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::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->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::Int32Ty)
300 return ConstantInt::get(DestTy, FloatToBits(FP->getValue()));
301 assert(DestTy == Type::Int64Ty &&
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 ConstantInt *CB = dyn_cast<ConstantInt>(Cond))
320 if (CB->getType() == Type::BoolTy)
321 return const_cast<Constant*>(CB->getBoolValue() ? V1 : V2);
323 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
324 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
325 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
326 if (V1 == V2) return const_cast<Constant*>(V1);
330 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
331 const Constant *Idx) {
332 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
333 return UndefValue::get(cast<PackedType>(Val->getType())->getElementType());
334 if (Val->isNullValue()) // ee(zero, x) -> zero
335 return Constant::getNullValue(
336 cast<PackedType>(Val->getType())->getElementType());
338 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
339 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
340 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue()));
341 } else if (isa<UndefValue>(Idx)) {
342 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
343 return const_cast<Constant*>(CVal->getOperand(0));
349 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
351 const Constant *Idx) {
352 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
354 uint64_t idxVal = CIdx->getZExtValue();
355 if (isa<UndefValue>(Val)) {
356 // Insertion of scalar constant into packed undef
357 // Optimize away insertion of undef
358 if (isa<UndefValue>(Elt))
359 return const_cast<Constant*>(Val);
360 // Otherwise break the aggregate undef into multiple undefs and do
363 cast<PackedType>(Val->getType())->getNumElements();
364 std::vector<Constant*> Ops;
366 for (unsigned i = 0; i < numOps; ++i) {
368 (i == idxVal) ? Elt : UndefValue::get(Elt->getType());
369 Ops.push_back(const_cast<Constant*>(Op));
371 return ConstantPacked::get(Ops);
373 if (isa<ConstantAggregateZero>(Val)) {
374 // Insertion of scalar constant into packed aggregate zero
375 // Optimize away insertion of zero
376 if (Elt->isNullValue())
377 return const_cast<Constant*>(Val);
378 // Otherwise break the aggregate zero into multiple zeros and do
381 cast<PackedType>(Val->getType())->getNumElements();
382 std::vector<Constant*> Ops;
384 for (unsigned i = 0; i < numOps; ++i) {
386 (i == idxVal) ? Elt : Constant::getNullValue(Elt->getType());
387 Ops.push_back(const_cast<Constant*>(Op));
389 return ConstantPacked::get(Ops);
391 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
392 // Insertion of scalar constant into packed constant
393 std::vector<Constant*> Ops;
394 Ops.reserve(CVal->getNumOperands());
395 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
397 (i == idxVal) ? Elt : cast<Constant>(CVal->getOperand(i));
398 Ops.push_back(const_cast<Constant*>(Op));
400 return ConstantPacked::get(Ops);
405 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
407 const Constant *Mask) {
412 /// EvalVectorOp - Given two packed constants and a function pointer, apply the
413 /// function pointer to each element pair, producing a new ConstantPacked
415 static Constant *EvalVectorOp(const ConstantPacked *V1,
416 const ConstantPacked *V2,
417 Constant *(*FP)(Constant*, Constant*)) {
418 std::vector<Constant*> Res;
419 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
420 Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
421 const_cast<Constant*>(V2->getOperand(i))));
422 return ConstantPacked::get(Res);
425 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
427 const Constant *C2) {
428 // Handle UndefValue up front
429 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
431 case Instruction::Add:
432 case Instruction::Sub:
433 case Instruction::Xor:
434 return UndefValue::get(C1->getType());
435 case Instruction::Mul:
436 case Instruction::And:
437 return Constant::getNullValue(C1->getType());
438 case Instruction::UDiv:
439 case Instruction::SDiv:
440 case Instruction::FDiv:
441 case Instruction::URem:
442 case Instruction::SRem:
443 case Instruction::FRem:
444 if (!isa<UndefValue>(C2)) // undef / X -> 0
445 return Constant::getNullValue(C1->getType());
446 return const_cast<Constant*>(C2); // X / undef -> undef
447 case Instruction::Or: // X | undef -> -1
448 if (const PackedType *PTy = dyn_cast<PackedType>(C1->getType()))
449 return ConstantPacked::getAllOnesValue(PTy);
450 return ConstantInt::getAllOnesValue(C1->getType());
451 case Instruction::LShr:
452 if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
453 return const_cast<Constant*>(C1); // undef lshr undef -> undef
454 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0
456 case Instruction::AShr:
457 if (!isa<UndefValue>(C2))
458 return const_cast<Constant*>(C1); // undef ashr X --> undef
459 else if (isa<UndefValue>(C1))
460 return const_cast<Constant*>(C1); // undef ashr undef -> undef
462 return const_cast<Constant*>(C1); // X ashr undef --> X
463 case Instruction::Shl:
464 // undef << X -> 0 or X << undef -> 0
465 return Constant::getNullValue(C1->getType());
469 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
470 if (isa<ConstantExpr>(C2)) {
471 // There are many possible foldings we could do here. We should probably
472 // at least fold add of a pointer with an integer into the appropriate
473 // getelementptr. This will improve alias analysis a bit.
475 // Just implement a couple of simple identities.
477 case Instruction::Add:
478 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X + 0 == X
480 case Instruction::Sub:
481 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X - 0 == X
483 case Instruction::Mul:
484 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X * 0 == 0
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::UDiv:
490 case Instruction::SDiv:
491 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
492 if (CI->getZExtValue() == 1)
493 return const_cast<Constant*>(C1); // X / 1 == X
495 case Instruction::URem:
496 case Instruction::SRem:
497 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
498 if (CI->getZExtValue() == 1)
499 return Constant::getNullValue(CI->getType()); // X % 1 == 0
501 case Instruction::And:
502 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
503 if (CI->isAllOnesValue())
504 return const_cast<Constant*>(C1); // X & -1 == X
505 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X & 0 == 0
506 if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
507 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
509 // Functions are at least 4-byte aligned. If and'ing the address of a
510 // function with a constant < 4, fold it to zero.
511 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
512 if (CI->getZExtValue() < 4 && isa<Function>(CPR))
513 return Constant::getNullValue(CI->getType());
516 case Instruction::Or:
517 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X | 0 == X
518 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
519 if (CI->isAllOnesValue())
520 return const_cast<Constant*>(C2); // X | -1 == -1
522 case Instruction::Xor:
523 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X ^ 0 == X
527 } else if (isa<ConstantExpr>(C2)) {
528 // If C2 is a constant expr and C1 isn't, flop them around and fold the
529 // other way if possible.
531 case Instruction::Add:
532 case Instruction::Mul:
533 case Instruction::And:
534 case Instruction::Or:
535 case Instruction::Xor:
536 // No change of opcode required.
537 return ConstantFoldBinaryInstruction(Opcode, C2, C1);
539 case Instruction::Shl:
540 case Instruction::LShr:
541 case Instruction::AShr:
542 case Instruction::Sub:
543 case Instruction::SDiv:
544 case Instruction::UDiv:
545 case Instruction::FDiv:
546 case Instruction::URem:
547 case Instruction::SRem:
548 case Instruction::FRem:
549 default: // These instructions cannot be flopped around.
554 // At this point we know neither constant is an UndefValue nor a ConstantExpr
555 // so look at directly computing the value.
556 if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
557 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
558 if (CI1->getType() == Type::BoolTy && CI2->getType() == Type::BoolTy) {
562 case Instruction::And:
563 return ConstantInt::get(CI1->getBoolValue() & CI2->getBoolValue());
564 case Instruction::Or:
565 return ConstantInt::get(CI1->getBoolValue() | CI2->getBoolValue());
566 case Instruction::Xor:
567 return ConstantInt::get(CI1->getBoolValue() ^ CI2->getBoolValue());
570 uint64_t C1Val = CI1->getZExtValue();
571 uint64_t C2Val = CI2->getZExtValue();
575 case Instruction::Add:
576 return ConstantInt::get(C1->getType(), C1Val + C2Val);
577 case Instruction::Sub:
578 return ConstantInt::get(C1->getType(), C1Val - C2Val);
579 case Instruction::Mul:
580 return ConstantInt::get(C1->getType(), C1Val * C2Val);
581 case Instruction::UDiv:
582 if (CI2->isNullValue()) // X / 0 -> can't fold
584 return ConstantInt::get(C1->getType(), C1Val / C2Val);
585 case Instruction::SDiv:
586 if (CI2->isNullValue()) return 0; // X / 0 -> can't fold
587 if (CI2->isAllOnesValue() &&
588 (((CI1->getType()->getPrimitiveSizeInBits() == 64) &&
589 (CI1->getSExtValue() == INT64_MIN)) ||
590 (CI1->getSExtValue() == -CI1->getSExtValue())))
591 return 0; // MIN_INT / -1 -> overflow
592 return ConstantInt::get(C1->getType(),
593 CI1->getSExtValue() / CI2->getSExtValue());
594 case Instruction::URem:
595 if (C2->isNullValue()) return 0; // X / 0 -> can't fold
596 return ConstantInt::get(C1->getType(), C1Val % C2Val);
597 case Instruction::SRem:
598 if (CI2->isNullValue()) return 0; // X % 0 -> can't fold
599 if (CI2->isAllOnesValue() &&
600 (((CI1->getType()->getPrimitiveSizeInBits() == 64) &&
601 (CI1->getSExtValue() == INT64_MIN)) ||
602 (CI1->getSExtValue() == -CI1->getSExtValue())))
603 return 0; // MIN_INT % -1 -> overflow
604 return ConstantInt::get(C1->getType(),
605 CI1->getSExtValue() % CI2->getSExtValue());
606 case Instruction::And:
607 return ConstantInt::get(C1->getType(), C1Val & C2Val);
608 case Instruction::Or:
609 return ConstantInt::get(C1->getType(), C1Val | C2Val);
610 case Instruction::Xor:
611 return ConstantInt::get(C1->getType(), C1Val ^ C2Val);
612 case Instruction::Shl:
613 return ConstantInt::get(C1->getType(), C1Val << C2Val);
614 case Instruction::LShr:
615 return ConstantInt::get(C1->getType(), C1Val >> C2Val);
616 case Instruction::AShr:
617 return ConstantInt::get(C1->getType(),
618 CI1->getSExtValue() >> C2Val);
622 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
623 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
624 double C1Val = CFP1->getValue();
625 double C2Val = CFP2->getValue();
629 case Instruction::Add:
630 return ConstantFP::get(CFP1->getType(), C1Val + C2Val);
631 case Instruction::Sub:
632 return ConstantFP::get(CFP1->getType(), C1Val - C2Val);
633 case Instruction::Mul:
634 return ConstantFP::get(CFP1->getType(), C1Val * C2Val);
635 case Instruction::FDiv:
636 if (CFP2->isExactlyValue(0.0))
637 return ConstantFP::get(CFP1->getType(),
638 std::numeric_limits<double>::infinity());
639 if (CFP2->isExactlyValue(-0.0))
640 return ConstantFP::get(CFP1->getType(),
641 -std::numeric_limits<double>::infinity());
642 return ConstantFP::get(CFP1->getType(), C1Val / C2Val);
643 case Instruction::FRem:
644 if (CFP2->isNullValue())
646 return ConstantFP::get(CFP1->getType(), std::fmod(C1Val, C2Val));
649 } else if (const ConstantPacked *CP1 = dyn_cast<ConstantPacked>(C1)) {
650 if (const ConstantPacked *CP2 = dyn_cast<ConstantPacked>(C2)) {
654 case Instruction::Add:
655 return EvalVectorOp(CP1, CP2, ConstantExpr::getAdd);
656 case Instruction::Sub:
657 return EvalVectorOp(CP1, CP2, ConstantExpr::getSub);
658 case Instruction::Mul:
659 return EvalVectorOp(CP1, CP2, ConstantExpr::getMul);
660 case Instruction::UDiv:
661 return EvalVectorOp(CP1, CP2, ConstantExpr::getUDiv);
662 case Instruction::SDiv:
663 return EvalVectorOp(CP1, CP2, ConstantExpr::getSDiv);
664 case Instruction::FDiv:
665 return EvalVectorOp(CP1, CP2, ConstantExpr::getFDiv);
666 case Instruction::URem:
667 return EvalVectorOp(CP1, CP2, ConstantExpr::getURem);
668 case Instruction::SRem:
669 return EvalVectorOp(CP1, CP2, ConstantExpr::getSRem);
670 case Instruction::FRem:
671 return EvalVectorOp(CP1, CP2, ConstantExpr::getFRem);
672 case Instruction::And:
673 return EvalVectorOp(CP1, CP2, ConstantExpr::getAnd);
674 case Instruction::Or:
675 return EvalVectorOp(CP1, CP2, ConstantExpr::getOr);
676 case Instruction::Xor:
677 return EvalVectorOp(CP1, CP2, ConstantExpr::getXor);
682 // We don't know how to fold this
686 /// isZeroSizedType - This type is zero sized if its an array or structure of
687 /// zero sized types. The only leaf zero sized type is an empty structure.
688 static bool isMaybeZeroSizedType(const Type *Ty) {
689 if (isa<OpaqueType>(Ty)) return true; // Can't say.
690 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
692 // If all of elements have zero size, this does too.
693 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
694 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
697 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
698 return isMaybeZeroSizedType(ATy->getElementType());
703 /// IdxCompare - Compare the two constants as though they were getelementptr
704 /// indices. This allows coersion of the types to be the same thing.
706 /// If the two constants are the "same" (after coersion), return 0. If the
707 /// first is less than the second, return -1, if the second is less than the
708 /// first, return 1. If the constants are not integral, return -2.
710 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
711 if (C1 == C2) return 0;
713 // Ok, we found a different index. If they are not ConstantInt, we can't do
714 // anything with them.
715 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
716 return -2; // don't know!
718 // Ok, we have two differing integer indices. Sign extend them to be the same
719 // type. Long is always big enough, so we use it.
720 if (C1->getType() != Type::Int64Ty)
721 C1 = ConstantExpr::getSExt(C1, Type::Int64Ty);
723 if (C2->getType() != Type::Int64Ty)
724 C2 = ConstantExpr::getSExt(C2, Type::Int64Ty);
726 if (C1 == C2) return 0; // They are equal
728 // If the type being indexed over is really just a zero sized type, there is
729 // no pointer difference being made here.
730 if (isMaybeZeroSizedType(ElTy))
733 // If they are really different, now that they are the same type, then we
734 // found a difference!
735 if (cast<ConstantInt>(C1)->getSExtValue() <
736 cast<ConstantInt>(C2)->getSExtValue())
742 /// evaluateFCmpRelation - This function determines if there is anything we can
743 /// decide about the two constants provided. This doesn't need to handle simple
744 /// things like ConstantFP comparisons, but should instead handle ConstantExprs.
745 /// If we can determine that the two constants have a particular relation to
746 /// each other, we should return the corresponding FCmpInst predicate,
747 /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
748 /// ConstantFoldCompareInstruction.
750 /// To simplify this code we canonicalize the relation so that the first
751 /// operand is always the most "complex" of the two. We consider ConstantFP
752 /// to be the simplest, and ConstantExprs to be the most complex.
753 static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1,
754 const Constant *V2) {
755 assert(V1->getType() == V2->getType() &&
756 "Cannot compare values of different types!");
757 // Handle degenerate case quickly
758 if (V1 == V2) return FCmpInst::FCMP_OEQ;
760 if (!isa<ConstantExpr>(V1)) {
761 if (!isa<ConstantExpr>(V2)) {
762 // We distilled thisUse the standard constant folder for a few cases
764 Constant *C1 = const_cast<Constant*>(V1);
765 Constant *C2 = const_cast<Constant*>(V2);
766 R = dyn_cast<ConstantInt>(
767 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2));
768 if (R && R->getBoolValue())
769 return FCmpInst::FCMP_OEQ;
770 R = dyn_cast<ConstantInt>(
771 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2));
772 if (R && R->getBoolValue())
773 return FCmpInst::FCMP_OLT;
774 R = dyn_cast<ConstantInt>(
775 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2));
776 if (R && R->getBoolValue())
777 return FCmpInst::FCMP_OGT;
779 // Nothing more we can do
780 return FCmpInst::BAD_FCMP_PREDICATE;
783 // If the first operand is simple and second is ConstantExpr, swap operands.
784 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
785 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
786 return FCmpInst::getSwappedPredicate(SwappedRelation);
788 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
789 // constantexpr or a simple constant.
790 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
791 switch (CE1->getOpcode()) {
792 case Instruction::FPTrunc:
793 case Instruction::FPExt:
794 case Instruction::UIToFP:
795 case Instruction::SIToFP:
796 // We might be able to do something with these but we don't right now.
802 // There are MANY other foldings that we could perform here. They will
803 // probably be added on demand, as they seem needed.
804 return FCmpInst::BAD_FCMP_PREDICATE;
807 /// evaluateICmpRelation - This function determines if there is anything we can
808 /// decide about the two constants provided. This doesn't need to handle simple
809 /// things like integer comparisons, but should instead handle ConstantExprs
810 /// and GlobalValues. If we can determine that the two constants have a
811 /// particular relation to each other, we should return the corresponding ICmp
812 /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.
814 /// To simplify this code we canonicalize the relation so that the first
815 /// operand is always the most "complex" of the two. We consider simple
816 /// constants (like ConstantInt) to be the simplest, followed by
817 /// GlobalValues, followed by ConstantExpr's (the most complex).
819 static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1,
822 assert(V1->getType() == V2->getType() &&
823 "Cannot compare different types of values!");
824 if (V1 == V2) return ICmpInst::ICMP_EQ;
826 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
827 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
828 // We distilled this down to a simple case, use the standard constant
831 Constant *C1 = const_cast<Constant*>(V1);
832 Constant *C2 = const_cast<Constant*>(V2);
833 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
834 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
835 if (R && R->getBoolValue())
837 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
838 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
839 if (R && R->getBoolValue())
841 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
842 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
843 if (R && R->getBoolValue())
846 // If we couldn't figure it out, bail.
847 return ICmpInst::BAD_ICMP_PREDICATE;
850 // If the first operand is simple, swap operands.
851 ICmpInst::Predicate SwappedRelation =
852 evaluateICmpRelation(V2, V1, isSigned);
853 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
854 return ICmpInst::getSwappedPredicate(SwappedRelation);
856 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
857 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
858 ICmpInst::Predicate SwappedRelation =
859 evaluateICmpRelation(V2, V1, isSigned);
860 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
861 return ICmpInst::getSwappedPredicate(SwappedRelation);
863 return ICmpInst::BAD_ICMP_PREDICATE;
866 // Now we know that the RHS is a GlobalValue or simple constant,
867 // which (since the types must match) means that it's a ConstantPointerNull.
868 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
869 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
870 return ICmpInst::ICMP_NE;
872 // GlobalVals can never be null.
873 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
874 if (!CPR1->hasExternalWeakLinkage())
875 return ICmpInst::ICMP_NE;
878 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
879 // constantexpr, a CPR, or a simple constant.
880 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
881 const Constant *CE1Op0 = CE1->getOperand(0);
883 switch (CE1->getOpcode()) {
884 case Instruction::Trunc:
885 case Instruction::FPTrunc:
886 case Instruction::FPExt:
887 case Instruction::FPToUI:
888 case Instruction::FPToSI:
889 break; // We can't evaluate floating point casts or truncations.
891 case Instruction::UIToFP:
892 case Instruction::SIToFP:
893 case Instruction::IntToPtr:
894 case Instruction::BitCast:
895 case Instruction::ZExt:
896 case Instruction::SExt:
897 case Instruction::PtrToInt:
898 // If the cast is not actually changing bits, and the second operand is a
899 // null pointer, do the comparison with the pre-casted value.
900 if (V2->isNullValue() &&
901 (isa<PointerType>(CE1->getType()) || CE1->getType()->isIntegral())) {
902 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
903 (CE1->getOpcode() == Instruction::SExt ? true :
904 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
905 return evaluateICmpRelation(
906 CE1Op0, Constant::getNullValue(CE1Op0->getType()), sgnd);
909 // If the dest type is a pointer type, and the RHS is a constantexpr cast
910 // from the same type as the src of the LHS, evaluate the inputs. This is
911 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)",
912 // which happens a lot in compilers with tagged integers.
913 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
914 if (CE2->isCast() && isa<PointerType>(CE1->getType()) &&
915 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
916 CE1->getOperand(0)->getType()->isIntegral()) {
917 bool sgnd = CE1->getOpcode() == Instruction::ZExt ? false :
918 (CE1->getOpcode() == Instruction::SExt ? true :
919 (CE1->getOpcode() == Instruction::PtrToInt ? false : isSigned));
920 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0),
925 case Instruction::GetElementPtr:
926 // Ok, since this is a getelementptr, we know that the constant has a
927 // pointer type. Check the various cases.
928 if (isa<ConstantPointerNull>(V2)) {
929 // If we are comparing a GEP to a null pointer, check to see if the base
930 // of the GEP equals the null pointer.
931 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
932 if (GV->hasExternalWeakLinkage())
933 // Weak linkage GVals could be zero or not. We're comparing that
934 // to null pointer so its greater-or-equal
935 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
937 // If its not weak linkage, the GVal must have a non-zero address
938 // so the result is greater-than
939 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
940 } else if (isa<ConstantPointerNull>(CE1Op0)) {
941 // If we are indexing from a null pointer, check to see if we have any
943 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
944 if (!CE1->getOperand(i)->isNullValue())
945 // Offsetting from null, must not be equal.
946 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
947 // Only zero indexes from null, must still be zero.
948 return ICmpInst::ICMP_EQ;
950 // Otherwise, we can't really say if the first operand is null or not.
951 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
952 if (isa<ConstantPointerNull>(CE1Op0)) {
953 if (CPR2->hasExternalWeakLinkage())
954 // Weak linkage GVals could be zero or not. We're comparing it to
955 // a null pointer, so its less-or-equal
956 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
958 // If its not weak linkage, the GVal must have a non-zero address
959 // so the result is less-than
960 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
961 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
963 // If this is a getelementptr of the same global, then it must be
964 // different. Because the types must match, the getelementptr could
965 // only have at most one index, and because we fold getelementptr's
966 // with a single zero index, it must be nonzero.
967 assert(CE1->getNumOperands() == 2 &&
968 !CE1->getOperand(1)->isNullValue() &&
969 "Suprising getelementptr!");
970 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
972 // If they are different globals, we don't know what the value is,
973 // but they can't be equal.
974 return ICmpInst::ICMP_NE;
978 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
979 const Constant *CE2Op0 = CE2->getOperand(0);
981 // There are MANY other foldings that we could perform here. They will
982 // probably be added on demand, as they seem needed.
983 switch (CE2->getOpcode()) {
985 case Instruction::GetElementPtr:
986 // By far the most common case to handle is when the base pointers are
987 // obviously to the same or different globals.
988 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
989 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
990 return ICmpInst::ICMP_NE;
991 // Ok, we know that both getelementptr instructions are based on the
992 // same global. From this, we can precisely determine the relative
993 // ordering of the resultant pointers.
996 // Compare all of the operands the GEP's have in common.
997 gep_type_iterator GTI = gep_type_begin(CE1);
998 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
1000 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
1001 GTI.getIndexedType())) {
1002 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
1003 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
1004 case -2: return ICmpInst::BAD_ICMP_PREDICATE;
1007 // Ok, we ran out of things they have in common. If any leftovers
1008 // are non-zero then we have a difference, otherwise we are equal.
1009 for (; i < CE1->getNumOperands(); ++i)
1010 if (!CE1->getOperand(i)->isNullValue())
1011 if (isa<ConstantInt>(CE1->getOperand(i)))
1012 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1014 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1016 for (; i < CE2->getNumOperands(); ++i)
1017 if (!CE2->getOperand(i)->isNullValue())
1018 if (isa<ConstantInt>(CE2->getOperand(i)))
1019 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1021 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1022 return ICmpInst::ICMP_EQ;
1031 return ICmpInst::BAD_ICMP_PREDICATE;
1034 Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
1036 const Constant *C2) {
1038 // Handle some degenerate cases first
1039 if (isa<UndefValue>(C1) || isa<UndefValue>(C2))
1040 return UndefValue::get(Type::BoolTy);
1042 // icmp eq/ne(null,GV) -> false/true
1043 if (C1->isNullValue()) {
1044 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
1045 if (!GV->hasExternalWeakLinkage()) // External weak GV can be null
1046 if (pred == ICmpInst::ICMP_EQ)
1047 return ConstantInt::getFalse();
1048 else if (pred == ICmpInst::ICMP_NE)
1049 return ConstantInt::getTrue();
1050 // icmp eq/ne(GV,null) -> false/true
1051 } else if (C2->isNullValue()) {
1052 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
1053 if (!GV->hasExternalWeakLinkage()) // External weak GV can be null
1054 if (pred == ICmpInst::ICMP_EQ)
1055 return ConstantInt::getFalse();
1056 else if (pred == ICmpInst::ICMP_NE)
1057 return ConstantInt::getTrue();
1060 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2) &&
1061 C1->getType() == Type::BoolTy && C2->getType() == Type::BoolTy) {
1062 bool C1Val = cast<ConstantInt>(C1)->getBoolValue();
1063 bool C2Val = cast<ConstantInt>(C2)->getBoolValue();
1065 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1066 case ICmpInst::ICMP_EQ: return ConstantInt::get(C1Val == C2Val);
1067 case ICmpInst::ICMP_NE: return ConstantInt::get(C1Val != C2Val);
1068 case ICmpInst::ICMP_ULT:return ConstantInt::get(C1Val < C2Val);
1069 case ICmpInst::ICMP_UGT:return ConstantInt::get(C1Val > C2Val);
1070 case ICmpInst::ICMP_ULE:return ConstantInt::get(C1Val <= C2Val);
1071 case ICmpInst::ICMP_UGE:return ConstantInt::get(C1Val >= C2Val);
1072 case ICmpInst::ICMP_SLT:return ConstantInt::get(C1Val < C2Val);
1073 case ICmpInst::ICMP_SGT:return ConstantInt::get(C1Val > C2Val);
1074 case ICmpInst::ICMP_SLE:return ConstantInt::get(C1Val <= C2Val);
1075 case ICmpInst::ICMP_SGE:return ConstantInt::get(C1Val >= C2Val);
1077 } else if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
1078 if (ICmpInst::isSignedPredicate(ICmpInst::Predicate(pred))) {
1079 int64_t V1 = cast<ConstantInt>(C1)->getSExtValue();
1080 int64_t V2 = cast<ConstantInt>(C2)->getSExtValue();
1082 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1083 case ICmpInst::ICMP_SLT:return ConstantInt::get(V1 < V2);
1084 case ICmpInst::ICMP_SGT:return ConstantInt::get(V1 > V2);
1085 case ICmpInst::ICMP_SLE:return ConstantInt::get(V1 <= V2);
1086 case ICmpInst::ICMP_SGE:return ConstantInt::get(V1 >= V2);
1089 uint64_t V1 = cast<ConstantInt>(C1)->getZExtValue();
1090 uint64_t V2 = cast<ConstantInt>(C2)->getZExtValue();
1092 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1093 case ICmpInst::ICMP_EQ: return ConstantInt::get(V1 == V2);
1094 case ICmpInst::ICMP_NE: return ConstantInt::get(V1 != V2);
1095 case ICmpInst::ICMP_ULT:return ConstantInt::get(V1 < V2);
1096 case ICmpInst::ICMP_UGT:return ConstantInt::get(V1 > V2);
1097 case ICmpInst::ICMP_ULE:return ConstantInt::get(V1 <= V2);
1098 case ICmpInst::ICMP_UGE:return ConstantInt::get(V1 >= V2);
1101 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
1102 double C1Val = cast<ConstantFP>(C1)->getValue();
1103 double C2Val = cast<ConstantFP>(C2)->getValue();
1105 default: assert(0 && "Invalid FCmp Predicate"); return 0;
1106 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse();
1107 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue();
1108 case FCmpInst::FCMP_UNO:
1109 return ConstantInt::get(C1Val != C1Val || C2Val != C2Val);
1110 case FCmpInst::FCMP_ORD:
1111 return ConstantInt::get(C1Val == C1Val && C2Val == C2Val);
1112 case FCmpInst::FCMP_UEQ:
1113 if (C1Val != C1Val || C2Val != C2Val)
1114 return ConstantInt::getTrue();
1116 case FCmpInst::FCMP_OEQ: return ConstantInt::get(C1Val == C2Val);
1117 case FCmpInst::FCMP_UNE:
1118 if (C1Val != C1Val || C2Val != C2Val)
1119 return ConstantInt::getTrue();
1121 case FCmpInst::FCMP_ONE: return ConstantInt::get(C1Val != C2Val);
1122 case FCmpInst::FCMP_ULT:
1123 if (C1Val != C1Val || C2Val != C2Val)
1124 return ConstantInt::getTrue();
1126 case FCmpInst::FCMP_OLT: return ConstantInt::get(C1Val < C2Val);
1127 case FCmpInst::FCMP_UGT:
1128 if (C1Val != C1Val || C2Val != C2Val)
1129 return ConstantInt::getTrue();
1131 case FCmpInst::FCMP_OGT: return ConstantInt::get(C1Val > C2Val);
1132 case FCmpInst::FCMP_ULE:
1133 if (C1Val != C1Val || C2Val != C2Val)
1134 return ConstantInt::getTrue();
1136 case FCmpInst::FCMP_OLE: return ConstantInt::get(C1Val <= C2Val);
1137 case FCmpInst::FCMP_UGE:
1138 if (C1Val != C1Val || C2Val != C2Val)
1139 return ConstantInt::getTrue();
1141 case FCmpInst::FCMP_OGE: return ConstantInt::get(C1Val >= C2Val);
1143 } else if (const ConstantPacked *CP1 = dyn_cast<ConstantPacked>(C1)) {
1144 if (const ConstantPacked *CP2 = dyn_cast<ConstantPacked>(C2)) {
1145 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) {
1146 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1147 Constant *C= ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ,
1148 const_cast<Constant*>(CP1->getOperand(i)),
1149 const_cast<Constant*>(CP2->getOperand(i)));
1150 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1153 // Otherwise, could not decide from any element pairs.
1155 } else if (pred == ICmpInst::ICMP_EQ) {
1156 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) {
1157 Constant *C = ConstantExpr::getICmp(ICmpInst::ICMP_EQ,
1158 const_cast<Constant*>(CP1->getOperand(i)),
1159 const_cast<Constant*>(CP2->getOperand(i)));
1160 if (ConstantInt *CB = dyn_cast<ConstantInt>(C))
1163 // Otherwise, could not decide from any element pairs.
1169 if (C1->getType()->isFloatingPoint()) {
1170 switch (evaluateFCmpRelation(C1, C2)) {
1171 default: assert(0 && "Unknown relation!");
1172 case FCmpInst::FCMP_UNO:
1173 case FCmpInst::FCMP_ORD:
1174 case FCmpInst::FCMP_UEQ:
1175 case FCmpInst::FCMP_UNE:
1176 case FCmpInst::FCMP_ULT:
1177 case FCmpInst::FCMP_UGT:
1178 case FCmpInst::FCMP_ULE:
1179 case FCmpInst::FCMP_UGE:
1180 case FCmpInst::FCMP_TRUE:
1181 case FCmpInst::FCMP_FALSE:
1182 case FCmpInst::BAD_FCMP_PREDICATE:
1183 break; // Couldn't determine anything about these constants.
1184 case FCmpInst::FCMP_OEQ: // We know that C1 == C2
1185 return ConstantInt::get(
1186 pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
1187 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
1188 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1189 case FCmpInst::FCMP_OLT: // We know that C1 < C2
1190 return ConstantInt::get(
1191 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1192 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
1193 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
1194 case FCmpInst::FCMP_OGT: // We know that C1 > C2
1195 return ConstantInt::get(
1196 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1197 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
1198 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1199 case FCmpInst::FCMP_OLE: // We know that C1 <= C2
1200 // We can only partially decide this relation.
1201 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1202 return ConstantInt::getFalse();
1203 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1204 return ConstantInt::getTrue();
1206 case FCmpInst::FCMP_OGE: // We known that C1 >= C2
1207 // We can only partially decide this relation.
1208 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1209 return ConstantInt::getFalse();
1210 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1211 return ConstantInt::getTrue();
1213 case ICmpInst::ICMP_NE: // We know that C1 != C2
1214 // We can only partially decide this relation.
1215 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
1216 return ConstantInt::getFalse();
1217 if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
1218 return ConstantInt::getTrue();
1222 // Evaluate the relation between the two constants, per the predicate.
1223 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) {
1224 default: assert(0 && "Unknown relational!");
1225 case ICmpInst::BAD_ICMP_PREDICATE:
1226 break; // Couldn't determine anything about these constants.
1227 case ICmpInst::ICMP_EQ: // We know the constants are equal!
1228 // If we know the constants are equal, we can decide the result of this
1229 // computation precisely.
1230 return ConstantInt::get(pred == ICmpInst::ICMP_EQ ||
1231 pred == ICmpInst::ICMP_ULE ||
1232 pred == ICmpInst::ICMP_SLE ||
1233 pred == ICmpInst::ICMP_UGE ||
1234 pred == ICmpInst::ICMP_SGE);
1235 case ICmpInst::ICMP_ULT:
1236 // If we know that C1 < C2, we can decide the result of this computation
1238 return ConstantInt::get(pred == ICmpInst::ICMP_ULT ||
1239 pred == ICmpInst::ICMP_NE ||
1240 pred == ICmpInst::ICMP_ULE);
1241 case ICmpInst::ICMP_SLT:
1242 // If we know that C1 < C2, we can decide the result of this computation
1244 return ConstantInt::get(pred == ICmpInst::ICMP_SLT ||
1245 pred == ICmpInst::ICMP_NE ||
1246 pred == ICmpInst::ICMP_SLE);
1247 case ICmpInst::ICMP_UGT:
1248 // If we know that C1 > C2, we can decide the result of this computation
1250 return ConstantInt::get(pred == ICmpInst::ICMP_UGT ||
1251 pred == ICmpInst::ICMP_NE ||
1252 pred == ICmpInst::ICMP_UGE);
1253 case ICmpInst::ICMP_SGT:
1254 // If we know that C1 > C2, we can decide the result of this computation
1256 return ConstantInt::get(pred == ICmpInst::ICMP_SGT ||
1257 pred == ICmpInst::ICMP_NE ||
1258 pred == ICmpInst::ICMP_SGE);
1259 case ICmpInst::ICMP_ULE:
1260 // If we know that C1 <= C2, we can only partially decide this relation.
1261 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getFalse();
1262 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getTrue();
1264 case ICmpInst::ICMP_SLE:
1265 // If we know that C1 <= C2, we can only partially decide this relation.
1266 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getFalse();
1267 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getTrue();
1270 case ICmpInst::ICMP_UGE:
1271 // If we know that C1 >= C2, we can only partially decide this relation.
1272 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getFalse();
1273 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getTrue();
1275 case ICmpInst::ICMP_SGE:
1276 // If we know that C1 >= C2, we can only partially decide this relation.
1277 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getFalse();
1278 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getTrue();
1281 case ICmpInst::ICMP_NE:
1282 // If we know that C1 != C2, we can only partially decide this relation.
1283 if (pred == ICmpInst::ICMP_EQ) return ConstantInt::getFalse();
1284 if (pred == ICmpInst::ICMP_NE) return ConstantInt::getTrue();
1288 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) {
1289 // If C2 is a constant expr and C1 isn't, flop them around and fold the
1290 // other way if possible.
1292 case ICmpInst::ICMP_EQ:
1293 case ICmpInst::ICMP_NE:
1294 // No change of predicate required.
1295 return ConstantFoldCompareInstruction(pred, C2, C1);
1297 case ICmpInst::ICMP_ULT:
1298 case ICmpInst::ICMP_SLT:
1299 case ICmpInst::ICMP_UGT:
1300 case ICmpInst::ICMP_SGT:
1301 case ICmpInst::ICMP_ULE:
1302 case ICmpInst::ICMP_SLE:
1303 case ICmpInst::ICMP_UGE:
1304 case ICmpInst::ICMP_SGE:
1305 // Change the predicate as necessary to swap the operands.
1306 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
1307 return ConstantFoldCompareInstruction(pred, C2, C1);
1309 default: // These predicates cannot be flopped around.
1317 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1318 const std::vector<Value*> &IdxList) {
1319 if (IdxList.size() == 0 ||
1320 (IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
1321 return const_cast<Constant*>(C);
1323 if (isa<UndefValue>(C)) {
1324 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1326 assert(Ty != 0 && "Invalid indices for GEP!");
1327 return UndefValue::get(PointerType::get(Ty));
1330 Constant *Idx0 = cast<Constant>(IdxList[0]);
1331 if (C->isNullValue()) {
1333 for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
1334 if (!cast<Constant>(IdxList[i])->isNullValue()) {
1339 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1341 assert(Ty != 0 && "Invalid indices for GEP!");
1342 return ConstantPointerNull::get(PointerType::get(Ty));
1345 if (IdxList.size() == 1) {
1346 const Type *ElTy = cast<PointerType>(C->getType())->getElementType();
1347 if (uint32_t ElSize = ElTy->getPrimitiveSize()) {
1348 // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm
1349 // type, we can statically fold this.
1350 Constant *R = ConstantInt::get(Type::Int32Ty, ElSize);
1351 // We know R is unsigned, Idx0 is signed because it must be an index
1352 // through a sequential type (gep pointer operand) which is always
1354 R = ConstantExpr::getSExtOrBitCast(R, Idx0->getType());
1355 R = ConstantExpr::getMul(R, Idx0); // signed multiply
1356 // R is a signed integer, C is the GEP pointer so -> IntToPtr
1357 return ConstantExpr::getIntToPtr(R, C->getType());
1362 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1363 // Combine Indices - If the source pointer to this getelementptr instruction
1364 // is a getelementptr instruction, combine the indices of the two
1365 // getelementptr instructions into a single instruction.
1367 if (CE->getOpcode() == Instruction::GetElementPtr) {
1368 const Type *LastTy = 0;
1369 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1373 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1374 std::vector<Value*> NewIndices;
1375 NewIndices.reserve(IdxList.size() + CE->getNumOperands());
1376 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1377 NewIndices.push_back(CE->getOperand(i));
1379 // Add the last index of the source with the first index of the new GEP.
1380 // Make sure to handle the case when they are actually different types.
1381 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1382 // Otherwise it must be an array.
1383 if (!Idx0->isNullValue()) {
1384 const Type *IdxTy = Combined->getType();
1385 if (IdxTy != Idx0->getType()) {
1386 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty);
1387 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
1389 Combined = ConstantExpr::get(Instruction::Add, C1, C2);
1392 ConstantExpr::get(Instruction::Add, Idx0, Combined);
1396 NewIndices.push_back(Combined);
1397 NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
1398 return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
1402 // Implement folding of:
1403 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1405 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1407 if (CE->isCast() && IdxList.size() > 1 && Idx0->isNullValue())
1408 if (const PointerType *SPT =
1409 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1410 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1411 if (const ArrayType *CAT =
1412 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1413 if (CAT->getElementType() == SAT->getElementType())
1414 return ConstantExpr::getGetElementPtr(
1415 (Constant*)CE->getOperand(0), IdxList);