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 /// BitCastConstantVector - 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 *BitCastConstantVector(ConstantVector *CV,
43 const VectorType *DstTy) {
44 // If this cast changes element count then we can't handle it here:
45 // doing so requires endianness information. This should be handled by
46 // Analysis/ConstantFolding.cpp
47 unsigned NumElts = DstTy->getNumElements();
48 if (NumElts != CV->getNumOperands())
51 // Check to verify that all elements of the input are simple.
52 for (unsigned i = 0; i != NumElts; ++i) {
53 if (!isa<ConstantInt>(CV->getOperand(i)) &&
54 !isa<ConstantFP>(CV->getOperand(i)))
58 // Bitcast each element now.
59 std::vector<Constant*> Result;
60 const Type *DstEltTy = DstTy->getElementType();
61 for (unsigned i = 0; i != NumElts; ++i)
62 Result.push_back(ConstantExpr::getBitCast(CV->getOperand(i), DstEltTy));
63 return ConstantVector::get(Result);
66 /// This function determines which opcode to use to fold two constant cast
67 /// expressions together. It uses CastInst::isEliminableCastPair to determine
68 /// the opcode. Consequently its just a wrapper around that function.
69 /// @brief Determine if it is valid to fold a cast of a cast
72 unsigned opc, ///< opcode of the second cast constant expression
73 const ConstantExpr*Op, ///< the first cast constant expression
74 const Type *DstTy ///< desintation type of the first cast
76 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
77 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
78 assert(CastInst::isCast(opc) && "Invalid cast opcode");
80 // The the types and opcodes for the two Cast constant expressions
81 const Type *SrcTy = Op->getOperand(0)->getType();
82 const Type *MidTy = Op->getType();
83 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
84 Instruction::CastOps secondOp = Instruction::CastOps(opc);
86 // Let CastInst::isEliminableCastPair do the heavy lifting.
87 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
91 static Constant *FoldBitCast(Constant *V, const Type *DestTy) {
92 const Type *SrcTy = V->getType();
94 return V; // no-op cast
96 // Check to see if we are casting a pointer to an aggregate to a pointer to
97 // the first element. If so, return the appropriate GEP instruction.
98 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
99 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
100 SmallVector<Value*, 8> IdxList;
101 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
102 const Type *ElTy = PTy->getElementType();
103 while (ElTy != DPTy->getElementType()) {
104 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
105 if (STy->getNumElements() == 0) break;
106 ElTy = STy->getElementType(0);
107 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
108 } else if (const SequentialType *STy = dyn_cast<SequentialType>(ElTy)) {
109 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
110 ElTy = STy->getElementType();
111 IdxList.push_back(IdxList[0]);
117 if (ElTy == DPTy->getElementType())
118 return ConstantExpr::getGetElementPtr(V, &IdxList[0], IdxList.size());
121 // Handle casts from one vector constant to another. We know that the src
122 // and dest type have the same size (otherwise its an illegal cast).
123 if (const VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) {
124 if (const VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) {
125 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
126 "Not cast between same sized vectors!");
127 // First, check for null. Undef is already handled.
128 if (isa<ConstantAggregateZero>(V))
129 return Constant::getNullValue(DestTy);
131 if (ConstantVector *CV = dyn_cast<ConstantVector>(V))
132 return BitCastConstantVector(CV, DestPTy);
136 // Finally, implement bitcast folding now. The code below doesn't handle
138 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
139 return ConstantPointerNull::get(cast<PointerType>(DestTy));
141 // Handle integral constant input.
142 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
143 if (DestTy->isInteger())
144 // Integral -> Integral. This is a no-op because the bit widths must
145 // be the same. Consequently, we just fold to V.
148 if (DestTy->isFloatingPoint()) {
149 assert((DestTy == Type::DoubleTy || DestTy == Type::FloatTy) &&
151 return ConstantFP::get(DestTy, APFloat(CI->getValue()));
153 // Otherwise, can't fold this (vector?)
157 // Handle ConstantFP input.
158 if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
160 if (DestTy == Type::Int32Ty) {
161 return ConstantInt::get(FP->getValueAPF().convertToAPInt());
163 assert(DestTy == Type::Int64Ty && "only support f32/f64 for now!");
164 return ConstantInt::get(FP->getValueAPF().convertToAPInt());
171 Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
172 const Type *DestTy) {
173 const Type *SrcTy = V->getType();
175 if (isa<UndefValue>(V)) {
176 // zext(undef) = 0, because the top bits will be zero.
177 // sext(undef) = 0, because the top bits will all be the same.
178 if (opc == Instruction::ZExt || opc == Instruction::SExt)
179 return Constant::getNullValue(DestTy);
180 return UndefValue::get(DestTy);
182 // No compile-time operations on this type yet.
183 if (V->getType() == Type::PPC_FP128Ty || DestTy == Type::PPC_FP128Ty)
186 // If the cast operand is a constant expression, there's a few things we can
187 // do to try to simplify it.
188 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
190 // Try hard to fold cast of cast because they are often eliminable.
191 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
192 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
193 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
194 // If all of the indexes in the GEP are null values, there is no pointer
195 // adjustment going on. We might as well cast the source pointer.
196 bool isAllNull = true;
197 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
198 if (!CE->getOperand(i)->isNullValue()) {
203 // This is casting one pointer type to another, always BitCast
204 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
208 // We actually have to do a cast now. Perform the cast according to the
211 case Instruction::FPTrunc:
212 case Instruction::FPExt:
213 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
214 APFloat Val = FPC->getValueAPF();
215 Val.convert(DestTy == Type::FloatTy ? APFloat::IEEEsingle :
216 DestTy == Type::DoubleTy ? APFloat::IEEEdouble :
217 DestTy == Type::X86_FP80Ty ? APFloat::x87DoubleExtended :
218 DestTy == Type::FP128Ty ? APFloat::IEEEquad :
220 APFloat::rmNearestTiesToEven);
221 return ConstantFP::get(DestTy, Val);
223 return 0; // Can't fold.
224 case Instruction::FPToUI:
225 case Instruction::FPToSI:
226 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
227 const APFloat &V = FPC->getValueAPF();
229 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
230 (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI,
231 APFloat::rmTowardZero);
232 APInt Val(DestBitWidth, 2, x);
233 return ConstantInt::get(Val);
235 if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
236 std::vector<Constant*> res;
237 const VectorType *DestVecTy = cast<VectorType>(DestTy);
238 const Type *DstEltTy = DestVecTy->getElementType();
239 for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
240 res.push_back(ConstantFoldCastInstruction(opc, V->getOperand(i),
242 return ConstantVector::get(DestVecTy, res);
244 return 0; // Can't fold.
245 case Instruction::IntToPtr: //always treated as unsigned
246 if (V->isNullValue()) // Is it an integral null value?
247 return ConstantPointerNull::get(cast<PointerType>(DestTy));
248 return 0; // Other pointer types cannot be casted
249 case Instruction::PtrToInt: // always treated as unsigned
250 if (V->isNullValue()) // is it a null pointer value?
251 return ConstantInt::get(DestTy, 0);
252 return 0; // Other pointer types cannot be casted
253 case Instruction::UIToFP:
254 case Instruction::SIToFP:
255 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
256 APInt api = CI->getValue();
257 const uint64_t zero[] = {0, 0};
258 uint32_t BitWidth = cast<IntegerType>(SrcTy)->getBitWidth();
259 APFloat apf = APFloat(APInt(DestTy->getPrimitiveSizeInBits(),
261 (void)apf.convertFromZeroExtendedInteger(api.getRawData(), BitWidth,
262 opc==Instruction::SIToFP,
263 APFloat::rmNearestTiesToEven);
264 return ConstantFP::get(DestTy, apf);
266 if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
267 std::vector<Constant*> res;
268 const VectorType *DestVecTy = cast<VectorType>(DestTy);
269 const Type *DstEltTy = DestVecTy->getElementType();
270 for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
271 res.push_back(ConstantFoldCastInstruction(opc, V->getOperand(i),
273 return ConstantVector::get(DestVecTy, res);
276 case Instruction::ZExt:
277 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
278 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
279 APInt Result(CI->getValue());
280 Result.zext(BitWidth);
281 return ConstantInt::get(Result);
284 case Instruction::SExt:
285 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
286 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
287 APInt Result(CI->getValue());
288 Result.sext(BitWidth);
289 return ConstantInt::get(Result);
292 case Instruction::Trunc:
293 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
294 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
295 APInt Result(CI->getValue());
296 Result.trunc(BitWidth);
297 return ConstantInt::get(Result);
300 case Instruction::BitCast:
301 return FoldBitCast(const_cast<Constant*>(V), DestTy);
303 assert(!"Invalid CE CastInst opcode");
307 assert(0 && "Failed to cast constant expression");
311 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
313 const Constant *V2) {
314 if (const ConstantInt *CB = dyn_cast<ConstantInt>(Cond))
315 return const_cast<Constant*>(CB->getZExtValue() ? V1 : V2);
317 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
318 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
319 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
320 if (V1 == V2) return const_cast<Constant*>(V1);
324 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
325 const Constant *Idx) {
326 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
327 return UndefValue::get(cast<VectorType>(Val->getType())->getElementType());
328 if (Val->isNullValue()) // ee(zero, x) -> zero
329 return Constant::getNullValue(
330 cast<VectorType>(Val->getType())->getElementType());
332 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
333 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
334 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue()));
335 } else if (isa<UndefValue>(Idx)) {
336 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
337 return const_cast<Constant*>(CVal->getOperand(0));
343 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
345 const Constant *Idx) {
346 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
348 APInt idxVal = CIdx->getValue();
349 if (isa<UndefValue>(Val)) {
350 // Insertion of scalar constant into vector undef
351 // Optimize away insertion of undef
352 if (isa<UndefValue>(Elt))
353 return const_cast<Constant*>(Val);
354 // Otherwise break the aggregate undef into multiple undefs and do
357 cast<VectorType>(Val->getType())->getNumElements();
358 std::vector<Constant*> Ops;
360 for (unsigned i = 0; i < numOps; ++i) {
362 (idxVal == i) ? Elt : UndefValue::get(Elt->getType());
363 Ops.push_back(const_cast<Constant*>(Op));
365 return ConstantVector::get(Ops);
367 if (isa<ConstantAggregateZero>(Val)) {
368 // Insertion of scalar constant into vector aggregate zero
369 // Optimize away insertion of zero
370 if (Elt->isNullValue())
371 return const_cast<Constant*>(Val);
372 // Otherwise break the aggregate zero into multiple zeros and do
375 cast<VectorType>(Val->getType())->getNumElements();
376 std::vector<Constant*> Ops;
378 for (unsigned i = 0; i < numOps; ++i) {
380 (idxVal == i) ? Elt : Constant::getNullValue(Elt->getType());
381 Ops.push_back(const_cast<Constant*>(Op));
383 return ConstantVector::get(Ops);
385 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
386 // Insertion of scalar constant into vector constant
387 std::vector<Constant*> Ops;
388 Ops.reserve(CVal->getNumOperands());
389 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
391 (idxVal == i) ? Elt : cast<Constant>(CVal->getOperand(i));
392 Ops.push_back(const_cast<Constant*>(Op));
394 return ConstantVector::get(Ops);
399 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
401 const Constant *Mask) {
406 /// EvalVectorOp - Given two vector constants and a function pointer, apply the
407 /// function pointer to each element pair, producing a new ConstantVector
408 /// constant. Either or both of V1 and V2 may be NULL, meaning a
409 /// ConstantAggregateZero operand.
410 static Constant *EvalVectorOp(const ConstantVector *V1,
411 const ConstantVector *V2,
412 const VectorType *VTy,
413 Constant *(*FP)(Constant*, Constant*)) {
414 std::vector<Constant*> Res;
415 const Type *EltTy = VTy->getElementType();
416 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
417 const Constant *C1 = V1 ? V1->getOperand(i) : Constant::getNullValue(EltTy);
418 const Constant *C2 = V2 ? V2->getOperand(i) : Constant::getNullValue(EltTy);
419 Res.push_back(FP(const_cast<Constant*>(C1),
420 const_cast<Constant*>(C2)));
422 return ConstantVector::get(Res);
425 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
427 const Constant *C2) {
428 // No compile-time operations on this type yet.
429 if (C1->getType() == Type::PPC_FP128Ty)
432 // Handle UndefValue up front
433 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
435 case Instruction::Add:
436 case Instruction::Sub:
437 case Instruction::Xor:
438 return UndefValue::get(C1->getType());
439 case Instruction::Mul:
440 case Instruction::And:
441 return Constant::getNullValue(C1->getType());
442 case Instruction::UDiv:
443 case Instruction::SDiv:
444 case Instruction::FDiv:
445 case Instruction::URem:
446 case Instruction::SRem:
447 case Instruction::FRem:
448 if (!isa<UndefValue>(C2)) // undef / X -> 0
449 return Constant::getNullValue(C1->getType());
450 return const_cast<Constant*>(C2); // X / undef -> undef
451 case Instruction::Or: // X | undef -> -1
452 if (const VectorType *PTy = dyn_cast<VectorType>(C1->getType()))
453 return ConstantVector::getAllOnesValue(PTy);
454 return ConstantInt::getAllOnesValue(C1->getType());
455 case Instruction::LShr:
456 if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
457 return const_cast<Constant*>(C1); // undef lshr undef -> undef
458 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0
460 case Instruction::AShr:
461 if (!isa<UndefValue>(C2))
462 return const_cast<Constant*>(C1); // undef ashr X --> undef
463 else if (isa<UndefValue>(C1))
464 return const_cast<Constant*>(C1); // undef ashr undef -> undef
466 return const_cast<Constant*>(C1); // X ashr undef --> X
467 case Instruction::Shl:
468 // undef << X -> 0 or X << undef -> 0
469 return Constant::getNullValue(C1->getType());
473 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
474 if (isa<ConstantExpr>(C2)) {
475 // There are many possible foldings we could do here. We should probably
476 // at least fold add of a pointer with an integer into the appropriate
477 // getelementptr. This will improve alias analysis a bit.
479 // Just implement a couple of simple identities.
481 case Instruction::Add:
482 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X + 0 == X
484 case Instruction::Sub:
485 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X - 0 == X
487 case Instruction::Mul:
488 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X * 0 == 0
489 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
490 if (CI->equalsInt(1))
491 return const_cast<Constant*>(C1); // X * 1 == X
493 case Instruction::UDiv:
494 case Instruction::SDiv:
495 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
496 if (CI->equalsInt(1))
497 return const_cast<Constant*>(C1); // X / 1 == X
499 case Instruction::URem:
500 case Instruction::SRem:
501 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
502 if (CI->equalsInt(1))
503 return Constant::getNullValue(CI->getType()); // X % 1 == 0
505 case Instruction::And:
506 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2)) {
507 if (CI->isZero()) return const_cast<Constant*>(C2); // X & 0 == 0
508 if (CI->isAllOnesValue())
509 return const_cast<Constant*>(C1); // X & -1 == X
511 // (zext i32 to i64) & 4294967295 -> (zext i32 to i64)
512 if (CE1->getOpcode() == Instruction::ZExt) {
513 APInt PossiblySetBits
514 = cast<IntegerType>(CE1->getOperand(0)->getType())->getMask();
515 PossiblySetBits.zext(C1->getType()->getPrimitiveSizeInBits());
516 if ((PossiblySetBits & CI->getValue()) == PossiblySetBits)
517 return const_cast<Constant*>(C1);
520 if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
521 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
523 // Functions are at least 4-byte aligned. If and'ing the address of a
524 // function with a constant < 4, fold it to zero.
525 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
526 if (CI->getValue().ult(APInt(CI->getType()->getBitWidth(),4)) &&
528 return Constant::getNullValue(CI->getType());
531 case Instruction::Or:
532 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X | 0 == X
533 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
534 if (CI->isAllOnesValue())
535 return const_cast<Constant*>(C2); // X | -1 == -1
537 case Instruction::Xor:
538 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X ^ 0 == X
540 case Instruction::AShr:
541 // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2
542 if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero.
543 return ConstantExpr::getLShr(const_cast<Constant*>(C1),
544 const_cast<Constant*>(C2));
548 } else if (isa<ConstantExpr>(C2)) {
549 // If C2 is a constant expr and C1 isn't, flop them around and fold the
550 // other way if possible.
552 case Instruction::Add:
553 case Instruction::Mul:
554 case Instruction::And:
555 case Instruction::Or:
556 case Instruction::Xor:
557 // No change of opcode required.
558 return ConstantFoldBinaryInstruction(Opcode, C2, C1);
560 case Instruction::Shl:
561 case Instruction::LShr:
562 case Instruction::AShr:
563 case Instruction::Sub:
564 case Instruction::SDiv:
565 case Instruction::UDiv:
566 case Instruction::FDiv:
567 case Instruction::URem:
568 case Instruction::SRem:
569 case Instruction::FRem:
570 default: // These instructions cannot be flopped around.
575 // At this point we know neither constant is an UndefValue nor a ConstantExpr
576 // so look at directly computing the value.
577 if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
578 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
579 using namespace APIntOps;
580 APInt C1V = CI1->getValue();
581 APInt C2V = CI2->getValue();
585 case Instruction::Add:
586 return ConstantInt::get(C1V + C2V);
587 case Instruction::Sub:
588 return ConstantInt::get(C1V - C2V);
589 case Instruction::Mul:
590 return ConstantInt::get(C1V * C2V);
591 case Instruction::UDiv:
592 if (CI2->isNullValue())
593 return 0; // X / 0 -> can't fold
594 return ConstantInt::get(C1V.udiv(C2V));
595 case Instruction::SDiv:
596 if (CI2->isNullValue())
597 return 0; // X / 0 -> can't fold
598 if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
599 return 0; // MIN_INT / -1 -> overflow
600 return ConstantInt::get(C1V.sdiv(C2V));
601 case Instruction::URem:
602 if (C2->isNullValue())
603 return 0; // X / 0 -> can't fold
604 return ConstantInt::get(C1V.urem(C2V));
605 case Instruction::SRem:
606 if (CI2->isNullValue())
607 return 0; // X % 0 -> can't fold
608 if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
609 return 0; // MIN_INT % -1 -> overflow
610 return ConstantInt::get(C1V.srem(C2V));
611 case Instruction::And:
612 return ConstantInt::get(C1V & C2V);
613 case Instruction::Or:
614 return ConstantInt::get(C1V | C2V);
615 case Instruction::Xor:
616 return ConstantInt::get(C1V ^ C2V);
617 case Instruction::Shl:
618 if (uint32_t shiftAmt = C2V.getZExtValue())
619 if (shiftAmt < C1V.getBitWidth())
620 return ConstantInt::get(C1V.shl(shiftAmt));
622 return UndefValue::get(C1->getType()); // too big shift is undef
623 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
624 case Instruction::LShr:
625 if (uint32_t shiftAmt = C2V.getZExtValue())
626 if (shiftAmt < C1V.getBitWidth())
627 return ConstantInt::get(C1V.lshr(shiftAmt));
629 return UndefValue::get(C1->getType()); // too big shift is undef
630 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
631 case Instruction::AShr:
632 if (uint32_t shiftAmt = C2V.getZExtValue())
633 if (shiftAmt < C1V.getBitWidth())
634 return ConstantInt::get(C1V.ashr(shiftAmt));
636 return UndefValue::get(C1->getType()); // too big shift is undef
637 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
640 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
641 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
642 APFloat C1V = CFP1->getValueAPF();
643 APFloat C2V = CFP2->getValueAPF();
644 APFloat C3V = C1V; // copy for modification
645 bool isDouble = CFP1->getType()==Type::DoubleTy;
649 case Instruction::Add:
650 (void)C3V.add(C2V, APFloat::rmNearestTiesToEven);
651 return ConstantFP::get(CFP1->getType(), C3V);
652 case Instruction::Sub:
653 (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven);
654 return ConstantFP::get(CFP1->getType(), C3V);
655 case Instruction::Mul:
656 (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven);
657 return ConstantFP::get(CFP1->getType(), C3V);
658 case Instruction::FDiv:
659 (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven);
660 return ConstantFP::get(CFP1->getType(), C3V);
661 case Instruction::FRem:
663 // IEEE 754, Section 7.1, #5
664 return ConstantFP::get(CFP1->getType(), isDouble ?
665 APFloat(std::numeric_limits<double>::quiet_NaN()) :
666 APFloat(std::numeric_limits<float>::quiet_NaN()));
667 (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven);
668 return ConstantFP::get(CFP1->getType(), C3V);
671 } else if (const VectorType *VTy = dyn_cast<VectorType>(C1->getType())) {
672 const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1);
673 const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2);
674 if ((CP1 != NULL || isa<ConstantAggregateZero>(C1)) &&
675 (CP2 != NULL || isa<ConstantAggregateZero>(C2))) {
679 case Instruction::Add:
680 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAdd);
681 case Instruction::Sub:
682 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSub);
683 case Instruction::Mul:
684 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getMul);
685 case Instruction::UDiv:
686 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getUDiv);
687 case Instruction::SDiv:
688 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSDiv);
689 case Instruction::FDiv:
690 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFDiv);
691 case Instruction::URem:
692 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getURem);
693 case Instruction::SRem:
694 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSRem);
695 case Instruction::FRem:
696 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFRem);
697 case Instruction::And:
698 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAnd);
699 case Instruction::Or:
700 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getOr);
701 case Instruction::Xor:
702 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getXor);
707 // We don't know how to fold this
711 /// isZeroSizedType - This type is zero sized if its an array or structure of
712 /// zero sized types. The only leaf zero sized type is an empty structure.
713 static bool isMaybeZeroSizedType(const Type *Ty) {
714 if (isa<OpaqueType>(Ty)) return true; // Can't say.
715 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
717 // If all of elements have zero size, this does too.
718 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
719 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
722 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
723 return isMaybeZeroSizedType(ATy->getElementType());
728 /// IdxCompare - Compare the two constants as though they were getelementptr
729 /// indices. This allows coersion of the types to be the same thing.
731 /// If the two constants are the "same" (after coersion), return 0. If the
732 /// first is less than the second, return -1, if the second is less than the
733 /// first, return 1. If the constants are not integral, return -2.
735 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
736 if (C1 == C2) return 0;
738 // Ok, we found a different index. If they are not ConstantInt, we can't do
739 // anything with them.
740 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
741 return -2; // don't know!
743 // Ok, we have two differing integer indices. Sign extend them to be the same
744 // type. Long is always big enough, so we use it.
745 if (C1->getType() != Type::Int64Ty)
746 C1 = ConstantExpr::getSExt(C1, Type::Int64Ty);
748 if (C2->getType() != Type::Int64Ty)
749 C2 = ConstantExpr::getSExt(C2, Type::Int64Ty);
751 if (C1 == C2) return 0; // They are equal
753 // If the type being indexed over is really just a zero sized type, there is
754 // no pointer difference being made here.
755 if (isMaybeZeroSizedType(ElTy))
758 // If they are really different, now that they are the same type, then we
759 // found a difference!
760 if (cast<ConstantInt>(C1)->getSExtValue() <
761 cast<ConstantInt>(C2)->getSExtValue())
767 /// evaluateFCmpRelation - This function determines if there is anything we can
768 /// decide about the two constants provided. This doesn't need to handle simple
769 /// things like ConstantFP comparisons, but should instead handle ConstantExprs.
770 /// If we can determine that the two constants have a particular relation to
771 /// each other, we should return the corresponding FCmpInst predicate,
772 /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
773 /// ConstantFoldCompareInstruction.
775 /// To simplify this code we canonicalize the relation so that the first
776 /// operand is always the most "complex" of the two. We consider ConstantFP
777 /// to be the simplest, and ConstantExprs to be the most complex.
778 static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1,
779 const Constant *V2) {
780 assert(V1->getType() == V2->getType() &&
781 "Cannot compare values of different types!");
783 // No compile-time operations on this type yet.
784 if (V1->getType() == Type::PPC_FP128Ty)
785 return FCmpInst::BAD_FCMP_PREDICATE;
787 // Handle degenerate case quickly
788 if (V1 == V2) return FCmpInst::FCMP_OEQ;
790 if (!isa<ConstantExpr>(V1)) {
791 if (!isa<ConstantExpr>(V2)) {
792 // We distilled thisUse the standard constant folder for a few cases
794 Constant *C1 = const_cast<Constant*>(V1);
795 Constant *C2 = const_cast<Constant*>(V2);
796 R = dyn_cast<ConstantInt>(
797 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2));
798 if (R && !R->isZero())
799 return FCmpInst::FCMP_OEQ;
800 R = dyn_cast<ConstantInt>(
801 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2));
802 if (R && !R->isZero())
803 return FCmpInst::FCMP_OLT;
804 R = dyn_cast<ConstantInt>(
805 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2));
806 if (R && !R->isZero())
807 return FCmpInst::FCMP_OGT;
809 // Nothing more we can do
810 return FCmpInst::BAD_FCMP_PREDICATE;
813 // If the first operand is simple and second is ConstantExpr, swap operands.
814 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
815 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
816 return FCmpInst::getSwappedPredicate(SwappedRelation);
818 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
819 // constantexpr or a simple constant.
820 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
821 switch (CE1->getOpcode()) {
822 case Instruction::FPTrunc:
823 case Instruction::FPExt:
824 case Instruction::UIToFP:
825 case Instruction::SIToFP:
826 // We might be able to do something with these but we don't right now.
832 // There are MANY other foldings that we could perform here. They will
833 // probably be added on demand, as they seem needed.
834 return FCmpInst::BAD_FCMP_PREDICATE;
837 /// evaluateICmpRelation - This function determines if there is anything we can
838 /// decide about the two constants provided. This doesn't need to handle simple
839 /// things like integer comparisons, but should instead handle ConstantExprs
840 /// and GlobalValues. If we can determine that the two constants have a
841 /// particular relation to each other, we should return the corresponding ICmp
842 /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.
844 /// To simplify this code we canonicalize the relation so that the first
845 /// operand is always the most "complex" of the two. We consider simple
846 /// constants (like ConstantInt) to be the simplest, followed by
847 /// GlobalValues, followed by ConstantExpr's (the most complex).
849 static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1,
852 assert(V1->getType() == V2->getType() &&
853 "Cannot compare different types of values!");
854 if (V1 == V2) return ICmpInst::ICMP_EQ;
856 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
857 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
858 // We distilled this down to a simple case, use the standard constant
861 Constant *C1 = const_cast<Constant*>(V1);
862 Constant *C2 = const_cast<Constant*>(V2);
863 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
864 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
865 if (R && !R->isZero())
867 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
868 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
869 if (R && !R->isZero())
871 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
872 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
873 if (R && !R->isZero())
876 // If we couldn't figure it out, bail.
877 return ICmpInst::BAD_ICMP_PREDICATE;
880 // If the first operand is simple, swap operands.
881 ICmpInst::Predicate SwappedRelation =
882 evaluateICmpRelation(V2, V1, isSigned);
883 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
884 return ICmpInst::getSwappedPredicate(SwappedRelation);
886 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
887 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
888 ICmpInst::Predicate SwappedRelation =
889 evaluateICmpRelation(V2, V1, isSigned);
890 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
891 return ICmpInst::getSwappedPredicate(SwappedRelation);
893 return ICmpInst::BAD_ICMP_PREDICATE;
896 // Now we know that the RHS is a GlobalValue or simple constant,
897 // which (since the types must match) means that it's a ConstantPointerNull.
898 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
899 // Don't try to decide equality of aliases.
900 if (!isa<GlobalAlias>(CPR1) && !isa<GlobalAlias>(CPR2))
901 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
902 return ICmpInst::ICMP_NE;
904 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
905 // GlobalVals can never be null. Don't try to evaluate aliases.
906 if (!CPR1->hasExternalWeakLinkage() && !isa<GlobalAlias>(CPR1))
907 return ICmpInst::ICMP_NE;
910 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
911 // constantexpr, a CPR, or a simple constant.
912 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
913 const Constant *CE1Op0 = CE1->getOperand(0);
915 switch (CE1->getOpcode()) {
916 case Instruction::Trunc:
917 case Instruction::FPTrunc:
918 case Instruction::FPExt:
919 case Instruction::FPToUI:
920 case Instruction::FPToSI:
921 break; // We can't evaluate floating point casts or truncations.
923 case Instruction::UIToFP:
924 case Instruction::SIToFP:
925 case Instruction::BitCast:
926 case Instruction::ZExt:
927 case Instruction::SExt:
928 // If the cast is not actually changing bits, and the second operand is a
929 // null pointer, do the comparison with the pre-casted value.
930 if (V2->isNullValue() &&
931 (isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) {
932 bool sgnd = isSigned;
933 if (CE1->getOpcode() == Instruction::ZExt) isSigned = false;
934 if (CE1->getOpcode() == Instruction::SExt) isSigned = true;
935 return evaluateICmpRelation(CE1Op0,
936 Constant::getNullValue(CE1Op0->getType()),
940 // If the dest type is a pointer type, and the RHS is a constantexpr cast
941 // from the same type as the src of the LHS, evaluate the inputs. This is
942 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)",
943 // which happens a lot in compilers with tagged integers.
944 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
945 if (CE2->isCast() && isa<PointerType>(CE1->getType()) &&
946 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
947 CE1->getOperand(0)->getType()->isInteger()) {
948 bool sgnd = isSigned;
949 if (CE1->getOpcode() == Instruction::ZExt) isSigned = false;
950 if (CE1->getOpcode() == Instruction::SExt) isSigned = true;
951 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0),
956 case Instruction::GetElementPtr:
957 // Ok, since this is a getelementptr, we know that the constant has a
958 // pointer type. Check the various cases.
959 if (isa<ConstantPointerNull>(V2)) {
960 // If we are comparing a GEP to a null pointer, check to see if the base
961 // of the GEP equals the null pointer.
962 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
963 if (GV->hasExternalWeakLinkage())
964 // Weak linkage GVals could be zero or not. We're comparing that
965 // to null pointer so its greater-or-equal
966 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
968 // If its not weak linkage, the GVal must have a non-zero address
969 // so the result is greater-than
970 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
971 } else if (isa<ConstantPointerNull>(CE1Op0)) {
972 // If we are indexing from a null pointer, check to see if we have any
974 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
975 if (!CE1->getOperand(i)->isNullValue())
976 // Offsetting from null, must not be equal.
977 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
978 // Only zero indexes from null, must still be zero.
979 return ICmpInst::ICMP_EQ;
981 // Otherwise, we can't really say if the first operand is null or not.
982 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
983 if (isa<ConstantPointerNull>(CE1Op0)) {
984 if (CPR2->hasExternalWeakLinkage())
985 // Weak linkage GVals could be zero or not. We're comparing it to
986 // a null pointer, so its less-or-equal
987 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
989 // If its not weak linkage, the GVal must have a non-zero address
990 // so the result is less-than
991 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
992 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
994 // If this is a getelementptr of the same global, then it must be
995 // different. Because the types must match, the getelementptr could
996 // only have at most one index, and because we fold getelementptr's
997 // with a single zero index, it must be nonzero.
998 assert(CE1->getNumOperands() == 2 &&
999 !CE1->getOperand(1)->isNullValue() &&
1000 "Suprising getelementptr!");
1001 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1003 // If they are different globals, we don't know what the value is,
1004 // but they can't be equal.
1005 return ICmpInst::ICMP_NE;
1009 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
1010 const Constant *CE2Op0 = CE2->getOperand(0);
1012 // There are MANY other foldings that we could perform here. They will
1013 // probably be added on demand, as they seem needed.
1014 switch (CE2->getOpcode()) {
1016 case Instruction::GetElementPtr:
1017 // By far the most common case to handle is when the base pointers are
1018 // obviously to the same or different globals.
1019 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
1020 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
1021 return ICmpInst::ICMP_NE;
1022 // Ok, we know that both getelementptr instructions are based on the
1023 // same global. From this, we can precisely determine the relative
1024 // ordering of the resultant pointers.
1027 // Compare all of the operands the GEP's have in common.
1028 gep_type_iterator GTI = gep_type_begin(CE1);
1029 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
1031 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
1032 GTI.getIndexedType())) {
1033 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
1034 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
1035 case -2: return ICmpInst::BAD_ICMP_PREDICATE;
1038 // Ok, we ran out of things they have in common. If any leftovers
1039 // are non-zero then we have a difference, otherwise we are equal.
1040 for (; i < CE1->getNumOperands(); ++i)
1041 if (!CE1->getOperand(i)->isNullValue())
1042 if (isa<ConstantInt>(CE1->getOperand(i)))
1043 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1045 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1047 for (; i < CE2->getNumOperands(); ++i)
1048 if (!CE2->getOperand(i)->isNullValue())
1049 if (isa<ConstantInt>(CE2->getOperand(i)))
1050 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1052 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1053 return ICmpInst::ICMP_EQ;
1062 return ICmpInst::BAD_ICMP_PREDICATE;
1065 Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
1067 const Constant *C2) {
1069 // Handle some degenerate cases first
1070 if (isa<UndefValue>(C1) || isa<UndefValue>(C2))
1071 return UndefValue::get(Type::Int1Ty);
1073 // No compile-time operations on this type yet.
1074 if (C1->getType() == Type::PPC_FP128Ty)
1077 // icmp eq/ne(null,GV) -> false/true
1078 if (C1->isNullValue()) {
1079 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
1080 // Don't try to evaluate aliases. External weak GV can be null.
1081 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage())
1082 if (pred == ICmpInst::ICMP_EQ)
1083 return ConstantInt::getFalse();
1084 else if (pred == ICmpInst::ICMP_NE)
1085 return ConstantInt::getTrue();
1086 // icmp eq/ne(GV,null) -> false/true
1087 } else if (C2->isNullValue()) {
1088 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
1089 // Don't try to evaluate aliases. External weak GV can be null.
1090 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage())
1091 if (pred == ICmpInst::ICMP_EQ)
1092 return ConstantInt::getFalse();
1093 else if (pred == ICmpInst::ICMP_NE)
1094 return ConstantInt::getTrue();
1097 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
1098 APInt V1 = cast<ConstantInt>(C1)->getValue();
1099 APInt V2 = cast<ConstantInt>(C2)->getValue();
1101 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1102 case ICmpInst::ICMP_EQ: return ConstantInt::get(Type::Int1Ty, V1 == V2);
1103 case ICmpInst::ICMP_NE: return ConstantInt::get(Type::Int1Ty, V1 != V2);
1104 case ICmpInst::ICMP_SLT:return ConstantInt::get(Type::Int1Ty, V1.slt(V2));
1105 case ICmpInst::ICMP_SGT:return ConstantInt::get(Type::Int1Ty, V1.sgt(V2));
1106 case ICmpInst::ICMP_SLE:return ConstantInt::get(Type::Int1Ty, V1.sle(V2));
1107 case ICmpInst::ICMP_SGE:return ConstantInt::get(Type::Int1Ty, V1.sge(V2));
1108 case ICmpInst::ICMP_ULT:return ConstantInt::get(Type::Int1Ty, V1.ult(V2));
1109 case ICmpInst::ICMP_UGT:return ConstantInt::get(Type::Int1Ty, V1.ugt(V2));
1110 case ICmpInst::ICMP_ULE:return ConstantInt::get(Type::Int1Ty, V1.ule(V2));
1111 case ICmpInst::ICMP_UGE:return ConstantInt::get(Type::Int1Ty, V1.uge(V2));
1113 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
1114 APFloat C1V = cast<ConstantFP>(C1)->getValueAPF();
1115 APFloat C2V = cast<ConstantFP>(C2)->getValueAPF();
1116 APFloat::cmpResult R = C1V.compare(C2V);
1118 default: assert(0 && "Invalid FCmp Predicate"); return 0;
1119 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse();
1120 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue();
1121 case FCmpInst::FCMP_UNO:
1122 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered);
1123 case FCmpInst::FCMP_ORD:
1124 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpUnordered);
1125 case FCmpInst::FCMP_UEQ:
1126 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1127 R==APFloat::cmpEqual);
1128 case FCmpInst::FCMP_OEQ:
1129 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpEqual);
1130 case FCmpInst::FCMP_UNE:
1131 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpEqual);
1132 case FCmpInst::FCMP_ONE:
1133 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan ||
1134 R==APFloat::cmpGreaterThan);
1135 case FCmpInst::FCMP_ULT:
1136 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1137 R==APFloat::cmpLessThan);
1138 case FCmpInst::FCMP_OLT:
1139 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan);
1140 case FCmpInst::FCMP_UGT:
1141 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1142 R==APFloat::cmpGreaterThan);
1143 case FCmpInst::FCMP_OGT:
1144 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan);
1145 case FCmpInst::FCMP_ULE:
1146 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpGreaterThan);
1147 case FCmpInst::FCMP_OLE:
1148 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan ||
1149 R==APFloat::cmpEqual);
1150 case FCmpInst::FCMP_UGE:
1151 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpLessThan);
1152 case FCmpInst::FCMP_OGE:
1153 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan ||
1154 R==APFloat::cmpEqual);
1156 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {
1157 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) {
1158 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) {
1159 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1160 Constant *C= ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ,
1161 const_cast<Constant*>(CP1->getOperand(i)),
1162 const_cast<Constant*>(CP2->getOperand(i)));
1163 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1166 // Otherwise, could not decide from any element pairs.
1168 } else if (pred == ICmpInst::ICMP_EQ) {
1169 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1170 Constant *C = ConstantExpr::getICmp(ICmpInst::ICMP_EQ,
1171 const_cast<Constant*>(CP1->getOperand(i)),
1172 const_cast<Constant*>(CP2->getOperand(i)));
1173 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1176 // Otherwise, could not decide from any element pairs.
1182 if (C1->getType()->isFloatingPoint()) {
1183 switch (evaluateFCmpRelation(C1, C2)) {
1184 default: assert(0 && "Unknown relation!");
1185 case FCmpInst::FCMP_UNO:
1186 case FCmpInst::FCMP_ORD:
1187 case FCmpInst::FCMP_UEQ:
1188 case FCmpInst::FCMP_UNE:
1189 case FCmpInst::FCMP_ULT:
1190 case FCmpInst::FCMP_UGT:
1191 case FCmpInst::FCMP_ULE:
1192 case FCmpInst::FCMP_UGE:
1193 case FCmpInst::FCMP_TRUE:
1194 case FCmpInst::FCMP_FALSE:
1195 case FCmpInst::BAD_FCMP_PREDICATE:
1196 break; // Couldn't determine anything about these constants.
1197 case FCmpInst::FCMP_OEQ: // We know that C1 == C2
1198 return ConstantInt::get(Type::Int1Ty,
1199 pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
1200 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
1201 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1202 case FCmpInst::FCMP_OLT: // We know that C1 < C2
1203 return ConstantInt::get(Type::Int1Ty,
1204 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1205 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
1206 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
1207 case FCmpInst::FCMP_OGT: // We know that C1 > C2
1208 return ConstantInt::get(Type::Int1Ty,
1209 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1210 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
1211 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1212 case FCmpInst::FCMP_OLE: // We know that C1 <= C2
1213 // We can only partially decide this relation.
1214 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1215 return ConstantInt::getFalse();
1216 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1217 return ConstantInt::getTrue();
1219 case FCmpInst::FCMP_OGE: // We known that C1 >= C2
1220 // We can only partially decide this relation.
1221 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1222 return ConstantInt::getFalse();
1223 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1224 return ConstantInt::getTrue();
1226 case ICmpInst::ICMP_NE: // We know that C1 != C2
1227 // We can only partially decide this relation.
1228 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
1229 return ConstantInt::getFalse();
1230 if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
1231 return ConstantInt::getTrue();
1235 // Evaluate the relation between the two constants, per the predicate.
1236 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) {
1237 default: assert(0 && "Unknown relational!");
1238 case ICmpInst::BAD_ICMP_PREDICATE:
1239 break; // Couldn't determine anything about these constants.
1240 case ICmpInst::ICMP_EQ: // We know the constants are equal!
1241 // If we know the constants are equal, we can decide the result of this
1242 // computation precisely.
1243 return ConstantInt::get(Type::Int1Ty,
1244 pred == ICmpInst::ICMP_EQ ||
1245 pred == ICmpInst::ICMP_ULE ||
1246 pred == ICmpInst::ICMP_SLE ||
1247 pred == ICmpInst::ICMP_UGE ||
1248 pred == ICmpInst::ICMP_SGE);
1249 case ICmpInst::ICMP_ULT:
1250 // If we know that C1 < C2, we can decide the result of this computation
1252 return ConstantInt::get(Type::Int1Ty,
1253 pred == ICmpInst::ICMP_ULT ||
1254 pred == ICmpInst::ICMP_NE ||
1255 pred == ICmpInst::ICMP_ULE);
1256 case ICmpInst::ICMP_SLT:
1257 // If we know that C1 < C2, we can decide the result of this computation
1259 return ConstantInt::get(Type::Int1Ty,
1260 pred == ICmpInst::ICMP_SLT ||
1261 pred == ICmpInst::ICMP_NE ||
1262 pred == ICmpInst::ICMP_SLE);
1263 case ICmpInst::ICMP_UGT:
1264 // If we know that C1 > C2, we can decide the result of this computation
1266 return ConstantInt::get(Type::Int1Ty,
1267 pred == ICmpInst::ICMP_UGT ||
1268 pred == ICmpInst::ICMP_NE ||
1269 pred == ICmpInst::ICMP_UGE);
1270 case ICmpInst::ICMP_SGT:
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_SGT ||
1275 pred == ICmpInst::ICMP_NE ||
1276 pred == ICmpInst::ICMP_SGE);
1277 case ICmpInst::ICMP_ULE:
1278 // If we know that C1 <= C2, we can only partially decide this relation.
1279 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getFalse();
1280 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getTrue();
1282 case ICmpInst::ICMP_SLE:
1283 // If we know that C1 <= C2, we can only partially decide this relation.
1284 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getFalse();
1285 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getTrue();
1288 case ICmpInst::ICMP_UGE:
1289 // If we know that C1 >= C2, we can only partially decide this relation.
1290 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getFalse();
1291 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getTrue();
1293 case ICmpInst::ICMP_SGE:
1294 // If we know that C1 >= C2, we can only partially decide this relation.
1295 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getFalse();
1296 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getTrue();
1299 case ICmpInst::ICMP_NE:
1300 // If we know that C1 != C2, we can only partially decide this relation.
1301 if (pred == ICmpInst::ICMP_EQ) return ConstantInt::getFalse();
1302 if (pred == ICmpInst::ICMP_NE) return ConstantInt::getTrue();
1306 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) {
1307 // If C2 is a constant expr and C1 isn't, flop them around and fold the
1308 // other way if possible.
1310 case ICmpInst::ICMP_EQ:
1311 case ICmpInst::ICMP_NE:
1312 // No change of predicate required.
1313 return ConstantFoldCompareInstruction(pred, C2, C1);
1315 case ICmpInst::ICMP_ULT:
1316 case ICmpInst::ICMP_SLT:
1317 case ICmpInst::ICMP_UGT:
1318 case ICmpInst::ICMP_SGT:
1319 case ICmpInst::ICMP_ULE:
1320 case ICmpInst::ICMP_SLE:
1321 case ICmpInst::ICMP_UGE:
1322 case ICmpInst::ICMP_SGE:
1323 // Change the predicate as necessary to swap the operands.
1324 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
1325 return ConstantFoldCompareInstruction(pred, C2, C1);
1327 default: // These predicates cannot be flopped around.
1335 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1336 Constant* const *Idxs,
1339 (NumIdx == 1 && Idxs[0]->isNullValue()))
1340 return const_cast<Constant*>(C);
1342 if (isa<UndefValue>(C)) {
1343 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(),
1345 (Value **)Idxs+NumIdx,
1347 assert(Ty != 0 && "Invalid indices for GEP!");
1348 return UndefValue::get(PointerType::get(Ty));
1351 Constant *Idx0 = Idxs[0];
1352 if (C->isNullValue()) {
1354 for (unsigned i = 0, e = NumIdx; i != e; ++i)
1355 if (!Idxs[i]->isNullValue()) {
1360 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(),
1362 (Value**)Idxs+NumIdx,
1364 assert(Ty != 0 && "Invalid indices for GEP!");
1365 return ConstantPointerNull::get(PointerType::get(Ty));
1369 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1370 // Combine Indices - If the source pointer to this getelementptr instruction
1371 // is a getelementptr instruction, combine the indices of the two
1372 // getelementptr instructions into a single instruction.
1374 if (CE->getOpcode() == Instruction::GetElementPtr) {
1375 const Type *LastTy = 0;
1376 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1380 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1381 SmallVector<Value*, 16> NewIndices;
1382 NewIndices.reserve(NumIdx + CE->getNumOperands());
1383 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1384 NewIndices.push_back(CE->getOperand(i));
1386 // Add the last index of the source with the first index of the new GEP.
1387 // Make sure to handle the case when they are actually different types.
1388 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1389 // Otherwise it must be an array.
1390 if (!Idx0->isNullValue()) {
1391 const Type *IdxTy = Combined->getType();
1392 if (IdxTy != Idx0->getType()) {
1393 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty);
1394 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
1396 Combined = ConstantExpr::get(Instruction::Add, C1, C2);
1399 ConstantExpr::get(Instruction::Add, Idx0, Combined);
1403 NewIndices.push_back(Combined);
1404 NewIndices.insert(NewIndices.end(), Idxs+1, Idxs+NumIdx);
1405 return ConstantExpr::getGetElementPtr(CE->getOperand(0), &NewIndices[0],
1410 // Implement folding of:
1411 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1413 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1415 if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue()) {
1416 if (const PointerType *SPT =
1417 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1418 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1419 if (const ArrayType *CAT =
1420 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1421 if (CAT->getElementType() == SAT->getElementType())
1422 return ConstantExpr::getGetElementPtr(
1423 (Constant*)CE->getOperand(0), Idxs, NumIdx);
1426 // Fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1)
1427 // Into: inttoptr (i64 0 to i8*)
1428 // This happens with pointers to member functions in C++.
1429 if (CE->getOpcode() == Instruction::IntToPtr && NumIdx == 1 &&
1430 isa<ConstantInt>(CE->getOperand(0)) && isa<ConstantInt>(Idxs[0]) &&
1431 cast<PointerType>(CE->getType())->getElementType() == Type::Int8Ty) {
1432 Constant *Base = CE->getOperand(0);
1433 Constant *Offset = Idxs[0];
1435 // Convert the smaller integer to the larger type.
1436 if (Offset->getType()->getPrimitiveSizeInBits() <
1437 Base->getType()->getPrimitiveSizeInBits())
1438 Offset = ConstantExpr::getSExt(Offset, Base->getType());
1439 else if (Base->getType()->getPrimitiveSizeInBits() <
1440 Offset->getType()->getPrimitiveSizeInBits())
1441 Base = ConstantExpr::getZExt(Base, Base->getType());
1443 Base = ConstantExpr::getAdd(Base, Offset);
1444 return ConstantExpr::getIntToPtr(Base, CE->getType());