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/GetElementPtrTypeIterator.h"
34 virtual ~ConstRules() {}
36 // Binary Operators...
37 virtual Constant *add(const Constant *V1, const Constant *V2) const = 0;
38 virtual Constant *sub(const Constant *V1, const Constant *V2) const = 0;
39 virtual Constant *mul(const Constant *V1, const Constant *V2) const = 0;
40 virtual Constant *div(const Constant *V1, const Constant *V2) const = 0;
41 virtual Constant *rem(const Constant *V1, const Constant *V2) const = 0;
42 virtual Constant *op_and(const Constant *V1, const Constant *V2) const = 0;
43 virtual Constant *op_or (const Constant *V1, const Constant *V2) const = 0;
44 virtual Constant *op_xor(const Constant *V1, const Constant *V2) const = 0;
45 virtual Constant *shl(const Constant *V1, const Constant *V2) const = 0;
46 virtual Constant *shr(const Constant *V1, const Constant *V2) const = 0;
47 virtual Constant *lessthan(const Constant *V1, const Constant *V2) const =0;
48 virtual Constant *equalto(const Constant *V1, const Constant *V2) const = 0;
51 virtual Constant *castToBool (const Constant *V) const = 0;
52 virtual Constant *castToSByte (const Constant *V) const = 0;
53 virtual Constant *castToUByte (const Constant *V) const = 0;
54 virtual Constant *castToShort (const Constant *V) const = 0;
55 virtual Constant *castToUShort(const Constant *V) const = 0;
56 virtual Constant *castToInt (const Constant *V) const = 0;
57 virtual Constant *castToUInt (const Constant *V) const = 0;
58 virtual Constant *castToLong (const Constant *V) const = 0;
59 virtual Constant *castToULong (const Constant *V) const = 0;
60 virtual Constant *castToFloat (const Constant *V) const = 0;
61 virtual Constant *castToDouble(const Constant *V) const = 0;
62 virtual Constant *castToPointer(const Constant *V,
63 const PointerType *Ty) const = 0;
65 // ConstRules::get - Return an instance of ConstRules for the specified
68 static ConstRules &get(const Constant *V1, const Constant *V2);
70 ConstRules(const ConstRules &); // Do not implement
71 ConstRules &operator=(const ConstRules &); // Do not implement
76 //===----------------------------------------------------------------------===//
77 // TemplateRules Class
78 //===----------------------------------------------------------------------===//
80 // TemplateRules - Implement a subclass of ConstRules that provides all
81 // operations as noops. All other rules classes inherit from this class so
82 // that if functionality is needed in the future, it can simply be added here
83 // and to ConstRules without changing anything else...
85 // This class also provides subclasses with typesafe implementations of methods
86 // so that don't have to do type casting.
88 template<class ArgType, class SubClassName>
89 class TemplateRules : public ConstRules {
92 //===--------------------------------------------------------------------===//
93 // Redirecting functions that cast to the appropriate types
94 //===--------------------------------------------------------------------===//
96 virtual Constant *add(const Constant *V1, const Constant *V2) const {
97 return SubClassName::Add((const ArgType *)V1, (const ArgType *)V2);
99 virtual Constant *sub(const Constant *V1, const Constant *V2) const {
100 return SubClassName::Sub((const ArgType *)V1, (const ArgType *)V2);
102 virtual Constant *mul(const Constant *V1, const Constant *V2) const {
103 return SubClassName::Mul((const ArgType *)V1, (const ArgType *)V2);
105 virtual Constant *div(const Constant *V1, const Constant *V2) const {
106 return SubClassName::Div((const ArgType *)V1, (const ArgType *)V2);
108 virtual Constant *rem(const Constant *V1, const Constant *V2) const {
109 return SubClassName::Rem((const ArgType *)V1, (const ArgType *)V2);
111 virtual Constant *op_and(const Constant *V1, const Constant *V2) const {
112 return SubClassName::And((const ArgType *)V1, (const ArgType *)V2);
114 virtual Constant *op_or(const Constant *V1, const Constant *V2) const {
115 return SubClassName::Or((const ArgType *)V1, (const ArgType *)V2);
117 virtual Constant *op_xor(const Constant *V1, const Constant *V2) const {
118 return SubClassName::Xor((const ArgType *)V1, (const ArgType *)V2);
120 virtual Constant *shl(const Constant *V1, const Constant *V2) const {
121 return SubClassName::Shl((const ArgType *)V1, (const ArgType *)V2);
123 virtual Constant *shr(const Constant *V1, const Constant *V2) const {
124 return SubClassName::Shr((const ArgType *)V1, (const ArgType *)V2);
127 virtual Constant *lessthan(const Constant *V1, const Constant *V2) const {
128 return SubClassName::LessThan((const ArgType *)V1, (const ArgType *)V2);
130 virtual Constant *equalto(const Constant *V1, const Constant *V2) const {
131 return SubClassName::EqualTo((const ArgType *)V1, (const ArgType *)V2);
134 // Casting operators. ick
135 virtual Constant *castToBool(const Constant *V) const {
136 return SubClassName::CastToBool((const ArgType*)V);
138 virtual Constant *castToSByte(const Constant *V) const {
139 return SubClassName::CastToSByte((const ArgType*)V);
141 virtual Constant *castToUByte(const Constant *V) const {
142 return SubClassName::CastToUByte((const ArgType*)V);
144 virtual Constant *castToShort(const Constant *V) const {
145 return SubClassName::CastToShort((const ArgType*)V);
147 virtual Constant *castToUShort(const Constant *V) const {
148 return SubClassName::CastToUShort((const ArgType*)V);
150 virtual Constant *castToInt(const Constant *V) const {
151 return SubClassName::CastToInt((const ArgType*)V);
153 virtual Constant *castToUInt(const Constant *V) const {
154 return SubClassName::CastToUInt((const ArgType*)V);
156 virtual Constant *castToLong(const Constant *V) const {
157 return SubClassName::CastToLong((const ArgType*)V);
159 virtual Constant *castToULong(const Constant *V) const {
160 return SubClassName::CastToULong((const ArgType*)V);
162 virtual Constant *castToFloat(const Constant *V) const {
163 return SubClassName::CastToFloat((const ArgType*)V);
165 virtual Constant *castToDouble(const Constant *V) const {
166 return SubClassName::CastToDouble((const ArgType*)V);
168 virtual Constant *castToPointer(const Constant *V,
169 const PointerType *Ty) const {
170 return SubClassName::CastToPointer((const ArgType*)V, Ty);
173 //===--------------------------------------------------------------------===//
174 // Default "noop" implementations
175 //===--------------------------------------------------------------------===//
177 static Constant *Add(const ArgType *V1, const ArgType *V2) { return 0; }
178 static Constant *Sub(const ArgType *V1, const ArgType *V2) { return 0; }
179 static Constant *Mul(const ArgType *V1, const ArgType *V2) { return 0; }
180 static Constant *Div(const ArgType *V1, const ArgType *V2) { return 0; }
181 static Constant *Rem(const ArgType *V1, const ArgType *V2) { return 0; }
182 static Constant *And(const ArgType *V1, const ArgType *V2) { return 0; }
183 static Constant *Or (const ArgType *V1, const ArgType *V2) { return 0; }
184 static Constant *Xor(const ArgType *V1, const ArgType *V2) { return 0; }
185 static Constant *Shl(const ArgType *V1, const ArgType *V2) { return 0; }
186 static Constant *Shr(const ArgType *V1, const ArgType *V2) { return 0; }
187 static Constant *LessThan(const ArgType *V1, const ArgType *V2) {
190 static Constant *EqualTo(const ArgType *V1, const ArgType *V2) {
194 // Casting operators. ick
195 static Constant *CastToBool (const Constant *V) { return 0; }
196 static Constant *CastToSByte (const Constant *V) { return 0; }
197 static Constant *CastToUByte (const Constant *V) { return 0; }
198 static Constant *CastToShort (const Constant *V) { return 0; }
199 static Constant *CastToUShort(const Constant *V) { return 0; }
200 static Constant *CastToInt (const Constant *V) { return 0; }
201 static Constant *CastToUInt (const Constant *V) { return 0; }
202 static Constant *CastToLong (const Constant *V) { return 0; }
203 static Constant *CastToULong (const Constant *V) { return 0; }
204 static Constant *CastToFloat (const Constant *V) { return 0; }
205 static Constant *CastToDouble(const Constant *V) { return 0; }
206 static Constant *CastToPointer(const Constant *,
207 const PointerType *) {return 0;}
210 virtual ~TemplateRules() {}
215 //===----------------------------------------------------------------------===//
217 //===----------------------------------------------------------------------===//
219 // EmptyRules provides a concrete base class of ConstRules that does nothing
221 struct EmptyRules : public TemplateRules<Constant, EmptyRules> {
222 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
223 if (V1 == V2) return ConstantBool::True;
230 //===----------------------------------------------------------------------===//
232 //===----------------------------------------------------------------------===//
234 // BoolRules provides a concrete base class of ConstRules for the 'bool' type.
236 struct BoolRules : public TemplateRules<ConstantBool, BoolRules> {
238 static Constant *LessThan(const ConstantBool *V1, const ConstantBool *V2){
239 return ConstantBool::get(V1->getValue() < V2->getValue());
242 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
243 return ConstantBool::get(V1 == V2);
246 static Constant *And(const ConstantBool *V1, const ConstantBool *V2) {
247 return ConstantBool::get(V1->getValue() & V2->getValue());
250 static Constant *Or(const ConstantBool *V1, const ConstantBool *V2) {
251 return ConstantBool::get(V1->getValue() | V2->getValue());
254 static Constant *Xor(const ConstantBool *V1, const ConstantBool *V2) {
255 return ConstantBool::get(V1->getValue() ^ V2->getValue());
258 // Casting operators. ick
259 #define DEF_CAST(TYPE, CLASS, CTYPE) \
260 static Constant *CastTo##TYPE (const ConstantBool *V) { \
261 return CLASS::get(Type::TYPE##Ty, (CTYPE)(bool)V->getValue()); \
264 DEF_CAST(Bool , ConstantBool, bool)
265 DEF_CAST(SByte , ConstantSInt, signed char)
266 DEF_CAST(UByte , ConstantUInt, unsigned char)
267 DEF_CAST(Short , ConstantSInt, signed short)
268 DEF_CAST(UShort, ConstantUInt, unsigned short)
269 DEF_CAST(Int , ConstantSInt, signed int)
270 DEF_CAST(UInt , ConstantUInt, unsigned int)
271 DEF_CAST(Long , ConstantSInt, int64_t)
272 DEF_CAST(ULong , ConstantUInt, uint64_t)
273 DEF_CAST(Float , ConstantFP , float)
274 DEF_CAST(Double, ConstantFP , double)
279 //===----------------------------------------------------------------------===//
280 // NullPointerRules Class
281 //===----------------------------------------------------------------------===//
283 // NullPointerRules provides a concrete base class of ConstRules for null
286 struct NullPointerRules : public TemplateRules<ConstantPointerNull,
288 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
289 return ConstantBool::True; // Null pointers are always equal
291 static Constant *CastToBool(const Constant *V) {
292 return ConstantBool::False;
294 static Constant *CastToSByte (const Constant *V) {
295 return ConstantSInt::get(Type::SByteTy, 0);
297 static Constant *CastToUByte (const Constant *V) {
298 return ConstantUInt::get(Type::UByteTy, 0);
300 static Constant *CastToShort (const Constant *V) {
301 return ConstantSInt::get(Type::ShortTy, 0);
303 static Constant *CastToUShort(const Constant *V) {
304 return ConstantUInt::get(Type::UShortTy, 0);
306 static Constant *CastToInt (const Constant *V) {
307 return ConstantSInt::get(Type::IntTy, 0);
309 static Constant *CastToUInt (const Constant *V) {
310 return ConstantUInt::get(Type::UIntTy, 0);
312 static Constant *CastToLong (const Constant *V) {
313 return ConstantSInt::get(Type::LongTy, 0);
315 static Constant *CastToULong (const Constant *V) {
316 return ConstantUInt::get(Type::ULongTy, 0);
318 static Constant *CastToFloat (const Constant *V) {
319 return ConstantFP::get(Type::FloatTy, 0);
321 static Constant *CastToDouble(const Constant *V) {
322 return ConstantFP::get(Type::DoubleTy, 0);
325 static Constant *CastToPointer(const ConstantPointerNull *V,
326 const PointerType *PTy) {
327 return ConstantPointerNull::get(PTy);
332 //===----------------------------------------------------------------------===//
334 //===----------------------------------------------------------------------===//
336 // DirectRules provides a concrete base classes of ConstRules for a variety of
337 // different types. This allows the C++ compiler to automatically generate our
338 // constant handling operations in a typesafe and accurate manner.
340 template<class ConstantClass, class BuiltinType, Type **Ty, class SuperClass>
341 struct DirectRules : public TemplateRules<ConstantClass, SuperClass> {
342 static Constant *Add(const ConstantClass *V1, const ConstantClass *V2) {
343 BuiltinType R = (BuiltinType)V1->getValue() + (BuiltinType)V2->getValue();
344 return ConstantClass::get(*Ty, R);
347 static Constant *Sub(const ConstantClass *V1, const ConstantClass *V2) {
348 BuiltinType R = (BuiltinType)V1->getValue() - (BuiltinType)V2->getValue();
349 return ConstantClass::get(*Ty, R);
352 static Constant *Mul(const ConstantClass *V1, const ConstantClass *V2) {
353 BuiltinType R = (BuiltinType)V1->getValue() * (BuiltinType)V2->getValue();
354 return ConstantClass::get(*Ty, R);
357 static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
358 if (V2->isNullValue()) return 0;
359 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
360 return ConstantClass::get(*Ty, R);
363 static Constant *LessThan(const ConstantClass *V1, const ConstantClass *V2) {
364 bool R = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue();
365 return ConstantBool::get(R);
368 static Constant *EqualTo(const ConstantClass *V1, const ConstantClass *V2) {
369 bool R = (BuiltinType)V1->getValue() == (BuiltinType)V2->getValue();
370 return ConstantBool::get(R);
373 static Constant *CastToPointer(const ConstantClass *V,
374 const PointerType *PTy) {
375 if (V->isNullValue()) // Is it a FP or Integral null value?
376 return ConstantPointerNull::get(PTy);
377 return 0; // Can't const prop other types of pointers
380 // Casting operators. ick
381 #define DEF_CAST(TYPE, CLASS, CTYPE) \
382 static Constant *CastTo##TYPE (const ConstantClass *V) { \
383 return CLASS::get(Type::TYPE##Ty, (CTYPE)(BuiltinType)V->getValue()); \
386 DEF_CAST(Bool , ConstantBool, bool)
387 DEF_CAST(SByte , ConstantSInt, signed char)
388 DEF_CAST(UByte , ConstantUInt, unsigned char)
389 DEF_CAST(Short , ConstantSInt, signed short)
390 DEF_CAST(UShort, ConstantUInt, unsigned short)
391 DEF_CAST(Int , ConstantSInt, signed int)
392 DEF_CAST(UInt , ConstantUInt, unsigned int)
393 DEF_CAST(Long , ConstantSInt, int64_t)
394 DEF_CAST(ULong , ConstantUInt, uint64_t)
395 DEF_CAST(Float , ConstantFP , float)
396 DEF_CAST(Double, ConstantFP , double)
401 //===----------------------------------------------------------------------===//
402 // DirectIntRules Class
403 //===----------------------------------------------------------------------===//
405 // DirectIntRules provides implementations of functions that are valid on
406 // integer types, but not all types in general.
408 template <class ConstantClass, class BuiltinType, Type **Ty>
409 struct DirectIntRules
410 : public DirectRules<ConstantClass, BuiltinType, Ty,
411 DirectIntRules<ConstantClass, BuiltinType, Ty> > {
413 static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
414 if (V2->isNullValue()) return 0;
415 if (V2->isAllOnesValue() && // MIN_INT / -1
416 (BuiltinType)V1->getValue() == -(BuiltinType)V1->getValue())
418 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
419 return ConstantClass::get(*Ty, R);
422 static Constant *Rem(const ConstantClass *V1,
423 const ConstantClass *V2) {
424 if (V2->isNullValue()) return 0; // X / 0
425 if (V2->isAllOnesValue() && // MIN_INT / -1
426 (BuiltinType)V1->getValue() == -(BuiltinType)V1->getValue())
428 BuiltinType R = (BuiltinType)V1->getValue() % (BuiltinType)V2->getValue();
429 return ConstantClass::get(*Ty, R);
432 static Constant *And(const ConstantClass *V1, const ConstantClass *V2) {
433 BuiltinType R = (BuiltinType)V1->getValue() & (BuiltinType)V2->getValue();
434 return ConstantClass::get(*Ty, R);
436 static Constant *Or(const ConstantClass *V1, const ConstantClass *V2) {
437 BuiltinType R = (BuiltinType)V1->getValue() | (BuiltinType)V2->getValue();
438 return ConstantClass::get(*Ty, R);
440 static Constant *Xor(const ConstantClass *V1, const ConstantClass *V2) {
441 BuiltinType R = (BuiltinType)V1->getValue() ^ (BuiltinType)V2->getValue();
442 return ConstantClass::get(*Ty, R);
445 static Constant *Shl(const ConstantClass *V1, const ConstantClass *V2) {
446 BuiltinType R = (BuiltinType)V1->getValue() << (BuiltinType)V2->getValue();
447 return ConstantClass::get(*Ty, R);
450 static Constant *Shr(const ConstantClass *V1, const ConstantClass *V2) {
451 BuiltinType R = (BuiltinType)V1->getValue() >> (BuiltinType)V2->getValue();
452 return ConstantClass::get(*Ty, R);
457 //===----------------------------------------------------------------------===//
458 // DirectFPRules Class
459 //===----------------------------------------------------------------------===//
461 /// DirectFPRules provides implementations of functions that are valid on
462 /// floating point types, but not all types in general.
464 template <class ConstantClass, class BuiltinType, Type **Ty>
466 : public DirectRules<ConstantClass, BuiltinType, Ty,
467 DirectFPRules<ConstantClass, BuiltinType, Ty> > {
468 static Constant *Rem(const ConstantClass *V1, const ConstantClass *V2) {
469 if (V2->isNullValue()) return 0;
470 BuiltinType Result = std::fmod((BuiltinType)V1->getValue(),
471 (BuiltinType)V2->getValue());
472 return ConstantClass::get(*Ty, Result);
474 static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
475 BuiltinType inf = std::numeric_limits<BuiltinType>::infinity();
476 if (V2->isExactlyValue(0.0)) return ConstantClass::get(*Ty, inf);
477 if (V2->isExactlyValue(-0.0)) return ConstantClass::get(*Ty, -inf);
478 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
479 return ConstantClass::get(*Ty, R);
484 /// ConstRules::get - This method returns the constant rules implementation that
485 /// implements the semantics of the two specified constants.
486 ConstRules &ConstRules::get(const Constant *V1, const Constant *V2) {
487 static EmptyRules EmptyR;
488 static BoolRules BoolR;
489 static NullPointerRules NullPointerR;
490 static DirectIntRules<ConstantSInt, signed char , &Type::SByteTy> SByteR;
491 static DirectIntRules<ConstantUInt, unsigned char , &Type::UByteTy> UByteR;
492 static DirectIntRules<ConstantSInt, signed short, &Type::ShortTy> ShortR;
493 static DirectIntRules<ConstantUInt, unsigned short, &Type::UShortTy> UShortR;
494 static DirectIntRules<ConstantSInt, signed int , &Type::IntTy> IntR;
495 static DirectIntRules<ConstantUInt, unsigned int , &Type::UIntTy> UIntR;
496 static DirectIntRules<ConstantSInt, int64_t , &Type::LongTy> LongR;
497 static DirectIntRules<ConstantUInt, uint64_t , &Type::ULongTy> ULongR;
498 static DirectFPRules <ConstantFP , float , &Type::FloatTy> FloatR;
499 static DirectFPRules <ConstantFP , double , &Type::DoubleTy> DoubleR;
501 if (isa<ConstantExpr>(V1) || isa<ConstantExpr>(V2) ||
502 isa<GlobalValue>(V1) || isa<GlobalValue>(V2) ||
503 isa<UndefValue>(V1) || isa<UndefValue>(V2))
506 switch (V1->getType()->getTypeID()) {
507 default: assert(0 && "Unknown value type for constant folding!");
508 case Type::BoolTyID: return BoolR;
509 case Type::PointerTyID: return NullPointerR;
510 case Type::SByteTyID: return SByteR;
511 case Type::UByteTyID: return UByteR;
512 case Type::ShortTyID: return ShortR;
513 case Type::UShortTyID: return UShortR;
514 case Type::IntTyID: return IntR;
515 case Type::UIntTyID: return UIntR;
516 case Type::LongTyID: return LongR;
517 case Type::ULongTyID: return ULongR;
518 case Type::FloatTyID: return FloatR;
519 case Type::DoubleTyID: return DoubleR;
524 //===----------------------------------------------------------------------===//
525 // ConstantFold*Instruction Implementations
526 //===----------------------------------------------------------------------===//
528 // These methods contain the special case hackery required to symbolically
529 // evaluate some constant expression cases, and use the ConstantRules class to
530 // evaluate normal constants.
532 static unsigned getSize(const Type *Ty) {
533 unsigned S = Ty->getPrimitiveSize();
534 return S ? S : 8; // Treat pointers at 8 bytes
537 Constant *llvm::ConstantFoldCastInstruction(const Constant *V,
538 const Type *DestTy) {
539 if (V->getType() == DestTy) return (Constant*)V;
541 // Cast of a global address to boolean is always true.
542 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
543 if (DestTy == Type::BoolTy)
544 // FIXME: When we support 'external weak' references, we have to prevent
545 // this transformation from happening. This code will need to be updated
546 // to ignore external weak symbols when we support it.
547 return ConstantBool::True;
548 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
549 if (CE->getOpcode() == Instruction::Cast) {
550 Constant *Op = const_cast<Constant*>(CE->getOperand(0));
551 // Try to not produce a cast of a cast, which is almost always redundant.
552 if (!Op->getType()->isFloatingPoint() &&
553 !CE->getType()->isFloatingPoint() &&
554 !DestTy->isFloatingPoint()) {
555 unsigned S1 = getSize(Op->getType()), S2 = getSize(CE->getType());
556 unsigned S3 = getSize(DestTy);
557 if (Op->getType() == DestTy && S3 >= S2)
559 if (S1 >= S2 && S2 >= S3)
560 return ConstantExpr::getCast(Op, DestTy);
561 if (S1 <= S2 && S2 >= S3 && S1 <= S3)
562 return ConstantExpr::getCast(Op, DestTy);
564 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
565 // If all of the indexes in the GEP are null values, there is no pointer
566 // adjustment going on. We might as well cast the source pointer.
567 bool isAllNull = true;
568 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
569 if (!CE->getOperand(i)->isNullValue()) {
574 return ConstantExpr::getCast(CE->getOperand(0), DestTy);
576 } else if (isa<UndefValue>(V)) {
577 return UndefValue::get(DestTy);
580 // Check to see if we are casting an pointer to an aggregate to a pointer to
581 // the first element. If so, return the appropriate GEP instruction.
582 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
583 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
584 std::vector<Value*> IdxList;
585 IdxList.push_back(Constant::getNullValue(Type::IntTy));
586 const Type *ElTy = PTy->getElementType();
587 while (ElTy != DPTy->getElementType()) {
588 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
589 if (STy->getNumElements() == 0) break;
590 ElTy = STy->getElementType(0);
591 IdxList.push_back(Constant::getNullValue(Type::UIntTy));
592 } else if (const SequentialType *STy = dyn_cast<SequentialType>(ElTy)) {
593 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
594 ElTy = STy->getElementType();
595 IdxList.push_back(IdxList[0]);
601 if (ElTy == DPTy->getElementType())
602 return ConstantExpr::getGetElementPtr(const_cast<Constant*>(V),IdxList);
605 ConstRules &Rules = ConstRules::get(V, V);
607 switch (DestTy->getTypeID()) {
608 case Type::BoolTyID: return Rules.castToBool(V);
609 case Type::UByteTyID: return Rules.castToUByte(V);
610 case Type::SByteTyID: return Rules.castToSByte(V);
611 case Type::UShortTyID: return Rules.castToUShort(V);
612 case Type::ShortTyID: return Rules.castToShort(V);
613 case Type::UIntTyID: return Rules.castToUInt(V);
614 case Type::IntTyID: return Rules.castToInt(V);
615 case Type::ULongTyID: return Rules.castToULong(V);
616 case Type::LongTyID: return Rules.castToLong(V);
617 case Type::FloatTyID: return Rules.castToFloat(V);
618 case Type::DoubleTyID: return Rules.castToDouble(V);
619 case Type::PointerTyID:
620 return Rules.castToPointer(V, cast<PointerType>(DestTy));
625 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
627 const Constant *V2) {
628 if (Cond == ConstantBool::True)
629 return const_cast<Constant*>(V1);
630 else if (Cond == ConstantBool::False)
631 return const_cast<Constant*>(V2);
633 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
634 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
635 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
639 /// isZeroSizedType - This type is zero sized if its an array or structure of
640 /// zero sized types. The only leaf zero sized type is an empty structure.
641 static bool isMaybeZeroSizedType(const Type *Ty) {
642 if (isa<OpaqueType>(Ty)) return true; // Can't say.
643 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
645 // If all of elements have zero size, this does too.
646 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
647 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
650 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
651 return isMaybeZeroSizedType(ATy->getElementType());
656 /// IdxCompare - Compare the two constants as though they were getelementptr
657 /// indices. This allows coersion of the types to be the same thing.
659 /// If the two constants are the "same" (after coersion), return 0. If the
660 /// first is less than the second, return -1, if the second is less than the
661 /// first, return 1. If the constants are not integral, return -2.
663 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
664 if (C1 == C2) return 0;
666 // Ok, we found a different index. Are either of the operands
667 // ConstantExprs? If so, we can't do anything with them.
668 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
669 return -2; // don't know!
671 // Ok, we have two differing integer indices. Sign extend them to be the same
672 // type. Long is always big enough, so we use it.
673 C1 = ConstantExpr::getSignExtend(C1, Type::LongTy);
674 C2 = ConstantExpr::getSignExtend(C2, Type::LongTy);
675 if (C1 == C2) return 0; // Are they just differing types?
677 // If the type being indexed over is really just a zero sized type, there is
678 // no pointer difference being made here.
679 if (isMaybeZeroSizedType(ElTy))
682 // If they are really different, now that they are the same type, then we
683 // found a difference!
684 if (cast<ConstantSInt>(C1)->getValue() < cast<ConstantSInt>(C2)->getValue())
690 /// evaluateRelation - This function determines if there is anything we can
691 /// decide about the two constants provided. This doesn't need to handle simple
692 /// things like integer comparisons, but should instead handle ConstantExprs
693 /// and GlobalValuess. If we can determine that the two constants have a
694 /// particular relation to each other, we should return the corresponding SetCC
695 /// code, otherwise return Instruction::BinaryOpsEnd.
697 /// To simplify this code we canonicalize the relation so that the first
698 /// operand is always the most "complex" of the two. We consider simple
699 /// constants (like ConstantInt) to be the simplest, followed by
700 /// GlobalValues, followed by ConstantExpr's (the most complex).
702 static Instruction::BinaryOps evaluateRelation(const Constant *V1,
703 const Constant *V2) {
704 assert(V1->getType() == V2->getType() &&
705 "Cannot compare different types of values!");
706 if (V1 == V2) return Instruction::SetEQ;
708 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
709 // If the first operand is simple, swap operands.
710 assert((isa<GlobalValue>(V2) || isa<ConstantExpr>(V2)) &&
711 "Simple cases should have been handled by caller!");
712 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
713 if (SwappedRelation != Instruction::BinaryOpsEnd)
714 return SetCondInst::getSwappedCondition(SwappedRelation);
716 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)){
717 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
718 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
719 if (SwappedRelation != Instruction::BinaryOpsEnd)
720 return SetCondInst::getSwappedCondition(SwappedRelation);
722 return Instruction::BinaryOpsEnd;
725 // Now we know that the RHS is a GlobalValue or simple constant,
726 // which (since the types must match) means that it's a ConstantPointerNull.
727 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
728 assert(CPR1 != CPR2 &&
729 "GVs for the same value exist at different addresses??");
730 // FIXME: If both globals are external weak, they might both be null!
731 return Instruction::SetNE;
733 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
734 // Global can never be null. FIXME: if we implement external weak
735 // linkage, this is not necessarily true!
736 return Instruction::SetNE;
740 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
741 // constantexpr, a CPR, or a simple constant.
742 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
743 Constant *CE1Op0 = CE1->getOperand(0);
745 switch (CE1->getOpcode()) {
746 case Instruction::Cast:
747 // If the cast is not actually changing bits, and the second operand is a
748 // null pointer, do the comparison with the pre-casted value.
749 if (V2->isNullValue() &&
750 CE1->getType()->isLosslesslyConvertibleTo(CE1Op0->getType()))
751 return evaluateRelation(CE1Op0,
752 Constant::getNullValue(CE1Op0->getType()));
755 case Instruction::GetElementPtr:
756 // Ok, since this is a getelementptr, we know that the constant has a
757 // pointer type. Check the various cases.
758 if (isa<ConstantPointerNull>(V2)) {
759 // If we are comparing a GEP to a null pointer, check to see if the base
760 // of the GEP equals the null pointer.
761 if (isa<GlobalValue>(CE1Op0)) {
762 // FIXME: this is not true when we have external weak references!
763 // No offset can go from a global to a null pointer.
764 return Instruction::SetGT;
765 } else if (isa<ConstantPointerNull>(CE1Op0)) {
766 // If we are indexing from a null pointer, check to see if we have any
768 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
769 if (!CE1->getOperand(i)->isNullValue())
770 // Offsetting from null, must not be equal.
771 return Instruction::SetGT;
772 // Only zero indexes from null, must still be zero.
773 return Instruction::SetEQ;
775 // Otherwise, we can't really say if the first operand is null or not.
776 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
777 if (isa<ConstantPointerNull>(CE1Op0)) {
778 // FIXME: This is not true with external weak references.
779 return Instruction::SetLT;
780 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
782 // If this is a getelementptr of the same global, then it must be
783 // different. Because the types must match, the getelementptr could
784 // only have at most one index, and because we fold getelementptr's
785 // with a single zero index, it must be nonzero.
786 assert(CE1->getNumOperands() == 2 &&
787 !CE1->getOperand(1)->isNullValue() &&
788 "Suprising getelementptr!");
789 return Instruction::SetGT;
791 // If they are different globals, we don't know what the value is,
792 // but they can't be equal.
793 return Instruction::SetNE;
797 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
798 const Constant *CE2Op0 = CE2->getOperand(0);
800 // There are MANY other foldings that we could perform here. They will
801 // probably be added on demand, as they seem needed.
802 switch (CE2->getOpcode()) {
804 case Instruction::GetElementPtr:
805 // By far the most common case to handle is when the base pointers are
806 // obviously to the same or different globals.
807 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
808 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
809 return Instruction::SetNE;
810 // Ok, we know that both getelementptr instructions are based on the
811 // same global. From this, we can precisely determine the relative
812 // ordering of the resultant pointers.
815 // Compare all of the operands the GEP's have in common.
816 gep_type_iterator GTI = gep_type_begin(CE1);
817 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
819 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
820 GTI.getIndexedType())) {
821 case -1: return Instruction::SetLT;
822 case 1: return Instruction::SetGT;
823 case -2: return Instruction::BinaryOpsEnd;
826 // Ok, we ran out of things they have in common. If any leftovers
827 // are non-zero then we have a difference, otherwise we are equal.
828 for (; i < CE1->getNumOperands(); ++i)
829 if (!CE1->getOperand(i)->isNullValue())
830 if (isa<ConstantIntegral>(CE1->getOperand(i)))
831 return Instruction::SetGT;
833 return Instruction::BinaryOpsEnd; // Might be equal.
835 for (; i < CE2->getNumOperands(); ++i)
836 if (!CE2->getOperand(i)->isNullValue())
837 if (isa<ConstantIntegral>(CE2->getOperand(i)))
838 return Instruction::SetLT;
840 return Instruction::BinaryOpsEnd; // Might be equal.
841 return Instruction::SetEQ;
851 return Instruction::BinaryOpsEnd;
854 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
856 const Constant *V2) {
860 case Instruction::Add: C = ConstRules::get(V1, V2).add(V1, V2); break;
861 case Instruction::Sub: C = ConstRules::get(V1, V2).sub(V1, V2); break;
862 case Instruction::Mul: C = ConstRules::get(V1, V2).mul(V1, V2); break;
863 case Instruction::Div: C = ConstRules::get(V1, V2).div(V1, V2); break;
864 case Instruction::Rem: C = ConstRules::get(V1, V2).rem(V1, V2); break;
865 case Instruction::And: C = ConstRules::get(V1, V2).op_and(V1, V2); break;
866 case Instruction::Or: C = ConstRules::get(V1, V2).op_or (V1, V2); break;
867 case Instruction::Xor: C = ConstRules::get(V1, V2).op_xor(V1, V2); break;
868 case Instruction::Shl: C = ConstRules::get(V1, V2).shl(V1, V2); break;
869 case Instruction::Shr: C = ConstRules::get(V1, V2).shr(V1, V2); break;
870 case Instruction::SetEQ: C = ConstRules::get(V1, V2).equalto(V1, V2); break;
871 case Instruction::SetLT: C = ConstRules::get(V1, V2).lessthan(V1, V2);break;
872 case Instruction::SetGT: C = ConstRules::get(V1, V2).lessthan(V2, V1);break;
873 case Instruction::SetNE: // V1 != V2 === !(V1 == V2)
874 C = ConstRules::get(V1, V2).equalto(V1, V2);
875 if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
877 case Instruction::SetLE: // V1 <= V2 === !(V2 < V1)
878 C = ConstRules::get(V1, V2).lessthan(V2, V1);
879 if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
881 case Instruction::SetGE: // V1 >= V2 === !(V1 < V2)
882 C = ConstRules::get(V1, V2).lessthan(V1, V2);
883 if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
887 // If we successfully folded the expression, return it now.
890 if (SetCondInst::isRelational(Opcode)) {
891 if (isa<UndefValue>(V1) || isa<UndefValue>(V2))
892 return UndefValue::get(Type::BoolTy);
893 switch (evaluateRelation(V1, V2)) {
894 default: assert(0 && "Unknown relational!");
895 case Instruction::BinaryOpsEnd:
896 break; // Couldn't determine anything about these constants.
897 case Instruction::SetEQ: // We know the constants are equal!
898 // If we know the constants are equal, we can decide the result of this
899 // computation precisely.
900 return ConstantBool::get(Opcode == Instruction::SetEQ ||
901 Opcode == Instruction::SetLE ||
902 Opcode == Instruction::SetGE);
903 case Instruction::SetLT:
904 // If we know that V1 < V2, we can decide the result of this computation
906 return ConstantBool::get(Opcode == Instruction::SetLT ||
907 Opcode == Instruction::SetNE ||
908 Opcode == Instruction::SetLE);
909 case Instruction::SetGT:
910 // If we know that V1 > V2, we can decide the result of this computation
912 return ConstantBool::get(Opcode == Instruction::SetGT ||
913 Opcode == Instruction::SetNE ||
914 Opcode == Instruction::SetGE);
915 case Instruction::SetLE:
916 // If we know that V1 <= V2, we can only partially decide this relation.
917 if (Opcode == Instruction::SetGT) return ConstantBool::False;
918 if (Opcode == Instruction::SetLT) return ConstantBool::True;
921 case Instruction::SetGE:
922 // If we know that V1 >= V2, we can only partially decide this relation.
923 if (Opcode == Instruction::SetLT) return ConstantBool::False;
924 if (Opcode == Instruction::SetGT) return ConstantBool::True;
927 case Instruction::SetNE:
928 // If we know that V1 != V2, we can only partially decide this relation.
929 if (Opcode == Instruction::SetEQ) return ConstantBool::False;
930 if (Opcode == Instruction::SetNE) return ConstantBool::True;
935 if (isa<UndefValue>(V1) || isa<UndefValue>(V2)) {
937 case Instruction::Add:
938 case Instruction::Sub:
939 case Instruction::Xor:
940 return UndefValue::get(V1->getType());
942 case Instruction::Mul:
943 case Instruction::And:
944 return Constant::getNullValue(V1->getType());
945 case Instruction::Div:
946 case Instruction::Rem:
947 if (!isa<UndefValue>(V2)) // undef/X -> 0
948 return Constant::getNullValue(V1->getType());
949 return const_cast<Constant*>(V2); // X/undef -> undef
950 case Instruction::Or: // X|undef -> -1
951 return ConstantInt::getAllOnesValue(V1->getType());
952 case Instruction::Shr:
953 if (!isa<UndefValue>(V2)) {
954 if (V1->getType()->isSigned())
955 return const_cast<Constant*>(V1); // undef >>s X -> undef
957 } else if (isa<UndefValue>(V1)) {
958 return const_cast<Constant*>(V1); // undef >> undef -> undef
960 if (V1->getType()->isSigned())
961 return const_cast<Constant*>(V1); // X >>s undef -> X
964 return Constant::getNullValue(V1->getType());
966 case Instruction::Shl:
967 // undef << X -> 0 X << undef -> 0
968 return Constant::getNullValue(V1->getType());
972 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(V1)) {
973 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
974 // There are many possible foldings we could do here. We should probably
975 // at least fold add of a pointer with an integer into the appropriate
976 // getelementptr. This will improve alias analysis a bit.
982 // Just implement a couple of simple identities.
984 case Instruction::Add:
985 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X + 0 == X
987 case Instruction::Sub:
988 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X - 0 == X
990 case Instruction::Mul:
991 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X * 0 == 0
992 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
993 if (CI->getRawValue() == 1)
994 return const_cast<Constant*>(V1); // X * 1 == X
996 case Instruction::Div:
997 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
998 if (CI->getRawValue() == 1)
999 return const_cast<Constant*>(V1); // X / 1 == X
1001 case Instruction::Rem:
1002 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1003 if (CI->getRawValue() == 1)
1004 return Constant::getNullValue(CI->getType()); // X % 1 == 0
1006 case Instruction::And:
1007 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1008 return const_cast<Constant*>(V1); // X & -1 == X
1009 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X & 0 == 0
1010 if (CE1->getOpcode() == Instruction::Cast &&
1011 isa<GlobalValue>(CE1->getOperand(0))) {
1012 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
1014 // Functions are at least 4-byte aligned. If and'ing the address of a
1015 // function with a constant < 4, fold it to zero.
1016 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1017 if (CI->getRawValue() < 4 && isa<Function>(CPR))
1018 return Constant::getNullValue(CI->getType());
1021 case Instruction::Or:
1022 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X | 0 == X
1023 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1024 return const_cast<Constant*>(V2); // X | -1 == -1
1026 case Instruction::Xor:
1027 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X ^ 0 == X
1032 } else if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
1033 // If V2 is a constant expr and V1 isn't, flop them around and fold the
1034 // other way if possible.
1036 case Instruction::Add:
1037 case Instruction::Mul:
1038 case Instruction::And:
1039 case Instruction::Or:
1040 case Instruction::Xor:
1041 case Instruction::SetEQ:
1042 case Instruction::SetNE:
1043 // No change of opcode required.
1044 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1046 case Instruction::SetLT:
1047 case Instruction::SetGT:
1048 case Instruction::SetLE:
1049 case Instruction::SetGE:
1050 // Change the opcode as necessary to swap the operands.
1051 Opcode = SetCondInst::getSwappedCondition((Instruction::BinaryOps)Opcode);
1052 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1054 case Instruction::Shl:
1055 case Instruction::Shr:
1056 case Instruction::Sub:
1057 case Instruction::Div:
1058 case Instruction::Rem:
1059 default: // These instructions cannot be flopped around.
1066 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1067 const std::vector<Value*> &IdxList) {
1068 if (IdxList.size() == 0 ||
1069 (IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
1070 return const_cast<Constant*>(C);
1072 if (isa<UndefValue>(C)) {
1073 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1075 assert(Ty != 0 && "Invalid indices for GEP!");
1076 return UndefValue::get(PointerType::get(Ty));
1079 Constant *Idx0 = cast<Constant>(IdxList[0]);
1080 if (C->isNullValue()) {
1082 for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
1083 if (!cast<Constant>(IdxList[i])->isNullValue()) {
1088 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1090 assert(Ty != 0 && "Invalid indices for GEP!");
1091 return ConstantPointerNull::get(PointerType::get(Ty));
1094 if (IdxList.size() == 1) {
1095 const Type *ElTy = cast<PointerType>(C->getType())->getElementType();
1096 if (unsigned ElSize = ElTy->getPrimitiveSize()) {
1097 // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm
1098 // type, we can statically fold this.
1099 Constant *R = ConstantUInt::get(Type::UIntTy, ElSize);
1100 R = ConstantExpr::getCast(R, Idx0->getType());
1101 R = ConstantExpr::getMul(R, Idx0);
1102 return ConstantExpr::getCast(R, C->getType());
1107 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1108 // Combine Indices - If the source pointer to this getelementptr instruction
1109 // is a getelementptr instruction, combine the indices of the two
1110 // getelementptr instructions into a single instruction.
1112 if (CE->getOpcode() == Instruction::GetElementPtr) {
1113 const Type *LastTy = 0;
1114 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1118 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1119 std::vector<Value*> NewIndices;
1120 NewIndices.reserve(IdxList.size() + CE->getNumOperands());
1121 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1122 NewIndices.push_back(CE->getOperand(i));
1124 // Add the last index of the source with the first index of the new GEP.
1125 // Make sure to handle the case when they are actually different types.
1126 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1127 // Otherwise it must be an array.
1128 if (!Idx0->isNullValue()) {
1129 const Type *IdxTy = Combined->getType();
1130 if (IdxTy != Idx0->getType()) IdxTy = Type::LongTy;
1132 ConstantExpr::get(Instruction::Add,
1133 ConstantExpr::getCast(Idx0, IdxTy),
1134 ConstantExpr::getCast(Combined, IdxTy));
1137 NewIndices.push_back(Combined);
1138 NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
1139 return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
1143 // Implement folding of:
1144 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1146 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1148 if (CE->getOpcode() == Instruction::Cast && IdxList.size() > 1 &&
1149 Idx0->isNullValue())
1150 if (const PointerType *SPT =
1151 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1152 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1153 if (const ArrayType *CAT =
1154 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1155 if (CAT->getElementType() == SAT->getElementType())
1156 return ConstantExpr::getGetElementPtr(
1157 (Constant*)CE->getOperand(0), IdxList);