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/ADT/SmallVector.h"
27 #include "llvm/Support/Compiler.h"
28 #include "llvm/Support/GetElementPtrTypeIterator.h"
29 #include "llvm/Support/ManagedStatic.h"
30 #include "llvm/Support/MathExtras.h"
34 //===----------------------------------------------------------------------===//
35 // ConstantFold*Instruction Implementations
36 //===----------------------------------------------------------------------===//
38 /// CastConstantVector - Convert the specified ConstantVector node to the
39 /// specified vector type. At this point, we know that the elements of the
40 /// input packed constant are all simple integer or FP values.
41 static Constant *CastConstantVector(ConstantVector *CV,
42 const VectorType *DstTy) {
43 unsigned SrcNumElts = CV->getType()->getNumElements();
44 unsigned DstNumElts = DstTy->getNumElements();
45 const Type *SrcEltTy = CV->getType()->getElementType();
46 const Type *DstEltTy = DstTy->getElementType();
48 // If both vectors have the same number of elements (thus, the elements
49 // are the same size), perform the conversion now.
50 if (SrcNumElts == DstNumElts) {
51 std::vector<Constant*> Result;
53 // If the src and dest elements are both integers, or both floats, we can
54 // just BitCast each element because the elements are the same size.
55 if ((SrcEltTy->isInteger() && DstEltTy->isInteger()) ||
56 (SrcEltTy->isFloatingPoint() && DstEltTy->isFloatingPoint())) {
57 for (unsigned i = 0; i != SrcNumElts; ++i)
59 ConstantExpr::getBitCast(CV->getOperand(i), DstEltTy));
60 return ConstantVector::get(Result);
63 // If this is an int-to-fp cast ..
64 if (SrcEltTy->isInteger()) {
65 // Ensure that it is int-to-fp cast
66 assert(DstEltTy->isFloatingPoint());
67 if (DstEltTy->getTypeID() == Type::DoubleTyID) {
68 for (unsigned i = 0; i != SrcNumElts; ++i) {
70 BitsToDouble(cast<ConstantInt>(CV->getOperand(i))->getZExtValue());
71 Result.push_back(ConstantFP::get(Type::DoubleTy, V));
73 return ConstantVector::get(Result);
75 assert(DstEltTy == Type::FloatTy && "Unknown fp type!");
76 for (unsigned i = 0; i != SrcNumElts; ++i) {
78 BitsToFloat(cast<ConstantInt>(CV->getOperand(i))->getZExtValue());
79 Result.push_back(ConstantFP::get(Type::FloatTy, V));
81 return ConstantVector::get(Result);
84 // Otherwise, this is an fp-to-int cast.
85 assert(SrcEltTy->isFloatingPoint() && DstEltTy->isInteger());
87 if (SrcEltTy->getTypeID() == Type::DoubleTyID) {
88 for (unsigned i = 0; i != SrcNumElts; ++i) {
90 DoubleToBits(cast<ConstantFP>(CV->getOperand(i))->getValue());
91 Constant *C = ConstantInt::get(Type::Int64Ty,
92 APIntOps::RoundDoubleToAPInt(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 = FloatToBits(cast<ConstantFP>(CV->getOperand(i))->getValue());
101 Constant *C = ConstantInt::get(Type::Int32Ty, V);
102 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy));
104 return ConstantVector::get(Result);
107 // Otherwise, this is a cast that changes element count and size. Handle
108 // casts which shrink the elements here.
110 // FIXME: We need to know endianness to do this!
115 /// This function determines which opcode to use to fold two constant cast
116 /// expressions together. It uses CastInst::isEliminableCastPair to determine
117 /// the opcode. Consequently its just a wrapper around that function.
118 /// @Determine if it is valid to fold a cast of a cast
120 foldConstantCastPair(
121 unsigned opc, ///< opcode of the second cast constant expression
122 const ConstantExpr*Op, ///< the first cast constant expression
123 const Type *DstTy ///< desintation type of the first cast
125 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
126 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
127 assert(CastInst::isCast(opc) && "Invalid cast opcode");
129 // The the types and opcodes for the two Cast constant expressions
130 const Type *SrcTy = Op->getOperand(0)->getType();
131 const Type *MidTy = Op->getType();
132 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
133 Instruction::CastOps secondOp = Instruction::CastOps(opc);
135 // Let CastInst::isEliminableCastPair do the heavy lifting.
136 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
140 Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
141 const Type *DestTy) {
142 const Type *SrcTy = V->getType();
144 if (isa<UndefValue>(V))
145 return UndefValue::get(DestTy);
147 // If the cast operand is a constant expression, there's a few things we can
148 // do to try to simplify it.
149 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
151 // Try hard to fold cast of cast because they are often eliminable.
152 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
153 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
154 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
155 // If all of the indexes in the GEP are null values, there is no pointer
156 // adjustment going on. We might as well cast the source pointer.
157 bool isAllNull = true;
158 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
159 if (!CE->getOperand(i)->isNullValue()) {
164 // This is casting one pointer type to another, always BitCast
165 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
169 // We actually have to do a cast now. Perform the cast according to the
172 case Instruction::FPTrunc:
173 case Instruction::FPExt:
174 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V))
175 return ConstantFP::get(DestTy, FPC->getValue());
176 return 0; // Can't fold.
177 case Instruction::FPToUI:
178 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
179 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
180 APInt Val(APIntOps::RoundDoubleToAPInt(FPC->getValue(), DestBitWidth));
181 return ConstantInt::get(DestTy, Val);
183 return 0; // Can't fold.
184 case Instruction::FPToSI:
185 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
186 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
187 APInt Val(APIntOps::RoundDoubleToAPInt(FPC->getValue(), DestBitWidth));
188 return ConstantInt::get(DestTy, Val);
190 return 0; // Can't fold.
191 case Instruction::IntToPtr: //always treated as unsigned
192 if (V->isNullValue()) // Is it an integral null value?
193 return ConstantPointerNull::get(cast<PointerType>(DestTy));
194 return 0; // Other pointer types cannot be casted
195 case Instruction::PtrToInt: // always treated as unsigned
196 if (V->isNullValue()) // is it a null pointer value?
197 return ConstantInt::get(DestTy, 0);
198 return 0; // Other pointer types cannot be casted
199 case Instruction::UIToFP:
200 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
201 return ConstantFP::get(DestTy, CI->getValue().roundToDouble());
203 case Instruction::SIToFP:
204 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
205 return ConstantFP::get(DestTy, CI->getValue().signedRoundToDouble());
207 case Instruction::ZExt:
208 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
209 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
210 APInt Result(CI->getValue());
211 Result.zext(BitWidth);
212 return ConstantInt::get(DestTy, Result);
215 case Instruction::SExt:
216 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
217 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
218 APInt Result(CI->getValue());
219 Result.sext(BitWidth);
220 return ConstantInt::get(DestTy, Result);
223 case Instruction::Trunc:
224 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
225 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
226 APInt Result(CI->getValue());
227 Result.trunc(BitWidth);
228 return ConstantInt::get(DestTy, Result);
231 case Instruction::BitCast:
233 return (Constant*)V; // no-op cast
235 // Check to see if we are casting a pointer to an aggregate to a pointer to
236 // the first element. If so, return the appropriate GEP instruction.
237 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
238 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
239 SmallVector<Value*, 8> IdxList;
240 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
241 const Type *ElTy = PTy->getElementType();
242 while (ElTy != DPTy->getElementType()) {
243 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
244 if (STy->getNumElements() == 0) break;
245 ElTy = STy->getElementType(0);
246 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
247 } else if (const SequentialType *STy =
248 dyn_cast<SequentialType>(ElTy)) {
249 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
250 ElTy = STy->getElementType();
251 IdxList.push_back(IdxList[0]);
257 if (ElTy == DPTy->getElementType())
258 return ConstantExpr::getGetElementPtr(
259 const_cast<Constant*>(V), &IdxList[0], IdxList.size());
262 // Handle casts from one packed constant to another. We know that the src
263 // and dest type have the same size (otherwise its an illegal cast).
264 if (const VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) {
265 if (const VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) {
266 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
267 "Not cast between same sized vectors!");
268 // First, check for null and undef
269 if (isa<ConstantAggregateZero>(V))
270 return Constant::getNullValue(DestTy);
271 if (isa<UndefValue>(V))
272 return UndefValue::get(DestTy);
274 if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
275 // This is a cast from a ConstantVector of one type to a
276 // ConstantVector of another type. Check to see if all elements of
277 // the input are simple.
278 bool AllSimpleConstants = true;
279 for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) {
280 if (!isa<ConstantInt>(CV->getOperand(i)) &&
281 !isa<ConstantFP>(CV->getOperand(i))) {
282 AllSimpleConstants = false;
287 // If all of the elements are simple constants, we can fold this.
288 if (AllSimpleConstants)
289 return CastConstantVector(const_cast<ConstantVector*>(CV), DestPTy);
294 // Finally, implement bitcast folding now. The code below doesn't handle
296 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
297 return ConstantPointerNull::get(cast<PointerType>(DestTy));
299 // Handle integral constant input.
300 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
301 if (DestTy->isInteger())
302 // Integral -> Integral. This is a no-op because the bit widths must
303 // be the same. Consequently, we just fold to V.
304 return const_cast<Constant*>(V);
306 if (DestTy->isFloatingPoint()) {
307 if (DestTy == Type::FloatTy)
308 return ConstantFP::get(DestTy, BitsToFloat(CI->getZExtValue()));
309 assert(DestTy == Type::DoubleTy && "Unknown FP type!");
310 return ConstantFP::get(DestTy, BitsToDouble(CI->getZExtValue()));
312 // Otherwise, can't fold this (packed?)
316 // Handle ConstantFP input.
317 if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
319 if (DestTy == Type::Int32Ty) {
320 return ConstantInt::get(DestTy, FloatToBits(FP->getValue()));
322 assert(DestTy == Type::Int64Ty && "only support f32/f64 for now!");
323 return ConstantInt::get(DestTy, DoubleToBits(FP->getValue()));
328 assert(!"Invalid CE CastInst opcode");
332 assert(0 && "Failed to cast constant expression");
336 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
338 const Constant *V2) {
339 if (const ConstantInt *CB = dyn_cast<ConstantInt>(Cond))
340 return const_cast<Constant*>(CB->getZExtValue() ? V1 : V2);
342 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
343 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
344 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
345 if (V1 == V2) return const_cast<Constant*>(V1);
349 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
350 const Constant *Idx) {
351 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
352 return UndefValue::get(cast<VectorType>(Val->getType())->getElementType());
353 if (Val->isNullValue()) // ee(zero, x) -> zero
354 return Constant::getNullValue(
355 cast<VectorType>(Val->getType())->getElementType());
357 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
358 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
359 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue()));
360 } else if (isa<UndefValue>(Idx)) {
361 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
362 return const_cast<Constant*>(CVal->getOperand(0));
368 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
370 const Constant *Idx) {
371 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
373 APInt idxVal = CIdx->getValue();
374 if (isa<UndefValue>(Val)) {
375 // Insertion of scalar constant into packed undef
376 // Optimize away insertion of undef
377 if (isa<UndefValue>(Elt))
378 return const_cast<Constant*>(Val);
379 // Otherwise break the aggregate undef into multiple undefs and do
382 cast<VectorType>(Val->getType())->getNumElements();
383 std::vector<Constant*> Ops;
385 for (unsigned i = 0; i < numOps; ++i) {
387 (idxVal == i) ? Elt : UndefValue::get(Elt->getType());
388 Ops.push_back(const_cast<Constant*>(Op));
390 return ConstantVector::get(Ops);
392 if (isa<ConstantAggregateZero>(Val)) {
393 // Insertion of scalar constant into packed aggregate zero
394 // Optimize away insertion of zero
395 if (Elt->isNullValue())
396 return const_cast<Constant*>(Val);
397 // Otherwise break the aggregate zero into multiple zeros and do
400 cast<VectorType>(Val->getType())->getNumElements();
401 std::vector<Constant*> Ops;
403 for (unsigned i = 0; i < numOps; ++i) {
405 (idxVal == i) ? Elt : Constant::getNullValue(Elt->getType());
406 Ops.push_back(const_cast<Constant*>(Op));
408 return ConstantVector::get(Ops);
410 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
411 // Insertion of scalar constant into packed constant
412 std::vector<Constant*> Ops;
413 Ops.reserve(CVal->getNumOperands());
414 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
416 (idxVal == i) ? Elt : cast<Constant>(CVal->getOperand(i));
417 Ops.push_back(const_cast<Constant*>(Op));
419 return ConstantVector::get(Ops);
424 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
426 const Constant *Mask) {
431 /// EvalVectorOp - Given two packed constants and a function pointer, apply the
432 /// function pointer to each element pair, producing a new ConstantVector
434 static Constant *EvalVectorOp(const ConstantVector *V1,
435 const ConstantVector *V2,
436 Constant *(*FP)(Constant*, Constant*)) {
437 std::vector<Constant*> Res;
438 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
439 Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
440 const_cast<Constant*>(V2->getOperand(i))));
441 return ConstantVector::get(Res);
444 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
446 const Constant *C2) {
447 // Handle UndefValue up front
448 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
450 case Instruction::Add:
451 case Instruction::Sub:
452 case Instruction::Xor:
453 return UndefValue::get(C1->getType());
454 case Instruction::Mul:
455 case Instruction::And:
456 return Constant::getNullValue(C1->getType());
457 case Instruction::UDiv:
458 case Instruction::SDiv:
459 case Instruction::FDiv:
460 case Instruction::URem:
461 case Instruction::SRem:
462 case Instruction::FRem:
463 if (!isa<UndefValue>(C2)) // undef / X -> 0
464 return Constant::getNullValue(C1->getType());
465 return const_cast<Constant*>(C2); // X / undef -> undef
466 case Instruction::Or: // X | undef -> -1
467 if (const VectorType *PTy = dyn_cast<VectorType>(C1->getType()))
468 return ConstantVector::getAllOnesValue(PTy);
469 return ConstantInt::getAllOnesValue(C1->getType());
470 case Instruction::LShr:
471 if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
472 return const_cast<Constant*>(C1); // undef lshr undef -> undef
473 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0
475 case Instruction::AShr:
476 if (!isa<UndefValue>(C2))
477 return const_cast<Constant*>(C1); // undef ashr X --> undef
478 else if (isa<UndefValue>(C1))
479 return const_cast<Constant*>(C1); // undef ashr undef -> undef
481 return const_cast<Constant*>(C1); // X ashr undef --> X
482 case Instruction::Shl:
483 // undef << X -> 0 or X << undef -> 0
484 return Constant::getNullValue(C1->getType());
488 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
489 if (isa<ConstantExpr>(C2)) {
490 // There are many possible foldings we could do here. We should probably
491 // at least fold add of a pointer with an integer into the appropriate
492 // getelementptr. This will improve alias analysis a bit.
494 // Just implement a couple of simple identities.
496 case Instruction::Add:
497 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X + 0 == X
499 case Instruction::Sub:
500 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X - 0 == X
502 case Instruction::Mul:
503 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X * 0 == 0
504 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
505 if (CI->equalsInt(1))
506 return const_cast<Constant*>(C1); // X * 1 == X
508 case Instruction::UDiv:
509 case Instruction::SDiv:
510 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
511 if (CI->equalsInt(1))
512 return const_cast<Constant*>(C1); // X / 1 == X
514 case Instruction::URem:
515 case Instruction::SRem:
516 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
517 if (CI->equalsInt(1))
518 return Constant::getNullValue(CI->getType()); // X % 1 == 0
520 case Instruction::And:
521 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
522 if (CI->isAllOnesValue())
523 return const_cast<Constant*>(C1); // X & -1 == X
524 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X & 0 == 0
525 if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
526 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
528 // Functions are at least 4-byte aligned. If and'ing the address of a
529 // function with a constant < 4, fold it to zero.
530 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
531 if (CI->getValue().ult(APInt(CI->getType()->getBitWidth(),4)) &&
533 return Constant::getNullValue(CI->getType());
536 case Instruction::Or:
537 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X | 0 == X
538 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
539 if (CI->isAllOnesValue())
540 return const_cast<Constant*>(C2); // X | -1 == -1
542 case Instruction::Xor:
543 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X ^ 0 == X
547 } else if (isa<ConstantExpr>(C2)) {
548 // If C2 is a constant expr and C1 isn't, flop them around and fold the
549 // other way if possible.
551 case Instruction::Add:
552 case Instruction::Mul:
553 case Instruction::And:
554 case Instruction::Or:
555 case Instruction::Xor:
556 // No change of opcode required.
557 return ConstantFoldBinaryInstruction(Opcode, C2, C1);
559 case Instruction::Shl:
560 case Instruction::LShr:
561 case Instruction::AShr:
562 case Instruction::Sub:
563 case Instruction::SDiv:
564 case Instruction::UDiv:
565 case Instruction::FDiv:
566 case Instruction::URem:
567 case Instruction::SRem:
568 case Instruction::FRem:
569 default: // These instructions cannot be flopped around.
574 // At this point we know neither constant is an UndefValue nor a ConstantExpr
575 // so look at directly computing the value.
576 if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
577 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
578 using namespace APIntOps;
579 APInt C1V = CI1->getValue();
580 APInt C2V = CI2->getValue();
584 case Instruction::Add:
585 return ConstantInt::get(C1->getType(), C1V + C2V);
586 case Instruction::Sub:
587 return ConstantInt::get(C1->getType(), C1V - C2V);
588 case Instruction::Mul:
589 return ConstantInt::get(C1->getType(), C1V * C2V);
590 case Instruction::UDiv:
591 if (CI2->isNullValue())
592 return 0; // X / 0 -> can't fold
593 return ConstantInt::get(C1->getType(), C1V.udiv(C2V));
594 case Instruction::SDiv:
595 if (CI2->isNullValue())
596 return 0; // X / 0 -> can't fold
597 if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
598 return 0; // MIN_INT / -1 -> overflow
599 return ConstantInt::get(C1->getType(), C1V.sdiv(C2V));
600 case Instruction::URem:
601 if (C2->isNullValue())
602 return 0; // X / 0 -> can't fold
603 return ConstantInt::get(C1->getType(), C1V.urem(C2V));
604 case Instruction::SRem:
605 if (CI2->isNullValue())
606 return 0; // X % 0 -> can't fold
607 if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
608 return 0; // MIN_INT % -1 -> overflow
609 return ConstantInt::get(C1->getType(), C1V.srem(C2V));
610 case Instruction::And:
611 return ConstantInt::get(C1->getType(), C1V & C2V);
612 case Instruction::Or:
613 return ConstantInt::get(C1->getType(), C1V | C2V);
614 case Instruction::Xor:
615 return ConstantInt::get(C1->getType(), C1V ^ C2V);
616 case Instruction::Shl:
617 if (uint32_t shiftAmt = C2V.getZExtValue())
618 if (shiftAmt < C1V.getBitWidth())
619 return ConstantInt::get(C1->getType(), C1V.shl(shiftAmt));
621 return UndefValue::get(C1->getType()); // too big shift is undef
622 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
623 case Instruction::LShr:
624 if (uint32_t shiftAmt = C2V.getZExtValue())
625 if (shiftAmt < C1V.getBitWidth())
626 return ConstantInt::get(C1->getType(), C1V.lshr(shiftAmt));
628 return UndefValue::get(C1->getType()); // too big shift is undef
629 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
630 case Instruction::AShr:
631 if (uint32_t shiftAmt = C2V.getZExtValue())
632 if (shiftAmt < C1V.getBitWidth())
633 return ConstantInt::get(C1->getType(), C1V.ashr(shiftAmt));
635 return UndefValue::get(C1->getType()); // too big shift is undef
636 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
639 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
640 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
641 double C1Val = CFP1->getValue();
642 double C2Val = CFP2->getValue();
646 case Instruction::Add:
647 return ConstantFP::get(CFP1->getType(), C1Val + C2Val);
648 case Instruction::Sub:
649 return ConstantFP::get(CFP1->getType(), C1Val - C2Val);
650 case Instruction::Mul:
651 return ConstantFP::get(CFP1->getType(), C1Val * C2Val);
652 case Instruction::FDiv:
653 if (CFP2->isExactlyValue(0.0))
654 return ConstantFP::get(CFP1->getType(),
655 std::numeric_limits<double>::infinity());
656 if (CFP2->isExactlyValue(-0.0))
657 return ConstantFP::get(CFP1->getType(),
658 -std::numeric_limits<double>::infinity());
659 return ConstantFP::get(CFP1->getType(), C1Val / C2Val);
660 case Instruction::FRem:
661 if (CFP2->isNullValue())
663 return ConstantFP::get(CFP1->getType(), std::fmod(C1Val, C2Val));
666 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {
667 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) {
671 case Instruction::Add:
672 return EvalVectorOp(CP1, CP2, ConstantExpr::getAdd);
673 case Instruction::Sub:
674 return EvalVectorOp(CP1, CP2, ConstantExpr::getSub);
675 case Instruction::Mul:
676 return EvalVectorOp(CP1, CP2, ConstantExpr::getMul);
677 case Instruction::UDiv:
678 return EvalVectorOp(CP1, CP2, ConstantExpr::getUDiv);
679 case Instruction::SDiv:
680 return EvalVectorOp(CP1, CP2, ConstantExpr::getSDiv);
681 case Instruction::FDiv:
682 return EvalVectorOp(CP1, CP2, ConstantExpr::getFDiv);
683 case Instruction::URem:
684 return EvalVectorOp(CP1, CP2, ConstantExpr::getURem);
685 case Instruction::SRem:
686 return EvalVectorOp(CP1, CP2, ConstantExpr::getSRem);
687 case Instruction::FRem:
688 return EvalVectorOp(CP1, CP2, ConstantExpr::getFRem);
689 case Instruction::And:
690 return EvalVectorOp(CP1, CP2, ConstantExpr::getAnd);
691 case Instruction::Or:
692 return EvalVectorOp(CP1, CP2, ConstantExpr::getOr);
693 case Instruction::Xor:
694 return EvalVectorOp(CP1, CP2, ConstantExpr::getXor);
699 // We don't know how to fold this
703 /// isZeroSizedType - This type is zero sized if its an array or structure of
704 /// zero sized types. The only leaf zero sized type is an empty structure.
705 static bool isMaybeZeroSizedType(const Type *Ty) {
706 if (isa<OpaqueType>(Ty)) return true; // Can't say.
707 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
709 // If all of elements have zero size, this does too.
710 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
711 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
714 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
715 return isMaybeZeroSizedType(ATy->getElementType());
720 /// IdxCompare - Compare the two constants as though they were getelementptr
721 /// indices. This allows coersion of the types to be the same thing.
723 /// If the two constants are the "same" (after coersion), return 0. If the
724 /// first is less than the second, return -1, if the second is less than the
725 /// first, return 1. If the constants are not integral, return -2.
727 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
728 if (C1 == C2) return 0;
730 // Ok, we found a different index. If they are not ConstantInt, we can't do
731 // anything with them.
732 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
733 return -2; // don't know!
735 // Ok, we have two differing integer indices. Sign extend them to be the same
736 // type. Long is always big enough, so we use it.
737 if (C1->getType() != Type::Int64Ty)
738 C1 = ConstantExpr::getSExt(C1, Type::Int64Ty);
740 if (C2->getType() != Type::Int64Ty)
741 C2 = ConstantExpr::getSExt(C2, Type::Int64Ty);
743 if (C1 == C2) return 0; // They are equal
745 // If the type being indexed over is really just a zero sized type, there is
746 // no pointer difference being made here.
747 if (isMaybeZeroSizedType(ElTy))
750 // If they are really different, now that they are the same type, then we
751 // found a difference!
752 if (cast<ConstantInt>(C1)->getSExtValue() <
753 cast<ConstantInt>(C2)->getSExtValue())
759 /// evaluateFCmpRelation - This function determines if there is anything we can
760 /// decide about the two constants provided. This doesn't need to handle simple
761 /// things like ConstantFP comparisons, but should instead handle ConstantExprs.
762 /// If we can determine that the two constants have a particular relation to
763 /// each other, we should return the corresponding FCmpInst predicate,
764 /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
765 /// ConstantFoldCompareInstruction.
767 /// To simplify this code we canonicalize the relation so that the first
768 /// operand is always the most "complex" of the two. We consider ConstantFP
769 /// to be the simplest, and ConstantExprs to be the most complex.
770 static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1,
771 const Constant *V2) {
772 assert(V1->getType() == V2->getType() &&
773 "Cannot compare values of different types!");
774 // Handle degenerate case quickly
775 if (V1 == V2) return FCmpInst::FCMP_OEQ;
777 if (!isa<ConstantExpr>(V1)) {
778 if (!isa<ConstantExpr>(V2)) {
779 // We distilled thisUse the standard constant folder for a few cases
781 Constant *C1 = const_cast<Constant*>(V1);
782 Constant *C2 = const_cast<Constant*>(V2);
783 R = dyn_cast<ConstantInt>(
784 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2));
785 if (R && !R->isNullValue())
786 return FCmpInst::FCMP_OEQ;
787 R = dyn_cast<ConstantInt>(
788 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2));
789 if (R && !R->isNullValue())
790 return FCmpInst::FCMP_OLT;
791 R = dyn_cast<ConstantInt>(
792 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2));
793 if (R && !R->isNullValue())
794 return FCmpInst::FCMP_OGT;
796 // Nothing more we can do
797 return FCmpInst::BAD_FCMP_PREDICATE;
800 // If the first operand is simple and second is ConstantExpr, swap operands.
801 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
802 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
803 return FCmpInst::getSwappedPredicate(SwappedRelation);
805 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
806 // constantexpr or a simple constant.
807 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
808 switch (CE1->getOpcode()) {
809 case Instruction::FPTrunc:
810 case Instruction::FPExt:
811 case Instruction::UIToFP:
812 case Instruction::SIToFP:
813 // We might be able to do something with these but we don't right now.
819 // There are MANY other foldings that we could perform here. They will
820 // probably be added on demand, as they seem needed.
821 return FCmpInst::BAD_FCMP_PREDICATE;
824 /// evaluateICmpRelation - This function determines if there is anything we can
825 /// decide about the two constants provided. This doesn't need to handle simple
826 /// things like integer comparisons, but should instead handle ConstantExprs
827 /// and GlobalValues. If we can determine that the two constants have a
828 /// particular relation to each other, we should return the corresponding ICmp
829 /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.
831 /// To simplify this code we canonicalize the relation so that the first
832 /// operand is always the most "complex" of the two. We consider simple
833 /// constants (like ConstantInt) to be the simplest, followed by
834 /// GlobalValues, followed by ConstantExpr's (the most complex).
836 static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1,
839 assert(V1->getType() == V2->getType() &&
840 "Cannot compare different types of values!");
841 if (V1 == V2) return ICmpInst::ICMP_EQ;
843 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
844 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
845 // We distilled this down to a simple case, use the standard constant
848 Constant *C1 = const_cast<Constant*>(V1);
849 Constant *C2 = const_cast<Constant*>(V2);
850 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
851 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
852 if (R && !R->isNullValue())
854 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
855 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
856 if (R && !R->isNullValue())
858 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
859 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
860 if (R && !R->isNullValue())
863 // If we couldn't figure it out, bail.
864 return ICmpInst::BAD_ICMP_PREDICATE;
867 // If the first operand is simple, swap operands.
868 ICmpInst::Predicate SwappedRelation =
869 evaluateICmpRelation(V2, V1, isSigned);
870 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
871 return ICmpInst::getSwappedPredicate(SwappedRelation);
873 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
874 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
875 ICmpInst::Predicate SwappedRelation =
876 evaluateICmpRelation(V2, V1, isSigned);
877 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
878 return ICmpInst::getSwappedPredicate(SwappedRelation);
880 return ICmpInst::BAD_ICMP_PREDICATE;
883 // Now we know that the RHS is a GlobalValue or simple constant,
884 // which (since the types must match) means that it's a ConstantPointerNull.
885 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
886 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
887 return ICmpInst::ICMP_NE;
889 // GlobalVals can never be null.
890 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
891 if (!CPR1->hasExternalWeakLinkage())
892 return ICmpInst::ICMP_NE;
895 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
896 // constantexpr, a CPR, or a simple constant.
897 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
898 const Constant *CE1Op0 = CE1->getOperand(0);
900 switch (CE1->getOpcode()) {
901 case Instruction::Trunc:
902 case Instruction::FPTrunc:
903 case Instruction::FPExt:
904 case Instruction::FPToUI:
905 case Instruction::FPToSI:
906 break; // We can't evaluate floating point casts or truncations.
908 case Instruction::UIToFP:
909 case Instruction::SIToFP:
910 case Instruction::IntToPtr:
911 case Instruction::BitCast:
912 case Instruction::ZExt:
913 case Instruction::SExt:
914 case Instruction::PtrToInt:
915 // If the cast is not actually changing bits, and the second operand is a
916 // null pointer, do the comparison with the pre-casted value.
917 if (V2->isNullValue() &&
918 (isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) {
919 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
920 (CE1->getOpcode() == Instruction::SExt ? true :
921 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
922 return evaluateICmpRelation(
923 CE1Op0, Constant::getNullValue(CE1Op0->getType()), sgnd);
926 // If the dest type is a pointer type, and the RHS is a constantexpr cast
927 // from the same type as the src of the LHS, evaluate the inputs. This is
928 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)",
929 // which happens a lot in compilers with tagged integers.
930 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
931 if (CE2->isCast() && isa<PointerType>(CE1->getType()) &&
932 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
933 CE1->getOperand(0)->getType()->isInteger()) {
934 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
935 (CE1->getOpcode() == Instruction::SExt ? true :
936 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
937 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0),
942 case Instruction::GetElementPtr:
943 // Ok, since this is a getelementptr, we know that the constant has a
944 // pointer type. Check the various cases.
945 if (isa<ConstantPointerNull>(V2)) {
946 // If we are comparing a GEP to a null pointer, check to see if the base
947 // of the GEP equals the null pointer.
948 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
949 if (GV->hasExternalWeakLinkage())
950 // Weak linkage GVals could be zero or not. We're comparing that
951 // to null pointer so its greater-or-equal
952 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
954 // If its not weak linkage, the GVal must have a non-zero address
955 // so the result is greater-than
956 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
957 } else if (isa<ConstantPointerNull>(CE1Op0)) {
958 // If we are indexing from a null pointer, check to see if we have any
960 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
961 if (!CE1->getOperand(i)->isNullValue())
962 // Offsetting from null, must not be equal.
963 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
964 // Only zero indexes from null, must still be zero.
965 return ICmpInst::ICMP_EQ;
967 // Otherwise, we can't really say if the first operand is null or not.
968 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
969 if (isa<ConstantPointerNull>(CE1Op0)) {
970 if (CPR2->hasExternalWeakLinkage())
971 // Weak linkage GVals could be zero or not. We're comparing it to
972 // a null pointer, so its less-or-equal
973 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
975 // If its not weak linkage, the GVal must have a non-zero address
976 // so the result is less-than
977 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
978 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
980 // If this is a getelementptr of the same global, then it must be
981 // different. Because the types must match, the getelementptr could
982 // only have at most one index, and because we fold getelementptr's
983 // with a single zero index, it must be nonzero.
984 assert(CE1->getNumOperands() == 2 &&
985 !CE1->getOperand(1)->isNullValue() &&
986 "Suprising getelementptr!");
987 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
989 // If they are different globals, we don't know what the value is,
990 // but they can't be equal.
991 return ICmpInst::ICMP_NE;
995 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
996 const Constant *CE2Op0 = CE2->getOperand(0);
998 // There are MANY other foldings that we could perform here. They will
999 // probably be added on demand, as they seem needed.
1000 switch (CE2->getOpcode()) {
1002 case Instruction::GetElementPtr:
1003 // By far the most common case to handle is when the base pointers are
1004 // obviously to the same or different globals.
1005 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
1006 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
1007 return ICmpInst::ICMP_NE;
1008 // Ok, we know that both getelementptr instructions are based on the
1009 // same global. From this, we can precisely determine the relative
1010 // ordering of the resultant pointers.
1013 // Compare all of the operands the GEP's have in common.
1014 gep_type_iterator GTI = gep_type_begin(CE1);
1015 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
1017 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
1018 GTI.getIndexedType())) {
1019 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
1020 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
1021 case -2: return ICmpInst::BAD_ICMP_PREDICATE;
1024 // Ok, we ran out of things they have in common. If any leftovers
1025 // are non-zero then we have a difference, otherwise we are equal.
1026 for (; i < CE1->getNumOperands(); ++i)
1027 if (!CE1->getOperand(i)->isNullValue())
1028 if (isa<ConstantInt>(CE1->getOperand(i)))
1029 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1031 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1033 for (; i < CE2->getNumOperands(); ++i)
1034 if (!CE2->getOperand(i)->isNullValue())
1035 if (isa<ConstantInt>(CE2->getOperand(i)))
1036 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1038 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1039 return ICmpInst::ICMP_EQ;
1048 return ICmpInst::BAD_ICMP_PREDICATE;
1051 Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
1053 const Constant *C2) {
1055 // Handle some degenerate cases first
1056 if (isa<UndefValue>(C1) || isa<UndefValue>(C2))
1057 return UndefValue::get(Type::Int1Ty);
1059 // icmp eq/ne(null,GV) -> false/true
1060 if (C1->isNullValue()) {
1061 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
1062 if (!GV->hasExternalWeakLinkage()) // External weak GV can be null
1063 if (pred == ICmpInst::ICMP_EQ)
1064 return ConstantInt::getFalse();
1065 else if (pred == ICmpInst::ICMP_NE)
1066 return ConstantInt::getTrue();
1067 // icmp eq/ne(GV,null) -> false/true
1068 } else if (C2->isNullValue()) {
1069 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
1070 if (!GV->hasExternalWeakLinkage()) // External weak GV can be null
1071 if (pred == ICmpInst::ICMP_EQ)
1072 return ConstantInt::getFalse();
1073 else if (pred == ICmpInst::ICMP_NE)
1074 return ConstantInt::getTrue();
1077 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
1078 APInt V1 = cast<ConstantInt>(C1)->getValue();
1079 APInt V2 = cast<ConstantInt>(C2)->getValue();
1081 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1082 case ICmpInst::ICMP_EQ: return ConstantInt::get(Type::Int1Ty, V1 == V2);
1083 case ICmpInst::ICMP_NE: return ConstantInt::get(Type::Int1Ty, V1 != V2);
1084 case ICmpInst::ICMP_SLT:return ConstantInt::get(Type::Int1Ty, V1.slt(V2));
1085 case ICmpInst::ICMP_SGT:return ConstantInt::get(Type::Int1Ty, V1.sgt(V2));
1086 case ICmpInst::ICMP_SLE:return ConstantInt::get(Type::Int1Ty, V1.sle(V2));
1087 case ICmpInst::ICMP_SGE:return ConstantInt::get(Type::Int1Ty, V1.sge(V2));
1088 case ICmpInst::ICMP_ULT:return ConstantInt::get(Type::Int1Ty, V1.ult(V2));
1089 case ICmpInst::ICMP_UGT:return ConstantInt::get(Type::Int1Ty, V1.ugt(V2));
1090 case ICmpInst::ICMP_ULE:return ConstantInt::get(Type::Int1Ty, V1.ule(V2));
1091 case ICmpInst::ICMP_UGE:return ConstantInt::get(Type::Int1Ty, V1.uge(V2));
1093 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
1094 double C1Val = cast<ConstantFP>(C1)->getValue();
1095 double C2Val = cast<ConstantFP>(C2)->getValue();
1097 default: assert(0 && "Invalid FCmp Predicate"); return 0;
1098 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse();
1099 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue();
1100 case FCmpInst::FCMP_UNO:
1101 return ConstantInt::get(Type::Int1Ty, C1Val != C1Val || C2Val != C2Val);
1102 case FCmpInst::FCMP_ORD:
1103 return ConstantInt::get(Type::Int1Ty, C1Val == C1Val && C2Val == C2Val);
1104 case FCmpInst::FCMP_UEQ:
1105 if (C1Val != C1Val || C2Val != C2Val)
1106 return ConstantInt::getTrue();
1108 case FCmpInst::FCMP_OEQ:
1109 return ConstantInt::get(Type::Int1Ty, C1Val == C2Val);
1110 case FCmpInst::FCMP_UNE:
1111 if (C1Val != C1Val || C2Val != C2Val)
1112 return ConstantInt::getTrue();
1114 case FCmpInst::FCMP_ONE:
1115 return ConstantInt::get(Type::Int1Ty, C1Val != C2Val);
1116 case FCmpInst::FCMP_ULT:
1117 if (C1Val != C1Val || C2Val != C2Val)
1118 return ConstantInt::getTrue();
1120 case FCmpInst::FCMP_OLT:
1121 return ConstantInt::get(Type::Int1Ty, C1Val < C2Val);
1122 case FCmpInst::FCMP_UGT:
1123 if (C1Val != C1Val || C2Val != C2Val)
1124 return ConstantInt::getTrue();
1126 case FCmpInst::FCMP_OGT:
1127 return ConstantInt::get(Type::Int1Ty, C1Val > C2Val);
1128 case FCmpInst::FCMP_ULE:
1129 if (C1Val != C1Val || C2Val != C2Val)
1130 return ConstantInt::getTrue();
1132 case FCmpInst::FCMP_OLE:
1133 return ConstantInt::get(Type::Int1Ty, C1Val <= C2Val);
1134 case FCmpInst::FCMP_UGE:
1135 if (C1Val != C1Val || C2Val != C2Val)
1136 return ConstantInt::getTrue();
1138 case FCmpInst::FCMP_OGE:
1139 return ConstantInt::get(Type::Int1Ty, C1Val >= C2Val);
1141 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {
1142 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) {
1143 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) {
1144 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1145 Constant *C= ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ,
1146 const_cast<Constant*>(CP1->getOperand(i)),
1147 const_cast<Constant*>(CP2->getOperand(i)));
1148 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1151 // Otherwise, could not decide from any element pairs.
1153 } else if (pred == ICmpInst::ICMP_EQ) {
1154 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1155 Constant *C = ConstantExpr::getICmp(ICmpInst::ICMP_EQ,
1156 const_cast<Constant*>(CP1->getOperand(i)),
1157 const_cast<Constant*>(CP2->getOperand(i)));
1158 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1161 // Otherwise, could not decide from any element pairs.
1167 if (C1->getType()->isFloatingPoint()) {
1168 switch (evaluateFCmpRelation(C1, C2)) {
1169 default: assert(0 && "Unknown relation!");
1170 case FCmpInst::FCMP_UNO:
1171 case FCmpInst::FCMP_ORD:
1172 case FCmpInst::FCMP_UEQ:
1173 case FCmpInst::FCMP_UNE:
1174 case FCmpInst::FCMP_ULT:
1175 case FCmpInst::FCMP_UGT:
1176 case FCmpInst::FCMP_ULE:
1177 case FCmpInst::FCMP_UGE:
1178 case FCmpInst::FCMP_TRUE:
1179 case FCmpInst::FCMP_FALSE:
1180 case FCmpInst::BAD_FCMP_PREDICATE:
1181 break; // Couldn't determine anything about these constants.
1182 case FCmpInst::FCMP_OEQ: // We know that C1 == C2
1183 return ConstantInt::get(Type::Int1Ty,
1184 pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
1185 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
1186 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1187 case FCmpInst::FCMP_OLT: // We know that C1 < C2
1188 return ConstantInt::get(Type::Int1Ty,
1189 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1190 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
1191 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
1192 case FCmpInst::FCMP_OGT: // We know that C1 > C2
1193 return ConstantInt::get(Type::Int1Ty,
1194 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1195 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
1196 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1197 case FCmpInst::FCMP_OLE: // We know that C1 <= C2
1198 // We can only partially decide this relation.
1199 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1200 return ConstantInt::getFalse();
1201 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1202 return ConstantInt::getTrue();
1204 case FCmpInst::FCMP_OGE: // We known that C1 >= C2
1205 // We can only partially decide this relation.
1206 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1207 return ConstantInt::getFalse();
1208 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1209 return ConstantInt::getTrue();
1211 case ICmpInst::ICMP_NE: // We know that C1 != C2
1212 // We can only partially decide this relation.
1213 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
1214 return ConstantInt::getFalse();
1215 if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
1216 return ConstantInt::getTrue();
1220 // Evaluate the relation between the two constants, per the predicate.
1221 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) {
1222 default: assert(0 && "Unknown relational!");
1223 case ICmpInst::BAD_ICMP_PREDICATE:
1224 break; // Couldn't determine anything about these constants.
1225 case ICmpInst::ICMP_EQ: // We know the constants are equal!
1226 // If we know the constants are equal, we can decide the result of this
1227 // computation precisely.
1228 return ConstantInt::get(Type::Int1Ty,
1229 pred == ICmpInst::ICMP_EQ ||
1230 pred == ICmpInst::ICMP_ULE ||
1231 pred == ICmpInst::ICMP_SLE ||
1232 pred == ICmpInst::ICMP_UGE ||
1233 pred == ICmpInst::ICMP_SGE);
1234 case ICmpInst::ICMP_ULT:
1235 // If we know that C1 < C2, we can decide the result of this computation
1237 return ConstantInt::get(Type::Int1Ty,
1238 pred == ICmpInst::ICMP_ULT ||
1239 pred == ICmpInst::ICMP_NE ||
1240 pred == ICmpInst::ICMP_ULE);
1241 case ICmpInst::ICMP_SLT:
1242 // If we know that C1 < C2, we can decide the result of this computation
1244 return ConstantInt::get(Type::Int1Ty,
1245 pred == ICmpInst::ICMP_SLT ||
1246 pred == ICmpInst::ICMP_NE ||
1247 pred == ICmpInst::ICMP_SLE);
1248 case ICmpInst::ICMP_UGT:
1249 // If we know that C1 > C2, we can decide the result of this computation
1251 return ConstantInt::get(Type::Int1Ty,
1252 pred == ICmpInst::ICMP_UGT ||
1253 pred == ICmpInst::ICMP_NE ||
1254 pred == ICmpInst::ICMP_UGE);
1255 case ICmpInst::ICMP_SGT:
1256 // If we know that C1 > C2, we can decide the result of this computation
1258 return ConstantInt::get(Type::Int1Ty,
1259 pred == ICmpInst::ICMP_SGT ||
1260 pred == ICmpInst::ICMP_NE ||
1261 pred == ICmpInst::ICMP_SGE);
1262 case ICmpInst::ICMP_ULE:
1263 // If we know that C1 <= C2, we can only partially decide this relation.
1264 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getFalse();
1265 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getTrue();
1267 case ICmpInst::ICMP_SLE:
1268 // If we know that C1 <= C2, we can only partially decide this relation.
1269 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getFalse();
1270 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getTrue();
1273 case ICmpInst::ICMP_UGE:
1274 // If we know that C1 >= C2, we can only partially decide this relation.
1275 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getFalse();
1276 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getTrue();
1278 case ICmpInst::ICMP_SGE:
1279 // If we know that C1 >= C2, we can only partially decide this relation.
1280 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getFalse();
1281 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getTrue();
1284 case ICmpInst::ICMP_NE:
1285 // If we know that C1 != C2, we can only partially decide this relation.
1286 if (pred == ICmpInst::ICMP_EQ) return ConstantInt::getFalse();
1287 if (pred == ICmpInst::ICMP_NE) return ConstantInt::getTrue();
1291 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) {
1292 // If C2 is a constant expr and C1 isn't, flop them around and fold the
1293 // other way if possible.
1295 case ICmpInst::ICMP_EQ:
1296 case ICmpInst::ICMP_NE:
1297 // No change of predicate required.
1298 return ConstantFoldCompareInstruction(pred, C2, C1);
1300 case ICmpInst::ICMP_ULT:
1301 case ICmpInst::ICMP_SLT:
1302 case ICmpInst::ICMP_UGT:
1303 case ICmpInst::ICMP_SGT:
1304 case ICmpInst::ICMP_ULE:
1305 case ICmpInst::ICMP_SLE:
1306 case ICmpInst::ICMP_UGE:
1307 case ICmpInst::ICMP_SGE:
1308 // Change the predicate as necessary to swap the operands.
1309 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
1310 return ConstantFoldCompareInstruction(pred, C2, C1);
1312 default: // These predicates cannot be flopped around.
1320 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1321 Constant* const *Idxs,
1324 (NumIdx == 1 && Idxs[0]->isNullValue()))
1325 return const_cast<Constant*>(C);
1327 if (isa<UndefValue>(C)) {
1328 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(),
1329 (Value**)Idxs, NumIdx,
1331 assert(Ty != 0 && "Invalid indices for GEP!");
1332 return UndefValue::get(PointerType::get(Ty));
1335 Constant *Idx0 = Idxs[0];
1336 if (C->isNullValue()) {
1338 for (unsigned i = 0, e = NumIdx; i != e; ++i)
1339 if (!Idxs[i]->isNullValue()) {
1344 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(),
1345 (Value**)Idxs, NumIdx,
1347 assert(Ty != 0 && "Invalid indices for GEP!");
1348 return ConstantPointerNull::get(PointerType::get(Ty));
1352 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1353 // Combine Indices - If the source pointer to this getelementptr instruction
1354 // is a getelementptr instruction, combine the indices of the two
1355 // getelementptr instructions into a single instruction.
1357 if (CE->getOpcode() == Instruction::GetElementPtr) {
1358 const Type *LastTy = 0;
1359 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1363 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1364 SmallVector<Value*, 16> NewIndices;
1365 NewIndices.reserve(NumIdx + CE->getNumOperands());
1366 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1367 NewIndices.push_back(CE->getOperand(i));
1369 // Add the last index of the source with the first index of the new GEP.
1370 // Make sure to handle the case when they are actually different types.
1371 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1372 // Otherwise it must be an array.
1373 if (!Idx0->isNullValue()) {
1374 const Type *IdxTy = Combined->getType();
1375 if (IdxTy != Idx0->getType()) {
1376 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty);
1377 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
1379 Combined = ConstantExpr::get(Instruction::Add, C1, C2);
1382 ConstantExpr::get(Instruction::Add, Idx0, Combined);
1386 NewIndices.push_back(Combined);
1387 NewIndices.insert(NewIndices.end(), Idxs+1, Idxs+NumIdx);
1388 return ConstantExpr::getGetElementPtr(CE->getOperand(0), &NewIndices[0],
1393 // Implement folding of:
1394 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1396 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1398 if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue())
1399 if (const PointerType *SPT =
1400 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1401 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1402 if (const ArrayType *CAT =
1403 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1404 if (CAT->getElementType() == SAT->getElementType())
1405 return ConstantExpr::getGetElementPtr(
1406 (Constant*)CE->getOperand(0), Idxs, NumIdx);