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->isIntegral() && DstEltTy->isIntegral()) ||
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->isIntegral()) {
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->isIntegral());
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::ULongTy, 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::UIntTy, 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 ConstantIntegral::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 ConstantIntegral::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 ConstantIntegral::get(DestTy, 0);
190 return 0; // Other pointer types cannot be casted
191 case Instruction::UIToFP:
192 if (const ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
193 return ConstantFP::get(DestTy, double(CI->getZExtValue()));
195 case Instruction::SIToFP:
196 if (const ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
197 return ConstantFP::get(DestTy, double(CI->getSExtValue()));
199 case Instruction::ZExt:
200 if (const ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
201 return ConstantInt::get(DestTy, CI->getZExtValue());
203 case Instruction::SExt:
204 if (const ConstantIntegral *CI = dyn_cast<ConstantIntegral>(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 ConstantIntegral::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::IntTy));
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::UIntTy));
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->isIntegral())
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->isIntegral()) {
299 if (DestTy == Type::IntTy || DestTy == Type::UIntTy)
300 return ConstantInt::get(DestTy, FloatToBits(FP->getValue()));
301 assert((DestTy == Type::LongTy || DestTy == Type::ULongTy)
302 && "Incorrect integer type for bitcast!");
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 ConstantBool *CB = dyn_cast<ConstantBool>(Cond))
320 return const_cast<Constant*>(CB->getValue() ? 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<PackedType>(Val->getType())->getElementType());
333 if (Val->isNullValue()) // ee(zero, x) -> zero
334 return Constant::getNullValue(
335 cast<PackedType>(Val->getType())->getElementType());
337 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(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<PackedType>(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 ConstantPacked::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<PackedType>(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 ConstantPacked::get(Ops);
390 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(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 ConstantPacked::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 ConstantPacked
414 static Constant *EvalVectorOp(const ConstantPacked *V1,
415 const ConstantPacked *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 ConstantPacked::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 return ConstantInt::getAllOnesValue(C1->getType());
448 case Instruction::LShr:
449 if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
450 return const_cast<Constant*>(C1); // undef lshr undef -> undef
451 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0
453 case Instruction::AShr:
454 if (!isa<UndefValue>(C2))
455 return const_cast<Constant*>(C1); // undef ashr X --> undef
456 else if (isa<UndefValue>(C1))
457 return const_cast<Constant*>(C1); // undef ashr undef -> undef
459 return const_cast<Constant*>(C1); // X ashr undef --> X
460 case Instruction::Shl:
461 // undef << X -> 0 or X << undef -> 0
462 return Constant::getNullValue(C1->getType());
466 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
467 if (isa<ConstantExpr>(C2)) {
468 // There are many possible foldings we could do here. We should probably
469 // at least fold add of a pointer with an integer into the appropriate
470 // getelementptr. This will improve alias analysis a bit.
472 // Just implement a couple of simple identities.
474 case Instruction::Add:
475 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X + 0 == X
477 case Instruction::Sub:
478 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X - 0 == X
480 case Instruction::Mul:
481 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X * 0 == 0
482 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
483 if (CI->getZExtValue() == 1)
484 return const_cast<Constant*>(C1); // X * 1 == X
486 case Instruction::UDiv:
487 case Instruction::SDiv:
488 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
489 if (CI->getZExtValue() == 1)
490 return const_cast<Constant*>(C1); // X / 1 == X
492 case Instruction::URem:
493 case Instruction::SRem:
494 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
495 if (CI->getZExtValue() == 1)
496 return Constant::getNullValue(CI->getType()); // X % 1 == 0
498 case Instruction::And:
499 if (cast<ConstantIntegral>(C2)->isAllOnesValue())
500 return const_cast<Constant*>(C1); // X & -1 == X
501 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X & 0 == 0
502 if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
503 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
505 // Functions are at least 4-byte aligned. If and'ing the address of a
506 // function with a constant < 4, fold it to zero.
507 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
508 if (CI->getZExtValue() < 4 && isa<Function>(CPR))
509 return Constant::getNullValue(CI->getType());
512 case Instruction::Or:
513 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X | 0 == X
514 if (cast<ConstantIntegral>(C2)->isAllOnesValue())
515 return const_cast<Constant*>(C2); // X | -1 == -1
517 case Instruction::Xor:
518 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X ^ 0 == X
522 } else if (isa<ConstantExpr>(C2)) {
523 // If C2 is a constant expr and C1 isn't, flop them around and fold the
524 // other way if possible.
526 case Instruction::Add:
527 case Instruction::Mul:
528 case Instruction::And:
529 case Instruction::Or:
530 case Instruction::Xor:
531 // No change of opcode required.
532 return ConstantFoldBinaryInstruction(Opcode, C2, C1);
534 case Instruction::Shl:
535 case Instruction::LShr:
536 case Instruction::AShr:
537 case Instruction::Sub:
538 case Instruction::SDiv:
539 case Instruction::UDiv:
540 case Instruction::FDiv:
541 case Instruction::URem:
542 case Instruction::SRem:
543 case Instruction::FRem:
544 default: // These instructions cannot be flopped around.
549 // At this point we know neither constant is an UndefValue nor a ConstantExpr
550 // so look at directly computing the
551 if (const ConstantBool *CB1 = dyn_cast<ConstantBool>(C1)) {
552 if (const ConstantBool *CB2 = dyn_cast<ConstantBool>(C2)) {
556 case Instruction::And:
557 return ConstantBool::get(CB1->getValue() & CB2->getValue());
558 case Instruction::Or:
559 return ConstantBool::get(CB1->getValue() | CB2->getValue());
560 case Instruction::Xor:
561 return ConstantBool::get(CB1->getValue() ^ CB2->getValue());
564 } else if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
565 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
566 uint64_t C1Val = CI1->getZExtValue();
567 uint64_t C2Val = CI2->getZExtValue();
571 case Instruction::Add:
572 return ConstantInt::get(C1->getType(), C1Val + C2Val);
573 case Instruction::Sub:
574 return ConstantInt::get(C1->getType(), C1Val - C2Val);
575 case Instruction::Mul:
576 return ConstantInt::get(C1->getType(), C1Val * C2Val);
577 case Instruction::UDiv:
578 if (CI2->isNullValue()) // X / 0 -> can't fold
580 return ConstantInt::get(C1->getType(), C1Val / C2Val);
581 case Instruction::SDiv:
582 if (CI2->isNullValue()) return 0; // X / 0 -> can't fold
583 if (CI2->isAllOnesValue() &&
584 (((CI1->getType()->getPrimitiveSizeInBits() == 64) &&
585 (CI1->getSExtValue() == INT64_MIN)) ||
586 (CI1->getSExtValue() == -CI1->getSExtValue())))
587 return 0; // MIN_INT / -1 -> overflow
588 return ConstantInt::get(C1->getType(),
589 CI1->getSExtValue() / CI2->getSExtValue());
590 case Instruction::URem:
591 if (C2->isNullValue()) return 0; // X / 0 -> can't fold
592 return ConstantInt::get(C1->getType(), C1Val % C2Val);
593 case Instruction::SRem:
594 if (CI2->isNullValue()) return 0; // X % 0 -> can't fold
595 if (CI2->isAllOnesValue() &&
596 (((CI1->getType()->getPrimitiveSizeInBits() == 64) &&
597 (CI1->getSExtValue() == INT64_MIN)) ||
598 (CI1->getSExtValue() == -CI1->getSExtValue())))
599 return 0; // MIN_INT % -1 -> overflow
600 return ConstantInt::get(C1->getType(),
601 CI1->getSExtValue() % CI2->getSExtValue());
602 case Instruction::And:
603 return ConstantInt::get(C1->getType(), C1Val & C2Val);
604 case Instruction::Or:
605 return ConstantInt::get(C1->getType(), C1Val | C2Val);
606 case Instruction::Xor:
607 return ConstantInt::get(C1->getType(), C1Val ^ C2Val);
608 case Instruction::Shl:
609 return ConstantInt::get(C1->getType(), C1Val << C2Val);
610 case Instruction::LShr:
611 return ConstantInt::get(C1->getType(), C1Val >> C2Val);
612 case Instruction::AShr:
613 return ConstantInt::get(C1->getType(),
614 CI1->getSExtValue() >> C2Val);
617 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
618 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
619 double C1Val = CFP1->getValue();
620 double C2Val = CFP2->getValue();
624 case Instruction::Add:
625 return ConstantFP::get(CFP1->getType(), C1Val + C2Val);
626 case Instruction::Sub:
627 return ConstantFP::get(CFP1->getType(), C1Val - C2Val);
628 case Instruction::Mul:
629 return ConstantFP::get(CFP1->getType(), C1Val * C2Val);
630 case Instruction::FDiv:
631 if (CFP2->isExactlyValue(0.0))
632 return ConstantFP::get(CFP1->getType(),
633 std::numeric_limits<double>::infinity());
634 if (CFP2->isExactlyValue(-0.0))
635 return ConstantFP::get(CFP1->getType(),
636 -std::numeric_limits<double>::infinity());
637 return ConstantFP::get(CFP1->getType(), C1Val / C2Val);
638 case Instruction::FRem:
639 if (CFP2->isNullValue())
641 return ConstantFP::get(CFP1->getType(), std::fmod(C1Val, C2Val));
644 } else if (const ConstantPacked *CP1 = dyn_cast<ConstantPacked>(C1)) {
645 if (const ConstantPacked *CP2 = dyn_cast<ConstantPacked>(C2)) {
649 case Instruction::Add:
650 return EvalVectorOp(CP1, CP2, ConstantExpr::getAdd);
651 case Instruction::Sub:
652 return EvalVectorOp(CP1, CP2, ConstantExpr::getSub);
653 case Instruction::Mul:
654 return EvalVectorOp(CP1, CP2, ConstantExpr::getMul);
655 case Instruction::UDiv:
656 return EvalVectorOp(CP1, CP2, ConstantExpr::getUDiv);
657 case Instruction::SDiv:
658 return EvalVectorOp(CP1, CP2, ConstantExpr::getSDiv);
659 case Instruction::FDiv:
660 return EvalVectorOp(CP1, CP2, ConstantExpr::getFDiv);
661 case Instruction::URem:
662 return EvalVectorOp(CP1, CP2, ConstantExpr::getURem);
663 case Instruction::SRem:
664 return EvalVectorOp(CP1, CP2, ConstantExpr::getSRem);
665 case Instruction::FRem:
666 return EvalVectorOp(CP1, CP2, ConstantExpr::getFRem);
667 case Instruction::And:
668 return EvalVectorOp(CP1, CP2, ConstantExpr::getAnd);
669 case Instruction::Or:
670 return EvalVectorOp(CP1, CP2, ConstantExpr::getOr);
671 case Instruction::Xor:
672 return EvalVectorOp(CP1, CP2, ConstantExpr::getXor);
677 // We don't know how to fold this
681 /// isZeroSizedType - This type is zero sized if its an array or structure of
682 /// zero sized types. The only leaf zero sized type is an empty structure.
683 static bool isMaybeZeroSizedType(const Type *Ty) {
684 if (isa<OpaqueType>(Ty)) return true; // Can't say.
685 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
687 // If all of elements have zero size, this does too.
688 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
689 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
692 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
693 return isMaybeZeroSizedType(ATy->getElementType());
698 /// IdxCompare - Compare the two constants as though they were getelementptr
699 /// indices. This allows coersion of the types to be the same thing.
701 /// If the two constants are the "same" (after coersion), return 0. If the
702 /// first is less than the second, return -1, if the second is less than the
703 /// first, return 1. If the constants are not integral, return -2.
705 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
706 if (C1 == C2) return 0;
708 // Ok, we found a different index. Are either of the operands ConstantExprs?
709 // If so, we can't do anything with them.
710 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
711 return -2; // don't know!
713 // Ok, we have two differing integer indices. Sign extend them to be the same
714 // type. Long is always big enough, so we use it.
715 if (C1->getType() != Type::LongTy && C1->getType() != Type::ULongTy)
716 C1 = ConstantExpr::getSExt(C1, Type::LongTy);
718 C1 = ConstantExpr::getBitCast(C1, Type::LongTy);
719 if (C2->getType() != Type::LongTy && C1->getType() != Type::ULongTy)
720 C2 = ConstantExpr::getSExt(C2, Type::LongTy);
722 C2 = ConstantExpr::getBitCast(C2, Type::LongTy);
724 if (C1 == C2) return 0; // Are they just differing types?
726 // If the type being indexed over is really just a zero sized type, there is
727 // no pointer difference being made here.
728 if (isMaybeZeroSizedType(ElTy))
731 // If they are really different, now that they are the same type, then we
732 // found a difference!
733 if (cast<ConstantInt>(C1)->getSExtValue() <
734 cast<ConstantInt>(C2)->getSExtValue())
740 /// evaluatFCmpeRelation - This function determines if there is anything we can
741 /// decide about the two constants provided. This doesn't need to handle simple
742 /// things like ConstantFP comparisons, but should instead handle ConstantExprs.
743 /// If we can determine that the two constants have a particular relation to
744 /// each other, we should return the corresponding FCmpInst predicate,
745 /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
746 /// ConstantFoldCompareInstruction.
748 /// To simplify this code we canonicalize the relation so that the first
749 /// operand is always the most "complex" of the two. We consider ConstantFP
750 /// to be the simplest, and ConstantExprs to be the most complex.
751 static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1,
752 const Constant *V2) {
753 assert(V1->getType() == V2->getType() &&
754 "Cannot compare values of different types!");
755 // Handle degenerate case quickly
756 if (V1 == V2) return FCmpInst::FCMP_OEQ;
758 if (!isa<ConstantExpr>(V1)) {
759 if (!isa<ConstantExpr>(V2)) {
760 // We distilled thisUse the standard constant folder for a few cases
762 Constant *C1 = const_cast<Constant*>(V1);
763 Constant *C2 = const_cast<Constant*>(V2);
764 R = dyn_cast<ConstantBool>(
765 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2));
766 if (R && R->getValue())
767 return FCmpInst::FCMP_OEQ;
768 R = dyn_cast<ConstantBool>(
769 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2));
770 if (R && R->getValue())
771 return FCmpInst::FCMP_OLT;
772 R = dyn_cast<ConstantBool>(
773 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2));
774 if (R && R->getValue())
775 return FCmpInst::FCMP_OGT;
777 // Nothing more we can do
778 return FCmpInst::BAD_FCMP_PREDICATE;
781 // If the first operand is simple and second is ConstantExpr, swap operands.
782 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
783 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
784 return FCmpInst::getSwappedPredicate(SwappedRelation);
786 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
787 // constantexpr or a simple constant.
788 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
789 switch (CE1->getOpcode()) {
790 case Instruction::FPTrunc:
791 case Instruction::FPExt:
792 case Instruction::UIToFP:
793 case Instruction::SIToFP:
794 // We might be able to do something with these but we don't right now.
800 // There are MANY other foldings that we could perform here. They will
801 // probably be added on demand, as they seem needed.
802 return FCmpInst::BAD_FCMP_PREDICATE;
805 /// evaluateICmpRelation - This function determines if there is anything we can
806 /// decide about the two constants provided. This doesn't need to handle simple
807 /// things like integer comparisons, but should instead handle ConstantExprs
808 /// and GlobalValues. If we can determine that the two constants have a
809 /// particular relation to each other, we should return the corresponding ICmp
810 /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.
812 /// To simplify this code we canonicalize the relation so that the first
813 /// operand is always the most "complex" of the two. We consider simple
814 /// constants (like ConstantInt) to be the simplest, followed by
815 /// GlobalValues, followed by ConstantExpr's (the most complex).
817 static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1,
820 assert(V1->getType() == V2->getType() &&
821 "Cannot compare different types of values!");
822 if (V1 == V2) return ICmpInst::ICMP_EQ;
824 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
825 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
826 // We distilled this down to a simple case, use the standard constant
829 Constant *C1 = const_cast<Constant*>(V1);
830 Constant *C2 = const_cast<Constant*>(V2);
831 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
832 R = dyn_cast<ConstantBool>(ConstantExpr::getICmp(pred, C1, C2));
833 if (R && R->getValue())
835 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
836 R = dyn_cast<ConstantBool>(ConstantExpr::getICmp(pred, C1, C2));
837 if (R && R->getValue())
839 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
840 R = dyn_cast<ConstantBool>(ConstantExpr::getICmp(pred, C1, C2));
841 if (R && R->getValue())
844 // If we couldn't figure it out, bail.
845 return ICmpInst::BAD_ICMP_PREDICATE;
848 // If the first operand is simple, swap operands.
849 ICmpInst::Predicate SwappedRelation =
850 evaluateICmpRelation(V2, V1, isSigned);
851 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
852 return ICmpInst::getSwappedPredicate(SwappedRelation);
854 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
855 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
856 ICmpInst::Predicate SwappedRelation =
857 evaluateICmpRelation(V2, V1, isSigned);
858 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
859 return ICmpInst::getSwappedPredicate(SwappedRelation);
861 return ICmpInst::BAD_ICMP_PREDICATE;
864 // Now we know that the RHS is a GlobalValue or simple constant,
865 // which (since the types must match) means that it's a ConstantPointerNull.
866 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
867 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
868 return ICmpInst::ICMP_NE;
870 // GlobalVals can never be null.
871 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
872 if (!CPR1->hasExternalWeakLinkage())
873 return ICmpInst::ICMP_NE;
876 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
877 // constantexpr, a CPR, or a simple constant.
878 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
879 const Constant *CE1Op0 = CE1->getOperand(0);
881 switch (CE1->getOpcode()) {
882 case Instruction::Trunc:
883 case Instruction::FPTrunc:
884 case Instruction::FPExt:
885 case Instruction::FPToUI:
886 case Instruction::FPToSI:
887 break; // We can't evaluate floating point casts or truncations.
889 case Instruction::UIToFP:
890 case Instruction::SIToFP:
891 case Instruction::IntToPtr:
892 case Instruction::BitCast:
893 case Instruction::ZExt:
894 case Instruction::SExt:
895 case Instruction::PtrToInt:
896 // If the cast is not actually changing bits, and the second operand is a
897 // null pointer, do the comparison with the pre-casted value.
898 if (V2->isNullValue() &&
899 (isa<PointerType>(CE1->getType()) || CE1->getType()->isIntegral())) {
900 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
901 (CE1->getOpcode() == Instruction::SExt ? true :
902 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
903 return evaluateICmpRelation(
904 CE1Op0, Constant::getNullValue(CE1Op0->getType()), sgnd);
907 // If the dest type is a pointer type, and the RHS is a constantexpr cast
908 // from the same type as the src of the LHS, evaluate the inputs. This is
909 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)",
910 // which happens a lot in compilers with tagged integers.
911 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
912 if (CE2->isCast() && isa<PointerType>(CE1->getType()) &&
913 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
914 CE1->getOperand(0)->getType()->isIntegral()) {
915 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
916 (CE1->getOpcode() == Instruction::SExt ? true :
917 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
918 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0),
923 case Instruction::GetElementPtr:
924 // Ok, since this is a getelementptr, we know that the constant has a
925 // pointer type. Check the various cases.
926 if (isa<ConstantPointerNull>(V2)) {
927 // If we are comparing a GEP to a null pointer, check to see if the base
928 // of the GEP equals the null pointer.
929 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
930 if (GV->hasExternalWeakLinkage())
931 // Weak linkage GVals could be zero or not. We're comparing that
932 // to null pointer so its greater-or-equal
933 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
935 // If its not weak linkage, the GVal must have a non-zero address
936 // so the result is greater-than
937 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
938 } else if (isa<ConstantPointerNull>(CE1Op0)) {
939 // If we are indexing from a null pointer, check to see if we have any
941 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
942 if (!CE1->getOperand(i)->isNullValue())
943 // Offsetting from null, must not be equal.
944 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
945 // Only zero indexes from null, must still be zero.
946 return ICmpInst::ICMP_EQ;
948 // Otherwise, we can't really say if the first operand is null or not.
949 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
950 if (isa<ConstantPointerNull>(CE1Op0)) {
951 if (CPR2->hasExternalWeakLinkage())
952 // Weak linkage GVals could be zero or not. We're comparing it to
953 // a null pointer, so its less-or-equal
954 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
956 // If its not weak linkage, the GVal must have a non-zero address
957 // so the result is less-than
958 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
959 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
961 // If this is a getelementptr of the same global, then it must be
962 // different. Because the types must match, the getelementptr could
963 // only have at most one index, and because we fold getelementptr's
964 // with a single zero index, it must be nonzero.
965 assert(CE1->getNumOperands() == 2 &&
966 !CE1->getOperand(1)->isNullValue() &&
967 "Suprising getelementptr!");
968 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
970 // If they are different globals, we don't know what the value is,
971 // but they can't be equal.
972 return ICmpInst::ICMP_NE;
976 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
977 const Constant *CE2Op0 = CE2->getOperand(0);
979 // There are MANY other foldings that we could perform here. They will
980 // probably be added on demand, as they seem needed.
981 switch (CE2->getOpcode()) {
983 case Instruction::GetElementPtr:
984 // By far the most common case to handle is when the base pointers are
985 // obviously to the same or different globals.
986 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
987 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
988 return ICmpInst::ICMP_NE;
989 // Ok, we know that both getelementptr instructions are based on the
990 // same global. From this, we can precisely determine the relative
991 // ordering of the resultant pointers.
994 // Compare all of the operands the GEP's have in common.
995 gep_type_iterator GTI = gep_type_begin(CE1);
996 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
998 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
999 GTI.getIndexedType())) {
1000 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
1001 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
1002 case -2: return ICmpInst::BAD_ICMP_PREDICATE;
1005 // Ok, we ran out of things they have in common. If any leftovers
1006 // are non-zero then we have a difference, otherwise we are equal.
1007 for (; i < CE1->getNumOperands(); ++i)
1008 if (!CE1->getOperand(i)->isNullValue())
1009 if (isa<ConstantIntegral>(CE1->getOperand(i)))
1010 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1012 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1014 for (; i < CE2->getNumOperands(); ++i)
1015 if (!CE2->getOperand(i)->isNullValue())
1016 if (isa<ConstantIntegral>(CE2->getOperand(i)))
1017 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1019 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1020 return ICmpInst::ICMP_EQ;
1029 return ICmpInst::BAD_ICMP_PREDICATE;
1032 Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
1034 const Constant *C2) {
1036 // Handle some degenerate cases first
1037 if (isa<UndefValue>(C1) || isa<UndefValue>(C2))
1038 return UndefValue::get(Type::BoolTy);
1040 // icmp eq/ne(null,GV) -> false/true
1041 if (C1->isNullValue()) {
1042 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
1043 if (!GV->hasExternalWeakLinkage()) // External weak GV can be null
1044 if (pred == ICmpInst::ICMP_EQ)
1045 return ConstantBool::getFalse();
1046 else if (pred == ICmpInst::ICMP_NE)
1047 return ConstantBool::getTrue();
1048 // icmp eq/ne(GV,null) -> false/true
1049 } else if (C2->isNullValue()) {
1050 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
1051 if (!GV->hasExternalWeakLinkage()) // External weak GV can be null
1052 if (pred == ICmpInst::ICMP_EQ)
1053 return ConstantBool::getFalse();
1054 else if (pred == ICmpInst::ICMP_NE)
1055 return ConstantBool::getTrue();
1058 if (isa<ConstantBool>(C1) && isa<ConstantBool>(C2)) {
1059 bool C1Val = cast<ConstantBool>(C1)->getValue();
1060 bool C2Val = cast<ConstantBool>(C2)->getValue();
1062 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1063 case ICmpInst::ICMP_EQ: return ConstantBool::get(C1Val == C2Val);
1064 case ICmpInst::ICMP_NE: return ConstantBool::get(C1Val != C2Val);
1065 case ICmpInst::ICMP_ULT:return ConstantBool::get(C1Val < C2Val);
1066 case ICmpInst::ICMP_UGT:return ConstantBool::get(C1Val > C2Val);
1067 case ICmpInst::ICMP_ULE:return ConstantBool::get(C1Val <= C2Val);
1068 case ICmpInst::ICMP_UGE:return ConstantBool::get(C1Val >= C2Val);
1069 case ICmpInst::ICMP_SLT:return ConstantBool::get(C1Val < C2Val);
1070 case ICmpInst::ICMP_SGT:return ConstantBool::get(C1Val > C2Val);
1071 case ICmpInst::ICMP_SLE:return ConstantBool::get(C1Val <= C2Val);
1072 case ICmpInst::ICMP_SGE:return ConstantBool::get(C1Val >= C2Val);
1074 } else if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
1075 if (ICmpInst::isSignedPredicate(ICmpInst::Predicate(pred))) {
1076 int64_t V1 = cast<ConstantInt>(C1)->getSExtValue();
1077 int64_t V2 = cast<ConstantInt>(C2)->getSExtValue();
1079 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1080 case ICmpInst::ICMP_SLT:return ConstantBool::get(V1 < V2);
1081 case ICmpInst::ICMP_SGT:return ConstantBool::get(V1 > V2);
1082 case ICmpInst::ICMP_SLE:return ConstantBool::get(V1 <= V2);
1083 case ICmpInst::ICMP_SGE:return ConstantBool::get(V1 >= V2);
1086 uint64_t V1 = cast<ConstantInt>(C1)->getZExtValue();
1087 uint64_t V2 = cast<ConstantInt>(C2)->getZExtValue();
1089 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1090 case ICmpInst::ICMP_EQ: return ConstantBool::get(V1 == V2);
1091 case ICmpInst::ICMP_NE: return ConstantBool::get(V1 != V2);
1092 case ICmpInst::ICMP_ULT:return ConstantBool::get(V1 < V2);
1093 case ICmpInst::ICMP_UGT:return ConstantBool::get(V1 > V2);
1094 case ICmpInst::ICMP_ULE:return ConstantBool::get(V1 <= V2);
1095 case ICmpInst::ICMP_UGE:return ConstantBool::get(V1 >= V2);
1098 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
1099 double C1Val = cast<ConstantFP>(C1)->getValue();
1100 double C2Val = cast<ConstantFP>(C2)->getValue();
1102 default: assert(0 && "Invalid FCmp Predicate"); return 0;
1103 case FCmpInst::FCMP_FALSE: return ConstantBool::getFalse();
1104 case FCmpInst::FCMP_TRUE: return ConstantBool::getTrue();
1105 case FCmpInst::FCMP_UNO:
1106 case FCmpInst::FCMP_ORD: break; // Can't fold these
1107 case FCmpInst::FCMP_UEQ:
1108 case FCmpInst::FCMP_OEQ: return ConstantBool::get(C1Val == C2Val);
1109 case FCmpInst::FCMP_ONE:
1110 case FCmpInst::FCMP_UNE: return ConstantBool::get(C1Val != C2Val);
1111 case FCmpInst::FCMP_OLT:
1112 case FCmpInst::FCMP_ULT: return ConstantBool::get(C1Val < C2Val);
1113 case FCmpInst::FCMP_UGT:
1114 case FCmpInst::FCMP_OGT: return ConstantBool::get(C1Val > C2Val);
1115 case FCmpInst::FCMP_OLE:
1116 case FCmpInst::FCMP_ULE: return ConstantBool::get(C1Val <= C2Val);
1117 case FCmpInst::FCMP_UGE:
1118 case FCmpInst::FCMP_OGE: return ConstantBool::get(C1Val >= C2Val);
1120 } else if (const ConstantPacked *CP1 = dyn_cast<ConstantPacked>(C1)) {
1121 if (const ConstantPacked *CP2 = dyn_cast<ConstantPacked>(C2)) {
1122 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) {
1123 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1124 Constant *C= ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ,
1125 const_cast<Constant*>(CP1->getOperand(i)),
1126 const_cast<Constant*>(CP2->getOperand(i)));
1127 if (ConstantBool *CB = dyn_cast<ConstantBool>(C))
1130 // Otherwise, could not decide from any element pairs.
1132 } else if (pred == ICmpInst::ICMP_EQ) {
1133 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1134 Constant *C = ConstantExpr::getICmp(ICmpInst::ICMP_EQ,
1135 const_cast<Constant*>(CP1->getOperand(i)),
1136 const_cast<Constant*>(CP2->getOperand(i)));
1137 if (ConstantBool *CB = dyn_cast<ConstantBool>(C))
1140 // Otherwise, could not decide from any element pairs.
1146 if (C1->getType()->isFloatingPoint()) {
1147 switch (evaluateFCmpRelation(C1, C2)) {
1148 default: assert(0 && "Unknown relation!");
1149 case FCmpInst::FCMP_UNO:
1150 case FCmpInst::FCMP_ORD:
1151 case FCmpInst::FCMP_UEQ:
1152 case FCmpInst::FCMP_UNE:
1153 case FCmpInst::FCMP_ULT:
1154 case FCmpInst::FCMP_UGT:
1155 case FCmpInst::FCMP_ULE:
1156 case FCmpInst::FCMP_UGE:
1157 case FCmpInst::FCMP_TRUE:
1158 case FCmpInst::FCMP_FALSE:
1159 case FCmpInst::BAD_FCMP_PREDICATE:
1160 break; // Couldn't determine anything about these constants.
1161 case FCmpInst::FCMP_OEQ: // We know that C1 == C2
1162 return ConstantBool::get(
1163 pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
1164 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
1165 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1166 case FCmpInst::FCMP_OLT: // We know that C1 < C2
1167 return ConstantBool::get(
1168 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1169 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
1170 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
1171 case FCmpInst::FCMP_OGT: // We know that C1 > C2
1172 return ConstantBool::get(
1173 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1174 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
1175 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1176 case FCmpInst::FCMP_OLE: // We know that C1 <= C2
1177 // We can only partially decide this relation.
1178 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1179 return ConstantBool::getFalse();
1180 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1181 return ConstantBool::getTrue();
1183 case FCmpInst::FCMP_OGE: // We known that C1 >= C2
1184 // We can only partially decide this relation.
1185 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1186 return ConstantBool::getFalse();
1187 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1188 return ConstantBool::getTrue();
1190 case ICmpInst::ICMP_NE: // We know that C1 != C2
1191 // We can only partially decide this relation.
1192 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
1193 return ConstantBool::getFalse();
1194 if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
1195 return ConstantBool::getTrue();
1199 // Evaluate the relation between the two constants, per the predicate.
1200 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) {
1201 default: assert(0 && "Unknown relational!");
1202 case ICmpInst::BAD_ICMP_PREDICATE:
1203 break; // Couldn't determine anything about these constants.
1204 case ICmpInst::ICMP_EQ: // We know the constants are equal!
1205 // If we know the constants are equal, we can decide the result of this
1206 // computation precisely.
1207 return ConstantBool::get(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 ConstantBool::get(pred == ICmpInst::ICMP_ULT ||
1216 pred == ICmpInst::ICMP_NE ||
1217 pred == ICmpInst::ICMP_ULE);
1218 case ICmpInst::ICMP_SLT:
1219 // If we know that C1 < C2, we can decide the result of this computation
1221 return ConstantBool::get(pred == ICmpInst::ICMP_SLT ||
1222 pred == ICmpInst::ICMP_NE ||
1223 pred == ICmpInst::ICMP_SLE);
1224 case ICmpInst::ICMP_UGT:
1225 // If we know that C1 > C2, we can decide the result of this computation
1227 return ConstantBool::get(pred == ICmpInst::ICMP_UGT ||
1228 pred == ICmpInst::ICMP_NE ||
1229 pred == ICmpInst::ICMP_UGE);
1230 case ICmpInst::ICMP_SGT:
1231 // If we know that C1 > C2, we can decide the result of this computation
1233 return ConstantBool::get(pred == ICmpInst::ICMP_SGT ||
1234 pred == ICmpInst::ICMP_NE ||
1235 pred == ICmpInst::ICMP_SGE);
1236 case ICmpInst::ICMP_ULE:
1237 // If we know that C1 <= C2, we can only partially decide this relation.
1238 if (pred == ICmpInst::ICMP_UGT) return ConstantBool::getFalse();
1239 if (pred == ICmpInst::ICMP_ULT) return ConstantBool::getTrue();
1241 case ICmpInst::ICMP_SLE:
1242 // If we know that C1 <= C2, we can only partially decide this relation.
1243 if (pred == ICmpInst::ICMP_SGT) return ConstantBool::getFalse();
1244 if (pred == ICmpInst::ICMP_SLT) return ConstantBool::getTrue();
1247 case ICmpInst::ICMP_UGE:
1248 // If we know that C1 >= C2, we can only partially decide this relation.
1249 if (pred == ICmpInst::ICMP_ULT) return ConstantBool::getFalse();
1250 if (pred == ICmpInst::ICMP_UGT) return ConstantBool::getTrue();
1252 case ICmpInst::ICMP_SGE:
1253 // If we know that C1 >= C2, we can only partially decide this relation.
1254 if (pred == ICmpInst::ICMP_SLT) return ConstantBool::getFalse();
1255 if (pred == ICmpInst::ICMP_SGT) return ConstantBool::getTrue();
1258 case ICmpInst::ICMP_NE:
1259 // If we know that C1 != C2, we can only partially decide this relation.
1260 if (pred == ICmpInst::ICMP_EQ) return ConstantBool::getFalse();
1261 if (pred == ICmpInst::ICMP_NE) return ConstantBool::getTrue();
1265 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) {
1266 // If C2 is a constant expr and C1 isn't, flop them around and fold the
1267 // other way if possible.
1269 case ICmpInst::ICMP_EQ:
1270 case ICmpInst::ICMP_NE:
1271 // No change of predicate required.
1272 return ConstantFoldCompareInstruction(pred, C2, C1);
1274 case ICmpInst::ICMP_ULT:
1275 case ICmpInst::ICMP_SLT:
1276 case ICmpInst::ICMP_UGT:
1277 case ICmpInst::ICMP_SGT:
1278 case ICmpInst::ICMP_ULE:
1279 case ICmpInst::ICMP_SLE:
1280 case ICmpInst::ICMP_UGE:
1281 case ICmpInst::ICMP_SGE:
1282 // Change the predicate as necessary to swap the operands.
1283 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
1284 return ConstantFoldCompareInstruction(pred, C2, C1);
1286 default: // These predicates cannot be flopped around.
1294 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1295 const std::vector<Value*> &IdxList) {
1296 if (IdxList.size() == 0 ||
1297 (IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
1298 return const_cast<Constant*>(C);
1300 if (isa<UndefValue>(C)) {
1301 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1303 assert(Ty != 0 && "Invalid indices for GEP!");
1304 return UndefValue::get(PointerType::get(Ty));
1307 Constant *Idx0 = cast<Constant>(IdxList[0]);
1308 if (C->isNullValue()) {
1310 for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
1311 if (!cast<Constant>(IdxList[i])->isNullValue()) {
1316 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1318 assert(Ty != 0 && "Invalid indices for GEP!");
1319 return ConstantPointerNull::get(PointerType::get(Ty));
1322 if (IdxList.size() == 1) {
1323 const Type *ElTy = cast<PointerType>(C->getType())->getElementType();
1324 if (uint32_t ElSize = ElTy->getPrimitiveSize()) {
1325 // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm
1326 // type, we can statically fold this.
1327 Constant *R = ConstantInt::get(Type::UIntTy, ElSize);
1328 // We know R is unsigned, Idx0 is signed because it must be an index
1329 // through a sequential type (gep pointer operand) which is always
1331 R = ConstantExpr::getSExtOrBitCast(R, Idx0->getType());
1332 R = ConstantExpr::getMul(R, Idx0); // signed multiply
1333 // R is a signed integer, C is the GEP pointer so -> IntToPtr
1334 return ConstantExpr::getIntToPtr(R, C->getType());
1339 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1340 // Combine Indices - If the source pointer to this getelementptr instruction
1341 // is a getelementptr instruction, combine the indices of the two
1342 // getelementptr instructions into a single instruction.
1344 if (CE->getOpcode() == Instruction::GetElementPtr) {
1345 const Type *LastTy = 0;
1346 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1350 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1351 std::vector<Value*> NewIndices;
1352 NewIndices.reserve(IdxList.size() + CE->getNumOperands());
1353 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1354 NewIndices.push_back(CE->getOperand(i));
1356 // Add the last index of the source with the first index of the new GEP.
1357 // Make sure to handle the case when they are actually different types.
1358 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1359 // Otherwise it must be an array.
1360 if (!Idx0->isNullValue()) {
1361 const Type *IdxTy = Combined->getType();
1362 if (IdxTy != Idx0->getType()) {
1363 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::LongTy);
1364 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
1366 Combined = ConstantExpr::get(Instruction::Add, C1, C2);
1369 ConstantExpr::get(Instruction::Add, Idx0, Combined);
1373 NewIndices.push_back(Combined);
1374 NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
1375 return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
1379 // Implement folding of:
1380 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1382 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1384 if (CE->isCast() && IdxList.size() > 1 && Idx0->isNullValue())
1385 if (const PointerType *SPT =
1386 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1387 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1388 if (const ArrayType *CAT =
1389 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1390 if (CAT->getElementType() == SAT->getElementType())
1391 return ConstantExpr::getGetElementPtr(
1392 (Constant*)CE->getOperand(0), IdxList);