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);
331 //===----------------------------------------------------------------------===//
332 // ConstantPackedRules Class
333 //===----------------------------------------------------------------------===//
335 /// PackedTypeRules provides a concrete base class of ConstRules for
336 /// ConstantPacked operands.
338 struct ConstantPackedRules
339 : public TemplateRules<ConstantPacked, ConstantPackedRules> {
343 //===----------------------------------------------------------------------===//
344 // GeneralPackedRules Class
345 //===----------------------------------------------------------------------===//
347 /// GeneralPackedRules provides a concrete base class of ConstRules for
348 /// PackedType operands, where both operands are not ConstantPacked. The usual
349 /// cause for this is that one operand is a ConstantAggregateZero.
351 struct GeneralPackedRules : public TemplateRules<Constant, GeneralPackedRules> {
355 //===----------------------------------------------------------------------===//
357 //===----------------------------------------------------------------------===//
359 // DirectRules provides a concrete base classes of ConstRules for a variety of
360 // different types. This allows the C++ compiler to automatically generate our
361 // constant handling operations in a typesafe and accurate manner.
363 template<class ConstantClass, class BuiltinType, Type **Ty, class SuperClass>
364 struct DirectRules : public TemplateRules<ConstantClass, SuperClass> {
365 static Constant *Add(const ConstantClass *V1, const ConstantClass *V2) {
366 BuiltinType R = (BuiltinType)V1->getValue() + (BuiltinType)V2->getValue();
367 return ConstantClass::get(*Ty, R);
370 static Constant *Sub(const ConstantClass *V1, const ConstantClass *V2) {
371 BuiltinType R = (BuiltinType)V1->getValue() - (BuiltinType)V2->getValue();
372 return ConstantClass::get(*Ty, R);
375 static Constant *Mul(const ConstantClass *V1, const ConstantClass *V2) {
376 BuiltinType R = (BuiltinType)V1->getValue() * (BuiltinType)V2->getValue();
377 return ConstantClass::get(*Ty, R);
380 static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
381 if (V2->isNullValue()) return 0;
382 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
383 return ConstantClass::get(*Ty, R);
386 static Constant *LessThan(const ConstantClass *V1, const ConstantClass *V2) {
387 bool R = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue();
388 return ConstantBool::get(R);
391 static Constant *EqualTo(const ConstantClass *V1, const ConstantClass *V2) {
392 bool R = (BuiltinType)V1->getValue() == (BuiltinType)V2->getValue();
393 return ConstantBool::get(R);
396 static Constant *CastToPointer(const ConstantClass *V,
397 const PointerType *PTy) {
398 if (V->isNullValue()) // Is it a FP or Integral null value?
399 return ConstantPointerNull::get(PTy);
400 return 0; // Can't const prop other types of pointers
403 // Casting operators. ick
404 #define DEF_CAST(TYPE, CLASS, CTYPE) \
405 static Constant *CastTo##TYPE (const ConstantClass *V) { \
406 return CLASS::get(Type::TYPE##Ty, (CTYPE)(BuiltinType)V->getValue()); \
409 DEF_CAST(Bool , ConstantBool, bool)
410 DEF_CAST(SByte , ConstantSInt, signed char)
411 DEF_CAST(UByte , ConstantUInt, unsigned char)
412 DEF_CAST(Short , ConstantSInt, signed short)
413 DEF_CAST(UShort, ConstantUInt, unsigned short)
414 DEF_CAST(Int , ConstantSInt, signed int)
415 DEF_CAST(UInt , ConstantUInt, unsigned int)
416 DEF_CAST(Long , ConstantSInt, int64_t)
417 DEF_CAST(ULong , ConstantUInt, uint64_t)
418 DEF_CAST(Float , ConstantFP , float)
419 DEF_CAST(Double, ConstantFP , double)
424 //===----------------------------------------------------------------------===//
425 // DirectIntRules Class
426 //===----------------------------------------------------------------------===//
428 // DirectIntRules provides implementations of functions that are valid on
429 // integer types, but not all types in general.
431 template <class ConstantClass, class BuiltinType, Type **Ty>
432 struct DirectIntRules
433 : public DirectRules<ConstantClass, BuiltinType, Ty,
434 DirectIntRules<ConstantClass, BuiltinType, Ty> > {
436 static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
437 if (V2->isNullValue()) return 0;
438 if (V2->isAllOnesValue() && // MIN_INT / -1
439 (BuiltinType)V1->getValue() == -(BuiltinType)V1->getValue())
441 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
442 return ConstantClass::get(*Ty, R);
445 static Constant *Rem(const ConstantClass *V1,
446 const ConstantClass *V2) {
447 if (V2->isNullValue()) return 0; // X / 0
448 if (V2->isAllOnesValue() && // MIN_INT / -1
449 (BuiltinType)V1->getValue() == -(BuiltinType)V1->getValue())
451 BuiltinType R = (BuiltinType)V1->getValue() % (BuiltinType)V2->getValue();
452 return ConstantClass::get(*Ty, R);
455 static Constant *And(const ConstantClass *V1, const ConstantClass *V2) {
456 BuiltinType R = (BuiltinType)V1->getValue() & (BuiltinType)V2->getValue();
457 return ConstantClass::get(*Ty, R);
459 static Constant *Or(const ConstantClass *V1, const ConstantClass *V2) {
460 BuiltinType R = (BuiltinType)V1->getValue() | (BuiltinType)V2->getValue();
461 return ConstantClass::get(*Ty, R);
463 static Constant *Xor(const ConstantClass *V1, const ConstantClass *V2) {
464 BuiltinType R = (BuiltinType)V1->getValue() ^ (BuiltinType)V2->getValue();
465 return ConstantClass::get(*Ty, R);
468 static Constant *Shl(const ConstantClass *V1, const ConstantClass *V2) {
469 BuiltinType R = (BuiltinType)V1->getValue() << (BuiltinType)V2->getValue();
470 return ConstantClass::get(*Ty, R);
473 static Constant *Shr(const ConstantClass *V1, const ConstantClass *V2) {
474 BuiltinType R = (BuiltinType)V1->getValue() >> (BuiltinType)V2->getValue();
475 return ConstantClass::get(*Ty, R);
480 //===----------------------------------------------------------------------===//
481 // DirectFPRules Class
482 //===----------------------------------------------------------------------===//
484 /// DirectFPRules provides implementations of functions that are valid on
485 /// floating point types, but not all types in general.
487 template <class ConstantClass, class BuiltinType, Type **Ty>
489 : public DirectRules<ConstantClass, BuiltinType, Ty,
490 DirectFPRules<ConstantClass, BuiltinType, Ty> > {
491 static Constant *Rem(const ConstantClass *V1, const ConstantClass *V2) {
492 if (V2->isNullValue()) return 0;
493 BuiltinType Result = std::fmod((BuiltinType)V1->getValue(),
494 (BuiltinType)V2->getValue());
495 return ConstantClass::get(*Ty, Result);
497 static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
498 BuiltinType inf = std::numeric_limits<BuiltinType>::infinity();
499 if (V2->isExactlyValue(0.0)) return ConstantClass::get(*Ty, inf);
500 if (V2->isExactlyValue(-0.0)) return ConstantClass::get(*Ty, -inf);
501 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
502 return ConstantClass::get(*Ty, R);
507 /// ConstRules::get - This method returns the constant rules implementation that
508 /// implements the semantics of the two specified constants.
509 ConstRules &ConstRules::get(const Constant *V1, const Constant *V2) {
510 static EmptyRules EmptyR;
511 static BoolRules BoolR;
512 static NullPointerRules NullPointerR;
513 static ConstantPackedRules ConstantPackedR;
514 static GeneralPackedRules GeneralPackedR;
515 static DirectIntRules<ConstantSInt, signed char , &Type::SByteTy> SByteR;
516 static DirectIntRules<ConstantUInt, unsigned char , &Type::UByteTy> UByteR;
517 static DirectIntRules<ConstantSInt, signed short, &Type::ShortTy> ShortR;
518 static DirectIntRules<ConstantUInt, unsigned short, &Type::UShortTy> UShortR;
519 static DirectIntRules<ConstantSInt, signed int , &Type::IntTy> IntR;
520 static DirectIntRules<ConstantUInt, unsigned int , &Type::UIntTy> UIntR;
521 static DirectIntRules<ConstantSInt, int64_t , &Type::LongTy> LongR;
522 static DirectIntRules<ConstantUInt, uint64_t , &Type::ULongTy> ULongR;
523 static DirectFPRules <ConstantFP , float , &Type::FloatTy> FloatR;
524 static DirectFPRules <ConstantFP , double , &Type::DoubleTy> DoubleR;
526 if (isa<ConstantExpr>(V1) || isa<ConstantExpr>(V2) ||
527 isa<GlobalValue>(V1) || isa<GlobalValue>(V2) ||
528 isa<UndefValue>(V1) || isa<UndefValue>(V2))
531 switch (V1->getType()->getTypeID()) {
532 default: assert(0 && "Unknown value type for constant folding!");
533 case Type::BoolTyID: return BoolR;
534 case Type::PointerTyID: return NullPointerR;
535 case Type::SByteTyID: return SByteR;
536 case Type::UByteTyID: return UByteR;
537 case Type::ShortTyID: return ShortR;
538 case Type::UShortTyID: return UShortR;
539 case Type::IntTyID: return IntR;
540 case Type::UIntTyID: return UIntR;
541 case Type::LongTyID: return LongR;
542 case Type::ULongTyID: return ULongR;
543 case Type::FloatTyID: return FloatR;
544 case Type::DoubleTyID: return DoubleR;
545 case Type::PackedTyID:
546 if (isa<ConstantPacked>(V1) && isa<ConstantPacked>(V2))
547 return ConstantPackedR;
548 return GeneralPackedR; // Constant folding rules for ConstantAggregateZero.
553 //===----------------------------------------------------------------------===//
554 // ConstantFold*Instruction Implementations
555 //===----------------------------------------------------------------------===//
557 // These methods contain the special case hackery required to symbolically
558 // evaluate some constant expression cases, and use the ConstantRules class to
559 // evaluate normal constants.
561 static unsigned getSize(const Type *Ty) {
562 unsigned S = Ty->getPrimitiveSize();
563 return S ? S : 8; // Treat pointers at 8 bytes
566 Constant *llvm::ConstantFoldCastInstruction(const Constant *V,
567 const Type *DestTy) {
568 if (V->getType() == DestTy) return (Constant*)V;
570 // Cast of a global address to boolean is always true.
571 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
572 if (DestTy == Type::BoolTy)
573 // FIXME: When we support 'external weak' references, we have to prevent
574 // this transformation from happening. This code will need to be updated
575 // to ignore external weak symbols when we support it.
576 return ConstantBool::True;
577 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
578 if (CE->getOpcode() == Instruction::Cast) {
579 Constant *Op = const_cast<Constant*>(CE->getOperand(0));
580 // Try to not produce a cast of a cast, which is almost always redundant.
581 if (!Op->getType()->isFloatingPoint() &&
582 !CE->getType()->isFloatingPoint() &&
583 !DestTy->isFloatingPoint()) {
584 unsigned S1 = getSize(Op->getType()), S2 = getSize(CE->getType());
585 unsigned S3 = getSize(DestTy);
586 if (Op->getType() == DestTy && S3 >= S2)
588 if (S1 >= S2 && S2 >= S3)
589 return ConstantExpr::getCast(Op, DestTy);
590 if (S1 <= S2 && S2 >= S3 && S1 <= S3)
591 return ConstantExpr::getCast(Op, DestTy);
593 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
594 // If all of the indexes in the GEP are null values, there is no pointer
595 // adjustment going on. We might as well cast the source pointer.
596 bool isAllNull = true;
597 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
598 if (!CE->getOperand(i)->isNullValue()) {
603 return ConstantExpr::getCast(CE->getOperand(0), DestTy);
605 } else if (isa<UndefValue>(V)) {
606 return UndefValue::get(DestTy);
609 // Check to see if we are casting an pointer to an aggregate to a pointer to
610 // the first element. If so, return the appropriate GEP instruction.
611 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
612 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
613 std::vector<Value*> IdxList;
614 IdxList.push_back(Constant::getNullValue(Type::IntTy));
615 const Type *ElTy = PTy->getElementType();
616 while (ElTy != DPTy->getElementType()) {
617 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
618 if (STy->getNumElements() == 0) break;
619 ElTy = STy->getElementType(0);
620 IdxList.push_back(Constant::getNullValue(Type::UIntTy));
621 } else if (const SequentialType *STy = dyn_cast<SequentialType>(ElTy)) {
622 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
623 ElTy = STy->getElementType();
624 IdxList.push_back(IdxList[0]);
630 if (ElTy == DPTy->getElementType())
631 return ConstantExpr::getGetElementPtr(const_cast<Constant*>(V),IdxList);
634 ConstRules &Rules = ConstRules::get(V, V);
636 switch (DestTy->getTypeID()) {
637 case Type::BoolTyID: return Rules.castToBool(V);
638 case Type::UByteTyID: return Rules.castToUByte(V);
639 case Type::SByteTyID: return Rules.castToSByte(V);
640 case Type::UShortTyID: return Rules.castToUShort(V);
641 case Type::ShortTyID: return Rules.castToShort(V);
642 case Type::UIntTyID: return Rules.castToUInt(V);
643 case Type::IntTyID: return Rules.castToInt(V);
644 case Type::ULongTyID: return Rules.castToULong(V);
645 case Type::LongTyID: return Rules.castToLong(V);
646 case Type::FloatTyID: return Rules.castToFloat(V);
647 case Type::DoubleTyID: return Rules.castToDouble(V);
648 case Type::PointerTyID:
649 return Rules.castToPointer(V, cast<PointerType>(DestTy));
654 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
656 const Constant *V2) {
657 if (Cond == ConstantBool::True)
658 return const_cast<Constant*>(V1);
659 else if (Cond == ConstantBool::False)
660 return const_cast<Constant*>(V2);
662 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
663 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
664 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
668 /// isZeroSizedType - This type is zero sized if its an array or structure of
669 /// zero sized types. The only leaf zero sized type is an empty structure.
670 static bool isMaybeZeroSizedType(const Type *Ty) {
671 if (isa<OpaqueType>(Ty)) return true; // Can't say.
672 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
674 // If all of elements have zero size, this does too.
675 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
676 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
679 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
680 return isMaybeZeroSizedType(ATy->getElementType());
685 /// IdxCompare - Compare the two constants as though they were getelementptr
686 /// indices. This allows coersion of the types to be the same thing.
688 /// If the two constants are the "same" (after coersion), return 0. If the
689 /// first is less than the second, return -1, if the second is less than the
690 /// first, return 1. If the constants are not integral, return -2.
692 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
693 if (C1 == C2) return 0;
695 // Ok, we found a different index. Are either of the operands
696 // ConstantExprs? If so, we can't do anything with them.
697 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
698 return -2; // don't know!
700 // Ok, we have two differing integer indices. Sign extend them to be the same
701 // type. Long is always big enough, so we use it.
702 C1 = ConstantExpr::getSignExtend(C1, Type::LongTy);
703 C2 = ConstantExpr::getSignExtend(C2, Type::LongTy);
704 if (C1 == C2) return 0; // Are they just differing types?
706 // If the type being indexed over is really just a zero sized type, there is
707 // no pointer difference being made here.
708 if (isMaybeZeroSizedType(ElTy))
711 // If they are really different, now that they are the same type, then we
712 // found a difference!
713 if (cast<ConstantSInt>(C1)->getValue() < cast<ConstantSInt>(C2)->getValue())
719 /// evaluateRelation - This function determines if there is anything we can
720 /// decide about the two constants provided. This doesn't need to handle simple
721 /// things like integer comparisons, but should instead handle ConstantExprs
722 /// and GlobalValuess. If we can determine that the two constants have a
723 /// particular relation to each other, we should return the corresponding SetCC
724 /// code, otherwise return Instruction::BinaryOpsEnd.
726 /// To simplify this code we canonicalize the relation so that the first
727 /// operand is always the most "complex" of the two. We consider simple
728 /// constants (like ConstantInt) to be the simplest, followed by
729 /// GlobalValues, followed by ConstantExpr's (the most complex).
731 static Instruction::BinaryOps evaluateRelation(const Constant *V1,
732 const Constant *V2) {
733 assert(V1->getType() == V2->getType() &&
734 "Cannot compare different types of values!");
735 if (V1 == V2) return Instruction::SetEQ;
737 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
738 // If the first operand is simple, swap operands.
739 assert((isa<GlobalValue>(V2) || isa<ConstantExpr>(V2)) &&
740 "Simple cases should have been handled by caller!");
741 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
742 if (SwappedRelation != Instruction::BinaryOpsEnd)
743 return SetCondInst::getSwappedCondition(SwappedRelation);
745 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)){
746 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
747 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
748 if (SwappedRelation != Instruction::BinaryOpsEnd)
749 return SetCondInst::getSwappedCondition(SwappedRelation);
751 return Instruction::BinaryOpsEnd;
754 // Now we know that the RHS is a GlobalValue or simple constant,
755 // which (since the types must match) means that it's a ConstantPointerNull.
756 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
757 assert(CPR1 != CPR2 &&
758 "GVs for the same value exist at different addresses??");
759 // FIXME: If both globals are external weak, they might both be null!
760 return Instruction::SetNE;
762 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
763 // Global can never be null. FIXME: if we implement external weak
764 // linkage, this is not necessarily true!
765 return Instruction::SetNE;
769 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
770 // constantexpr, a CPR, or a simple constant.
771 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
772 Constant *CE1Op0 = CE1->getOperand(0);
774 switch (CE1->getOpcode()) {
775 case Instruction::Cast:
776 // If the cast is not actually changing bits, and the second operand is a
777 // null pointer, do the comparison with the pre-casted value.
778 if (V2->isNullValue() &&
779 CE1->getType()->isLosslesslyConvertibleTo(CE1Op0->getType()))
780 return evaluateRelation(CE1Op0,
781 Constant::getNullValue(CE1Op0->getType()));
784 case Instruction::GetElementPtr:
785 // Ok, since this is a getelementptr, we know that the constant has a
786 // pointer type. Check the various cases.
787 if (isa<ConstantPointerNull>(V2)) {
788 // If we are comparing a GEP to a null pointer, check to see if the base
789 // of the GEP equals the null pointer.
790 if (isa<GlobalValue>(CE1Op0)) {
791 // FIXME: this is not true when we have external weak references!
792 // No offset can go from a global to a null pointer.
793 return Instruction::SetGT;
794 } else if (isa<ConstantPointerNull>(CE1Op0)) {
795 // If we are indexing from a null pointer, check to see if we have any
797 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
798 if (!CE1->getOperand(i)->isNullValue())
799 // Offsetting from null, must not be equal.
800 return Instruction::SetGT;
801 // Only zero indexes from null, must still be zero.
802 return Instruction::SetEQ;
804 // Otherwise, we can't really say if the first operand is null or not.
805 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
806 if (isa<ConstantPointerNull>(CE1Op0)) {
807 // FIXME: This is not true with external weak references.
808 return Instruction::SetLT;
809 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
811 // If this is a getelementptr of the same global, then it must be
812 // different. Because the types must match, the getelementptr could
813 // only have at most one index, and because we fold getelementptr's
814 // with a single zero index, it must be nonzero.
815 assert(CE1->getNumOperands() == 2 &&
816 !CE1->getOperand(1)->isNullValue() &&
817 "Suprising getelementptr!");
818 return Instruction::SetGT;
820 // If they are different globals, we don't know what the value is,
821 // but they can't be equal.
822 return Instruction::SetNE;
826 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
827 const Constant *CE2Op0 = CE2->getOperand(0);
829 // There are MANY other foldings that we could perform here. They will
830 // probably be added on demand, as they seem needed.
831 switch (CE2->getOpcode()) {
833 case Instruction::GetElementPtr:
834 // By far the most common case to handle is when the base pointers are
835 // obviously to the same or different globals.
836 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
837 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
838 return Instruction::SetNE;
839 // Ok, we know that both getelementptr instructions are based on the
840 // same global. From this, we can precisely determine the relative
841 // ordering of the resultant pointers.
844 // Compare all of the operands the GEP's have in common.
845 gep_type_iterator GTI = gep_type_begin(CE1);
846 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
848 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
849 GTI.getIndexedType())) {
850 case -1: return Instruction::SetLT;
851 case 1: return Instruction::SetGT;
852 case -2: return Instruction::BinaryOpsEnd;
855 // Ok, we ran out of things they have in common. If any leftovers
856 // are non-zero then we have a difference, otherwise we are equal.
857 for (; i < CE1->getNumOperands(); ++i)
858 if (!CE1->getOperand(i)->isNullValue())
859 if (isa<ConstantIntegral>(CE1->getOperand(i)))
860 return Instruction::SetGT;
862 return Instruction::BinaryOpsEnd; // Might be equal.
864 for (; i < CE2->getNumOperands(); ++i)
865 if (!CE2->getOperand(i)->isNullValue())
866 if (isa<ConstantIntegral>(CE2->getOperand(i)))
867 return Instruction::SetLT;
869 return Instruction::BinaryOpsEnd; // Might be equal.
870 return Instruction::SetEQ;
880 return Instruction::BinaryOpsEnd;
883 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
885 const Constant *V2) {
889 case Instruction::Add: C = ConstRules::get(V1, V2).add(V1, V2); break;
890 case Instruction::Sub: C = ConstRules::get(V1, V2).sub(V1, V2); break;
891 case Instruction::Mul: C = ConstRules::get(V1, V2).mul(V1, V2); break;
892 case Instruction::Div: C = ConstRules::get(V1, V2).div(V1, V2); break;
893 case Instruction::Rem: C = ConstRules::get(V1, V2).rem(V1, V2); break;
894 case Instruction::And: C = ConstRules::get(V1, V2).op_and(V1, V2); break;
895 case Instruction::Or: C = ConstRules::get(V1, V2).op_or (V1, V2); break;
896 case Instruction::Xor: C = ConstRules::get(V1, V2).op_xor(V1, V2); break;
897 case Instruction::Shl: C = ConstRules::get(V1, V2).shl(V1, V2); break;
898 case Instruction::Shr: C = ConstRules::get(V1, V2).shr(V1, V2); break;
899 case Instruction::SetEQ: C = ConstRules::get(V1, V2).equalto(V1, V2); break;
900 case Instruction::SetLT: C = ConstRules::get(V1, V2).lessthan(V1, V2);break;
901 case Instruction::SetGT: C = ConstRules::get(V1, V2).lessthan(V2, V1);break;
902 case Instruction::SetNE: // V1 != V2 === !(V1 == V2)
903 C = ConstRules::get(V1, V2).equalto(V1, V2);
904 if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
906 case Instruction::SetLE: // V1 <= V2 === !(V2 < V1)
907 C = ConstRules::get(V1, V2).lessthan(V2, V1);
908 if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
910 case Instruction::SetGE: // V1 >= V2 === !(V1 < V2)
911 C = ConstRules::get(V1, V2).lessthan(V1, V2);
912 if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
916 // If we successfully folded the expression, return it now.
919 if (SetCondInst::isRelational(Opcode)) {
920 if (isa<UndefValue>(V1) || isa<UndefValue>(V2))
921 return UndefValue::get(Type::BoolTy);
922 switch (evaluateRelation(V1, V2)) {
923 default: assert(0 && "Unknown relational!");
924 case Instruction::BinaryOpsEnd:
925 break; // Couldn't determine anything about these constants.
926 case Instruction::SetEQ: // We know the constants are equal!
927 // If we know the constants are equal, we can decide the result of this
928 // computation precisely.
929 return ConstantBool::get(Opcode == Instruction::SetEQ ||
930 Opcode == Instruction::SetLE ||
931 Opcode == Instruction::SetGE);
932 case Instruction::SetLT:
933 // If we know that V1 < V2, we can decide the result of this computation
935 return ConstantBool::get(Opcode == Instruction::SetLT ||
936 Opcode == Instruction::SetNE ||
937 Opcode == Instruction::SetLE);
938 case Instruction::SetGT:
939 // If we know that V1 > V2, we can decide the result of this computation
941 return ConstantBool::get(Opcode == Instruction::SetGT ||
942 Opcode == Instruction::SetNE ||
943 Opcode == Instruction::SetGE);
944 case Instruction::SetLE:
945 // If we know that V1 <= V2, we can only partially decide this relation.
946 if (Opcode == Instruction::SetGT) return ConstantBool::False;
947 if (Opcode == Instruction::SetLT) return ConstantBool::True;
950 case Instruction::SetGE:
951 // If we know that V1 >= V2, we can only partially decide this relation.
952 if (Opcode == Instruction::SetLT) return ConstantBool::False;
953 if (Opcode == Instruction::SetGT) return ConstantBool::True;
956 case Instruction::SetNE:
957 // If we know that V1 != V2, we can only partially decide this relation.
958 if (Opcode == Instruction::SetEQ) return ConstantBool::False;
959 if (Opcode == Instruction::SetNE) return ConstantBool::True;
964 if (isa<UndefValue>(V1) || isa<UndefValue>(V2)) {
966 case Instruction::Add:
967 case Instruction::Sub:
968 case Instruction::Xor:
969 return UndefValue::get(V1->getType());
971 case Instruction::Mul:
972 case Instruction::And:
973 return Constant::getNullValue(V1->getType());
974 case Instruction::Div:
975 case Instruction::Rem:
976 if (!isa<UndefValue>(V2)) // undef/X -> 0
977 return Constant::getNullValue(V1->getType());
978 return const_cast<Constant*>(V2); // X/undef -> undef
979 case Instruction::Or: // X|undef -> -1
980 return ConstantInt::getAllOnesValue(V1->getType());
981 case Instruction::Shr:
982 if (!isa<UndefValue>(V2)) {
983 if (V1->getType()->isSigned())
984 return const_cast<Constant*>(V1); // undef >>s X -> undef
986 } else if (isa<UndefValue>(V1)) {
987 return const_cast<Constant*>(V1); // undef >> undef -> undef
989 if (V1->getType()->isSigned())
990 return const_cast<Constant*>(V1); // X >>s undef -> X
993 return Constant::getNullValue(V1->getType());
995 case Instruction::Shl:
996 // undef << X -> 0 X << undef -> 0
997 return Constant::getNullValue(V1->getType());
1001 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(V1)) {
1002 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
1003 // There are many possible foldings we could do here. We should probably
1004 // at least fold add of a pointer with an integer into the appropriate
1005 // getelementptr. This will improve alias analysis a bit.
1011 // Just implement a couple of simple identities.
1013 case Instruction::Add:
1014 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X + 0 == X
1016 case Instruction::Sub:
1017 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X - 0 == X
1019 case Instruction::Mul:
1020 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X * 0 == 0
1021 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1022 if (CI->getRawValue() == 1)
1023 return const_cast<Constant*>(V1); // X * 1 == X
1025 case Instruction::Div:
1026 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1027 if (CI->getRawValue() == 1)
1028 return const_cast<Constant*>(V1); // X / 1 == X
1030 case Instruction::Rem:
1031 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1032 if (CI->getRawValue() == 1)
1033 return Constant::getNullValue(CI->getType()); // X % 1 == 0
1035 case Instruction::And:
1036 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1037 return const_cast<Constant*>(V1); // X & -1 == X
1038 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X & 0 == 0
1039 if (CE1->getOpcode() == Instruction::Cast &&
1040 isa<GlobalValue>(CE1->getOperand(0))) {
1041 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
1043 // Functions are at least 4-byte aligned. If and'ing the address of a
1044 // function with a constant < 4, fold it to zero.
1045 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1046 if (CI->getRawValue() < 4 && isa<Function>(CPR))
1047 return Constant::getNullValue(CI->getType());
1050 case Instruction::Or:
1051 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X | 0 == X
1052 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1053 return const_cast<Constant*>(V2); // X | -1 == -1
1055 case Instruction::Xor:
1056 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X ^ 0 == X
1061 } else if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
1062 // If V2 is a constant expr and V1 isn't, flop them around and fold the
1063 // other way if possible.
1065 case Instruction::Add:
1066 case Instruction::Mul:
1067 case Instruction::And:
1068 case Instruction::Or:
1069 case Instruction::Xor:
1070 case Instruction::SetEQ:
1071 case Instruction::SetNE:
1072 // No change of opcode required.
1073 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1075 case Instruction::SetLT:
1076 case Instruction::SetGT:
1077 case Instruction::SetLE:
1078 case Instruction::SetGE:
1079 // Change the opcode as necessary to swap the operands.
1080 Opcode = SetCondInst::getSwappedCondition((Instruction::BinaryOps)Opcode);
1081 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1083 case Instruction::Shl:
1084 case Instruction::Shr:
1085 case Instruction::Sub:
1086 case Instruction::Div:
1087 case Instruction::Rem:
1088 default: // These instructions cannot be flopped around.
1095 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1096 const std::vector<Value*> &IdxList) {
1097 if (IdxList.size() == 0 ||
1098 (IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
1099 return const_cast<Constant*>(C);
1101 if (isa<UndefValue>(C)) {
1102 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1104 assert(Ty != 0 && "Invalid indices for GEP!");
1105 return UndefValue::get(PointerType::get(Ty));
1108 Constant *Idx0 = cast<Constant>(IdxList[0]);
1109 if (C->isNullValue()) {
1111 for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
1112 if (!cast<Constant>(IdxList[i])->isNullValue()) {
1117 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1119 assert(Ty != 0 && "Invalid indices for GEP!");
1120 return ConstantPointerNull::get(PointerType::get(Ty));
1123 if (IdxList.size() == 1) {
1124 const Type *ElTy = cast<PointerType>(C->getType())->getElementType();
1125 if (unsigned ElSize = ElTy->getPrimitiveSize()) {
1126 // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm
1127 // type, we can statically fold this.
1128 Constant *R = ConstantUInt::get(Type::UIntTy, ElSize);
1129 R = ConstantExpr::getCast(R, Idx0->getType());
1130 R = ConstantExpr::getMul(R, Idx0);
1131 return ConstantExpr::getCast(R, C->getType());
1136 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1137 // Combine Indices - If the source pointer to this getelementptr instruction
1138 // is a getelementptr instruction, combine the indices of the two
1139 // getelementptr instructions into a single instruction.
1141 if (CE->getOpcode() == Instruction::GetElementPtr) {
1142 const Type *LastTy = 0;
1143 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1147 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1148 std::vector<Value*> NewIndices;
1149 NewIndices.reserve(IdxList.size() + CE->getNumOperands());
1150 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1151 NewIndices.push_back(CE->getOperand(i));
1153 // Add the last index of the source with the first index of the new GEP.
1154 // Make sure to handle the case when they are actually different types.
1155 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1156 // Otherwise it must be an array.
1157 if (!Idx0->isNullValue()) {
1158 const Type *IdxTy = Combined->getType();
1159 if (IdxTy != Idx0->getType()) IdxTy = Type::LongTy;
1161 ConstantExpr::get(Instruction::Add,
1162 ConstantExpr::getCast(Idx0, IdxTy),
1163 ConstantExpr::getCast(Combined, IdxTy));
1166 NewIndices.push_back(Combined);
1167 NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
1168 return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
1172 // Implement folding of:
1173 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1175 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1177 if (CE->getOpcode() == Instruction::Cast && IdxList.size() > 1 &&
1178 Idx0->isNullValue())
1179 if (const PointerType *SPT =
1180 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1181 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1182 if (const ArrayType *CAT =
1183 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1184 if (CAT->getElementType() == SAT->getElementType())
1185 return ConstantExpr::getGetElementPtr(
1186 (Constant*)CE->getOperand(0), IdxList);