getValue();
215 const uint64_t zero[] = {0, 0};
216 uint32_t BitWidth = cast<IntegerType>(SrcTy)->getBitWidth();
217 APFloat apf = APFloat(APInt(DestTy->getPrimitiveSizeInBits(),
219 (void)apf.convertFromInteger(api.getRawData(), BitWidth,
220 opc==Instruction::SIToFP,
221 APFloat::rmNearestTiesToEven);
222 return ConstantFP::get(DestTy, apf);
225 case Instruction::ZExt:
226 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
227 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
228 APInt Result(CI->getValue());
229 Result.zext(BitWidth);
230 return ConstantInt::get(Result);
233 case Instruction::SExt:
234 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
235 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
236 APInt Result(CI->getValue());
237 Result.sext(BitWidth);
238 return ConstantInt::get(Result);
241 case Instruction::Trunc:
242 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
243 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
244 APInt Result(CI->getValue());
245 Result.trunc(BitWidth);
246 return ConstantInt::get(Result);
249 case Instruction::BitCast:
251 return (Constant*)V; // no-op cast
253 // Check to see if we are casting a pointer to an aggregate to a pointer to
254 // the first element. If so, return the appropriate GEP instruction.
255 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
256 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
257 SmallVector<Value*, 8> IdxList;
258 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
259 const Type *ElTy = PTy->getElementType();
260 while (ElTy != DPTy->getElementType()) {
261 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
262 if (STy->getNumElements() == 0) break;
263 ElTy = STy->getElementType(0);
264 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
265 } else if (const SequentialType *STy =
266 dyn_cast<SequentialType>(ElTy)) {
267 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
268 ElTy = STy->getElementType();
269 IdxList.push_back(IdxList[0]);
275 if (ElTy == DPTy->getElementType())
276 return ConstantExpr::getGetElementPtr(
277 const_cast<Constant*>(V), &IdxList[0], IdxList.size());
280 // Handle casts from one vector constant to another. We know that the src
281 // and dest type have the same size (otherwise its an illegal cast).
282 if (const VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) {
283 if (const VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) {
284 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
285 "Not cast between same sized vectors!");
286 // First, check for null and undef
287 if (isa<ConstantAggregateZero>(V))
288 return Constant::getNullValue(DestTy);
289 if (isa<UndefValue>(V))
290 return UndefValue::get(DestTy);
292 if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
293 // This is a cast from a ConstantVector of one type to a
294 // ConstantVector of another type. Check to see if all elements of
295 // the input are simple.
296 bool AllSimpleConstants = true;
297 for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) {
298 if (!isa<ConstantInt>(CV->getOperand(i)) &&
299 !isa<ConstantFP>(CV->getOperand(i))) {
300 AllSimpleConstants = false;
305 // If all of the elements are simple constants, we can fold this.
306 if (AllSimpleConstants)
307 return CastConstantVector(const_cast<ConstantVector*>(CV), DestPTy);
312 // Finally, implement bitcast folding now. The code below doesn't handle
314 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
315 return ConstantPointerNull::get(cast<PointerType>(DestTy));
317 // Handle integral constant input.
318 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
319 if (DestTy->isInteger())
320 // Integral -> Integral. This is a no-op because the bit widths must
321 // be the same. Consequently, we just fold to V.
322 return const_cast<Constant*>(V);
324 if (DestTy->isFloatingPoint()) {
325 assert((DestTy == Type::DoubleTy || DestTy == Type::FloatTy) &&
327 return ConstantFP::get(DestTy, APFloat(CI->getValue()));
329 // Otherwise, can't fold this (vector?)
333 // Handle ConstantFP input.
334 if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
336 if (DestTy == Type::Int32Ty) {
337 return ConstantInt::get(FP->getValueAPF().convertToAPInt());
339 assert(DestTy == Type::Int64Ty && "only support f32/f64 for now!");
340 return ConstantInt::get(FP->getValueAPF().convertToAPInt());
345 assert(!"Invalid CE CastInst opcode");
349 assert(0 && "Failed to cast constant expression");
353 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
355 const Constant *V2) {
356 if (const ConstantInt *CB = dyn_cast<ConstantInt>(Cond))
357 return const_cast<Constant*>(CB->getZExtValue() ? V1 : V2);
359 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
360 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
361 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
362 if (V1 == V2) return const_cast<Constant*>(V1);
366 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
367 const Constant *Idx) {
368 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
369 return UndefValue::get(cast<VectorType>(Val->getType())->getElementType());
370 if (Val->isNullValue()) // ee(zero, x) -> zero
371 return Constant::getNullValue(
372 cast<VectorType>(Val->getType())->getElementType());
374 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
375 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
376 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue()));
377 } else if (isa<UndefValue>(Idx)) {
378 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
379 return const_cast<Constant*>(CVal->getOperand(0));
385 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
387 const Constant *Idx) {
388 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
390 APInt idxVal = CIdx->getValue();
391 if (isa<UndefValue>(Val)) {
392 // Insertion of scalar constant into vector undef
393 // Optimize away insertion of undef
394 if (isa<UndefValue>(Elt))
395 return const_cast<Constant*>(Val);
396 // Otherwise break the aggregate undef into multiple undefs and do
399 cast<VectorType>(Val->getType())->getNumElements();
400 std::vector<Constant*> Ops;
402 for (unsigned i = 0; i < numOps; ++i) {
404 (idxVal == i) ? Elt : UndefValue::get(Elt->getType());
405 Ops.push_back(const_cast<Constant*>(Op));
407 return ConstantVector::get(Ops);
409 if (isa<ConstantAggregateZero>(Val)) {
410 // Insertion of scalar constant into vector aggregate zero
411 // Optimize away insertion of zero
412 if (Elt->isNullValue())
413 return const_cast<Constant*>(Val);
414 // Otherwise break the aggregate zero into multiple zeros and do
417 cast<VectorType>(Val->getType())->getNumElements();
418 std::vector<Constant*> Ops;
420 for (unsigned i = 0; i < numOps; ++i) {
422 (idxVal == i) ? Elt : Constant::getNullValue(Elt->getType());
423 Ops.push_back(const_cast<Constant*>(Op));
425 return ConstantVector::get(Ops);
427 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
428 // Insertion of scalar constant into vector constant
429 std::vector<Constant*> Ops;
430 Ops.reserve(CVal->getNumOperands());
431 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
433 (idxVal == i) ? Elt : cast<Constant>(CVal->getOperand(i));
434 Ops.push_back(const_cast<Constant*>(Op));
436 return ConstantVector::get(Ops);
441 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
443 const Constant *Mask) {
448 /// EvalVectorOp - Given two vector constants and a function pointer, apply the
449 /// function pointer to each element pair, producing a new ConstantVector
451 static Constant *EvalVectorOp(const ConstantVector *V1,
452 const ConstantVector *V2,
453 Constant *(*FP)(Constant*, Constant*)) {
454 std::vector<Constant*> Res;
455 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
456 Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
457 const_cast<Constant*>(V2->getOperand(i))));
458 return ConstantVector::get(Res);
461 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
463 const Constant *C2) {
464 // Handle UndefValue up front
465 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
467 case Instruction::Add:
468 case Instruction::Sub:
469 case Instruction::Xor:
470 return UndefValue::get(C1->getType());
471 case Instruction::Mul:
472 case Instruction::And:
473 return Constant::getNullValue(C1->getType());
474 case Instruction::UDiv:
475 case Instruction::SDiv:
476 case Instruction::FDiv:
477 case Instruction::URem:
478 case Instruction::SRem:
479 case Instruction::FRem:
480 if (!isa<UndefValue>(C2)) // undef / X -> 0
481 return Constant::getNullValue(C1->getType());
482 return const_cast<Constant*>(C2); // X / undef -> undef
483 case Instruction::Or: // X | undef -> -1
484 if (const VectorType *PTy = dyn_cast<VectorType>(C1->getType()))
485 return ConstantVector::getAllOnesValue(PTy);
486 return ConstantInt::getAllOnesValue(C1->getType());
487 case Instruction::LShr:
488 if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
489 return const_cast<Constant*>(C1); // undef lshr undef -> undef
490 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0
492 case Instruction::AShr:
493 if (!isa<UndefValue>(C2))
494 return const_cast<Constant*>(C1); // undef ashr X --> undef
495 else if (isa<UndefValue>(C1))
496 return const_cast<Constant*>(C1); // undef ashr undef -> undef
498 return const_cast<Constant*>(C1); // X ashr undef --> X
499 case Instruction::Shl:
500 // undef << X -> 0 or X << undef -> 0
501 return Constant::getNullValue(C1->getType());
505 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
506 if (isa<ConstantExpr>(C2)) {
507 // There are many possible foldings we could do here. We should probably
508 // at least fold add of a pointer with an integer into the appropriate
509 // getelementptr. This will improve alias analysis a bit.
511 // Just implement a couple of simple identities.
513 case Instruction::Add:
514 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X + 0 == X
516 case Instruction::Sub:
517 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X - 0 == X
519 case Instruction::Mul:
520 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X * 0 == 0
521 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
522 if (CI->equalsInt(1))
523 return const_cast<Constant*>(C1); // X * 1 == X
525 case Instruction::UDiv:
526 case Instruction::SDiv:
527 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
528 if (CI->equalsInt(1))
529 return const_cast<Constant*>(C1); // X / 1 == X
531 case Instruction::URem:
532 case Instruction::SRem:
533 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
534 if (CI->equalsInt(1))
535 return Constant::getNullValue(CI->getType()); // X % 1 == 0
537 case Instruction::And:
538 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2)) {
539 if (CI->isZero()) return const_cast<Constant*>(C2); // X & 0 == 0
540 if (CI->isAllOnesValue())
541 return const_cast<Constant*>(C1); // X & -1 == X
543 // (zext i32 to i64) & 4294967295 -> (zext i32 to i64)
544 if (CE1->getOpcode() == Instruction::ZExt) {
545 APInt PossiblySetBits
546 = cast<IntegerType>(CE1->getOperand(0)->getType())->getMask();
547 PossiblySetBits.zext(C1->getType()->getPrimitiveSizeInBits());
548 if ((PossiblySetBits & CI->getValue()) == PossiblySetBits)
549 return const_cast<Constant*>(C1);
552 if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
553 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
555 // Functions are at least 4-byte aligned. If and'ing the address of a
556 // function with a constant < 4, fold it to zero.
557 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
558 if (CI->getValue().ult(APInt(CI->getType()->getBitWidth(),4)) &&
560 return Constant::getNullValue(CI->getType());
563 case Instruction::Or:
564 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X | 0 == X
565 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
566 if (CI->isAllOnesValue())
567 return const_cast<Constant*>(C2); // X | -1 == -1
569 case Instruction::Xor:
570 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X ^ 0 == X
572 case Instruction::AShr:
573 // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2
574 if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero.
575 return ConstantExpr::getLShr(const_cast<Constant*>(C1),
576 const_cast<Constant*>(C2));
580 } else if (isa<ConstantExpr>(C2)) {
581 // If C2 is a constant expr and C1 isn't, flop them around and fold the
582 // other way if possible.
584 case Instruction::Add:
585 case Instruction::Mul:
586 case Instruction::And:
587 case Instruction::Or:
588 case Instruction::Xor:
589 // No change of opcode required.
590 return ConstantFoldBinaryInstruction(Opcode, C2, C1);
592 case Instruction::Shl:
593 case Instruction::LShr:
594 case Instruction::AShr:
595 case Instruction::Sub:
596 case Instruction::SDiv:
597 case Instruction::UDiv:
598 case Instruction::FDiv:
599 case Instruction::URem:
600 case Instruction::SRem:
601 case Instruction::FRem:
602 default: // These instructions cannot be flopped around.
607 // At this point we know neither constant is an UndefValue nor a ConstantExpr
608 // so look at directly computing the value.
609 if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
610 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
611 using namespace APIntOps;
612 APInt C1V = CI1->getValue();
613 APInt C2V = CI2->getValue();
617 case Instruction::Add:
618 return ConstantInt::get(C1V + C2V);
619 case Instruction::Sub:
620 return ConstantInt::get(C1V - C2V);
621 case Instruction::Mul:
622 return ConstantInt::get(C1V * C2V);
623 case Instruction::UDiv:
624 if (CI2->isNullValue())
625 return 0; // X / 0 -> can't fold
626 return ConstantInt::get(C1V.udiv(C2V));
627 case Instruction::SDiv:
628 if (CI2->isNullValue())
629 return 0; // X / 0 -> can't fold
630 if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
631 return 0; // MIN_INT / -1 -> overflow
632 return ConstantInt::get(C1V.sdiv(C2V));
633 case Instruction::URem:
634 if (C2->isNullValue())
635 return 0; // X / 0 -> can't fold
636 return ConstantInt::get(C1V.urem(C2V));
637 case Instruction::SRem:
638 if (CI2->isNullValue())
639 return 0; // X % 0 -> can't fold
640 if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
641 return 0; // MIN_INT % -1 -> overflow
642 return ConstantInt::get(C1V.srem(C2V));
643 case Instruction::And:
644 return ConstantInt::get(C1V & C2V);
645 case Instruction::Or:
646 return ConstantInt::get(C1V | C2V);
647 case Instruction::Xor:
648 return ConstantInt::get(C1V ^ C2V);
649 case Instruction::Shl:
650 if (uint32_t shiftAmt = C2V.getZExtValue())
651 if (shiftAmt < C1V.getBitWidth())
652 return ConstantInt::get(C1V.shl(shiftAmt));
654 return UndefValue::get(C1->getType()); // too big shift is undef
655 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
656 case Instruction::LShr:
657 if (uint32_t shiftAmt = C2V.getZExtValue())
658 if (shiftAmt < C1V.getBitWidth())
659 return ConstantInt::get(C1V.lshr(shiftAmt));
661 return UndefValue::get(C1->getType()); // too big shift is undef
662 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
663 case Instruction::AShr:
664 if (uint32_t shiftAmt = C2V.getZExtValue())
665 if (shiftAmt < C1V.getBitWidth())
666 return ConstantInt::get(C1V.ashr(shiftAmt));
668 return UndefValue::get(C1->getType()); // too big shift is undef
669 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
672 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
673 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
674 APFloat C1V = CFP1->getValueAPF();
675 APFloat C2V = CFP2->getValueAPF();
676 APFloat C3V = C1V; // copy for modification
677 bool isDouble = CFP1->getType()==Type::DoubleTy;
681 case Instruction::Add:
682 (void)C3V.add(C2V, APFloat::rmNearestTiesToEven);
683 return ConstantFP::get(CFP1->getType(), C3V);
684 case Instruction::Sub:
685 (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven);
686 return ConstantFP::get(CFP1->getType(), C3V);
687 case Instruction::Mul:
688 (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven);
689 return ConstantFP::get(CFP1->getType(), C3V);
690 case Instruction::FDiv:
691 (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven);
692 return ConstantFP::get(CFP1->getType(), C3V);
693 case Instruction::FRem:
695 // IEEE 754, Section 7.1, #5
696 return ConstantFP::get(CFP1->getType(), isDouble ?
697 APFloat(std::numeric_limits<double>::quiet_NaN()) :
698 APFloat(std::numeric_limits<float>::quiet_NaN()));
699 (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven);
700 return ConstantFP::get(CFP1->getType(), C3V);
703 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {
704 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) {
708 case Instruction::Add:
709 return EvalVectorOp(CP1, CP2, ConstantExpr::getAdd);
710 case Instruction::Sub:
711 return EvalVectorOp(CP1, CP2, ConstantExpr::getSub);
712 case Instruction::Mul:
713 return EvalVectorOp(CP1, CP2, ConstantExpr::getMul);
714 case Instruction::UDiv:
715 return EvalVectorOp(CP1, CP2, ConstantExpr::getUDiv);
716 case Instruction::SDiv:
717 return EvalVectorOp(CP1, CP2, ConstantExpr::getSDiv);
718 case Instruction::FDiv:
719 return EvalVectorOp(CP1, CP2, ConstantExpr::getFDiv);
720 case Instruction::URem:
721 return EvalVectorOp(CP1, CP2, ConstantExpr::getURem);
722 case Instruction::SRem:
723 return EvalVectorOp(CP1, CP2, ConstantExpr::getSRem);
724 case Instruction::FRem:
725 return EvalVectorOp(CP1, CP2, ConstantExpr::getFRem);
726 case Instruction::And:
727 return EvalVectorOp(CP1, CP2, ConstantExpr::getAnd);
728 case Instruction::Or:
729 return EvalVectorOp(CP1, CP2, ConstantExpr::getOr);
730 case Instruction::Xor:
731 return EvalVectorOp(CP1, CP2, ConstantExpr::getXor);
736 // We don't know how to fold this
740 /// isZeroSizedType - This type is zero sized if its an array or structure of
741 /// zero sized types. The only leaf zero sized type is an empty structure.
742 static bool isMaybeZeroSizedType(const Type *Ty) {
743 if (isa<OpaqueType>(Ty)) return true; // Can't say.
744 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
746 // If all of elements have zero size, this does too.
747 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
748 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
751 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
752 return isMaybeZeroSizedType(ATy->getElementType());
757 /// IdxCompare - Compare the two constants as though they were getelementptr
758 /// indices. This allows coersion of the types to be the same thing.
760 /// If the two constants are the "same" (after coersion), return 0. If the
761 /// first is less than the second, return -1, if the second is less than the
762 /// first, return 1. If the constants are not integral, return -2.
764 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
765 if (C1 == C2) return 0;
767 // Ok, we found a different index. If they are not ConstantInt, we can't do
768 // anything with them.
769 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
770 return -2; // don't know!
772 // Ok, we have two differing integer indices. Sign extend them to be the same
773 // type. Long is always big enough, so we use it.
774 if (C1->getType() != Type::Int64Ty)
775 C1 = ConstantExpr::getSExt(C1, Type::Int64Ty);
777 if (C2->getType() != Type::Int64Ty)
778 C2 = ConstantExpr::getSExt(C2, Type::Int64Ty);
780 if (C1 == C2) return 0; // They are equal
782 // If the type being indexed over is really just a zero sized type, there is
783 // no pointer difference being made here.
784 if (isMaybeZeroSizedType(ElTy))
787 // If they are really different, now that they are the same type, then we
788 // found a difference!
789 if (cast<ConstantInt>(C1)->getSExtValue() <
790 cast<ConstantInt>(C2)->getSExtValue())
796 /// evaluateFCmpRelation - This function determines if there is anything we can
797 /// decide about the two constants provided. This doesn't need to handle simple
798 /// things like ConstantFP comparisons, but should instead handle ConstantExprs.
799 /// If we can determine that the two constants have a particular relation to
800 /// each other, we should return the corresponding FCmpInst predicate,
801 /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
802 /// ConstantFoldCompareInstruction.
804 /// To simplify this code we canonicalize the relation so that the first
805 /// operand is always the most "complex" of the two. We consider ConstantFP
806 /// to be the simplest, and ConstantExprs to be the most complex.
807 static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1,
808 const Constant *V2) {
809 assert(V1->getType() == V2->getType() &&
810 "Cannot compare values of different types!");
811 // Handle degenerate case quickly
812 if (V1 == V2) return FCmpInst::FCMP_OEQ;
814 if (!isa<ConstantExpr>(V1)) {
815 if (!isa<ConstantExpr>(V2)) {
816 // We distilled thisUse the standard constant folder for a few cases
818 Constant *C1 = const_cast<Constant*>(V1);
819 Constant *C2 = const_cast<Constant*>(V2);
820 R = dyn_cast<ConstantInt>(
821 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2));
822 if (R && !R->isZero())
823 return FCmpInst::FCMP_OEQ;
824 R = dyn_cast<ConstantInt>(
825 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2));
826 if (R && !R->isZero())
827 return FCmpInst::FCMP_OLT;
828 R = dyn_cast<ConstantInt>(
829 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2));
830 if (R && !R->isZero())
831 return FCmpInst::FCMP_OGT;
833 // Nothing more we can do
834 return FCmpInst::BAD_FCMP_PREDICATE;
837 // If the first operand is simple and second is ConstantExpr, swap operands.
838 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
839 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
840 return FCmpInst::getSwappedPredicate(SwappedRelation);
842 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
843 // constantexpr or a simple constant.
844 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
845 switch (CE1->getOpcode()) {
846 case Instruction::FPTrunc:
847 case Instruction::FPExt:
848 case Instruction::UIToFP:
849 case Instruction::SIToFP:
850 // We might be able to do something with these but we don't right now.
856 // There are MANY other foldings that we could perform here. They will
857 // probably be added on demand, as they seem needed.
858 return FCmpInst::BAD_FCMP_PREDICATE;
861 /// evaluateICmpRelation - This function determines if there is anything we can
862 /// decide about the two constants provided. This doesn't need to handle simple
863 /// things like integer comparisons, but should instead handle ConstantExprs
864 /// and GlobalValues. If we can determine that the two constants have a
865 /// particular relation to each other, we should return the corresponding ICmp
866 /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.
868 /// To simplify this code we canonicalize the relation so that the first
869 /// operand is always the most "complex" of the two. We consider simple
870 /// constants (like ConstantInt) to be the simplest, followed by
871 /// GlobalValues, followed by ConstantExpr's (the most complex).
873 static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1,
876 assert(V1->getType() == V2->getType() &&
877 "Cannot compare different types of values!");
878 if (V1 == V2) return ICmpInst::ICMP_EQ;
880 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
881 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
882 // We distilled this down to a simple case, use the standard constant
885 Constant *C1 = const_cast<Constant*>(V1);
886 Constant *C2 = const_cast<Constant*>(V2);
887 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
888 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
889 if (R && !R->isZero())
891 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
892 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
893 if (R && !R->isZero())
895 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
896 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
897 if (R && !R->isZero())
900 // If we couldn't figure it out, bail.
901 return ICmpInst::BAD_ICMP_PREDICATE;
904 // If the first operand is simple, swap operands.
905 ICmpInst::Predicate SwappedRelation =
906 evaluateICmpRelation(V2, V1, isSigned);
907 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
908 return ICmpInst::getSwappedPredicate(SwappedRelation);
910 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
911 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
912 ICmpInst::Predicate SwappedRelation =
913 evaluateICmpRelation(V2, V1, isSigned);
914 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
915 return ICmpInst::getSwappedPredicate(SwappedRelation);
917 return ICmpInst::BAD_ICMP_PREDICATE;
920 // Now we know that the RHS is a GlobalValue or simple constant,
921 // which (since the types must match) means that it's a ConstantPointerNull.
922 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
923 // Don't try to decide equality of aliases.
924 if (!isa<GlobalAlias>(CPR1) && !isa<GlobalAlias>(CPR2))
925 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
926 return ICmpInst::ICMP_NE;
928 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
929 // GlobalVals can never be null. Don't try to evaluate aliases.
930 if (!CPR1->hasExternalWeakLinkage() && !isa<GlobalAlias>(CPR1))
931 return ICmpInst::ICMP_NE;
934 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
935 // constantexpr, a CPR, or a simple constant.
936 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
937 const Constant *CE1Op0 = CE1->getOperand(0);
939 switch (CE1->getOpcode()) {
940 case Instruction::Trunc:
941 case Instruction::FPTrunc:
942 case Instruction::FPExt:
943 case Instruction::FPToUI:
944 case Instruction::FPToSI:
945 break; // We can't evaluate floating point casts or truncations.
947 case Instruction::UIToFP:
948 case Instruction::SIToFP:
949 case Instruction::IntToPtr:
950 case Instruction::BitCast:
951 case Instruction::ZExt:
952 case Instruction::SExt:
953 case Instruction::PtrToInt:
954 // If the cast is not actually changing bits, and the second operand is a
955 // null pointer, do the comparison with the pre-casted value.
956 if (V2->isNullValue() &&
957 (isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) {
958 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
959 (CE1->getOpcode() == Instruction::SExt ? true :
960 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
961 return evaluateICmpRelation(
962 CE1Op0, Constant::getNullValue(CE1Op0->getType()), sgnd);
965 // If the dest type is a pointer type, and the RHS is a constantexpr cast
966 // from the same type as the src of the LHS, evaluate the inputs. This is
967 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)",
968 // which happens a lot in compilers with tagged integers.
969 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
970 if (CE2->isCast() && isa<PointerType>(CE1->getType()) &&
971 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
972 CE1->getOperand(0)->getType()->isInteger()) {
973 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
974 (CE1->getOpcode() == Instruction::SExt ? true :
975 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
976 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0),
981 case Instruction::GetElementPtr:
982 // Ok, since this is a getelementptr, we know that the constant has a
983 // pointer type. Check the various cases.
984 if (isa<ConstantPointerNull>(V2)) {
985 // If we are comparing a GEP to a null pointer, check to see if the base
986 // of the GEP equals the null pointer.
987 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
988 if (GV->hasExternalWeakLinkage())
989 // Weak linkage GVals could be zero or not. We're comparing that
990 // to null pointer so its greater-or-equal
991 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
993 // If its not weak linkage, the GVal must have a non-zero address
994 // so the result is greater-than
995 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
996 } else if (isa<ConstantPointerNull>(CE1Op0)) {
997 // If we are indexing from a null pointer, check to see if we have any
999 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
1000 if (!CE1->getOperand(i)->isNullValue())
1001 // Offsetting from null, must not be equal.
1002 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1003 // Only zero indexes from null, must still be zero.
1004 return ICmpInst::ICMP_EQ;
1006 // Otherwise, we can't really say if the first operand is null or not.
1007 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1008 if (isa<ConstantPointerNull>(CE1Op0)) {
1009 if (CPR2->hasExternalWeakLinkage())
1010 // Weak linkage GVals could be zero or not. We're comparing it to
1011 // a null pointer, so its less-or-equal
1012 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
1014 // If its not weak linkage, the GVal must have a non-zero address
1015 // so the result is less-than
1016 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1017 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
1019 // If this is a getelementptr of the same global, then it must be
1020 // different. Because the types must match, the getelementptr could
1021 // only have at most one index, and because we fold getelementptr's
1022 // with a single zero index, it must be nonzero.
1023 assert(CE1->getNumOperands() == 2 &&
1024 !CE1->getOperand(1)->isNullValue() &&
1025 "Suprising getelementptr!");
1026 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1028 // If they are different globals, we don't know what the value is,
1029 // but they can't be equal.
1030 return ICmpInst::ICMP_NE;
1034 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
1035 const Constant *CE2Op0 = CE2->getOperand(0);
1037 // There are MANY other foldings that we could perform here. They will
1038 // probably be added on demand, as they seem needed.
1039 switch (CE2->getOpcode()) {
1041 case Instruction::GetElementPtr:
1042 // By far the most common case to handle is when the base pointers are
1043 // obviously to the same or different globals.
1044 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
1045 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
1046 return ICmpInst::ICMP_NE;
1047 // Ok, we know that both getelementptr instructions are based on the
1048 // same global. From this, we can precisely determine the relative
1049 // ordering of the resultant pointers.
1052 // Compare all of the operands the GEP's have in common.
1053 gep_type_iterator GTI = gep_type_begin(CE1);
1054 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
1056 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
1057 GTI.getIndexedType())) {
1058 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
1059 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
1060 case -2: return ICmpInst::BAD_ICMP_PREDICATE;
1063 // Ok, we ran out of things they have in common. If any leftovers
1064 // are non-zero then we have a difference, otherwise we are equal.
1065 for (; i < CE1->getNumOperands(); ++i)
1066 if (!CE1->getOperand(i)->isNullValue())
1067 if (isa<ConstantInt>(CE1->getOperand(i)))
1068 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1070 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1072 for (; i < CE2->getNumOperands(); ++i)
1073 if (!CE2->getOperand(i)->isNullValue())
1074 if (isa<ConstantInt>(CE2->getOperand(i)))
1075 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1077 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1078 return ICmpInst::ICMP_EQ;
1087 return ICmpInst::BAD_ICMP_PREDICATE;
1090 Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
1092 const Constant *C2) {
1094 // Handle some degenerate cases first
1095 if (isa<UndefValue>(C1) || isa<UndefValue>(C2))
1096 return UndefValue::get(Type::Int1Ty);
1098 // icmp eq/ne(null,GV) -> false/true
1099 if (C1->isNullValue()) {
1100 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
1101 // Don't try to evaluate aliases. External weak GV can be null.
1102 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage())
1103 if (pred == ICmpInst::ICMP_EQ)
1104 return ConstantInt::getFalse();
1105 else if (pred == ICmpInst::ICMP_NE)
1106 return ConstantInt::getTrue();
1107 // icmp eq/ne(GV,null) -> false/true
1108 } else if (C2->isNullValue()) {
1109 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
1110 // Don't try to evaluate aliases. External weak GV can be null.
1111 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage())
1112 if (pred == ICmpInst::ICMP_EQ)
1113 return ConstantInt::getFalse();
1114 else if (pred == ICmpInst::ICMP_NE)
1115 return ConstantInt::getTrue();
1118 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
1119 APInt V1 = cast<ConstantInt>(C1)->getValue();
1120 APInt V2 = cast<ConstantInt>(C2)->getValue();
1122 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1123 case ICmpInst::ICMP_EQ: return ConstantInt::get(Type::Int1Ty, V1 == V2);
1124 case ICmpInst::ICMP_NE: return ConstantInt::get(Type::Int1Ty, V1 != V2);
1125 case ICmpInst::ICMP_SLT:return ConstantInt::get(Type::Int1Ty, V1.slt(V2));
1126 case ICmpInst::ICMP_SGT:return ConstantInt::get(Type::Int1Ty, V1.sgt(V2));
1127 case ICmpInst::ICMP_SLE:return ConstantInt::get(Type::Int1Ty, V1.sle(V2));
1128 case ICmpInst::ICMP_SGE:return ConstantInt::get(Type::Int1Ty, V1.sge(V2));
1129 case ICmpInst::ICMP_ULT:return ConstantInt::get(Type::Int1Ty, V1.ult(V2));
1130 case ICmpInst::ICMP_UGT:return ConstantInt::get(Type::Int1Ty, V1.ugt(V2));
1131 case ICmpInst::ICMP_ULE:return ConstantInt::get(Type::Int1Ty, V1.ule(V2));
1132 case ICmpInst::ICMP_UGE:return ConstantInt::get(Type::Int1Ty, V1.uge(V2));
1134 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
1135 APFloat C1V = cast<ConstantFP>(C1)->getValueAPF();
1136 APFloat C2V = cast<ConstantFP>(C2)->getValueAPF();
1137 APFloat::cmpResult R = C1V.compare(C2V);
1139 default: assert(0 && "Invalid FCmp Predicate"); return 0;
1140 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse();
1141 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue();
1142 case FCmpInst::FCMP_UNO:
1143 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered);
1144 case FCmpInst::FCMP_ORD:
1145 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpUnordered);
1146 case FCmpInst::FCMP_UEQ:
1147 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1148 R==APFloat::cmpEqual);
1149 case FCmpInst::FCMP_OEQ:
1150 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpEqual);
1151 case FCmpInst::FCMP_UNE:
1152 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpEqual);
1153 case FCmpInst::FCMP_ONE:
1154 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan ||
1155 R==APFloat::cmpGreaterThan);
1156 case FCmpInst::FCMP_ULT:
1157 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1158 R==APFloat::cmpLessThan);
1159 case FCmpInst::FCMP_OLT:
1160 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan);
1161 case FCmpInst::FCMP_UGT:
1162 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1163 R==APFloat::cmpGreaterThan);
1164 case FCmpInst::FCMP_OGT:
1165 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan);
1166 case FCmpInst::FCMP_ULE:
1167 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpGreaterThan);
1168 case FCmpInst::FCMP_OLE:
1169 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan ||
1170 R==APFloat::cmpEqual);
1171 case FCmpInst::FCMP_UGE:
1172 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpLessThan);
1173 case FCmpInst::FCMP_OGE:
1174 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan ||
1175 R==APFloat::cmpEqual);
1177 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {
1178 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) {
1179 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) {
1180 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1181 Constant *C= ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ,
1182 const_cast<Constant*>(CP1->getOperand(i)),
1183 const_cast<Constant*>(CP2->getOperand(i)));
1184 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1187 // Otherwise, could not decide from any element pairs.
1189 } else if (pred == ICmpInst::ICMP_EQ) {
1190 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1191 Constant *C = ConstantExpr::getICmp(ICmpInst::ICMP_EQ,
1192 const_cast<Constant*>(CP1->getOperand(i)),
1193 const_cast<Constant*>(CP2->getOperand(i)));
1194 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1197 // Otherwise, could not decide from any element pairs.
1203 if (C1->getType()->isFloatingPoint()) {
1204 switch (evaluateFCmpRelation(C1, C2)) {
1205 default: assert(0 && "Unknown relation!");
1206 case FCmpInst::FCMP_UNO:
1207 case FCmpInst::FCMP_ORD:
1208 case FCmpInst::FCMP_UEQ:
1209 case FCmpInst::FCMP_UNE:
1210 case FCmpInst::FCMP_ULT:
1211 case FCmpInst::FCMP_UGT:
1212 case FCmpInst::FCMP_ULE:
1213 case FCmpInst::FCMP_UGE:
1214 case FCmpInst::FCMP_TRUE:
1215 case FCmpInst::FCMP_FALSE:
1216 case FCmpInst::BAD_FCMP_PREDICATE:
1217 break; // Couldn't determine anything about these constants.
1218 case FCmpInst::FCMP_OEQ: // We know that C1 == C2
1219 return ConstantInt::get(Type::Int1Ty,
1220 pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
1221 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
1222 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1223 case FCmpInst::FCMP_OLT: // We know that C1 < C2
1224 return ConstantInt::get(Type::Int1Ty,
1225 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1226 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
1227 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
1228 case FCmpInst::FCMP_OGT: // We know that C1 > C2
1229 return ConstantInt::get(Type::Int1Ty,
1230 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1231 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
1232 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1233 case FCmpInst::FCMP_OLE: // We know that C1 <= C2
1234 // We can only partially decide this relation.
1235 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1236 return ConstantInt::getFalse();
1237 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1238 return ConstantInt::getTrue();
1240 case FCmpInst::FCMP_OGE: // We known that C1 >= C2
1241 // We can only partially decide this relation.
1242 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1243 return ConstantInt::getFalse();
1244 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1245 return ConstantInt::getTrue();
1247 case ICmpInst::ICMP_NE: // We know that C1 != C2
1248 // We can only partially decide this relation.
1249 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
1250 return ConstantInt::getFalse();
1251 if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
1252 return ConstantInt::getTrue();
1256 // Evaluate the relation between the two constants, per the predicate.
1257 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) {
1258 default: assert(0 && "Unknown relational!");
1259 case ICmpInst::BAD_ICMP_PREDICATE:
1260 break; // Couldn't determine anything about these constants.
1261 case ICmpInst::ICMP_EQ: // We know the constants are equal!
1262 // If we know the constants are equal, we can decide the result of this
1263 // computation precisely.
1264 return ConstantInt::get(Type::Int1Ty,
1265 pred == ICmpInst::ICMP_EQ ||
1266 pred == ICmpInst::ICMP_ULE ||
1267 pred == ICmpInst::ICMP_SLE ||
1268 pred == ICmpInst::ICMP_UGE ||
1269 pred == ICmpInst::ICMP_SGE);
1270 case ICmpInst::ICMP_ULT:
1271 // If we know that C1 < C2, we can decide the result of this computation
1273 return ConstantInt::get(Type::Int1Ty,
1274 pred == ICmpInst::ICMP_ULT ||
1275 pred == ICmpInst::ICMP_NE ||
1276 pred == ICmpInst::ICMP_ULE);
1277 case ICmpInst::ICMP_SLT:
1278 // If we know that C1 < C2, we can decide the result of this computation
1280 return ConstantInt::get(Type::Int1Ty,
1281 pred == ICmpInst::ICMP_SLT ||
1282 pred == ICmpInst::ICMP_NE ||
1283 pred == ICmpInst::ICMP_SLE);
1284 case ICmpInst::ICMP_UGT:
1285 // If we know that C1 > C2, we can decide the result of this computation
1287 return ConstantInt::get(Type::Int1Ty,
1288 pred == ICmpInst::ICMP_UGT ||
1289 pred == ICmpInst::ICMP_NE ||
1290 pred == ICmpInst::ICMP_UGE);
1291 case ICmpInst::ICMP_SGT:
1292 // If we know that C1 > C2, we can decide the result of this computation
1294 return ConstantInt::get(Type::Int1Ty,
1295 pred == ICmpInst::ICMP_SGT ||
1296 pred == ICmpInst::ICMP_NE ||
1297 pred == ICmpInst::ICMP_SGE);
1298 case ICmpInst::ICMP_ULE:
1299 // If we know that C1 <= C2, we can only partially decide this relation.
1300 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getFalse();
1301 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getTrue();
1303 case ICmpInst::ICMP_SLE:
1304 // If we know that C1 <= C2, we can only partially decide this relation.
1305 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getFalse();
1306 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getTrue();
1309 case ICmpInst::ICMP_UGE:
1310 // If we know that C1 >= C2, we can only partially decide this relation.
1311 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getFalse();
1312 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getTrue();
1314 case ICmpInst::ICMP_SGE:
1315 // If we know that C1 >= C2, we can only partially decide this relation.
1316 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getFalse();
1317 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getTrue();
1320 case ICmpInst::ICMP_NE:
1321 // If we know that C1 != C2, we can only partially decide this relation.
1322 if (pred == ICmpInst::ICMP_EQ) return ConstantInt::getFalse();
1323 if (pred == ICmpInst::ICMP_NE) return ConstantInt::getTrue();
1327 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) {
1328 // If C2 is a constant expr and C1 isn't, flop them around and fold the
1329 // other way if possible.
1331 case ICmpInst::ICMP_EQ:
1332 case ICmpInst::ICMP_NE:
1333 // No change of predicate required.
1334 return ConstantFoldCompareInstruction(pred, C2, C1);
1336 case ICmpInst::ICMP_ULT:
1337 case ICmpInst::ICMP_SLT:
1338 case ICmpInst::ICMP_UGT:
1339 case ICmpInst::ICMP_SGT:
1340 case ICmpInst::ICMP_ULE:
1341 case ICmpInst::ICMP_SLE:
1342 case ICmpInst::ICMP_UGE:
1343 case ICmpInst::ICMP_SGE:
1344 // Change the predicate as necessary to swap the operands.
1345 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
1346 return ConstantFoldCompareInstruction(pred, C2, C1);
1348 default: // These predicates cannot be flopped around.
1356 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1357 Constant* const *Idxs,
1360 (NumIdx == 1 && Idxs[0]->isNullValue()))
1361 return const_cast<Constant*>(C);
1363 if (isa<UndefValue>(C)) {
1364 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(),
1366 (Value **)Idxs+NumIdx,
1368 assert(Ty != 0 && "Invalid indices for GEP!");
1369 return UndefValue::get(PointerType::get(Ty));
1372 Constant *Idx0 = Idxs[0];
1373 if (C->isNullValue()) {
1375 for (unsigned i = 0, e = NumIdx; i != e; ++i)
1376 if (!Idxs[i]->isNullValue()) {
1381 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(),
1383 (Value**)Idxs+NumIdx,
1385 assert(Ty != 0 && "Invalid indices for GEP!");
1386 return ConstantPointerNull::get(PointerType::get(Ty));
1390 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1391 // Combine Indices - If the source pointer to this getelementptr instruction
1392 // is a getelementptr instruction, combine the indices of the two
1393 // getelementptr instructions into a single instruction.
1395 if (CE->getOpcode() == Instruction::GetElementPtr) {
1396 const Type *LastTy = 0;
1397 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1401 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1402 SmallVector<Value*, 16> NewIndices;
1403 NewIndices.reserve(NumIdx + CE->getNumOperands());
1404 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1405 NewIndices.push_back(CE->getOperand(i));
1407 // Add the last index of the source with the first index of the new GEP.
1408 // Make sure to handle the case when they are actually different types.
1409 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1410 // Otherwise it must be an array.
1411 if (!Idx0->isNullValue()) {
1412 const Type *IdxTy = Combined->getType();
1413 if (IdxTy != Idx0->getType()) {
1414 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty);
1415 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
1417 Combined = ConstantExpr::get(Instruction::Add, C1, C2);
1420 ConstantExpr::get(Instruction::Add, Idx0, Combined);
1424 NewIndices.push_back(Combined);
1425 NewIndices.insert(NewIndices.end(), Idxs+1, Idxs+NumIdx);
1426 return ConstantExpr::getGetElementPtr(CE->getOperand(0), &NewIndices[0],
1431 // Implement folding of:
1432 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1434 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1436 if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue()) {
1437 if (const PointerType *SPT =
1438 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1439 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1440 if (const ArrayType *CAT =
1441 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1442 if (CAT->getElementType() == SAT->getElementType())
1443 return ConstantExpr::getGetElementPtr(
1444 (Constant*)CE->getOperand(0), Idxs, NumIdx);
1447 // Fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1)
1448 // Into: inttoptr (i64 0 to i8*)
1449 // This happens with pointers to member functions in C++.
1450 if (CE->getOpcode() == Instruction::IntToPtr && NumIdx == 1 &&
1451 isa<ConstantInt>(CE->getOperand(0)) && isa<ConstantInt>(Idxs[0]) &&
1452 cast<PointerType>(CE->getType())->getElementType() == Type::Int8Ty) {
1453 Constant *Base = CE->getOperand(0);
1454 Constant *Offset = Idxs[0];
1456 // Convert the smaller integer to the larger type.
1457 if (Offset->getType()->getPrimitiveSizeInBits() <
1458 Base->getType()->getPrimitiveSizeInBits())
1459 Offset = ConstantExpr::getSExt(Offset, Base->getType());
1460 else if (Base->getType()->getPrimitiveSizeInBits() <
1461 Offset->getType()->getPrimitiveSizeInBits())
1462 Base = ConstantExpr::getZExt(Base, Base->getType());
1464 Base = ConstantExpr::getAdd(Base, Offset);
1465 return ConstantExpr::getIntToPtr(Base, CE->getType());