1 //===- ConstantFold.cpp - LLVM constant folder ----------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements folding of constants for LLVM. This implements the
11 // (internal) ConstantFold.h interface, which is used by the
12 // ConstantExpr::get* methods to automatically fold constants when possible.
14 // The current constant folding implementation is implemented in two pieces: the
15 // template-based folder for simple primitive constants like ConstantInt, and
16 // the special case hackery that we use to symbolically evaluate expressions
17 // that use ConstantExprs.
19 //===----------------------------------------------------------------------===//
21 #include "ConstantFold.h"
22 #include "llvm/Constants.h"
23 #include "llvm/Instructions.h"
24 #include "llvm/DerivedTypes.h"
25 #include "llvm/Function.h"
26 #include "llvm/GlobalAlias.h"
27 #include "llvm/ADT/SmallVector.h"
28 #include "llvm/Support/Compiler.h"
29 #include "llvm/Support/GetElementPtrTypeIterator.h"
30 #include "llvm/Support/ManagedStatic.h"
31 #include "llvm/Support/MathExtras.h"
35 //===----------------------------------------------------------------------===//
36 // ConstantFold*Instruction Implementations
37 //===----------------------------------------------------------------------===//
39 /// CastConstantVector - Convert the specified ConstantVector node to the
40 /// specified vector type. At this point, we know that the elements of the
41 /// input vector constant are all simple integer or FP values.
42 static Constant *CastConstantVector(ConstantVector *CV,
43 const VectorType *DstTy) {
44 unsigned SrcNumElts = CV->getType()->getNumElements();
45 unsigned DstNumElts = DstTy->getNumElements();
46 const Type *SrcEltTy = CV->getType()->getElementType();
47 const Type *DstEltTy = DstTy->getElementType();
49 // If both vectors have the same number of elements (thus, the elements
50 // are the same size), perform the conversion now.
51 if (SrcNumElts == DstNumElts) {
52 std::vector<Constant*> Result;
54 // If the src and dest elements are both integers, or both floats, we can
55 // just BitCast each element because the elements are the same size.
56 if ((SrcEltTy->isInteger() && DstEltTy->isInteger()) ||
57 (SrcEltTy->isFloatingPoint() && DstEltTy->isFloatingPoint())) {
58 for (unsigned i = 0; i != SrcNumElts; ++i)
60 ConstantExpr::getBitCast(CV->getOperand(i), DstEltTy));
61 return ConstantVector::get(Result);
64 // If this is an int-to-fp cast ..
65 if (SrcEltTy->isInteger()) {
66 // Ensure that it is int-to-fp cast
67 assert(DstEltTy->isFloatingPoint());
68 if (DstEltTy->getTypeID() == Type::DoubleTyID) {
69 for (unsigned i = 0; i != SrcNumElts; ++i) {
70 ConstantInt *CI = cast<ConstantInt>(CV->getOperand(i));
71 double V = CI->getValue().bitsToDouble();
72 Result.push_back(ConstantFP::get(Type::DoubleTy, APFloat(V)));
74 return ConstantVector::get(Result);
76 assert(DstEltTy == Type::FloatTy && "Unknown fp type!");
77 for (unsigned i = 0; i != SrcNumElts; ++i) {
78 ConstantInt *CI = cast<ConstantInt>(CV->getOperand(i));
79 float V = CI->getValue().bitsToFloat();
80 Result.push_back(ConstantFP::get(Type::FloatTy, APFloat(V)));
82 return ConstantVector::get(Result);
85 // Otherwise, this is an fp-to-int cast.
86 assert(SrcEltTy->isFloatingPoint() && DstEltTy->isInteger());
88 if (SrcEltTy->getTypeID() == Type::DoubleTyID) {
89 for (unsigned i = 0; i != SrcNumElts; ++i) {
90 uint64_t V = cast<ConstantFP>(CV->getOperand(i))->
91 getValueAPF().convertToAPInt().getZExtValue();
92 Constant *C = ConstantInt::get(Type::Int64Ty, V);
93 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy ));
95 return ConstantVector::get(Result);
98 assert(SrcEltTy->getTypeID() == Type::FloatTyID);
99 for (unsigned i = 0; i != SrcNumElts; ++i) {
100 uint32_t V = (uint32_t)cast<ConstantFP>(CV->getOperand(i))->
101 getValueAPF().convertToAPInt().getZExtValue();
102 Constant *C = ConstantInt::get(Type::Int32Ty, V);
103 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy));
105 return ConstantVector::get(Result);
108 // Otherwise, this is a cast that changes element count and size. Handle
109 // casts which shrink the elements here.
111 // FIXME: We need to know endianness to do this!
116 /// This function determines which opcode to use to fold two constant cast
117 /// expressions together. It uses CastInst::isEliminableCastPair to determine
118 /// the opcode. Consequently its just a wrapper around that function.
119 /// @brief Determine if it is valid to fold a cast of a cast
121 foldConstantCastPair(
122 unsigned opc, ///< opcode of the second cast constant expression
123 const ConstantExpr*Op, ///< the first cast constant expression
124 const Type *DstTy ///< desintation type of the first cast
126 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
127 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
128 assert(CastInst::isCast(opc) && "Invalid cast opcode");
130 // The the types and opcodes for the two Cast constant expressions
131 const Type *SrcTy = Op->getOperand(0)->getType();
132 const Type *MidTy = Op->getType();
133 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
134 Instruction::CastOps secondOp = Instruction::CastOps(opc);
136 // Let CastInst::isEliminableCastPair do the heavy lifting.
137 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
141 Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
142 const Type *DestTy) {
143 const Type *SrcTy = V->getType();
145 if (isa<UndefValue>(V)) {
146 // zext(undef) = 0, because the top bits will be zero.
147 // sext(undef) = 0, because the top bits will all be the same.
148 if (opc == Instruction::ZExt || opc == Instruction::SExt)
149 return Constant::getNullValue(DestTy);
150 return UndefValue::get(DestTy);
152 // No compile-time operations on this type yet.
153 if (V->getType() == Type::PPC_FP128Ty || DestTy == Type::PPC_FP128Ty)
156 // If the cast operand is a constant expression, there's a few things we can
157 // do to try to simplify it.
158 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
160 // Try hard to fold cast of cast because they are often eliminable.
161 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
162 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
163 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
164 // If all of the indexes in the GEP are null values, there is no pointer
165 // adjustment going on. We might as well cast the source pointer.
166 bool isAllNull = true;
167 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
168 if (!CE->getOperand(i)->isNullValue()) {
173 // This is casting one pointer type to another, always BitCast
174 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
178 // We actually have to do a cast now. Perform the cast according to the
181 case Instruction::FPTrunc:
182 case Instruction::FPExt:
183 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
184 APFloat Val = FPC->getValueAPF();
185 Val.convert(DestTy == Type::FloatTy ? APFloat::IEEEsingle :
186 DestTy == Type::DoubleTy ? APFloat::IEEEdouble :
187 DestTy == Type::X86_FP80Ty ? APFloat::x87DoubleExtended :
188 DestTy == Type::FP128Ty ? APFloat::IEEEquad :
190 APFloat::rmNearestTiesToEven);
191 return ConstantFP::get(DestTy, Val);
193 return 0; // Can't fold.
194 case Instruction::FPToUI:
195 case Instruction::FPToSI:
196 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
197 const APFloat &V = FPC->getValueAPF();
199 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
200 (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI,
201 APFloat::rmTowardZero);
202 APInt Val(DestBitWidth, 2, x);
203 return ConstantInt::get(Val);
205 return 0; // Can't fold.
206 case Instruction::IntToPtr: //always treated as unsigned
207 if (V->isNullValue()) // Is it an integral null value?
208 return ConstantPointerNull::get(cast<PointerType>(DestTy));
209 return 0; // Other pointer types cannot be casted
210 case Instruction::PtrToInt: // always treated as unsigned
211 if (V->isNullValue()) // is it a null pointer value?
212 return ConstantInt::get(DestTy, 0);
213 return 0; // Other pointer types cannot be casted
214 case Instruction::UIToFP:
215 case Instruction::SIToFP:
216 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
217 APInt api = CI->getValue();
218 const uint64_t zero[] = {0, 0};
219 uint32_t BitWidth = cast<IntegerType>(SrcTy)->getBitWidth();
220 APFloat apf = APFloat(APInt(DestTy->getPrimitiveSizeInBits(),
222 (void)apf.convertFromZeroExtendedInteger(api.getRawData(), BitWidth,
223 opc==Instruction::SIToFP,
224 APFloat::rmNearestTiesToEven);
225 return ConstantFP::get(DestTy, apf);
228 case Instruction::ZExt:
229 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
230 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
231 APInt Result(CI->getValue());
232 Result.zext(BitWidth);
233 return ConstantInt::get(Result);
236 case Instruction::SExt:
237 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
238 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
239 APInt Result(CI->getValue());
240 Result.sext(BitWidth);
241 return ConstantInt::get(Result);
244 case Instruction::Trunc:
245 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
246 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
247 APInt Result(CI->getValue());
248 Result.trunc(BitWidth);
249 return ConstantInt::get(Result);
252 case Instruction::BitCast:
254 return (Constant*)V; // no-op cast
256 // Check to see if we are casting a pointer to an aggregate to a pointer to
257 // the first element. If so, return the appropriate GEP instruction.
258 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
259 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
260 SmallVector<Value*, 8> IdxList;
261 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
262 const Type *ElTy = PTy->getElementType();
263 while (ElTy != DPTy->getElementType()) {
264 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
265 if (STy->getNumElements() == 0) break;
266 ElTy = STy->getElementType(0);
267 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
268 } else if (const SequentialType *STy =
269 dyn_cast<SequentialType>(ElTy)) {
270 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
271 ElTy = STy->getElementType();
272 IdxList.push_back(IdxList[0]);
278 if (ElTy == DPTy->getElementType())
279 return ConstantExpr::getGetElementPtr(
280 const_cast<Constant*>(V), &IdxList[0], IdxList.size());
283 // Handle casts from one vector constant to another. We know that the src
284 // and dest type have the same size (otherwise its an illegal cast).
285 if (const VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) {
286 if (const VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) {
287 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
288 "Not cast between same sized vectors!");
289 // First, check for null and undef
290 if (isa<ConstantAggregateZero>(V))
291 return Constant::getNullValue(DestTy);
292 if (isa<UndefValue>(V))
293 return UndefValue::get(DestTy);
295 if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
296 // This is a cast from a ConstantVector of one type to a
297 // ConstantVector of another type. Check to see if all elements of
298 // the input are simple.
299 bool AllSimpleConstants = true;
300 for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) {
301 if (!isa<ConstantInt>(CV->getOperand(i)) &&
302 !isa<ConstantFP>(CV->getOperand(i))) {
303 AllSimpleConstants = false;
308 // If all of the elements are simple constants, we can fold this.
309 if (AllSimpleConstants)
310 return CastConstantVector(const_cast<ConstantVector*>(CV), DestPTy);
315 // Finally, implement bitcast folding now. The code below doesn't handle
317 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
318 return ConstantPointerNull::get(cast<PointerType>(DestTy));
320 // Handle integral constant input.
321 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
322 if (DestTy->isInteger())
323 // Integral -> Integral. This is a no-op because the bit widths must
324 // be the same. Consequently, we just fold to V.
325 return const_cast<Constant*>(V);
327 if (DestTy->isFloatingPoint()) {
328 assert((DestTy == Type::DoubleTy || DestTy == Type::FloatTy) &&
330 return ConstantFP::get(DestTy, APFloat(CI->getValue()));
332 // Otherwise, can't fold this (vector?)
336 // Handle ConstantFP input.
337 if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
339 if (DestTy == Type::Int32Ty) {
340 return ConstantInt::get(FP->getValueAPF().convertToAPInt());
342 assert(DestTy == Type::Int64Ty && "only support f32/f64 for now!");
343 return ConstantInt::get(FP->getValueAPF().convertToAPInt());
348 assert(!"Invalid CE CastInst opcode");
352 assert(0 && "Failed to cast constant expression");
356 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
358 const Constant *V2) {
359 if (const ConstantInt *CB = dyn_cast<ConstantInt>(Cond))
360 return const_cast<Constant*>(CB->getZExtValue() ? V1 : V2);
362 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
363 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
364 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
365 if (V1 == V2) return const_cast<Constant*>(V1);
369 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
370 const Constant *Idx) {
371 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
372 return UndefValue::get(cast<VectorType>(Val->getType())->getElementType());
373 if (Val->isNullValue()) // ee(zero, x) -> zero
374 return Constant::getNullValue(
375 cast<VectorType>(Val->getType())->getElementType());
377 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
378 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
379 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue()));
380 } else if (isa<UndefValue>(Idx)) {
381 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
382 return const_cast<Constant*>(CVal->getOperand(0));
388 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
390 const Constant *Idx) {
391 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
393 APInt idxVal = CIdx->getValue();
394 if (isa<UndefValue>(Val)) {
395 // Insertion of scalar constant into vector undef
396 // Optimize away insertion of undef
397 if (isa<UndefValue>(Elt))
398 return const_cast<Constant*>(Val);
399 // Otherwise break the aggregate undef into multiple undefs and do
402 cast<VectorType>(Val->getType())->getNumElements();
403 std::vector<Constant*> Ops;
405 for (unsigned i = 0; i < numOps; ++i) {
407 (idxVal == i) ? Elt : UndefValue::get(Elt->getType());
408 Ops.push_back(const_cast<Constant*>(Op));
410 return ConstantVector::get(Ops);
412 if (isa<ConstantAggregateZero>(Val)) {
413 // Insertion of scalar constant into vector aggregate zero
414 // Optimize away insertion of zero
415 if (Elt->isNullValue())
416 return const_cast<Constant*>(Val);
417 // Otherwise break the aggregate zero into multiple zeros and do
420 cast<VectorType>(Val->getType())->getNumElements();
421 std::vector<Constant*> Ops;
423 for (unsigned i = 0; i < numOps; ++i) {
425 (idxVal == i) ? Elt : Constant::getNullValue(Elt->getType());
426 Ops.push_back(const_cast<Constant*>(Op));
428 return ConstantVector::get(Ops);
430 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
431 // Insertion of scalar constant into vector constant
432 std::vector<Constant*> Ops;
433 Ops.reserve(CVal->getNumOperands());
434 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
436 (idxVal == i) ? Elt : cast<Constant>(CVal->getOperand(i));
437 Ops.push_back(const_cast<Constant*>(Op));
439 return ConstantVector::get(Ops);
444 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
446 const Constant *Mask) {
451 /// EvalVectorOp - Given two vector constants and a function pointer, apply the
452 /// function pointer to each element pair, producing a new ConstantVector
454 static Constant *EvalVectorOp(const ConstantVector *V1,
455 const ConstantVector *V2,
456 Constant *(*FP)(Constant*, Constant*)) {
457 std::vector<Constant*> Res;
458 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
459 Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
460 const_cast<Constant*>(V2->getOperand(i))));
461 return ConstantVector::get(Res);
464 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
466 const Constant *C2) {
467 // Handle UndefValue up front
468 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
470 case Instruction::Add:
471 case Instruction::Sub:
472 case Instruction::Xor:
473 return UndefValue::get(C1->getType());
474 case Instruction::Mul:
475 case Instruction::And:
476 return Constant::getNullValue(C1->getType());
477 case Instruction::UDiv:
478 case Instruction::SDiv:
479 case Instruction::FDiv:
480 case Instruction::URem:
481 case Instruction::SRem:
482 case Instruction::FRem:
483 if (!isa<UndefValue>(C2)) // undef / X -> 0
484 return Constant::getNullValue(C1->getType());
485 return const_cast<Constant*>(C2); // X / undef -> undef
486 case Instruction::Or: // X | undef -> -1
487 if (const VectorType *PTy = dyn_cast<VectorType>(C1->getType()))
488 return ConstantVector::getAllOnesValue(PTy);
489 return ConstantInt::getAllOnesValue(C1->getType());
490 case Instruction::LShr:
491 if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
492 return const_cast<Constant*>(C1); // undef lshr undef -> undef
493 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0
495 case Instruction::AShr:
496 if (!isa<UndefValue>(C2))
497 return const_cast<Constant*>(C1); // undef ashr X --> undef
498 else if (isa<UndefValue>(C1))
499 return const_cast<Constant*>(C1); // undef ashr undef -> undef
501 return const_cast<Constant*>(C1); // X ashr undef --> X
502 case Instruction::Shl:
503 // undef << X -> 0 or X << undef -> 0
504 return Constant::getNullValue(C1->getType());
508 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
509 if (isa<ConstantExpr>(C2)) {
510 // There are many possible foldings we could do here. We should probably
511 // at least fold add of a pointer with an integer into the appropriate
512 // getelementptr. This will improve alias analysis a bit.
514 // Just implement a couple of simple identities.
516 case Instruction::Add:
517 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X + 0 == X
519 case Instruction::Sub:
520 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X - 0 == X
522 case Instruction::Mul:
523 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X * 0 == 0
524 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
525 if (CI->equalsInt(1))
526 return const_cast<Constant*>(C1); // X * 1 == X
528 case Instruction::UDiv:
529 case Instruction::SDiv:
530 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
531 if (CI->equalsInt(1))
532 return const_cast<Constant*>(C1); // X / 1 == X
534 case Instruction::URem:
535 case Instruction::SRem:
536 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
537 if (CI->equalsInt(1))
538 return Constant::getNullValue(CI->getType()); // X % 1 == 0
540 case Instruction::And:
541 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2)) {
542 if (CI->isZero()) return const_cast<Constant*>(C2); // X & 0 == 0
543 if (CI->isAllOnesValue())
544 return const_cast<Constant*>(C1); // X & -1 == X
546 // (zext i32 to i64) & 4294967295 -> (zext i32 to i64)
547 if (CE1->getOpcode() == Instruction::ZExt) {
548 APInt PossiblySetBits
549 = cast<IntegerType>(CE1->getOperand(0)->getType())->getMask();
550 PossiblySetBits.zext(C1->getType()->getPrimitiveSizeInBits());
551 if ((PossiblySetBits & CI->getValue()) == PossiblySetBits)
552 return const_cast<Constant*>(C1);
555 if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
556 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
558 // Functions are at least 4-byte aligned. If and'ing the address of a
559 // function with a constant < 4, fold it to zero.
560 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
561 if (CI->getValue().ult(APInt(CI->getType()->getBitWidth(),4)) &&
563 return Constant::getNullValue(CI->getType());
566 case Instruction::Or:
567 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X | 0 == X
568 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
569 if (CI->isAllOnesValue())
570 return const_cast<Constant*>(C2); // X | -1 == -1
572 case Instruction::Xor:
573 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X ^ 0 == X
575 case Instruction::AShr:
576 // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2
577 if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero.
578 return ConstantExpr::getLShr(const_cast<Constant*>(C1),
579 const_cast<Constant*>(C2));
583 } else if (isa<ConstantExpr>(C2)) {
584 // If C2 is a constant expr and C1 isn't, flop them around and fold the
585 // other way if possible.
587 case Instruction::Add:
588 case Instruction::Mul:
589 case Instruction::And:
590 case Instruction::Or:
591 case Instruction::Xor:
592 // No change of opcode required.
593 return ConstantFoldBinaryInstruction(Opcode, C2, C1);
595 case Instruction::Shl:
596 case Instruction::LShr:
597 case Instruction::AShr:
598 case Instruction::Sub:
599 case Instruction::SDiv:
600 case Instruction::UDiv:
601 case Instruction::FDiv:
602 case Instruction::URem:
603 case Instruction::SRem:
604 case Instruction::FRem:
605 default: // These instructions cannot be flopped around.
610 // At this point we know neither constant is an UndefValue nor a ConstantExpr
611 // so look at directly computing the value.
612 if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
613 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
614 using namespace APIntOps;
615 APInt C1V = CI1->getValue();
616 APInt C2V = CI2->getValue();
620 case Instruction::Add:
621 return ConstantInt::get(C1V + C2V);
622 case Instruction::Sub:
623 return ConstantInt::get(C1V - C2V);
624 case Instruction::Mul:
625 return ConstantInt::get(C1V * C2V);
626 case Instruction::UDiv:
627 if (CI2->isNullValue())
628 return 0; // X / 0 -> can't fold
629 return ConstantInt::get(C1V.udiv(C2V));
630 case Instruction::SDiv:
631 if (CI2->isNullValue())
632 return 0; // X / 0 -> can't fold
633 if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
634 return 0; // MIN_INT / -1 -> overflow
635 return ConstantInt::get(C1V.sdiv(C2V));
636 case Instruction::URem:
637 if (C2->isNullValue())
638 return 0; // X / 0 -> can't fold
639 return ConstantInt::get(C1V.urem(C2V));
640 case Instruction::SRem:
641 if (CI2->isNullValue())
642 return 0; // X % 0 -> can't fold
643 if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
644 return 0; // MIN_INT % -1 -> overflow
645 return ConstantInt::get(C1V.srem(C2V));
646 case Instruction::And:
647 return ConstantInt::get(C1V & C2V);
648 case Instruction::Or:
649 return ConstantInt::get(C1V | C2V);
650 case Instruction::Xor:
651 return ConstantInt::get(C1V ^ C2V);
652 case Instruction::Shl:
653 if (uint32_t shiftAmt = C2V.getZExtValue())
654 if (shiftAmt < C1V.getBitWidth())
655 return ConstantInt::get(C1V.shl(shiftAmt));
657 return UndefValue::get(C1->getType()); // too big shift is undef
658 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
659 case Instruction::LShr:
660 if (uint32_t shiftAmt = C2V.getZExtValue())
661 if (shiftAmt < C1V.getBitWidth())
662 return ConstantInt::get(C1V.lshr(shiftAmt));
664 return UndefValue::get(C1->getType()); // too big shift is undef
665 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
666 case Instruction::AShr:
667 if (uint32_t shiftAmt = C2V.getZExtValue())
668 if (shiftAmt < C1V.getBitWidth())
669 return ConstantInt::get(C1V.ashr(shiftAmt));
671 return UndefValue::get(C1->getType()); // too big shift is undef
672 return const_cast<ConstantInt*>(CI1); // Zero shift is identity
675 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
676 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
677 APFloat C1V = CFP1->getValueAPF();
678 APFloat C2V = CFP2->getValueAPF();
679 APFloat C3V = C1V; // copy for modification
680 bool isDouble = CFP1->getType()==Type::DoubleTy;
684 case Instruction::Add:
685 (void)C3V.add(C2V, APFloat::rmNearestTiesToEven);
686 return ConstantFP::get(CFP1->getType(), C3V);
687 case Instruction::Sub:
688 (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven);
689 return ConstantFP::get(CFP1->getType(), C3V);
690 case Instruction::Mul:
691 (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven);
692 return ConstantFP::get(CFP1->getType(), C3V);
693 case Instruction::FDiv:
694 (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven);
695 return ConstantFP::get(CFP1->getType(), C3V);
696 case Instruction::FRem:
698 // IEEE 754, Section 7.1, #5
699 return ConstantFP::get(CFP1->getType(), isDouble ?
700 APFloat(std::numeric_limits<double>::quiet_NaN()) :
701 APFloat(std::numeric_limits<float>::quiet_NaN()));
702 (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven);
703 return ConstantFP::get(CFP1->getType(), C3V);
706 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {
707 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) {
711 case Instruction::Add:
712 return EvalVectorOp(CP1, CP2, ConstantExpr::getAdd);
713 case Instruction::Sub:
714 return EvalVectorOp(CP1, CP2, ConstantExpr::getSub);
715 case Instruction::Mul:
716 return EvalVectorOp(CP1, CP2, ConstantExpr::getMul);
717 case Instruction::UDiv:
718 return EvalVectorOp(CP1, CP2, ConstantExpr::getUDiv);
719 case Instruction::SDiv:
720 return EvalVectorOp(CP1, CP2, ConstantExpr::getSDiv);
721 case Instruction::FDiv:
722 return EvalVectorOp(CP1, CP2, ConstantExpr::getFDiv);
723 case Instruction::URem:
724 return EvalVectorOp(CP1, CP2, ConstantExpr::getURem);
725 case Instruction::SRem:
726 return EvalVectorOp(CP1, CP2, ConstantExpr::getSRem);
727 case Instruction::FRem:
728 return EvalVectorOp(CP1, CP2, ConstantExpr::getFRem);
729 case Instruction::And:
730 return EvalVectorOp(CP1, CP2, ConstantExpr::getAnd);
731 case Instruction::Or:
732 return EvalVectorOp(CP1, CP2, ConstantExpr::getOr);
733 case Instruction::Xor:
734 return EvalVectorOp(CP1, CP2, ConstantExpr::getXor);
739 // We don't know how to fold this
743 /// isZeroSizedType - This type is zero sized if its an array or structure of
744 /// zero sized types. The only leaf zero sized type is an empty structure.
745 static bool isMaybeZeroSizedType(const Type *Ty) {
746 if (isa<OpaqueType>(Ty)) return true; // Can't say.
747 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
749 // If all of elements have zero size, this does too.
750 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
751 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
754 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
755 return isMaybeZeroSizedType(ATy->getElementType());
760 /// IdxCompare - Compare the two constants as though they were getelementptr
761 /// indices. This allows coersion of the types to be the same thing.
763 /// If the two constants are the "same" (after coersion), return 0. If the
764 /// first is less than the second, return -1, if the second is less than the
765 /// first, return 1. If the constants are not integral, return -2.
767 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
768 if (C1 == C2) return 0;
770 // Ok, we found a different index. If they are not ConstantInt, we can't do
771 // anything with them.
772 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
773 return -2; // don't know!
775 // Ok, we have two differing integer indices. Sign extend them to be the same
776 // type. Long is always big enough, so we use it.
777 if (C1->getType() != Type::Int64Ty)
778 C1 = ConstantExpr::getSExt(C1, Type::Int64Ty);
780 if (C2->getType() != Type::Int64Ty)
781 C2 = ConstantExpr::getSExt(C2, Type::Int64Ty);
783 if (C1 == C2) return 0; // They are equal
785 // If the type being indexed over is really just a zero sized type, there is
786 // no pointer difference being made here.
787 if (isMaybeZeroSizedType(ElTy))
790 // If they are really different, now that they are the same type, then we
791 // found a difference!
792 if (cast<ConstantInt>(C1)->getSExtValue() <
793 cast<ConstantInt>(C2)->getSExtValue())
799 /// evaluateFCmpRelation - This function determines if there is anything we can
800 /// decide about the two constants provided. This doesn't need to handle simple
801 /// things like ConstantFP comparisons, but should instead handle ConstantExprs.
802 /// If we can determine that the two constants have a particular relation to
803 /// each other, we should return the corresponding FCmpInst predicate,
804 /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
805 /// ConstantFoldCompareInstruction.
807 /// To simplify this code we canonicalize the relation so that the first
808 /// operand is always the most "complex" of the two. We consider ConstantFP
809 /// to be the simplest, and ConstantExprs to be the most complex.
810 static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1,
811 const Constant *V2) {
812 assert(V1->getType() == V2->getType() &&
813 "Cannot compare values of different types!");
815 // No compile-time operations on this type yet.
816 if (V1->getType() == Type::PPC_FP128Ty)
817 return FCmpInst::BAD_FCMP_PREDICATE;
819 // Handle degenerate case quickly
820 if (V1 == V2) return FCmpInst::FCMP_OEQ;
822 if (!isa<ConstantExpr>(V1)) {
823 if (!isa<ConstantExpr>(V2)) {
824 // We distilled thisUse the standard constant folder for a few cases
826 Constant *C1 = const_cast<Constant*>(V1);
827 Constant *C2 = const_cast<Constant*>(V2);
828 R = dyn_cast<ConstantInt>(
829 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2));
830 if (R && !R->isZero())
831 return FCmpInst::FCMP_OEQ;
832 R = dyn_cast<ConstantInt>(
833 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2));
834 if (R && !R->isZero())
835 return FCmpInst::FCMP_OLT;
836 R = dyn_cast<ConstantInt>(
837 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2));
838 if (R && !R->isZero())
839 return FCmpInst::FCMP_OGT;
841 // Nothing more we can do
842 return FCmpInst::BAD_FCMP_PREDICATE;
845 // If the first operand is simple and second is ConstantExpr, swap operands.
846 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
847 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
848 return FCmpInst::getSwappedPredicate(SwappedRelation);
850 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
851 // constantexpr or a simple constant.
852 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
853 switch (CE1->getOpcode()) {
854 case Instruction::FPTrunc:
855 case Instruction::FPExt:
856 case Instruction::UIToFP:
857 case Instruction::SIToFP:
858 // We might be able to do something with these but we don't right now.
864 // There are MANY other foldings that we could perform here. They will
865 // probably be added on demand, as they seem needed.
866 return FCmpInst::BAD_FCMP_PREDICATE;
869 /// evaluateICmpRelation - This function determines if there is anything we can
870 /// decide about the two constants provided. This doesn't need to handle simple
871 /// things like integer comparisons, but should instead handle ConstantExprs
872 /// and GlobalValues. If we can determine that the two constants have a
873 /// particular relation to each other, we should return the corresponding ICmp
874 /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.
876 /// To simplify this code we canonicalize the relation so that the first
877 /// operand is always the most "complex" of the two. We consider simple
878 /// constants (like ConstantInt) to be the simplest, followed by
879 /// GlobalValues, followed by ConstantExpr's (the most complex).
881 static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1,
884 assert(V1->getType() == V2->getType() &&
885 "Cannot compare different types of values!");
886 if (V1 == V2) return ICmpInst::ICMP_EQ;
888 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
889 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
890 // We distilled this down to a simple case, use the standard constant
893 Constant *C1 = const_cast<Constant*>(V1);
894 Constant *C2 = const_cast<Constant*>(V2);
895 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
896 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
897 if (R && !R->isZero())
899 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
900 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
901 if (R && !R->isZero())
903 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
904 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
905 if (R && !R->isZero())
908 // If we couldn't figure it out, bail.
909 return ICmpInst::BAD_ICMP_PREDICATE;
912 // If the first operand is simple, swap operands.
913 ICmpInst::Predicate SwappedRelation =
914 evaluateICmpRelation(V2, V1, isSigned);
915 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
916 return ICmpInst::getSwappedPredicate(SwappedRelation);
918 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
919 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
920 ICmpInst::Predicate SwappedRelation =
921 evaluateICmpRelation(V2, V1, isSigned);
922 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
923 return ICmpInst::getSwappedPredicate(SwappedRelation);
925 return ICmpInst::BAD_ICMP_PREDICATE;
928 // Now we know that the RHS is a GlobalValue or simple constant,
929 // which (since the types must match) means that it's a ConstantPointerNull.
930 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
931 // Don't try to decide equality of aliases.
932 if (!isa<GlobalAlias>(CPR1) && !isa<GlobalAlias>(CPR2))
933 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
934 return ICmpInst::ICMP_NE;
936 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
937 // GlobalVals can never be null. Don't try to evaluate aliases.
938 if (!CPR1->hasExternalWeakLinkage() && !isa<GlobalAlias>(CPR1))
939 return ICmpInst::ICMP_NE;
942 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
943 // constantexpr, a CPR, or a simple constant.
944 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
945 const Constant *CE1Op0 = CE1->getOperand(0);
947 switch (CE1->getOpcode()) {
948 case Instruction::Trunc:
949 case Instruction::FPTrunc:
950 case Instruction::FPExt:
951 case Instruction::FPToUI:
952 case Instruction::FPToSI:
953 break; // We can't evaluate floating point casts or truncations.
955 case Instruction::UIToFP:
956 case Instruction::SIToFP:
957 case Instruction::IntToPtr:
958 case Instruction::BitCast:
959 case Instruction::ZExt:
960 case Instruction::SExt:
961 case Instruction::PtrToInt:
962 // If the cast is not actually changing bits, and the second operand is a
963 // null pointer, do the comparison with the pre-casted value.
964 if (V2->isNullValue() &&
965 (isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) {
966 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
967 (CE1->getOpcode() == Instruction::SExt ? true :
968 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
969 return evaluateICmpRelation(
970 CE1Op0, Constant::getNullValue(CE1Op0->getType()), sgnd);
973 // If the dest type is a pointer type, and the RHS is a constantexpr cast
974 // from the same type as the src of the LHS, evaluate the inputs. This is
975 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)",
976 // which happens a lot in compilers with tagged integers.
977 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
978 if (CE2->isCast() && isa<PointerType>(CE1->getType()) &&
979 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
980 CE1->getOperand(0)->getType()->isInteger()) {
981 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
982 (CE1->getOpcode() == Instruction::SExt ? true :
983 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
984 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0),
989 case Instruction::GetElementPtr:
990 // Ok, since this is a getelementptr, we know that the constant has a
991 // pointer type. Check the various cases.
992 if (isa<ConstantPointerNull>(V2)) {
993 // If we are comparing a GEP to a null pointer, check to see if the base
994 // of the GEP equals the null pointer.
995 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
996 if (GV->hasExternalWeakLinkage())
997 // Weak linkage GVals could be zero or not. We're comparing that
998 // to null pointer so its greater-or-equal
999 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
1001 // If its not weak linkage, the GVal must have a non-zero address
1002 // so the result is greater-than
1003 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1004 } else if (isa<ConstantPointerNull>(CE1Op0)) {
1005 // If we are indexing from a null pointer, check to see if we have any
1006 // non-zero indices.
1007 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
1008 if (!CE1->getOperand(i)->isNullValue())
1009 // Offsetting from null, must not be equal.
1010 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1011 // Only zero indexes from null, must still be zero.
1012 return ICmpInst::ICMP_EQ;
1014 // Otherwise, we can't really say if the first operand is null or not.
1015 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1016 if (isa<ConstantPointerNull>(CE1Op0)) {
1017 if (CPR2->hasExternalWeakLinkage())
1018 // Weak linkage GVals could be zero or not. We're comparing it to
1019 // a null pointer, so its less-or-equal
1020 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
1022 // If its not weak linkage, the GVal must have a non-zero address
1023 // so the result is less-than
1024 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1025 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
1027 // If this is a getelementptr of the same global, then it must be
1028 // different. Because the types must match, the getelementptr could
1029 // only have at most one index, and because we fold getelementptr's
1030 // with a single zero index, it must be nonzero.
1031 assert(CE1->getNumOperands() == 2 &&
1032 !CE1->getOperand(1)->isNullValue() &&
1033 "Suprising getelementptr!");
1034 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1036 // If they are different globals, we don't know what the value is,
1037 // but they can't be equal.
1038 return ICmpInst::ICMP_NE;
1042 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
1043 const Constant *CE2Op0 = CE2->getOperand(0);
1045 // There are MANY other foldings that we could perform here. They will
1046 // probably be added on demand, as they seem needed.
1047 switch (CE2->getOpcode()) {
1049 case Instruction::GetElementPtr:
1050 // By far the most common case to handle is when the base pointers are
1051 // obviously to the same or different globals.
1052 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
1053 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
1054 return ICmpInst::ICMP_NE;
1055 // Ok, we know that both getelementptr instructions are based on the
1056 // same global. From this, we can precisely determine the relative
1057 // ordering of the resultant pointers.
1060 // Compare all of the operands the GEP's have in common.
1061 gep_type_iterator GTI = gep_type_begin(CE1);
1062 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
1064 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
1065 GTI.getIndexedType())) {
1066 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
1067 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
1068 case -2: return ICmpInst::BAD_ICMP_PREDICATE;
1071 // Ok, we ran out of things they have in common. If any leftovers
1072 // are non-zero then we have a difference, otherwise we are equal.
1073 for (; i < CE1->getNumOperands(); ++i)
1074 if (!CE1->getOperand(i)->isNullValue())
1075 if (isa<ConstantInt>(CE1->getOperand(i)))
1076 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1078 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1080 for (; i < CE2->getNumOperands(); ++i)
1081 if (!CE2->getOperand(i)->isNullValue())
1082 if (isa<ConstantInt>(CE2->getOperand(i)))
1083 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1085 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1086 return ICmpInst::ICMP_EQ;
1095 return ICmpInst::BAD_ICMP_PREDICATE;
1098 Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
1100 const Constant *C2) {
1102 // Handle some degenerate cases first
1103 if (isa<UndefValue>(C1) || isa<UndefValue>(C2))
1104 return UndefValue::get(Type::Int1Ty);
1106 // No compile-time operations on this type yet.
1107 if (C1->getType() == Type::PPC_FP128Ty)
1110 // icmp eq/ne(null,GV) -> false/true
1111 if (C1->isNullValue()) {
1112 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
1113 // Don't try to evaluate aliases. External weak GV can be null.
1114 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage())
1115 if (pred == ICmpInst::ICMP_EQ)
1116 return ConstantInt::getFalse();
1117 else if (pred == ICmpInst::ICMP_NE)
1118 return ConstantInt::getTrue();
1119 // icmp eq/ne(GV,null) -> false/true
1120 } else if (C2->isNullValue()) {
1121 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
1122 // Don't try to evaluate aliases. External weak GV can be null.
1123 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage())
1124 if (pred == ICmpInst::ICMP_EQ)
1125 return ConstantInt::getFalse();
1126 else if (pred == ICmpInst::ICMP_NE)
1127 return ConstantInt::getTrue();
1130 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
1131 APInt V1 = cast<ConstantInt>(C1)->getValue();
1132 APInt V2 = cast<ConstantInt>(C2)->getValue();
1134 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1135 case ICmpInst::ICMP_EQ: return ConstantInt::get(Type::Int1Ty, V1 == V2);
1136 case ICmpInst::ICMP_NE: return ConstantInt::get(Type::Int1Ty, V1 != V2);
1137 case ICmpInst::ICMP_SLT:return ConstantInt::get(Type::Int1Ty, V1.slt(V2));
1138 case ICmpInst::ICMP_SGT:return ConstantInt::get(Type::Int1Ty, V1.sgt(V2));
1139 case ICmpInst::ICMP_SLE:return ConstantInt::get(Type::Int1Ty, V1.sle(V2));
1140 case ICmpInst::ICMP_SGE:return ConstantInt::get(Type::Int1Ty, V1.sge(V2));
1141 case ICmpInst::ICMP_ULT:return ConstantInt::get(Type::Int1Ty, V1.ult(V2));
1142 case ICmpInst::ICMP_UGT:return ConstantInt::get(Type::Int1Ty, V1.ugt(V2));
1143 case ICmpInst::ICMP_ULE:return ConstantInt::get(Type::Int1Ty, V1.ule(V2));
1144 case ICmpInst::ICMP_UGE:return ConstantInt::get(Type::Int1Ty, V1.uge(V2));
1146 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
1147 APFloat C1V = cast<ConstantFP>(C1)->getValueAPF();
1148 APFloat C2V = cast<ConstantFP>(C2)->getValueAPF();
1149 APFloat::cmpResult R = C1V.compare(C2V);
1151 default: assert(0 && "Invalid FCmp Predicate"); return 0;
1152 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse();
1153 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue();
1154 case FCmpInst::FCMP_UNO:
1155 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered);
1156 case FCmpInst::FCMP_ORD:
1157 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpUnordered);
1158 case FCmpInst::FCMP_UEQ:
1159 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1160 R==APFloat::cmpEqual);
1161 case FCmpInst::FCMP_OEQ:
1162 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpEqual);
1163 case FCmpInst::FCMP_UNE:
1164 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpEqual);
1165 case FCmpInst::FCMP_ONE:
1166 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan ||
1167 R==APFloat::cmpGreaterThan);
1168 case FCmpInst::FCMP_ULT:
1169 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1170 R==APFloat::cmpLessThan);
1171 case FCmpInst::FCMP_OLT:
1172 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan);
1173 case FCmpInst::FCMP_UGT:
1174 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1175 R==APFloat::cmpGreaterThan);
1176 case FCmpInst::FCMP_OGT:
1177 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan);
1178 case FCmpInst::FCMP_ULE:
1179 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpGreaterThan);
1180 case FCmpInst::FCMP_OLE:
1181 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan ||
1182 R==APFloat::cmpEqual);
1183 case FCmpInst::FCMP_UGE:
1184 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpLessThan);
1185 case FCmpInst::FCMP_OGE:
1186 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan ||
1187 R==APFloat::cmpEqual);
1189 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {
1190 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) {
1191 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) {
1192 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1193 Constant *C= ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ,
1194 const_cast<Constant*>(CP1->getOperand(i)),
1195 const_cast<Constant*>(CP2->getOperand(i)));
1196 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1199 // Otherwise, could not decide from any element pairs.
1201 } else if (pred == ICmpInst::ICMP_EQ) {
1202 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1203 Constant *C = ConstantExpr::getICmp(ICmpInst::ICMP_EQ,
1204 const_cast<Constant*>(CP1->getOperand(i)),
1205 const_cast<Constant*>(CP2->getOperand(i)));
1206 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1209 // Otherwise, could not decide from any element pairs.
1215 if (C1->getType()->isFloatingPoint()) {
1216 switch (evaluateFCmpRelation(C1, C2)) {
1217 default: assert(0 && "Unknown relation!");
1218 case FCmpInst::FCMP_UNO:
1219 case FCmpInst::FCMP_ORD:
1220 case FCmpInst::FCMP_UEQ:
1221 case FCmpInst::FCMP_UNE:
1222 case FCmpInst::FCMP_ULT:
1223 case FCmpInst::FCMP_UGT:
1224 case FCmpInst::FCMP_ULE:
1225 case FCmpInst::FCMP_UGE:
1226 case FCmpInst::FCMP_TRUE:
1227 case FCmpInst::FCMP_FALSE:
1228 case FCmpInst::BAD_FCMP_PREDICATE:
1229 break; // Couldn't determine anything about these constants.
1230 case FCmpInst::FCMP_OEQ: // We know that C1 == C2
1231 return ConstantInt::get(Type::Int1Ty,
1232 pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
1233 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
1234 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1235 case FCmpInst::FCMP_OLT: // We know that C1 < C2
1236 return ConstantInt::get(Type::Int1Ty,
1237 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1238 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
1239 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
1240 case FCmpInst::FCMP_OGT: // We know that C1 > C2
1241 return ConstantInt::get(Type::Int1Ty,
1242 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1243 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
1244 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1245 case FCmpInst::FCMP_OLE: // We know that C1 <= C2
1246 // We can only partially decide this relation.
1247 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1248 return ConstantInt::getFalse();
1249 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1250 return ConstantInt::getTrue();
1252 case FCmpInst::FCMP_OGE: // We known that C1 >= C2
1253 // We can only partially decide this relation.
1254 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1255 return ConstantInt::getFalse();
1256 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1257 return ConstantInt::getTrue();
1259 case ICmpInst::ICMP_NE: // We know that C1 != C2
1260 // We can only partially decide this relation.
1261 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
1262 return ConstantInt::getFalse();
1263 if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
1264 return ConstantInt::getTrue();
1268 // Evaluate the relation between the two constants, per the predicate.
1269 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) {
1270 default: assert(0 && "Unknown relational!");
1271 case ICmpInst::BAD_ICMP_PREDICATE:
1272 break; // Couldn't determine anything about these constants.
1273 case ICmpInst::ICMP_EQ: // We know the constants are equal!
1274 // If we know the constants are equal, we can decide the result of this
1275 // computation precisely.
1276 return ConstantInt::get(Type::Int1Ty,
1277 pred == ICmpInst::ICMP_EQ ||
1278 pred == ICmpInst::ICMP_ULE ||
1279 pred == ICmpInst::ICMP_SLE ||
1280 pred == ICmpInst::ICMP_UGE ||
1281 pred == ICmpInst::ICMP_SGE);
1282 case ICmpInst::ICMP_ULT:
1283 // If we know that C1 < C2, we can decide the result of this computation
1285 return ConstantInt::get(Type::Int1Ty,
1286 pred == ICmpInst::ICMP_ULT ||
1287 pred == ICmpInst::ICMP_NE ||
1288 pred == ICmpInst::ICMP_ULE);
1289 case ICmpInst::ICMP_SLT:
1290 // If we know that C1 < C2, we can decide the result of this computation
1292 return ConstantInt::get(Type::Int1Ty,
1293 pred == ICmpInst::ICMP_SLT ||
1294 pred == ICmpInst::ICMP_NE ||
1295 pred == ICmpInst::ICMP_SLE);
1296 case ICmpInst::ICMP_UGT:
1297 // If we know that C1 > C2, we can decide the result of this computation
1299 return ConstantInt::get(Type::Int1Ty,
1300 pred == ICmpInst::ICMP_UGT ||
1301 pred == ICmpInst::ICMP_NE ||
1302 pred == ICmpInst::ICMP_UGE);
1303 case ICmpInst::ICMP_SGT:
1304 // If we know that C1 > C2, we can decide the result of this computation
1306 return ConstantInt::get(Type::Int1Ty,
1307 pred == ICmpInst::ICMP_SGT ||
1308 pred == ICmpInst::ICMP_NE ||
1309 pred == ICmpInst::ICMP_SGE);
1310 case ICmpInst::ICMP_ULE:
1311 // If we know that C1 <= C2, we can only partially decide this relation.
1312 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getFalse();
1313 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getTrue();
1315 case ICmpInst::ICMP_SLE:
1316 // If we know that C1 <= C2, we can only partially decide this relation.
1317 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getFalse();
1318 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getTrue();
1321 case ICmpInst::ICMP_UGE:
1322 // If we know that C1 >= C2, we can only partially decide this relation.
1323 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getFalse();
1324 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getTrue();
1326 case ICmpInst::ICMP_SGE:
1327 // If we know that C1 >= C2, we can only partially decide this relation.
1328 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getFalse();
1329 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getTrue();
1332 case ICmpInst::ICMP_NE:
1333 // If we know that C1 != C2, we can only partially decide this relation.
1334 if (pred == ICmpInst::ICMP_EQ) return ConstantInt::getFalse();
1335 if (pred == ICmpInst::ICMP_NE) return ConstantInt::getTrue();
1339 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) {
1340 // If C2 is a constant expr and C1 isn't, flop them around and fold the
1341 // other way if possible.
1343 case ICmpInst::ICMP_EQ:
1344 case ICmpInst::ICMP_NE:
1345 // No change of predicate required.
1346 return ConstantFoldCompareInstruction(pred, C2, C1);
1348 case ICmpInst::ICMP_ULT:
1349 case ICmpInst::ICMP_SLT:
1350 case ICmpInst::ICMP_UGT:
1351 case ICmpInst::ICMP_SGT:
1352 case ICmpInst::ICMP_ULE:
1353 case ICmpInst::ICMP_SLE:
1354 case ICmpInst::ICMP_UGE:
1355 case ICmpInst::ICMP_SGE:
1356 // Change the predicate as necessary to swap the operands.
1357 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
1358 return ConstantFoldCompareInstruction(pred, C2, C1);
1360 default: // These predicates cannot be flopped around.
1368 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1369 Constant* const *Idxs,
1372 (NumIdx == 1 && Idxs[0]->isNullValue()))
1373 return const_cast<Constant*>(C);
1375 if (isa<UndefValue>(C)) {
1376 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(),
1378 (Value **)Idxs+NumIdx,
1380 assert(Ty != 0 && "Invalid indices for GEP!");
1381 return UndefValue::get(PointerType::get(Ty));
1384 Constant *Idx0 = Idxs[0];
1385 if (C->isNullValue()) {
1387 for (unsigned i = 0, e = NumIdx; i != e; ++i)
1388 if (!Idxs[i]->isNullValue()) {
1393 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(),
1395 (Value**)Idxs+NumIdx,
1397 assert(Ty != 0 && "Invalid indices for GEP!");
1398 return ConstantPointerNull::get(PointerType::get(Ty));
1402 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1403 // Combine Indices - If the source pointer to this getelementptr instruction
1404 // is a getelementptr instruction, combine the indices of the two
1405 // getelementptr instructions into a single instruction.
1407 if (CE->getOpcode() == Instruction::GetElementPtr) {
1408 const Type *LastTy = 0;
1409 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1413 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1414 SmallVector<Value*, 16> NewIndices;
1415 NewIndices.reserve(NumIdx + CE->getNumOperands());
1416 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1417 NewIndices.push_back(CE->getOperand(i));
1419 // Add the last index of the source with the first index of the new GEP.
1420 // Make sure to handle the case when they are actually different types.
1421 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1422 // Otherwise it must be an array.
1423 if (!Idx0->isNullValue()) {
1424 const Type *IdxTy = Combined->getType();
1425 if (IdxTy != Idx0->getType()) {
1426 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty);
1427 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
1429 Combined = ConstantExpr::get(Instruction::Add, C1, C2);
1432 ConstantExpr::get(Instruction::Add, Idx0, Combined);
1436 NewIndices.push_back(Combined);
1437 NewIndices.insert(NewIndices.end(), Idxs+1, Idxs+NumIdx);
1438 return ConstantExpr::getGetElementPtr(CE->getOperand(0), &NewIndices[0],
1443 // Implement folding of:
1444 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1446 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1448 if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue()) {
1449 if (const PointerType *SPT =
1450 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1451 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1452 if (const ArrayType *CAT =
1453 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1454 if (CAT->getElementType() == SAT->getElementType())
1455 return ConstantExpr::getGetElementPtr(
1456 (Constant*)CE->getOperand(0), Idxs, NumIdx);
1459 // Fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1)
1460 // Into: inttoptr (i64 0 to i8*)
1461 // This happens with pointers to member functions in C++.
1462 if (CE->getOpcode() == Instruction::IntToPtr && NumIdx == 1 &&
1463 isa<ConstantInt>(CE->getOperand(0)) && isa<ConstantInt>(Idxs[0]) &&
1464 cast<PointerType>(CE->getType())->getElementType() == Type::Int8Ty) {
1465 Constant *Base = CE->getOperand(0);
1466 Constant *Offset = Idxs[0];
1468 // Convert the smaller integer to the larger type.
1469 if (Offset->getType()->getPrimitiveSizeInBits() <
1470 Base->getType()->getPrimitiveSizeInBits())
1471 Offset = ConstantExpr::getSExt(Offset, Base->getType());
1472 else if (Base->getType()->getPrimitiveSizeInBits() <
1473 Offset->getType()->getPrimitiveSizeInBits())
1474 Base = ConstantExpr::getZExt(Base, Base->getType());
1476 Base = ConstantExpr::getAdd(Base, Offset);
1477 return ConstantExpr::getIntToPtr(Base, CE->getType());