1 //===- ConstantFolding.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) ConstantFolding.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 "ConstantFolding.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 *CP,
42 const VectorType *DstTy) {
43 unsigned SrcNumElts = CP->getType()->getNumElements();
44 unsigned DstNumElts = DstTy->getNumElements();
45 const Type *SrcEltTy = CP->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(CP->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>(CP->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>(CP->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>(CP->getOperand(i))->getValue());
91 Constant *C = ConstantInt::get(Type::Int64Ty, V);
92 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy ));
94 return ConstantVector::get(Result);
97 assert(SrcEltTy->getTypeID() == Type::FloatTyID);
98 for (unsigned i = 0; i != SrcNumElts; ++i) {
99 uint32_t V = FloatToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
100 Constant *C = ConstantInt::get(Type::Int32Ty, V);
101 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy));
103 return ConstantVector::get(Result);
106 // Otherwise, this is a cast that changes element count and size. Handle
107 // casts which shrink the elements here.
109 // FIXME: We need to know endianness to do this!
114 /// This function determines which opcode to use to fold two constant cast
115 /// expressions together. It uses CastInst::isEliminableCastPair to determine
116 /// the opcode. Consequently its just a wrapper around that function.
117 /// @Determine if it is valid to fold a cast of a cast
119 foldConstantCastPair(
120 unsigned opc, ///< opcode of the second cast constant expression
121 const ConstantExpr*Op, ///< the first cast constant expression
122 const Type *DstTy ///< desintation type of the first cast
124 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
125 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
126 assert(CastInst::isCast(opc) && "Invalid cast opcode");
128 // The the types and opcodes for the two Cast constant expressions
129 const Type *SrcTy = Op->getOperand(0)->getType();
130 const Type *MidTy = Op->getType();
131 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
132 Instruction::CastOps secondOp = Instruction::CastOps(opc);
134 // Let CastInst::isEliminableCastPair do the heavy lifting.
135 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
139 Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
140 const Type *DestTy) {
141 const Type *SrcTy = V->getType();
143 if (isa<UndefValue>(V))
144 return UndefValue::get(DestTy);
146 // If the cast operand is a constant expression, there's a few things we can
147 // do to try to simplify it.
148 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
150 // Try hard to fold cast of cast because they are often eliminable.
151 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
152 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
153 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
154 // If all of the indexes in the GEP are null values, there is no pointer
155 // adjustment going on. We might as well cast the source pointer.
156 bool isAllNull = true;
157 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
158 if (!CE->getOperand(i)->isNullValue()) {
163 // This is casting one pointer type to another, always BitCast
164 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
168 // We actually have to do a cast now. Perform the cast according to the
171 case Instruction::FPTrunc:
172 case Instruction::FPExt:
173 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V))
174 return ConstantFP::get(DestTy, FPC->getValue());
175 return 0; // Can't fold.
176 case Instruction::FPToUI:
177 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V))
178 return ConstantInt::get(DestTy,(uint64_t) FPC->getValue());
179 return 0; // Can't fold.
180 case Instruction::FPToSI:
181 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V))
182 return ConstantInt::get(DestTy,(int64_t) FPC->getValue());
183 return 0; // Can't fold.
184 case Instruction::IntToPtr: //always treated as unsigned
185 if (V->isNullValue()) // Is it an integral null value?
186 return ConstantPointerNull::get(cast<PointerType>(DestTy));
187 return 0; // Other pointer types cannot be casted
188 case Instruction::PtrToInt: // always treated as unsigned
189 if (V->isNullValue()) // is it a null pointer value?
190 return ConstantInt::get(DestTy, 0);
191 return 0; // Other pointer types cannot be casted
192 case Instruction::UIToFP:
193 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
194 return ConstantFP::get(DestTy, double(CI->getZExtValue()));
196 case Instruction::SIToFP:
197 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
198 return ConstantFP::get(DestTy, double(CI->getSExtValue()));
200 case Instruction::ZExt:
201 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
202 return ConstantInt::get(DestTy, CI->getZExtValue());
204 case Instruction::SExt:
205 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
206 return ConstantInt::get(DestTy, CI->getSExtValue());
208 case Instruction::Trunc:
209 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) // Can't trunc a bool
210 return ConstantInt::get(DestTy, CI->getZExtValue());
212 case Instruction::BitCast:
214 return (Constant*)V; // no-op cast
216 // Check to see if we are casting a pointer to an aggregate to a pointer to
217 // the first element. If so, return the appropriate GEP instruction.
218 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
219 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
220 SmallVector<Value*, 8> IdxList;
221 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
222 const Type *ElTy = PTy->getElementType();
223 while (ElTy != DPTy->getElementType()) {
224 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
225 if (STy->getNumElements() == 0) break;
226 ElTy = STy->getElementType(0);
227 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
228 } else if (const SequentialType *STy =
229 dyn_cast<SequentialType>(ElTy)) {
230 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
231 ElTy = STy->getElementType();
232 IdxList.push_back(IdxList[0]);
238 if (ElTy == DPTy->getElementType())
239 return ConstantExpr::getGetElementPtr(
240 const_cast<Constant*>(V), &IdxList[0], IdxList.size());
243 // Handle casts from one packed constant to another. We know that the src
244 // and dest type have the same size (otherwise its an illegal cast).
245 if (const VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) {
246 if (const VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) {
247 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
248 "Not cast between same sized vectors!");
249 // First, check for null and undef
250 if (isa<ConstantAggregateZero>(V))
251 return Constant::getNullValue(DestTy);
252 if (isa<UndefValue>(V))
253 return UndefValue::get(DestTy);
255 if (const ConstantVector *CP = dyn_cast<ConstantVector>(V)) {
256 // This is a cast from a ConstantVector of one type to a
257 // ConstantVector of another type. Check to see if all elements of
258 // the input are simple.
259 bool AllSimpleConstants = true;
260 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
261 if (!isa<ConstantInt>(CP->getOperand(i)) &&
262 !isa<ConstantFP>(CP->getOperand(i))) {
263 AllSimpleConstants = false;
268 // If all of the elements are simple constants, we can fold this.
269 if (AllSimpleConstants)
270 return CastConstantVector(const_cast<ConstantVector*>(CP), DestPTy);
275 // Finally, implement bitcast folding now. The code below doesn't handle
277 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
278 return ConstantPointerNull::get(cast<PointerType>(DestTy));
280 // Handle integral constant input.
281 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
282 // Integral -> Integral, must be changing sign.
283 if (DestTy->isInteger())
284 return ConstantInt::get(DestTy, CI->getZExtValue());
286 if (DestTy->isFloatingPoint()) {
287 if (DestTy == Type::FloatTy)
288 return ConstantFP::get(DestTy, BitsToFloat(CI->getZExtValue()));
289 assert(DestTy == Type::DoubleTy && "Unknown FP type!");
290 return ConstantFP::get(DestTy, BitsToDouble(CI->getZExtValue()));
292 // Otherwise, can't fold this (packed?)
296 // Handle ConstantFP input.
297 if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
299 if (DestTy == Type::Int32Ty) {
300 return ConstantInt::get(DestTy, FloatToBits(FP->getValue()));
302 assert(DestTy == Type::Int64Ty && "only support f32/f64 for now!");
303 return ConstantInt::get(DestTy, DoubleToBits(FP->getValue()));
308 assert(!"Invalid CE CastInst opcode");
312 assert(0 && "Failed to cast constant expression");
316 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
318 const Constant *V2) {
319 if (const ConstantInt *CB = dyn_cast<ConstantInt>(Cond))
320 return const_cast<Constant*>(CB->getZExtValue() ? V1 : V2);
322 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
323 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
324 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
325 if (V1 == V2) return const_cast<Constant*>(V1);
329 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
330 const Constant *Idx) {
331 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
332 return UndefValue::get(cast<VectorType>(Val->getType())->getElementType());
333 if (Val->isNullValue()) // ee(zero, x) -> zero
334 return Constant::getNullValue(
335 cast<VectorType>(Val->getType())->getElementType());
337 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
338 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
339 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue()));
340 } else if (isa<UndefValue>(Idx)) {
341 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
342 return const_cast<Constant*>(CVal->getOperand(0));
348 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
350 const Constant *Idx) {
351 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
353 uint64_t idxVal = CIdx->getZExtValue();
354 if (isa<UndefValue>(Val)) {
355 // Insertion of scalar constant into packed undef
356 // Optimize away insertion of undef
357 if (isa<UndefValue>(Elt))
358 return const_cast<Constant*>(Val);
359 // Otherwise break the aggregate undef into multiple undefs and do
362 cast<VectorType>(Val->getType())->getNumElements();
363 std::vector<Constant*> Ops;
365 for (unsigned i = 0; i < numOps; ++i) {
367 (i == idxVal) ? Elt : UndefValue::get(Elt->getType());
368 Ops.push_back(const_cast<Constant*>(Op));
370 return ConstantVector::get(Ops);
372 if (isa<ConstantAggregateZero>(Val)) {
373 // Insertion of scalar constant into packed aggregate zero
374 // Optimize away insertion of zero
375 if (Elt->isNullValue())
376 return const_cast<Constant*>(Val);
377 // Otherwise break the aggregate zero into multiple zeros and do
380 cast<VectorType>(Val->getType())->getNumElements();
381 std::vector<Constant*> Ops;
383 for (unsigned i = 0; i < numOps; ++i) {
385 (i == idxVal) ? Elt : Constant::getNullValue(Elt->getType());
386 Ops.push_back(const_cast<Constant*>(Op));
388 return ConstantVector::get(Ops);
390 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
391 // Insertion of scalar constant into packed constant
392 std::vector<Constant*> Ops;
393 Ops.reserve(CVal->getNumOperands());
394 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
396 (i == idxVal) ? Elt : cast<Constant>(CVal->getOperand(i));
397 Ops.push_back(const_cast<Constant*>(Op));
399 return ConstantVector::get(Ops);
404 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
406 const Constant *Mask) {
411 /// EvalVectorOp - Given two packed constants and a function pointer, apply the
412 /// function pointer to each element pair, producing a new ConstantVector
414 static Constant *EvalVectorOp(const ConstantVector *V1,
415 const ConstantVector *V2,
416 Constant *(*FP)(Constant*, Constant*)) {
417 std::vector<Constant*> Res;
418 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
419 Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
420 const_cast<Constant*>(V2->getOperand(i))));
421 return ConstantVector::get(Res);
424 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
426 const Constant *C2) {
427 // Handle UndefValue up front
428 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
430 case Instruction::Add:
431 case Instruction::Sub:
432 case Instruction::Xor:
433 return UndefValue::get(C1->getType());
434 case Instruction::Mul:
435 case Instruction::And:
436 return Constant::getNullValue(C1->getType());
437 case Instruction::UDiv:
438 case Instruction::SDiv:
439 case Instruction::FDiv:
440 case Instruction::URem:
441 case Instruction::SRem:
442 case Instruction::FRem:
443 if (!isa<UndefValue>(C2)) // undef / X -> 0
444 return Constant::getNullValue(C1->getType());
445 return const_cast<Constant*>(C2); // X / undef -> undef
446 case Instruction::Or: // X | undef -> -1
447 if (const VectorType *PTy = dyn_cast<VectorType>(C1->getType()))
448 return ConstantVector::getAllOnesValue(PTy);
449 return ConstantInt::getAllOnesValue(C1->getType());
450 case Instruction::LShr:
451 if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
452 return const_cast<Constant*>(C1); // undef lshr undef -> undef
453 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0
455 case Instruction::AShr:
456 if (!isa<UndefValue>(C2))
457 return const_cast<Constant*>(C1); // undef ashr X --> undef
458 else if (isa<UndefValue>(C1))
459 return const_cast<Constant*>(C1); // undef ashr undef -> undef
461 return const_cast<Constant*>(C1); // X ashr undef --> X
462 case Instruction::Shl:
463 // undef << X -> 0 or X << undef -> 0
464 return Constant::getNullValue(C1->getType());
468 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
469 if (isa<ConstantExpr>(C2)) {
470 // There are many possible foldings we could do here. We should probably
471 // at least fold add of a pointer with an integer into the appropriate
472 // getelementptr. This will improve alias analysis a bit.
474 // Just implement a couple of simple identities.
476 case Instruction::Add:
477 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X + 0 == X
479 case Instruction::Sub:
480 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X - 0 == X
482 case Instruction::Mul:
483 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X * 0 == 0
484 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
485 if (CI->getZExtValue() == 1)
486 return const_cast<Constant*>(C1); // X * 1 == X
488 case Instruction::UDiv:
489 case Instruction::SDiv:
490 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
491 if (CI->getZExtValue() == 1)
492 return const_cast<Constant*>(C1); // X / 1 == X
494 case Instruction::URem:
495 case Instruction::SRem:
496 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
497 if (CI->getZExtValue() == 1)
498 return Constant::getNullValue(CI->getType()); // X % 1 == 0
500 case Instruction::And:
501 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
502 if (CI->isAllOnesValue())
503 return const_cast<Constant*>(C1); // X & -1 == X
504 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X & 0 == 0
505 if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
506 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
508 // Functions are at least 4-byte aligned. If and'ing the address of a
509 // function with a constant < 4, fold it to zero.
510 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
511 if (CI->getZExtValue() < 4 && isa<Function>(CPR))
512 return Constant::getNullValue(CI->getType());
515 case Instruction::Or:
516 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X | 0 == X
517 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
518 if (CI->isAllOnesValue())
519 return const_cast<Constant*>(C2); // X | -1 == -1
521 case Instruction::Xor:
522 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X ^ 0 == X
526 } else if (isa<ConstantExpr>(C2)) {
527 // If C2 is a constant expr and C1 isn't, flop them around and fold the
528 // other way if possible.
530 case Instruction::Add:
531 case Instruction::Mul:
532 case Instruction::And:
533 case Instruction::Or:
534 case Instruction::Xor:
535 // No change of opcode required.
536 return ConstantFoldBinaryInstruction(Opcode, C2, C1);
538 case Instruction::Shl:
539 case Instruction::LShr:
540 case Instruction::AShr:
541 case Instruction::Sub:
542 case Instruction::SDiv:
543 case Instruction::UDiv:
544 case Instruction::FDiv:
545 case Instruction::URem:
546 case Instruction::SRem:
547 case Instruction::FRem:
548 default: // These instructions cannot be flopped around.
553 // At this point we know neither constant is an UndefValue nor a ConstantExpr
554 // so look at directly computing the value.
555 if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
556 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
557 uint64_t C1Val = CI1->getZExtValue();
558 uint64_t C2Val = CI2->getZExtValue();
562 case Instruction::Add:
563 return ConstantInt::get(C1->getType(), C1Val + C2Val);
564 case Instruction::Sub:
565 return ConstantInt::get(C1->getType(), C1Val - C2Val);
566 case Instruction::Mul:
567 return ConstantInt::get(C1->getType(), C1Val * C2Val);
568 case Instruction::UDiv:
569 if (CI2->isNullValue()) // X / 0 -> can't fold
571 return ConstantInt::get(C1->getType(), C1Val / C2Val);
572 case Instruction::SDiv:
573 if (CI2->isNullValue()) return 0; // X / 0 -> can't fold
574 if (CI2->isAllOnesValue() &&
575 (((CI1->getType()->getPrimitiveSizeInBits() == 64) &&
576 (CI1->getSExtValue() == INT64_MIN)) ||
577 (CI1->getSExtValue() == -CI1->getSExtValue() &&
578 CI1->getSExtValue())))
579 return 0; // MIN_INT / -1 -> overflow
580 return ConstantInt::get(C1->getType(),
581 CI1->getSExtValue() / CI2->getSExtValue());
582 case Instruction::URem:
583 if (C2->isNullValue()) return 0; // X / 0 -> can't fold
584 return ConstantInt::get(C1->getType(), C1Val % C2Val);
585 case Instruction::SRem:
586 if (CI2->isNullValue()) return 0; // X % 0 -> can't fold
587 if (CI2->isAllOnesValue() &&
588 (((CI1->getType()->getPrimitiveSizeInBits() == 64) &&
589 (CI1->getSExtValue() == INT64_MIN)) ||
590 (CI1->getSExtValue() == -CI1->getSExtValue())))
591 return 0; // MIN_INT % -1 -> overflow
592 return ConstantInt::get(C1->getType(),
593 CI1->getSExtValue() % CI2->getSExtValue());
594 case Instruction::And:
595 return ConstantInt::get(C1->getType(), C1Val & C2Val);
596 case Instruction::Or:
597 return ConstantInt::get(C1->getType(), C1Val | C2Val);
598 case Instruction::Xor:
599 return ConstantInt::get(C1->getType(), C1Val ^ C2Val);
600 case Instruction::Shl:
601 return ConstantInt::get(C1->getType(), C1Val << C2Val);
602 case Instruction::LShr:
603 return ConstantInt::get(C1->getType(), C1Val >> C2Val);
604 case Instruction::AShr:
605 return ConstantInt::get(C1->getType(),
606 CI1->getSExtValue() >> C2Val);
609 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
610 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
611 double C1Val = CFP1->getValue();
612 double C2Val = CFP2->getValue();
616 case Instruction::Add:
617 return ConstantFP::get(CFP1->getType(), C1Val + C2Val);
618 case Instruction::Sub:
619 return ConstantFP::get(CFP1->getType(), C1Val - C2Val);
620 case Instruction::Mul:
621 return ConstantFP::get(CFP1->getType(), C1Val * C2Val);
622 case Instruction::FDiv:
623 if (CFP2->isExactlyValue(0.0))
624 return ConstantFP::get(CFP1->getType(),
625 std::numeric_limits<double>::infinity());
626 if (CFP2->isExactlyValue(-0.0))
627 return ConstantFP::get(CFP1->getType(),
628 -std::numeric_limits<double>::infinity());
629 return ConstantFP::get(CFP1->getType(), C1Val / C2Val);
630 case Instruction::FRem:
631 if (CFP2->isNullValue())
633 return ConstantFP::get(CFP1->getType(), std::fmod(C1Val, C2Val));
636 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {
637 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) {
641 case Instruction::Add:
642 return EvalVectorOp(CP1, CP2, ConstantExpr::getAdd);
643 case Instruction::Sub:
644 return EvalVectorOp(CP1, CP2, ConstantExpr::getSub);
645 case Instruction::Mul:
646 return EvalVectorOp(CP1, CP2, ConstantExpr::getMul);
647 case Instruction::UDiv:
648 return EvalVectorOp(CP1, CP2, ConstantExpr::getUDiv);
649 case Instruction::SDiv:
650 return EvalVectorOp(CP1, CP2, ConstantExpr::getSDiv);
651 case Instruction::FDiv:
652 return EvalVectorOp(CP1, CP2, ConstantExpr::getFDiv);
653 case Instruction::URem:
654 return EvalVectorOp(CP1, CP2, ConstantExpr::getURem);
655 case Instruction::SRem:
656 return EvalVectorOp(CP1, CP2, ConstantExpr::getSRem);
657 case Instruction::FRem:
658 return EvalVectorOp(CP1, CP2, ConstantExpr::getFRem);
659 case Instruction::And:
660 return EvalVectorOp(CP1, CP2, ConstantExpr::getAnd);
661 case Instruction::Or:
662 return EvalVectorOp(CP1, CP2, ConstantExpr::getOr);
663 case Instruction::Xor:
664 return EvalVectorOp(CP1, CP2, ConstantExpr::getXor);
669 // We don't know how to fold this
673 /// isZeroSizedType - This type is zero sized if its an array or structure of
674 /// zero sized types. The only leaf zero sized type is an empty structure.
675 static bool isMaybeZeroSizedType(const Type *Ty) {
676 if (isa<OpaqueType>(Ty)) return true; // Can't say.
677 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
679 // If all of elements have zero size, this does too.
680 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
681 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
684 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
685 return isMaybeZeroSizedType(ATy->getElementType());
690 /// IdxCompare - Compare the two constants as though they were getelementptr
691 /// indices. This allows coersion of the types to be the same thing.
693 /// If the two constants are the "same" (after coersion), return 0. If the
694 /// first is less than the second, return -1, if the second is less than the
695 /// first, return 1. If the constants are not integral, return -2.
697 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
698 if (C1 == C2) return 0;
700 // Ok, we found a different index. If they are not ConstantInt, we can't do
701 // anything with them.
702 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
703 return -2; // don't know!
705 // Ok, we have two differing integer indices. Sign extend them to be the same
706 // type. Long is always big enough, so we use it.
707 if (C1->getType() != Type::Int64Ty)
708 C1 = ConstantExpr::getSExt(C1, Type::Int64Ty);
710 if (C2->getType() != Type::Int64Ty)
711 C2 = ConstantExpr::getSExt(C2, Type::Int64Ty);
713 if (C1 == C2) return 0; // They are equal
715 // If the type being indexed over is really just a zero sized type, there is
716 // no pointer difference being made here.
717 if (isMaybeZeroSizedType(ElTy))
720 // If they are really different, now that they are the same type, then we
721 // found a difference!
722 if (cast<ConstantInt>(C1)->getSExtValue() <
723 cast<ConstantInt>(C2)->getSExtValue())
729 /// evaluateFCmpRelation - This function determines if there is anything we can
730 /// decide about the two constants provided. This doesn't need to handle simple
731 /// things like ConstantFP comparisons, but should instead handle ConstantExprs.
732 /// If we can determine that the two constants have a particular relation to
733 /// each other, we should return the corresponding FCmpInst predicate,
734 /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
735 /// ConstantFoldCompareInstruction.
737 /// To simplify this code we canonicalize the relation so that the first
738 /// operand is always the most "complex" of the two. We consider ConstantFP
739 /// to be the simplest, and ConstantExprs to be the most complex.
740 static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1,
741 const Constant *V2) {
742 assert(V1->getType() == V2->getType() &&
743 "Cannot compare values of different types!");
744 // Handle degenerate case quickly
745 if (V1 == V2) return FCmpInst::FCMP_OEQ;
747 if (!isa<ConstantExpr>(V1)) {
748 if (!isa<ConstantExpr>(V2)) {
749 // We distilled thisUse the standard constant folder for a few cases
751 Constant *C1 = const_cast<Constant*>(V1);
752 Constant *C2 = const_cast<Constant*>(V2);
753 R = dyn_cast<ConstantInt>(
754 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2));
755 if (R && R->getZExtValue())
756 return FCmpInst::FCMP_OEQ;
757 R = dyn_cast<ConstantInt>(
758 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2));
759 if (R && R->getZExtValue())
760 return FCmpInst::FCMP_OLT;
761 R = dyn_cast<ConstantInt>(
762 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2));
763 if (R && R->getZExtValue())
764 return FCmpInst::FCMP_OGT;
766 // Nothing more we can do
767 return FCmpInst::BAD_FCMP_PREDICATE;
770 // If the first operand is simple and second is ConstantExpr, swap operands.
771 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
772 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
773 return FCmpInst::getSwappedPredicate(SwappedRelation);
775 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
776 // constantexpr or a simple constant.
777 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
778 switch (CE1->getOpcode()) {
779 case Instruction::FPTrunc:
780 case Instruction::FPExt:
781 case Instruction::UIToFP:
782 case Instruction::SIToFP:
783 // We might be able to do something with these but we don't right now.
789 // There are MANY other foldings that we could perform here. They will
790 // probably be added on demand, as they seem needed.
791 return FCmpInst::BAD_FCMP_PREDICATE;
794 /// evaluateICmpRelation - This function determines if there is anything we can
795 /// decide about the two constants provided. This doesn't need to handle simple
796 /// things like integer comparisons, but should instead handle ConstantExprs
797 /// and GlobalValues. If we can determine that the two constants have a
798 /// particular relation to each other, we should return the corresponding ICmp
799 /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.
801 /// To simplify this code we canonicalize the relation so that the first
802 /// operand is always the most "complex" of the two. We consider simple
803 /// constants (like ConstantInt) to be the simplest, followed by
804 /// GlobalValues, followed by ConstantExpr's (the most complex).
806 static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1,
809 assert(V1->getType() == V2->getType() &&
810 "Cannot compare different types of values!");
811 if (V1 == V2) return ICmpInst::ICMP_EQ;
813 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
814 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
815 // We distilled this down to a simple case, use the standard constant
818 Constant *C1 = const_cast<Constant*>(V1);
819 Constant *C2 = const_cast<Constant*>(V2);
820 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
821 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
822 if (R && R->getZExtValue())
824 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
825 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
826 if (R && R->getZExtValue())
828 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
829 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
830 if (R && R->getZExtValue())
833 // If we couldn't figure it out, bail.
834 return ICmpInst::BAD_ICMP_PREDICATE;
837 // If the first operand is simple, swap operands.
838 ICmpInst::Predicate SwappedRelation =
839 evaluateICmpRelation(V2, V1, isSigned);
840 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
841 return ICmpInst::getSwappedPredicate(SwappedRelation);
843 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
844 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
845 ICmpInst::Predicate SwappedRelation =
846 evaluateICmpRelation(V2, V1, isSigned);
847 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
848 return ICmpInst::getSwappedPredicate(SwappedRelation);
850 return ICmpInst::BAD_ICMP_PREDICATE;
853 // Now we know that the RHS is a GlobalValue or simple constant,
854 // which (since the types must match) means that it's a ConstantPointerNull.
855 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
856 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
857 return ICmpInst::ICMP_NE;
859 // GlobalVals can never be null.
860 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
861 if (!CPR1->hasExternalWeakLinkage())
862 return ICmpInst::ICMP_NE;
865 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
866 // constantexpr, a CPR, or a simple constant.
867 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
868 const Constant *CE1Op0 = CE1->getOperand(0);
870 switch (CE1->getOpcode()) {
871 case Instruction::Trunc:
872 case Instruction::FPTrunc:
873 case Instruction::FPExt:
874 case Instruction::FPToUI:
875 case Instruction::FPToSI:
876 break; // We can't evaluate floating point casts or truncations.
878 case Instruction::UIToFP:
879 case Instruction::SIToFP:
880 case Instruction::IntToPtr:
881 case Instruction::BitCast:
882 case Instruction::ZExt:
883 case Instruction::SExt:
884 case Instruction::PtrToInt:
885 // If the cast is not actually changing bits, and the second operand is a
886 // null pointer, do the comparison with the pre-casted value.
887 if (V2->isNullValue() &&
888 (isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) {
889 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
890 (CE1->getOpcode() == Instruction::SExt ? true :
891 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
892 return evaluateICmpRelation(
893 CE1Op0, Constant::getNullValue(CE1Op0->getType()), sgnd);
896 // If the dest type is a pointer type, and the RHS is a constantexpr cast
897 // from the same type as the src of the LHS, evaluate the inputs. This is
898 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)",
899 // which happens a lot in compilers with tagged integers.
900 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
901 if (CE2->isCast() && isa<PointerType>(CE1->getType()) &&
902 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
903 CE1->getOperand(0)->getType()->isInteger()) {
904 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
905 (CE1->getOpcode() == Instruction::SExt ? true :
906 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
907 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0),
912 case Instruction::GetElementPtr:
913 // Ok, since this is a getelementptr, we know that the constant has a
914 // pointer type. Check the various cases.
915 if (isa<ConstantPointerNull>(V2)) {
916 // If we are comparing a GEP to a null pointer, check to see if the base
917 // of the GEP equals the null pointer.
918 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
919 if (GV->hasExternalWeakLinkage())
920 // Weak linkage GVals could be zero or not. We're comparing that
921 // to null pointer so its greater-or-equal
922 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
924 // If its not weak linkage, the GVal must have a non-zero address
925 // so the result is greater-than
926 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
927 } else if (isa<ConstantPointerNull>(CE1Op0)) {
928 // If we are indexing from a null pointer, check to see if we have any
930 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
931 if (!CE1->getOperand(i)->isNullValue())
932 // Offsetting from null, must not be equal.
933 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
934 // Only zero indexes from null, must still be zero.
935 return ICmpInst::ICMP_EQ;
937 // Otherwise, we can't really say if the first operand is null or not.
938 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
939 if (isa<ConstantPointerNull>(CE1Op0)) {
940 if (CPR2->hasExternalWeakLinkage())
941 // Weak linkage GVals could be zero or not. We're comparing it to
942 // a null pointer, so its less-or-equal
943 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
945 // If its not weak linkage, the GVal must have a non-zero address
946 // so the result is less-than
947 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
948 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
950 // If this is a getelementptr of the same global, then it must be
951 // different. Because the types must match, the getelementptr could
952 // only have at most one index, and because we fold getelementptr's
953 // with a single zero index, it must be nonzero.
954 assert(CE1->getNumOperands() == 2 &&
955 !CE1->getOperand(1)->isNullValue() &&
956 "Suprising getelementptr!");
957 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
959 // If they are different globals, we don't know what the value is,
960 // but they can't be equal.
961 return ICmpInst::ICMP_NE;
965 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
966 const Constant *CE2Op0 = CE2->getOperand(0);
968 // There are MANY other foldings that we could perform here. They will
969 // probably be added on demand, as they seem needed.
970 switch (CE2->getOpcode()) {
972 case Instruction::GetElementPtr:
973 // By far the most common case to handle is when the base pointers are
974 // obviously to the same or different globals.
975 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
976 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
977 return ICmpInst::ICMP_NE;
978 // Ok, we know that both getelementptr instructions are based on the
979 // same global. From this, we can precisely determine the relative
980 // ordering of the resultant pointers.
983 // Compare all of the operands the GEP's have in common.
984 gep_type_iterator GTI = gep_type_begin(CE1);
985 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
987 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
988 GTI.getIndexedType())) {
989 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
990 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
991 case -2: return ICmpInst::BAD_ICMP_PREDICATE;
994 // Ok, we ran out of things they have in common. If any leftovers
995 // are non-zero then we have a difference, otherwise we are equal.
996 for (; i < CE1->getNumOperands(); ++i)
997 if (!CE1->getOperand(i)->isNullValue())
998 if (isa<ConstantInt>(CE1->getOperand(i)))
999 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1001 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1003 for (; i < CE2->getNumOperands(); ++i)
1004 if (!CE2->getOperand(i)->isNullValue())
1005 if (isa<ConstantInt>(CE2->getOperand(i)))
1006 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1008 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1009 return ICmpInst::ICMP_EQ;
1018 return ICmpInst::BAD_ICMP_PREDICATE;
1021 Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
1023 const Constant *C2) {
1025 // Handle some degenerate cases first
1026 if (isa<UndefValue>(C1) || isa<UndefValue>(C2))
1027 return UndefValue::get(Type::Int1Ty);
1029 // icmp eq/ne(null,GV) -> false/true
1030 if (C1->isNullValue()) {
1031 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
1032 if (!GV->hasExternalWeakLinkage()) // External weak GV can be null
1033 if (pred == ICmpInst::ICMP_EQ)
1034 return ConstantInt::getFalse();
1035 else if (pred == ICmpInst::ICMP_NE)
1036 return ConstantInt::getTrue();
1037 // icmp eq/ne(GV,null) -> false/true
1038 } else if (C2->isNullValue()) {
1039 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
1040 if (!GV->hasExternalWeakLinkage()) // External weak GV can be null
1041 if (pred == ICmpInst::ICMP_EQ)
1042 return ConstantInt::getFalse();
1043 else if (pred == ICmpInst::ICMP_NE)
1044 return ConstantInt::getTrue();
1047 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
1048 if (ICmpInst::isSignedPredicate(ICmpInst::Predicate(pred))) {
1049 int64_t V1 = cast<ConstantInt>(C1)->getSExtValue();
1050 int64_t V2 = cast<ConstantInt>(C2)->getSExtValue();
1052 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1053 case ICmpInst::ICMP_SLT:return ConstantInt::get(Type::Int1Ty, V1 < V2);
1054 case ICmpInst::ICMP_SGT:return ConstantInt::get(Type::Int1Ty, V1 > V2);
1055 case ICmpInst::ICMP_SLE:return ConstantInt::get(Type::Int1Ty, V1 <= V2);
1056 case ICmpInst::ICMP_SGE:return ConstantInt::get(Type::Int1Ty, V1 >= V2);
1059 uint64_t V1 = cast<ConstantInt>(C1)->getZExtValue();
1060 uint64_t V2 = cast<ConstantInt>(C2)->getZExtValue();
1062 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1063 case ICmpInst::ICMP_EQ: return ConstantInt::get(Type::Int1Ty, V1 == V2);
1064 case ICmpInst::ICMP_NE: return ConstantInt::get(Type::Int1Ty, V1 != V2);
1065 case ICmpInst::ICMP_ULT:return ConstantInt::get(Type::Int1Ty, V1 < V2);
1066 case ICmpInst::ICMP_UGT:return ConstantInt::get(Type::Int1Ty, V1 > V2);
1067 case ICmpInst::ICMP_ULE:return ConstantInt::get(Type::Int1Ty, V1 <= V2);
1068 case ICmpInst::ICMP_UGE:return ConstantInt::get(Type::Int1Ty, V1 >= V2);
1071 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
1072 double C1Val = cast<ConstantFP>(C1)->getValue();
1073 double C2Val = cast<ConstantFP>(C2)->getValue();
1075 default: assert(0 && "Invalid FCmp Predicate"); return 0;
1076 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse();
1077 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue();
1078 case FCmpInst::FCMP_UNO:
1079 return ConstantInt::get(Type::Int1Ty, C1Val != C1Val || C2Val != C2Val);
1080 case FCmpInst::FCMP_ORD:
1081 return ConstantInt::get(Type::Int1Ty, C1Val == C1Val && C2Val == C2Val);
1082 case FCmpInst::FCMP_UEQ:
1083 if (C1Val != C1Val || C2Val != C2Val)
1084 return ConstantInt::getTrue();
1086 case FCmpInst::FCMP_OEQ:
1087 return ConstantInt::get(Type::Int1Ty, C1Val == C2Val);
1088 case FCmpInst::FCMP_UNE:
1089 if (C1Val != C1Val || C2Val != C2Val)
1090 return ConstantInt::getTrue();
1092 case FCmpInst::FCMP_ONE:
1093 return ConstantInt::get(Type::Int1Ty, C1Val != C2Val);
1094 case FCmpInst::FCMP_ULT:
1095 if (C1Val != C1Val || C2Val != C2Val)
1096 return ConstantInt::getTrue();
1098 case FCmpInst::FCMP_OLT:
1099 return ConstantInt::get(Type::Int1Ty, C1Val < C2Val);
1100 case FCmpInst::FCMP_UGT:
1101 if (C1Val != C1Val || C2Val != C2Val)
1102 return ConstantInt::getTrue();
1104 case FCmpInst::FCMP_OGT:
1105 return ConstantInt::get(Type::Int1Ty, C1Val > C2Val);
1106 case FCmpInst::FCMP_ULE:
1107 if (C1Val != C1Val || C2Val != C2Val)
1108 return ConstantInt::getTrue();
1110 case FCmpInst::FCMP_OLE:
1111 return ConstantInt::get(Type::Int1Ty, C1Val <= C2Val);
1112 case FCmpInst::FCMP_UGE:
1113 if (C1Val != C1Val || C2Val != C2Val)
1114 return ConstantInt::getTrue();
1116 case FCmpInst::FCMP_OGE:
1117 return ConstantInt::get(Type::Int1Ty, C1Val >= C2Val);
1119 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {
1120 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) {
1121 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) {
1122 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1123 Constant *C= ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ,
1124 const_cast<Constant*>(CP1->getOperand(i)),
1125 const_cast<Constant*>(CP2->getOperand(i)));
1126 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1129 // Otherwise, could not decide from any element pairs.
1131 } else if (pred == ICmpInst::ICMP_EQ) {
1132 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1133 Constant *C = ConstantExpr::getICmp(ICmpInst::ICMP_EQ,
1134 const_cast<Constant*>(CP1->getOperand(i)),
1135 const_cast<Constant*>(CP2->getOperand(i)));
1136 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1139 // Otherwise, could not decide from any element pairs.
1145 if (C1->getType()->isFloatingPoint()) {
1146 switch (evaluateFCmpRelation(C1, C2)) {
1147 default: assert(0 && "Unknown relation!");
1148 case FCmpInst::FCMP_UNO:
1149 case FCmpInst::FCMP_ORD:
1150 case FCmpInst::FCMP_UEQ:
1151 case FCmpInst::FCMP_UNE:
1152 case FCmpInst::FCMP_ULT:
1153 case FCmpInst::FCMP_UGT:
1154 case FCmpInst::FCMP_ULE:
1155 case FCmpInst::FCMP_UGE:
1156 case FCmpInst::FCMP_TRUE:
1157 case FCmpInst::FCMP_FALSE:
1158 case FCmpInst::BAD_FCMP_PREDICATE:
1159 break; // Couldn't determine anything about these constants.
1160 case FCmpInst::FCMP_OEQ: // We know that C1 == C2
1161 return ConstantInt::get(Type::Int1Ty,
1162 pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
1163 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
1164 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1165 case FCmpInst::FCMP_OLT: // We know that C1 < C2
1166 return ConstantInt::get(Type::Int1Ty,
1167 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1168 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
1169 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
1170 case FCmpInst::FCMP_OGT: // We know that C1 > C2
1171 return ConstantInt::get(Type::Int1Ty,
1172 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1173 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
1174 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1175 case FCmpInst::FCMP_OLE: // We know that C1 <= C2
1176 // We can only partially decide this relation.
1177 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1178 return ConstantInt::getFalse();
1179 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1180 return ConstantInt::getTrue();
1182 case FCmpInst::FCMP_OGE: // We known that C1 >= C2
1183 // We can only partially decide this relation.
1184 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1185 return ConstantInt::getFalse();
1186 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1187 return ConstantInt::getTrue();
1189 case ICmpInst::ICMP_NE: // We know that C1 != C2
1190 // We can only partially decide this relation.
1191 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
1192 return ConstantInt::getFalse();
1193 if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
1194 return ConstantInt::getTrue();
1198 // Evaluate the relation between the two constants, per the predicate.
1199 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) {
1200 default: assert(0 && "Unknown relational!");
1201 case ICmpInst::BAD_ICMP_PREDICATE:
1202 break; // Couldn't determine anything about these constants.
1203 case ICmpInst::ICMP_EQ: // We know the constants are equal!
1204 // If we know the constants are equal, we can decide the result of this
1205 // computation precisely.
1206 return ConstantInt::get(Type::Int1Ty,
1207 pred == ICmpInst::ICMP_EQ ||
1208 pred == ICmpInst::ICMP_ULE ||
1209 pred == ICmpInst::ICMP_SLE ||
1210 pred == ICmpInst::ICMP_UGE ||
1211 pred == ICmpInst::ICMP_SGE);
1212 case ICmpInst::ICMP_ULT:
1213 // If we know that C1 < C2, we can decide the result of this computation
1215 return ConstantInt::get(Type::Int1Ty,
1216 pred == ICmpInst::ICMP_ULT ||
1217 pred == ICmpInst::ICMP_NE ||
1218 pred == ICmpInst::ICMP_ULE);
1219 case ICmpInst::ICMP_SLT:
1220 // If we know that C1 < C2, we can decide the result of this computation
1222 return ConstantInt::get(Type::Int1Ty,
1223 pred == ICmpInst::ICMP_SLT ||
1224 pred == ICmpInst::ICMP_NE ||
1225 pred == ICmpInst::ICMP_SLE);
1226 case ICmpInst::ICMP_UGT:
1227 // If we know that C1 > C2, we can decide the result of this computation
1229 return ConstantInt::get(Type::Int1Ty,
1230 pred == ICmpInst::ICMP_UGT ||
1231 pred == ICmpInst::ICMP_NE ||
1232 pred == ICmpInst::ICMP_UGE);
1233 case ICmpInst::ICMP_SGT:
1234 // If we know that C1 > C2, we can decide the result of this computation
1236 return ConstantInt::get(Type::Int1Ty,
1237 pred == ICmpInst::ICMP_SGT ||
1238 pred == ICmpInst::ICMP_NE ||
1239 pred == ICmpInst::ICMP_SGE);
1240 case ICmpInst::ICMP_ULE:
1241 // If we know that C1 <= C2, we can only partially decide this relation.
1242 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getFalse();
1243 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getTrue();
1245 case ICmpInst::ICMP_SLE:
1246 // If we know that C1 <= C2, we can only partially decide this relation.
1247 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getFalse();
1248 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getTrue();
1251 case ICmpInst::ICMP_UGE:
1252 // If we know that C1 >= C2, we can only partially decide this relation.
1253 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getFalse();
1254 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getTrue();
1256 case ICmpInst::ICMP_SGE:
1257 // If we know that C1 >= C2, we can only partially decide this relation.
1258 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getFalse();
1259 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getTrue();
1262 case ICmpInst::ICMP_NE:
1263 // If we know that C1 != C2, we can only partially decide this relation.
1264 if (pred == ICmpInst::ICMP_EQ) return ConstantInt::getFalse();
1265 if (pred == ICmpInst::ICMP_NE) return ConstantInt::getTrue();
1269 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) {
1270 // If C2 is a constant expr and C1 isn't, flop them around and fold the
1271 // other way if possible.
1273 case ICmpInst::ICMP_EQ:
1274 case ICmpInst::ICMP_NE:
1275 // No change of predicate required.
1276 return ConstantFoldCompareInstruction(pred, C2, C1);
1278 case ICmpInst::ICMP_ULT:
1279 case ICmpInst::ICMP_SLT:
1280 case ICmpInst::ICMP_UGT:
1281 case ICmpInst::ICMP_SGT:
1282 case ICmpInst::ICMP_ULE:
1283 case ICmpInst::ICMP_SLE:
1284 case ICmpInst::ICMP_UGE:
1285 case ICmpInst::ICMP_SGE:
1286 // Change the predicate as necessary to swap the operands.
1287 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
1288 return ConstantFoldCompareInstruction(pred, C2, C1);
1290 default: // These predicates cannot be flopped around.
1298 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1299 Constant* const *Idxs,
1302 (NumIdx == 1 && Idxs[0]->isNullValue()))
1303 return const_cast<Constant*>(C);
1305 if (isa<UndefValue>(C)) {
1306 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(),
1307 (Value**)Idxs, NumIdx,
1309 assert(Ty != 0 && "Invalid indices for GEP!");
1310 return UndefValue::get(PointerType::get(Ty));
1313 Constant *Idx0 = Idxs[0];
1314 if (C->isNullValue()) {
1316 for (unsigned i = 0, e = NumIdx; i != e; ++i)
1317 if (!Idxs[i]->isNullValue()) {
1322 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(),
1323 (Value**)Idxs, NumIdx,
1325 assert(Ty != 0 && "Invalid indices for GEP!");
1326 return ConstantPointerNull::get(PointerType::get(Ty));
1330 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1331 // Combine Indices - If the source pointer to this getelementptr instruction
1332 // is a getelementptr instruction, combine the indices of the two
1333 // getelementptr instructions into a single instruction.
1335 if (CE->getOpcode() == Instruction::GetElementPtr) {
1336 const Type *LastTy = 0;
1337 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1341 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1342 SmallVector<Value*, 16> NewIndices;
1343 NewIndices.reserve(NumIdx + CE->getNumOperands());
1344 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1345 NewIndices.push_back(CE->getOperand(i));
1347 // Add the last index of the source with the first index of the new GEP.
1348 // Make sure to handle the case when they are actually different types.
1349 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1350 // Otherwise it must be an array.
1351 if (!Idx0->isNullValue()) {
1352 const Type *IdxTy = Combined->getType();
1353 if (IdxTy != Idx0->getType()) {
1354 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty);
1355 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
1357 Combined = ConstantExpr::get(Instruction::Add, C1, C2);
1360 ConstantExpr::get(Instruction::Add, Idx0, Combined);
1364 NewIndices.push_back(Combined);
1365 NewIndices.insert(NewIndices.end(), Idxs+1, Idxs+NumIdx);
1366 return ConstantExpr::getGetElementPtr(CE->getOperand(0), &NewIndices[0],
1371 // Implement folding of:
1372 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1374 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1376 if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue())
1377 if (const PointerType *SPT =
1378 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1379 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1380 if (const ArrayType *CAT =
1381 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1382 if (CAT->getElementType() == SAT->getElementType())
1383 return ConstantExpr::getGetElementPtr(
1384 (Constant*)CE->getOperand(0), Idxs, NumIdx);