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/Support/Compiler.h"
27 #include "llvm/Support/GetElementPtrTypeIterator.h"
28 #include "llvm/Support/ManagedStatic.h"
29 #include "llvm/Support/MathExtras.h"
33 //===----------------------------------------------------------------------===//
34 // ConstantFold*Instruction Implementations
35 //===----------------------------------------------------------------------===//
37 /// CastConstantPacked - Convert the specified ConstantPacked node to the
38 /// specified packed type. At this point, we know that the elements of the
39 /// input packed constant are all simple integer or FP values.
40 static Constant *CastConstantPacked(ConstantPacked *CP,
41 const PackedType *DstTy) {
42 unsigned SrcNumElts = CP->getType()->getNumElements();
43 unsigned DstNumElts = DstTy->getNumElements();
44 const Type *SrcEltTy = CP->getType()->getElementType();
45 const Type *DstEltTy = DstTy->getElementType();
47 // If both vectors have the same number of elements (thus, the elements
48 // are the same size), perform the conversion now.
49 if (SrcNumElts == DstNumElts) {
50 std::vector<Constant*> Result;
52 // If the src and dest elements are both integers, or both floats, we can
53 // just BitCast each element because the elements are the same size.
54 if ((SrcEltTy->isInteger() && DstEltTy->isInteger()) ||
55 (SrcEltTy->isFloatingPoint() && DstEltTy->isFloatingPoint())) {
56 for (unsigned i = 0; i != SrcNumElts; ++i)
58 ConstantExpr::getBitCast(CP->getOperand(i), DstEltTy));
59 return ConstantPacked::get(Result);
62 // If this is an int-to-fp cast ..
63 if (SrcEltTy->isInteger()) {
64 // Ensure that it is int-to-fp cast
65 assert(DstEltTy->isFloatingPoint());
66 if (DstEltTy->getTypeID() == Type::DoubleTyID) {
67 for (unsigned i = 0; i != SrcNumElts; ++i) {
69 BitsToDouble(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
70 Result.push_back(ConstantFP::get(Type::DoubleTy, V));
72 return ConstantPacked::get(Result);
74 assert(DstEltTy == Type::FloatTy && "Unknown fp type!");
75 for (unsigned i = 0; i != SrcNumElts; ++i) {
77 BitsToFloat(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
78 Result.push_back(ConstantFP::get(Type::FloatTy, V));
80 return ConstantPacked::get(Result);
83 // Otherwise, this is an fp-to-int cast.
84 assert(SrcEltTy->isFloatingPoint() && DstEltTy->isInteger());
86 if (SrcEltTy->getTypeID() == Type::DoubleTyID) {
87 for (unsigned i = 0; i != SrcNumElts; ++i) {
89 DoubleToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
90 Constant *C = ConstantInt::get(Type::Int64Ty, V);
91 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy ));
93 return ConstantPacked::get(Result);
96 assert(SrcEltTy->getTypeID() == Type::FloatTyID);
97 for (unsigned i = 0; i != SrcNumElts; ++i) {
98 uint32_t V = FloatToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
99 Constant *C = ConstantInt::get(Type::Int32Ty, V);
100 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy));
102 return ConstantPacked::get(Result);
105 // Otherwise, this is a cast that changes element count and size. Handle
106 // casts which shrink the elements here.
108 // FIXME: We need to know endianness to do this!
113 /// This function determines which opcode to use to fold two constant cast
114 /// expressions together. It uses CastInst::isEliminableCastPair to determine
115 /// the opcode. Consequently its just a wrapper around that function.
116 /// @Determine if it is valid to fold a cast of a cast
118 foldConstantCastPair(
119 unsigned opc, ///< opcode of the second cast constant expression
120 const ConstantExpr*Op, ///< the first cast constant expression
121 const Type *DstTy ///< desintation type of the first cast
123 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
124 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
125 assert(CastInst::isCast(opc) && "Invalid cast opcode");
127 // The the types and opcodes for the two Cast constant expressions
128 const Type *SrcTy = Op->getOperand(0)->getType();
129 const Type *MidTy = Op->getType();
130 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
131 Instruction::CastOps secondOp = Instruction::CastOps(opc);
133 // Let CastInst::isEliminableCastPair do the heavy lifting.
134 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
138 Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
139 const Type *DestTy) {
140 const Type *SrcTy = V->getType();
142 if (isa<UndefValue>(V))
143 return UndefValue::get(DestTy);
145 // If the cast operand is a constant expression, there's a few things we can
146 // do to try to simplify it.
147 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
149 // Try hard to fold cast of cast because they are often eliminable.
150 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
151 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
152 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
153 // If all of the indexes in the GEP are null values, there is no pointer
154 // adjustment going on. We might as well cast the source pointer.
155 bool isAllNull = true;
156 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
157 if (!CE->getOperand(i)->isNullValue()) {
162 // This is casting one pointer type to another, always BitCast
163 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
167 // We actually have to do a cast now. Perform the cast according to the
170 case Instruction::FPTrunc:
171 case Instruction::FPExt:
172 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V))
173 return ConstantFP::get(DestTy, FPC->getValue());
174 return 0; // Can't fold.
175 case Instruction::FPToUI:
176 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V))
177 return ConstantInt::get(DestTy,(uint64_t) FPC->getValue());
178 return 0; // Can't fold.
179 case Instruction::FPToSI:
180 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V))
181 return ConstantInt::get(DestTy,(int64_t) FPC->getValue());
182 return 0; // Can't fold.
183 case Instruction::IntToPtr: //always treated as unsigned
184 if (V->isNullValue()) // Is it an integral null value?
185 return ConstantPointerNull::get(cast<PointerType>(DestTy));
186 return 0; // Other pointer types cannot be casted
187 case Instruction::PtrToInt: // always treated as unsigned
188 if (V->isNullValue()) // is it a null pointer value?
189 return ConstantInt::get(DestTy, 0);
190 return 0; // Other pointer types cannot be casted
191 case Instruction::UIToFP:
192 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
193 return ConstantFP::get(DestTy, double(CI->getZExtValue()));
195 case Instruction::SIToFP:
196 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
197 return ConstantFP::get(DestTy, double(CI->getSExtValue()));
199 case Instruction::ZExt:
200 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
201 return ConstantInt::get(DestTy, CI->getZExtValue());
203 case Instruction::SExt:
204 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
205 return ConstantInt::get(DestTy, CI->getSExtValue());
207 case Instruction::Trunc:
208 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) // Can't trunc a bool
209 return ConstantInt::get(DestTy, CI->getZExtValue());
211 case Instruction::BitCast:
213 return (Constant*)V; // no-op cast
215 // Check to see if we are casting a pointer to an aggregate to a pointer to
216 // the first element. If so, return the appropriate GEP instruction.
217 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
218 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
219 std::vector<Value*> IdxList;
220 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
221 const Type *ElTy = PTy->getElementType();
222 while (ElTy != DPTy->getElementType()) {
223 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
224 if (STy->getNumElements() == 0) break;
225 ElTy = STy->getElementType(0);
226 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
227 } else if (const SequentialType *STy =
228 dyn_cast<SequentialType>(ElTy)) {
229 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
230 ElTy = STy->getElementType();
231 IdxList.push_back(IdxList[0]);
237 if (ElTy == DPTy->getElementType())
238 return ConstantExpr::getGetElementPtr(
239 const_cast<Constant*>(V),IdxList);
242 // Handle casts from one packed constant to another. We know that the src
243 // and dest type have the same size (otherwise its an illegal cast).
244 if (const PackedType *DestPTy = dyn_cast<PackedType>(DestTy)) {
245 if (const PackedType *SrcTy = dyn_cast<PackedType>(V->getType())) {
246 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
247 "Not cast between same sized vectors!");
248 // First, check for null and undef
249 if (isa<ConstantAggregateZero>(V))
250 return Constant::getNullValue(DestTy);
251 if (isa<UndefValue>(V))
252 return UndefValue::get(DestTy);
254 if (const ConstantPacked *CP = dyn_cast<ConstantPacked>(V)) {
255 // This is a cast from a ConstantPacked of one type to a
256 // ConstantPacked of another type. Check to see if all elements of
257 // the input are simple.
258 bool AllSimpleConstants = true;
259 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
260 if (!isa<ConstantInt>(CP->getOperand(i)) &&
261 !isa<ConstantFP>(CP->getOperand(i))) {
262 AllSimpleConstants = false;
267 // If all of the elements are simple constants, we can fold this.
268 if (AllSimpleConstants)
269 return CastConstantPacked(const_cast<ConstantPacked*>(CP), DestPTy);
274 // Finally, implement bitcast folding now. The code below doesn't handle
276 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
277 return ConstantPointerNull::get(cast<PointerType>(DestTy));
279 // Handle integral constant input.
280 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
281 // Integral -> Integral, must be changing sign.
282 if (DestTy->isInteger())
283 return ConstantInt::get(DestTy, CI->getZExtValue());
285 if (DestTy->isFloatingPoint()) {
286 if (DestTy == Type::FloatTy)
287 return ConstantFP::get(DestTy, BitsToFloat(CI->getZExtValue()));
288 assert(DestTy == Type::DoubleTy && "Unknown FP type!");
289 return ConstantFP::get(DestTy, BitsToDouble(CI->getZExtValue()));
291 // Otherwise, can't fold this (packed?)
295 // Handle ConstantFP input.
296 if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
298 if (DestTy->isInteger())
299 return ConstantInt::get(DestTy, DoubleToBits(FP->getValue()));
303 assert(!"Invalid CE CastInst opcode");
307 assert(0 && "Failed to cast constant expression");
311 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
313 const Constant *V2) {
314 if (const ConstantInt *CB = dyn_cast<ConstantInt>(Cond))
315 return const_cast<Constant*>(CB->getZExtValue() ? V1 : V2);
317 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
318 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
319 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
320 if (V1 == V2) return const_cast<Constant*>(V1);
324 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
325 const Constant *Idx) {
326 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
327 return UndefValue::get(cast<PackedType>(Val->getType())->getElementType());
328 if (Val->isNullValue()) // ee(zero, x) -> zero
329 return Constant::getNullValue(
330 cast<PackedType>(Val->getType())->getElementType());
332 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
333 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
334 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue()));
335 } else if (isa<UndefValue>(Idx)) {
336 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
337 return const_cast<Constant*>(CVal->getOperand(0));
343 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
345 const Constant *Idx) {
346 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
348 uint64_t idxVal = CIdx->getZExtValue();
349 if (isa<UndefValue>(Val)) {
350 // Insertion of scalar constant into packed undef
351 // Optimize away insertion of undef
352 if (isa<UndefValue>(Elt))
353 return const_cast<Constant*>(Val);
354 // Otherwise break the aggregate undef into multiple undefs and do
357 cast<PackedType>(Val->getType())->getNumElements();
358 std::vector<Constant*> Ops;
360 for (unsigned i = 0; i < numOps; ++i) {
362 (i == idxVal) ? Elt : UndefValue::get(Elt->getType());
363 Ops.push_back(const_cast<Constant*>(Op));
365 return ConstantPacked::get(Ops);
367 if (isa<ConstantAggregateZero>(Val)) {
368 // Insertion of scalar constant into packed aggregate zero
369 // Optimize away insertion of zero
370 if (Elt->isNullValue())
371 return const_cast<Constant*>(Val);
372 // Otherwise break the aggregate zero into multiple zeros and do
375 cast<PackedType>(Val->getType())->getNumElements();
376 std::vector<Constant*> Ops;
378 for (unsigned i = 0; i < numOps; ++i) {
380 (i == idxVal) ? Elt : Constant::getNullValue(Elt->getType());
381 Ops.push_back(const_cast<Constant*>(Op));
383 return ConstantPacked::get(Ops);
385 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
386 // Insertion of scalar constant into packed constant
387 std::vector<Constant*> Ops;
388 Ops.reserve(CVal->getNumOperands());
389 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
391 (i == idxVal) ? Elt : cast<Constant>(CVal->getOperand(i));
392 Ops.push_back(const_cast<Constant*>(Op));
394 return ConstantPacked::get(Ops);
399 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
401 const Constant *Mask) {
406 /// EvalVectorOp - Given two packed constants and a function pointer, apply the
407 /// function pointer to each element pair, producing a new ConstantPacked
409 static Constant *EvalVectorOp(const ConstantPacked *V1,
410 const ConstantPacked *V2,
411 Constant *(*FP)(Constant*, Constant*)) {
412 std::vector<Constant*> Res;
413 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
414 Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
415 const_cast<Constant*>(V2->getOperand(i))));
416 return ConstantPacked::get(Res);
419 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
421 const Constant *C2) {
422 // Handle UndefValue up front
423 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
425 case Instruction::Add:
426 case Instruction::Sub:
427 case Instruction::Xor:
428 return UndefValue::get(C1->getType());
429 case Instruction::Mul:
430 case Instruction::And:
431 return Constant::getNullValue(C1->getType());
432 case Instruction::UDiv:
433 case Instruction::SDiv:
434 case Instruction::FDiv:
435 case Instruction::URem:
436 case Instruction::SRem:
437 case Instruction::FRem:
438 if (!isa<UndefValue>(C2)) // undef / X -> 0
439 return Constant::getNullValue(C1->getType());
440 return const_cast<Constant*>(C2); // X / undef -> undef
441 case Instruction::Or: // X | undef -> -1
442 if (const PackedType *PTy = dyn_cast<PackedType>(C1->getType()))
443 return ConstantPacked::getAllOnesValue(PTy);
444 return ConstantInt::getAllOnesValue(C1->getType());
445 case Instruction::LShr:
446 if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
447 return const_cast<Constant*>(C1); // undef lshr undef -> undef
448 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0
450 case Instruction::AShr:
451 if (!isa<UndefValue>(C2))
452 return const_cast<Constant*>(C1); // undef ashr X --> undef
453 else if (isa<UndefValue>(C1))
454 return const_cast<Constant*>(C1); // undef ashr undef -> undef
456 return const_cast<Constant*>(C1); // X ashr undef --> X
457 case Instruction::Shl:
458 // undef << X -> 0 or X << undef -> 0
459 return Constant::getNullValue(C1->getType());
463 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
464 if (isa<ConstantExpr>(C2)) {
465 // There are many possible foldings we could do here. We should probably
466 // at least fold add of a pointer with an integer into the appropriate
467 // getelementptr. This will improve alias analysis a bit.
469 // Just implement a couple of simple identities.
471 case Instruction::Add:
472 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X + 0 == X
474 case Instruction::Sub:
475 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X - 0 == X
477 case Instruction::Mul:
478 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X * 0 == 0
479 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
480 if (CI->getZExtValue() == 1)
481 return const_cast<Constant*>(C1); // X * 1 == X
483 case Instruction::UDiv:
484 case Instruction::SDiv:
485 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
486 if (CI->getZExtValue() == 1)
487 return const_cast<Constant*>(C1); // X / 1 == X
489 case Instruction::URem:
490 case Instruction::SRem:
491 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
492 if (CI->getZExtValue() == 1)
493 return Constant::getNullValue(CI->getType()); // X % 1 == 0
495 case Instruction::And:
496 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
497 if (CI->isAllOnesValue())
498 return const_cast<Constant*>(C1); // X & -1 == X
499 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X & 0 == 0
500 if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
501 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
503 // Functions are at least 4-byte aligned. If and'ing the address of a
504 // function with a constant < 4, fold it to zero.
505 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
506 if (CI->getZExtValue() < 4 && isa<Function>(CPR))
507 return Constant::getNullValue(CI->getType());
510 case Instruction::Or:
511 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X | 0 == X
512 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
513 if (CI->isAllOnesValue())
514 return const_cast<Constant*>(C2); // X | -1 == -1
516 case Instruction::Xor:
517 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X ^ 0 == X
521 } else if (isa<ConstantExpr>(C2)) {
522 // If C2 is a constant expr and C1 isn't, flop them around and fold the
523 // other way if possible.
525 case Instruction::Add:
526 case Instruction::Mul:
527 case Instruction::And:
528 case Instruction::Or:
529 case Instruction::Xor:
530 // No change of opcode required.
531 return ConstantFoldBinaryInstruction(Opcode, C2, C1);
533 case Instruction::Shl:
534 case Instruction::LShr:
535 case Instruction::AShr:
536 case Instruction::Sub:
537 case Instruction::SDiv:
538 case Instruction::UDiv:
539 case Instruction::FDiv:
540 case Instruction::URem:
541 case Instruction::SRem:
542 case Instruction::FRem:
543 default: // These instructions cannot be flopped around.
548 // At this point we know neither constant is an UndefValue nor a ConstantExpr
549 // so look at directly computing the value.
550 if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
551 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
552 uint64_t C1Val = CI1->getZExtValue();
553 uint64_t C2Val = CI2->getZExtValue();
557 case Instruction::Add:
558 return ConstantInt::get(C1->getType(), C1Val + C2Val);
559 case Instruction::Sub:
560 return ConstantInt::get(C1->getType(), C1Val - C2Val);
561 case Instruction::Mul:
562 return ConstantInt::get(C1->getType(), C1Val * C2Val);
563 case Instruction::UDiv:
564 if (CI2->isNullValue()) // X / 0 -> can't fold
566 return ConstantInt::get(C1->getType(), C1Val / C2Val);
567 case Instruction::SDiv:
568 if (CI2->isNullValue()) return 0; // X / 0 -> can't fold
569 if (CI2->isAllOnesValue() &&
570 (((CI1->getType()->getPrimitiveSizeInBits() == 64) &&
571 (CI1->getSExtValue() == INT64_MIN)) ||
572 (CI1->getSExtValue() == -CI1->getSExtValue())))
573 return 0; // MIN_INT / -1 -> overflow
574 return ConstantInt::get(C1->getType(),
575 CI1->getSExtValue() / CI2->getSExtValue());
576 case Instruction::URem:
577 if (C2->isNullValue()) return 0; // X / 0 -> can't fold
578 return ConstantInt::get(C1->getType(), C1Val % C2Val);
579 case Instruction::SRem:
580 if (CI2->isNullValue()) return 0; // X % 0 -> can't fold
581 if (CI2->isAllOnesValue() &&
582 (((CI1->getType()->getPrimitiveSizeInBits() == 64) &&
583 (CI1->getSExtValue() == INT64_MIN)) ||
584 (CI1->getSExtValue() == -CI1->getSExtValue())))
585 return 0; // MIN_INT % -1 -> overflow
586 return ConstantInt::get(C1->getType(),
587 CI1->getSExtValue() % CI2->getSExtValue());
588 case Instruction::And:
589 return ConstantInt::get(C1->getType(), C1Val & C2Val);
590 case Instruction::Or:
591 return ConstantInt::get(C1->getType(), C1Val | C2Val);
592 case Instruction::Xor:
593 return ConstantInt::get(C1->getType(), C1Val ^ C2Val);
594 case Instruction::Shl:
595 return ConstantInt::get(C1->getType(), C1Val << C2Val);
596 case Instruction::LShr:
597 return ConstantInt::get(C1->getType(), C1Val >> C2Val);
598 case Instruction::AShr:
599 return ConstantInt::get(C1->getType(),
600 CI1->getSExtValue() >> C2Val);
603 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
604 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
605 double C1Val = CFP1->getValue();
606 double C2Val = CFP2->getValue();
610 case Instruction::Add:
611 return ConstantFP::get(CFP1->getType(), C1Val + C2Val);
612 case Instruction::Sub:
613 return ConstantFP::get(CFP1->getType(), C1Val - C2Val);
614 case Instruction::Mul:
615 return ConstantFP::get(CFP1->getType(), C1Val * C2Val);
616 case Instruction::FDiv:
617 if (CFP2->isExactlyValue(0.0))
618 return ConstantFP::get(CFP1->getType(),
619 std::numeric_limits<double>::infinity());
620 if (CFP2->isExactlyValue(-0.0))
621 return ConstantFP::get(CFP1->getType(),
622 -std::numeric_limits<double>::infinity());
623 return ConstantFP::get(CFP1->getType(), C1Val / C2Val);
624 case Instruction::FRem:
625 if (CFP2->isNullValue())
627 return ConstantFP::get(CFP1->getType(), std::fmod(C1Val, C2Val));
630 } else if (const ConstantPacked *CP1 = dyn_cast<ConstantPacked>(C1)) {
631 if (const ConstantPacked *CP2 = dyn_cast<ConstantPacked>(C2)) {
635 case Instruction::Add:
636 return EvalVectorOp(CP1, CP2, ConstantExpr::getAdd);
637 case Instruction::Sub:
638 return EvalVectorOp(CP1, CP2, ConstantExpr::getSub);
639 case Instruction::Mul:
640 return EvalVectorOp(CP1, CP2, ConstantExpr::getMul);
641 case Instruction::UDiv:
642 return EvalVectorOp(CP1, CP2, ConstantExpr::getUDiv);
643 case Instruction::SDiv:
644 return EvalVectorOp(CP1, CP2, ConstantExpr::getSDiv);
645 case Instruction::FDiv:
646 return EvalVectorOp(CP1, CP2, ConstantExpr::getFDiv);
647 case Instruction::URem:
648 return EvalVectorOp(CP1, CP2, ConstantExpr::getURem);
649 case Instruction::SRem:
650 return EvalVectorOp(CP1, CP2, ConstantExpr::getSRem);
651 case Instruction::FRem:
652 return EvalVectorOp(CP1, CP2, ConstantExpr::getFRem);
653 case Instruction::And:
654 return EvalVectorOp(CP1, CP2, ConstantExpr::getAnd);
655 case Instruction::Or:
656 return EvalVectorOp(CP1, CP2, ConstantExpr::getOr);
657 case Instruction::Xor:
658 return EvalVectorOp(CP1, CP2, ConstantExpr::getXor);
663 // We don't know how to fold this
667 /// isZeroSizedType - This type is zero sized if its an array or structure of
668 /// zero sized types. The only leaf zero sized type is an empty structure.
669 static bool isMaybeZeroSizedType(const Type *Ty) {
670 if (isa<OpaqueType>(Ty)) return true; // Can't say.
671 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
673 // If all of elements have zero size, this does too.
674 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
675 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
678 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
679 return isMaybeZeroSizedType(ATy->getElementType());
684 /// IdxCompare - Compare the two constants as though they were getelementptr
685 /// indices. This allows coersion of the types to be the same thing.
687 /// If the two constants are the "same" (after coersion), return 0. If the
688 /// first is less than the second, return -1, if the second is less than the
689 /// first, return 1. If the constants are not integral, return -2.
691 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
692 if (C1 == C2) return 0;
694 // Ok, we found a different index. If they are not ConstantInt, we can't do
695 // anything with them.
696 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
697 return -2; // don't know!
699 // Ok, we have two differing integer indices. Sign extend them to be the same
700 // type. Long is always big enough, so we use it.
701 if (C1->getType() != Type::Int64Ty)
702 C1 = ConstantExpr::getSExt(C1, Type::Int64Ty);
704 if (C2->getType() != Type::Int64Ty)
705 C2 = ConstantExpr::getSExt(C2, Type::Int64Ty);
707 if (C1 == C2) return 0; // They are equal
709 // If the type being indexed over is really just a zero sized type, there is
710 // no pointer difference being made here.
711 if (isMaybeZeroSizedType(ElTy))
714 // If they are really different, now that they are the same type, then we
715 // found a difference!
716 if (cast<ConstantInt>(C1)->getSExtValue() <
717 cast<ConstantInt>(C2)->getSExtValue())
723 /// evaluateFCmpRelation - This function determines if there is anything we can
724 /// decide about the two constants provided. This doesn't need to handle simple
725 /// things like ConstantFP comparisons, but should instead handle ConstantExprs.
726 /// If we can determine that the two constants have a particular relation to
727 /// each other, we should return the corresponding FCmpInst predicate,
728 /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
729 /// ConstantFoldCompareInstruction.
731 /// To simplify this code we canonicalize the relation so that the first
732 /// operand is always the most "complex" of the two. We consider ConstantFP
733 /// to be the simplest, and ConstantExprs to be the most complex.
734 static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1,
735 const Constant *V2) {
736 assert(V1->getType() == V2->getType() &&
737 "Cannot compare values of different types!");
738 // Handle degenerate case quickly
739 if (V1 == V2) return FCmpInst::FCMP_OEQ;
741 if (!isa<ConstantExpr>(V1)) {
742 if (!isa<ConstantExpr>(V2)) {
743 // We distilled thisUse the standard constant folder for a few cases
745 Constant *C1 = const_cast<Constant*>(V1);
746 Constant *C2 = const_cast<Constant*>(V2);
747 R = dyn_cast<ConstantInt>(
748 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2));
749 if (R && R->getZExtValue())
750 return FCmpInst::FCMP_OEQ;
751 R = dyn_cast<ConstantInt>(
752 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2));
753 if (R && R->getZExtValue())
754 return FCmpInst::FCMP_OLT;
755 R = dyn_cast<ConstantInt>(
756 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2));
757 if (R && R->getZExtValue())
758 return FCmpInst::FCMP_OGT;
760 // Nothing more we can do
761 return FCmpInst::BAD_FCMP_PREDICATE;
764 // If the first operand is simple and second is ConstantExpr, swap operands.
765 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
766 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
767 return FCmpInst::getSwappedPredicate(SwappedRelation);
769 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
770 // constantexpr or a simple constant.
771 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
772 switch (CE1->getOpcode()) {
773 case Instruction::FPTrunc:
774 case Instruction::FPExt:
775 case Instruction::UIToFP:
776 case Instruction::SIToFP:
777 // We might be able to do something with these but we don't right now.
783 // There are MANY other foldings that we could perform here. They will
784 // probably be added on demand, as they seem needed.
785 return FCmpInst::BAD_FCMP_PREDICATE;
788 /// evaluateICmpRelation - This function determines if there is anything we can
789 /// decide about the two constants provided. This doesn't need to handle simple
790 /// things like integer comparisons, but should instead handle ConstantExprs
791 /// and GlobalValues. If we can determine that the two constants have a
792 /// particular relation to each other, we should return the corresponding ICmp
793 /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.
795 /// To simplify this code we canonicalize the relation so that the first
796 /// operand is always the most "complex" of the two. We consider simple
797 /// constants (like ConstantInt) to be the simplest, followed by
798 /// GlobalValues, followed by ConstantExpr's (the most complex).
800 static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1,
803 assert(V1->getType() == V2->getType() &&
804 "Cannot compare different types of values!");
805 if (V1 == V2) return ICmpInst::ICMP_EQ;
807 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
808 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
809 // We distilled this down to a simple case, use the standard constant
812 Constant *C1 = const_cast<Constant*>(V1);
813 Constant *C2 = const_cast<Constant*>(V2);
814 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
815 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
816 if (R && R->getZExtValue())
818 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
819 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
820 if (R && R->getZExtValue())
822 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
823 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
824 if (R && R->getZExtValue())
827 // If we couldn't figure it out, bail.
828 return ICmpInst::BAD_ICMP_PREDICATE;
831 // If the first operand is simple, swap operands.
832 ICmpInst::Predicate SwappedRelation =
833 evaluateICmpRelation(V2, V1, isSigned);
834 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
835 return ICmpInst::getSwappedPredicate(SwappedRelation);
837 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
838 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
839 ICmpInst::Predicate SwappedRelation =
840 evaluateICmpRelation(V2, V1, isSigned);
841 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
842 return ICmpInst::getSwappedPredicate(SwappedRelation);
844 return ICmpInst::BAD_ICMP_PREDICATE;
847 // Now we know that the RHS is a GlobalValue or simple constant,
848 // which (since the types must match) means that it's a ConstantPointerNull.
849 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
850 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
851 return ICmpInst::ICMP_NE;
853 // GlobalVals can never be null.
854 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
855 if (!CPR1->hasExternalWeakLinkage())
856 return ICmpInst::ICMP_NE;
859 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
860 // constantexpr, a CPR, or a simple constant.
861 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
862 const Constant *CE1Op0 = CE1->getOperand(0);
864 switch (CE1->getOpcode()) {
865 case Instruction::Trunc:
866 case Instruction::FPTrunc:
867 case Instruction::FPExt:
868 case Instruction::FPToUI:
869 case Instruction::FPToSI:
870 break; // We can't evaluate floating point casts or truncations.
872 case Instruction::UIToFP:
873 case Instruction::SIToFP:
874 case Instruction::IntToPtr:
875 case Instruction::BitCast:
876 case Instruction::ZExt:
877 case Instruction::SExt:
878 case Instruction::PtrToInt:
879 // If the cast is not actually changing bits, and the second operand is a
880 // null pointer, do the comparison with the pre-casted value.
881 if (V2->isNullValue() &&
882 (isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) {
883 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
884 (CE1->getOpcode() == Instruction::SExt ? true :
885 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
886 return evaluateICmpRelation(
887 CE1Op0, Constant::getNullValue(CE1Op0->getType()), sgnd);
890 // If the dest type is a pointer type, and the RHS is a constantexpr cast
891 // from the same type as the src of the LHS, evaluate the inputs. This is
892 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)",
893 // which happens a lot in compilers with tagged integers.
894 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
895 if (CE2->isCast() && isa<PointerType>(CE1->getType()) &&
896 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
897 CE1->getOperand(0)->getType()->isInteger()) {
898 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
899 (CE1->getOpcode() == Instruction::SExt ? true :
900 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
901 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0),
906 case Instruction::GetElementPtr:
907 // Ok, since this is a getelementptr, we know that the constant has a
908 // pointer type. Check the various cases.
909 if (isa<ConstantPointerNull>(V2)) {
910 // If we are comparing a GEP to a null pointer, check to see if the base
911 // of the GEP equals the null pointer.
912 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
913 if (GV->hasExternalWeakLinkage())
914 // Weak linkage GVals could be zero or not. We're comparing that
915 // to null pointer so its greater-or-equal
916 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
918 // If its not weak linkage, the GVal must have a non-zero address
919 // so the result is greater-than
920 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
921 } else if (isa<ConstantPointerNull>(CE1Op0)) {
922 // If we are indexing from a null pointer, check to see if we have any
924 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
925 if (!CE1->getOperand(i)->isNullValue())
926 // Offsetting from null, must not be equal.
927 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
928 // Only zero indexes from null, must still be zero.
929 return ICmpInst::ICMP_EQ;
931 // Otherwise, we can't really say if the first operand is null or not.
932 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
933 if (isa<ConstantPointerNull>(CE1Op0)) {
934 if (CPR2->hasExternalWeakLinkage())
935 // Weak linkage GVals could be zero or not. We're comparing it to
936 // a null pointer, so its less-or-equal
937 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
939 // If its not weak linkage, the GVal must have a non-zero address
940 // so the result is less-than
941 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
942 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
944 // If this is a getelementptr of the same global, then it must be
945 // different. Because the types must match, the getelementptr could
946 // only have at most one index, and because we fold getelementptr's
947 // with a single zero index, it must be nonzero.
948 assert(CE1->getNumOperands() == 2 &&
949 !CE1->getOperand(1)->isNullValue() &&
950 "Suprising getelementptr!");
951 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
953 // If they are different globals, we don't know what the value is,
954 // but they can't be equal.
955 return ICmpInst::ICMP_NE;
959 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
960 const Constant *CE2Op0 = CE2->getOperand(0);
962 // There are MANY other foldings that we could perform here. They will
963 // probably be added on demand, as they seem needed.
964 switch (CE2->getOpcode()) {
966 case Instruction::GetElementPtr:
967 // By far the most common case to handle is when the base pointers are
968 // obviously to the same or different globals.
969 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
970 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
971 return ICmpInst::ICMP_NE;
972 // Ok, we know that both getelementptr instructions are based on the
973 // same global. From this, we can precisely determine the relative
974 // ordering of the resultant pointers.
977 // Compare all of the operands the GEP's have in common.
978 gep_type_iterator GTI = gep_type_begin(CE1);
979 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
981 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
982 GTI.getIndexedType())) {
983 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
984 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
985 case -2: return ICmpInst::BAD_ICMP_PREDICATE;
988 // Ok, we ran out of things they have in common. If any leftovers
989 // are non-zero then we have a difference, otherwise we are equal.
990 for (; i < CE1->getNumOperands(); ++i)
991 if (!CE1->getOperand(i)->isNullValue())
992 if (isa<ConstantInt>(CE1->getOperand(i)))
993 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
995 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
997 for (; i < CE2->getNumOperands(); ++i)
998 if (!CE2->getOperand(i)->isNullValue())
999 if (isa<ConstantInt>(CE2->getOperand(i)))
1000 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1002 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1003 return ICmpInst::ICMP_EQ;
1012 return ICmpInst::BAD_ICMP_PREDICATE;
1015 Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
1017 const Constant *C2) {
1019 // Handle some degenerate cases first
1020 if (isa<UndefValue>(C1) || isa<UndefValue>(C2))
1021 return UndefValue::get(Type::Int1Ty);
1023 // icmp eq/ne(null,GV) -> false/true
1024 if (C1->isNullValue()) {
1025 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
1026 if (!GV->hasExternalWeakLinkage()) // External weak GV can be null
1027 if (pred == ICmpInst::ICMP_EQ)
1028 return ConstantInt::getFalse();
1029 else if (pred == ICmpInst::ICMP_NE)
1030 return ConstantInt::getTrue();
1031 // icmp eq/ne(GV,null) -> false/true
1032 } else if (C2->isNullValue()) {
1033 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
1034 if (!GV->hasExternalWeakLinkage()) // External weak GV can be null
1035 if (pred == ICmpInst::ICMP_EQ)
1036 return ConstantInt::getFalse();
1037 else if (pred == ICmpInst::ICMP_NE)
1038 return ConstantInt::getTrue();
1041 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
1042 if (ICmpInst::isSignedPredicate(ICmpInst::Predicate(pred))) {
1043 int64_t V1 = cast<ConstantInt>(C1)->getSExtValue();
1044 int64_t V2 = cast<ConstantInt>(C2)->getSExtValue();
1046 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1047 case ICmpInst::ICMP_SLT:return ConstantInt::get(Type::Int1Ty, V1 < V2);
1048 case ICmpInst::ICMP_SGT:return ConstantInt::get(Type::Int1Ty, V1 > V2);
1049 case ICmpInst::ICMP_SLE:return ConstantInt::get(Type::Int1Ty, V1 <= V2);
1050 case ICmpInst::ICMP_SGE:return ConstantInt::get(Type::Int1Ty, V1 >= V2);
1053 uint64_t V1 = cast<ConstantInt>(C1)->getZExtValue();
1054 uint64_t V2 = cast<ConstantInt>(C2)->getZExtValue();
1056 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1057 case ICmpInst::ICMP_EQ: return ConstantInt::get(Type::Int1Ty, V1 == V2);
1058 case ICmpInst::ICMP_NE: return ConstantInt::get(Type::Int1Ty, V1 != V2);
1059 case ICmpInst::ICMP_ULT:return ConstantInt::get(Type::Int1Ty, V1 < V2);
1060 case ICmpInst::ICMP_UGT:return ConstantInt::get(Type::Int1Ty, V1 > V2);
1061 case ICmpInst::ICMP_ULE:return ConstantInt::get(Type::Int1Ty, V1 <= V2);
1062 case ICmpInst::ICMP_UGE:return ConstantInt::get(Type::Int1Ty, V1 >= V2);
1065 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
1066 double C1Val = cast<ConstantFP>(C1)->getValue();
1067 double C2Val = cast<ConstantFP>(C2)->getValue();
1069 default: assert(0 && "Invalid FCmp Predicate"); return 0;
1070 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse();
1071 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue();
1072 case FCmpInst::FCMP_UNO:
1073 return ConstantInt::get(Type::Int1Ty, C1Val != C1Val || C2Val != C2Val);
1074 case FCmpInst::FCMP_ORD:
1075 return ConstantInt::get(Type::Int1Ty, C1Val == C1Val && C2Val == C2Val);
1076 case FCmpInst::FCMP_UEQ:
1077 if (C1Val != C1Val || C2Val != C2Val)
1078 return ConstantInt::getTrue();
1080 case FCmpInst::FCMP_OEQ:
1081 return ConstantInt::get(Type::Int1Ty, C1Val == C2Val);
1082 case FCmpInst::FCMP_UNE:
1083 if (C1Val != C1Val || C2Val != C2Val)
1084 return ConstantInt::getTrue();
1086 case FCmpInst::FCMP_ONE:
1087 return ConstantInt::get(Type::Int1Ty, C1Val != C2Val);
1088 case FCmpInst::FCMP_ULT:
1089 if (C1Val != C1Val || C2Val != C2Val)
1090 return ConstantInt::getTrue();
1092 case FCmpInst::FCMP_OLT:
1093 return ConstantInt::get(Type::Int1Ty, C1Val < C2Val);
1094 case FCmpInst::FCMP_UGT:
1095 if (C1Val != C1Val || C2Val != C2Val)
1096 return ConstantInt::getTrue();
1098 case FCmpInst::FCMP_OGT:
1099 return ConstantInt::get(Type::Int1Ty, C1Val > C2Val);
1100 case FCmpInst::FCMP_ULE:
1101 if (C1Val != C1Val || C2Val != C2Val)
1102 return ConstantInt::getTrue();
1104 case FCmpInst::FCMP_OLE:
1105 return ConstantInt::get(Type::Int1Ty, C1Val <= C2Val);
1106 case FCmpInst::FCMP_UGE:
1107 if (C1Val != C1Val || C2Val != C2Val)
1108 return ConstantInt::getTrue();
1110 case FCmpInst::FCMP_OGE:
1111 return ConstantInt::get(Type::Int1Ty, C1Val >= C2Val);
1113 } else if (const ConstantPacked *CP1 = dyn_cast<ConstantPacked>(C1)) {
1114 if (const ConstantPacked *CP2 = dyn_cast<ConstantPacked>(C2)) {
1115 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) {
1116 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1117 Constant *C= ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ,
1118 const_cast<Constant*>(CP1->getOperand(i)),
1119 const_cast<Constant*>(CP2->getOperand(i)));
1120 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1123 // Otherwise, could not decide from any element pairs.
1125 } else if (pred == ICmpInst::ICMP_EQ) {
1126 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1127 Constant *C = ConstantExpr::getICmp(ICmpInst::ICMP_EQ,
1128 const_cast<Constant*>(CP1->getOperand(i)),
1129 const_cast<Constant*>(CP2->getOperand(i)));
1130 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1133 // Otherwise, could not decide from any element pairs.
1139 if (C1->getType()->isFloatingPoint()) {
1140 switch (evaluateFCmpRelation(C1, C2)) {
1141 default: assert(0 && "Unknown relation!");
1142 case FCmpInst::FCMP_UNO:
1143 case FCmpInst::FCMP_ORD:
1144 case FCmpInst::FCMP_UEQ:
1145 case FCmpInst::FCMP_UNE:
1146 case FCmpInst::FCMP_ULT:
1147 case FCmpInst::FCMP_UGT:
1148 case FCmpInst::FCMP_ULE:
1149 case FCmpInst::FCMP_UGE:
1150 case FCmpInst::FCMP_TRUE:
1151 case FCmpInst::FCMP_FALSE:
1152 case FCmpInst::BAD_FCMP_PREDICATE:
1153 break; // Couldn't determine anything about these constants.
1154 case FCmpInst::FCMP_OEQ: // We know that C1 == C2
1155 return ConstantInt::get(Type::Int1Ty,
1156 pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
1157 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
1158 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1159 case FCmpInst::FCMP_OLT: // We know that C1 < C2
1160 return ConstantInt::get(Type::Int1Ty,
1161 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1162 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
1163 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
1164 case FCmpInst::FCMP_OGT: // We know that C1 > C2
1165 return ConstantInt::get(Type::Int1Ty,
1166 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1167 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
1168 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1169 case FCmpInst::FCMP_OLE: // We know that C1 <= C2
1170 // We can only partially decide this relation.
1171 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1172 return ConstantInt::getFalse();
1173 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1174 return ConstantInt::getTrue();
1176 case FCmpInst::FCMP_OGE: // We known that C1 >= C2
1177 // We can only partially decide this relation.
1178 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1179 return ConstantInt::getFalse();
1180 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1181 return ConstantInt::getTrue();
1183 case ICmpInst::ICMP_NE: // We know that C1 != C2
1184 // We can only partially decide this relation.
1185 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
1186 return ConstantInt::getFalse();
1187 if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
1188 return ConstantInt::getTrue();
1192 // Evaluate the relation between the two constants, per the predicate.
1193 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) {
1194 default: assert(0 && "Unknown relational!");
1195 case ICmpInst::BAD_ICMP_PREDICATE:
1196 break; // Couldn't determine anything about these constants.
1197 case ICmpInst::ICMP_EQ: // We know the constants are equal!
1198 // If we know the constants are equal, we can decide the result of this
1199 // computation precisely.
1200 return ConstantInt::get(Type::Int1Ty,
1201 pred == ICmpInst::ICMP_EQ ||
1202 pred == ICmpInst::ICMP_ULE ||
1203 pred == ICmpInst::ICMP_SLE ||
1204 pred == ICmpInst::ICMP_UGE ||
1205 pred == ICmpInst::ICMP_SGE);
1206 case ICmpInst::ICMP_ULT:
1207 // If we know that C1 < C2, we can decide the result of this computation
1209 return ConstantInt::get(Type::Int1Ty,
1210 pred == ICmpInst::ICMP_ULT ||
1211 pred == ICmpInst::ICMP_NE ||
1212 pred == ICmpInst::ICMP_ULE);
1213 case ICmpInst::ICMP_SLT:
1214 // If we know that C1 < C2, we can decide the result of this computation
1216 return ConstantInt::get(Type::Int1Ty,
1217 pred == ICmpInst::ICMP_SLT ||
1218 pred == ICmpInst::ICMP_NE ||
1219 pred == ICmpInst::ICMP_SLE);
1220 case ICmpInst::ICMP_UGT:
1221 // If we know that C1 > C2, we can decide the result of this computation
1223 return ConstantInt::get(Type::Int1Ty,
1224 pred == ICmpInst::ICMP_UGT ||
1225 pred == ICmpInst::ICMP_NE ||
1226 pred == ICmpInst::ICMP_UGE);
1227 case ICmpInst::ICMP_SGT:
1228 // If we know that C1 > C2, we can decide the result of this computation
1230 return ConstantInt::get(Type::Int1Ty,
1231 pred == ICmpInst::ICMP_SGT ||
1232 pred == ICmpInst::ICMP_NE ||
1233 pred == ICmpInst::ICMP_SGE);
1234 case ICmpInst::ICMP_ULE:
1235 // If we know that C1 <= C2, we can only partially decide this relation.
1236 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getFalse();
1237 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getTrue();
1239 case ICmpInst::ICMP_SLE:
1240 // If we know that C1 <= C2, we can only partially decide this relation.
1241 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getFalse();
1242 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getTrue();
1245 case ICmpInst::ICMP_UGE:
1246 // If we know that C1 >= C2, we can only partially decide this relation.
1247 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getFalse();
1248 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getTrue();
1250 case ICmpInst::ICMP_SGE:
1251 // If we know that C1 >= C2, we can only partially decide this relation.
1252 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getFalse();
1253 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getTrue();
1256 case ICmpInst::ICMP_NE:
1257 // If we know that C1 != C2, we can only partially decide this relation.
1258 if (pred == ICmpInst::ICMP_EQ) return ConstantInt::getFalse();
1259 if (pred == ICmpInst::ICMP_NE) return ConstantInt::getTrue();
1263 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) {
1264 // If C2 is a constant expr and C1 isn't, flop them around and fold the
1265 // other way if possible.
1267 case ICmpInst::ICMP_EQ:
1268 case ICmpInst::ICMP_NE:
1269 // No change of predicate required.
1270 return ConstantFoldCompareInstruction(pred, C2, C1);
1272 case ICmpInst::ICMP_ULT:
1273 case ICmpInst::ICMP_SLT:
1274 case ICmpInst::ICMP_UGT:
1275 case ICmpInst::ICMP_SGT:
1276 case ICmpInst::ICMP_ULE:
1277 case ICmpInst::ICMP_SLE:
1278 case ICmpInst::ICMP_UGE:
1279 case ICmpInst::ICMP_SGE:
1280 // Change the predicate as necessary to swap the operands.
1281 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
1282 return ConstantFoldCompareInstruction(pred, C2, C1);
1284 default: // These predicates cannot be flopped around.
1292 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1293 const std::vector<Value*> &IdxList) {
1294 if (IdxList.size() == 0 ||
1295 (IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
1296 return const_cast<Constant*>(C);
1298 if (isa<UndefValue>(C)) {
1299 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1301 assert(Ty != 0 && "Invalid indices for GEP!");
1302 return UndefValue::get(PointerType::get(Ty));
1305 Constant *Idx0 = cast<Constant>(IdxList[0]);
1306 if (C->isNullValue()) {
1308 for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
1309 if (!cast<Constant>(IdxList[i])->isNullValue()) {
1314 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1316 assert(Ty != 0 && "Invalid indices for GEP!");
1317 return ConstantPointerNull::get(PointerType::get(Ty));
1321 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1322 // Combine Indices - If the source pointer to this getelementptr instruction
1323 // is a getelementptr instruction, combine the indices of the two
1324 // getelementptr instructions into a single instruction.
1326 if (CE->getOpcode() == Instruction::GetElementPtr) {
1327 const Type *LastTy = 0;
1328 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1332 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1333 std::vector<Value*> NewIndices;
1334 NewIndices.reserve(IdxList.size() + CE->getNumOperands());
1335 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1336 NewIndices.push_back(CE->getOperand(i));
1338 // Add the last index of the source with the first index of the new GEP.
1339 // Make sure to handle the case when they are actually different types.
1340 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1341 // Otherwise it must be an array.
1342 if (!Idx0->isNullValue()) {
1343 const Type *IdxTy = Combined->getType();
1344 if (IdxTy != Idx0->getType()) {
1345 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty);
1346 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
1348 Combined = ConstantExpr::get(Instruction::Add, C1, C2);
1351 ConstantExpr::get(Instruction::Add, Idx0, Combined);
1355 NewIndices.push_back(Combined);
1356 NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
1357 return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
1361 // Implement folding of:
1362 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1364 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1366 if (CE->isCast() && IdxList.size() > 1 && Idx0->isNullValue())
1367 if (const PointerType *SPT =
1368 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1369 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1370 if (const ArrayType *CAT =
1371 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1372 if (CAT->getElementType() == SAT->getElementType())
1373 return ConstantExpr::getGetElementPtr(
1374 (Constant*)CE->getOperand(0), IdxList);