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"
27 #include "llvm/Support/MathExtras.h"
35 virtual ~ConstRules() {}
37 // Binary Operators...
38 virtual Constant *add(const Constant *V1, const Constant *V2) const = 0;
39 virtual Constant *sub(const Constant *V1, const Constant *V2) const = 0;
40 virtual Constant *mul(const Constant *V1, const Constant *V2) const = 0;
41 virtual Constant *div(const Constant *V1, const Constant *V2) const = 0;
42 virtual Constant *rem(const Constant *V1, const Constant *V2) const = 0;
43 virtual Constant *op_and(const Constant *V1, const Constant *V2) const = 0;
44 virtual Constant *op_or (const Constant *V1, const Constant *V2) const = 0;
45 virtual Constant *op_xor(const Constant *V1, const Constant *V2) const = 0;
46 virtual Constant *shl(const Constant *V1, const Constant *V2) const = 0;
47 virtual Constant *shr(const Constant *V1, const Constant *V2) const = 0;
48 virtual Constant *lessthan(const Constant *V1, const Constant *V2) const =0;
49 virtual Constant *equalto(const Constant *V1, const Constant *V2) const = 0;
52 virtual Constant *castToBool (const Constant *V) const = 0;
53 virtual Constant *castToSByte (const Constant *V) const = 0;
54 virtual Constant *castToUByte (const Constant *V) const = 0;
55 virtual Constant *castToShort (const Constant *V) const = 0;
56 virtual Constant *castToUShort(const Constant *V) const = 0;
57 virtual Constant *castToInt (const Constant *V) const = 0;
58 virtual Constant *castToUInt (const Constant *V) const = 0;
59 virtual Constant *castToLong (const Constant *V) const = 0;
60 virtual Constant *castToULong (const Constant *V) const = 0;
61 virtual Constant *castToFloat (const Constant *V) const = 0;
62 virtual Constant *castToDouble(const Constant *V) const = 0;
63 virtual Constant *castToPointer(const Constant *V,
64 const PointerType *Ty) const = 0;
66 // ConstRules::get - Return an instance of ConstRules for the specified
69 static ConstRules &get(const Constant *V1, const Constant *V2);
71 ConstRules(const ConstRules &); // Do not implement
72 ConstRules &operator=(const ConstRules &); // Do not implement
77 //===----------------------------------------------------------------------===//
78 // TemplateRules Class
79 //===----------------------------------------------------------------------===//
81 // TemplateRules - Implement a subclass of ConstRules that provides all
82 // operations as noops. All other rules classes inherit from this class so
83 // that if functionality is needed in the future, it can simply be added here
84 // and to ConstRules without changing anything else...
86 // This class also provides subclasses with typesafe implementations of methods
87 // so that don't have to do type casting.
89 template<class ArgType, class SubClassName>
90 class TemplateRules : public ConstRules {
93 //===--------------------------------------------------------------------===//
94 // Redirecting functions that cast to the appropriate types
95 //===--------------------------------------------------------------------===//
97 virtual Constant *add(const Constant *V1, const Constant *V2) const {
98 return SubClassName::Add((const ArgType *)V1, (const ArgType *)V2);
100 virtual Constant *sub(const Constant *V1, const Constant *V2) const {
101 return SubClassName::Sub((const ArgType *)V1, (const ArgType *)V2);
103 virtual Constant *mul(const Constant *V1, const Constant *V2) const {
104 return SubClassName::Mul((const ArgType *)V1, (const ArgType *)V2);
106 virtual Constant *div(const Constant *V1, const Constant *V2) const {
107 return SubClassName::Div((const ArgType *)V1, (const ArgType *)V2);
109 virtual Constant *rem(const Constant *V1, const Constant *V2) const {
110 return SubClassName::Rem((const ArgType *)V1, (const ArgType *)V2);
112 virtual Constant *op_and(const Constant *V1, const Constant *V2) const {
113 return SubClassName::And((const ArgType *)V1, (const ArgType *)V2);
115 virtual Constant *op_or(const Constant *V1, const Constant *V2) const {
116 return SubClassName::Or((const ArgType *)V1, (const ArgType *)V2);
118 virtual Constant *op_xor(const Constant *V1, const Constant *V2) const {
119 return SubClassName::Xor((const ArgType *)V1, (const ArgType *)V2);
121 virtual Constant *shl(const Constant *V1, const Constant *V2) const {
122 return SubClassName::Shl((const ArgType *)V1, (const ArgType *)V2);
124 virtual Constant *shr(const Constant *V1, const Constant *V2) const {
125 return SubClassName::Shr((const ArgType *)V1, (const ArgType *)V2);
128 virtual Constant *lessthan(const Constant *V1, const Constant *V2) const {
129 return SubClassName::LessThan((const ArgType *)V1, (const ArgType *)V2);
131 virtual Constant *equalto(const Constant *V1, const Constant *V2) const {
132 return SubClassName::EqualTo((const ArgType *)V1, (const ArgType *)V2);
135 // Casting operators. ick
136 virtual Constant *castToBool(const Constant *V) const {
137 return SubClassName::CastToBool((const ArgType*)V);
139 virtual Constant *castToSByte(const Constant *V) const {
140 return SubClassName::CastToSByte((const ArgType*)V);
142 virtual Constant *castToUByte(const Constant *V) const {
143 return SubClassName::CastToUByte((const ArgType*)V);
145 virtual Constant *castToShort(const Constant *V) const {
146 return SubClassName::CastToShort((const ArgType*)V);
148 virtual Constant *castToUShort(const Constant *V) const {
149 return SubClassName::CastToUShort((const ArgType*)V);
151 virtual Constant *castToInt(const Constant *V) const {
152 return SubClassName::CastToInt((const ArgType*)V);
154 virtual Constant *castToUInt(const Constant *V) const {
155 return SubClassName::CastToUInt((const ArgType*)V);
157 virtual Constant *castToLong(const Constant *V) const {
158 return SubClassName::CastToLong((const ArgType*)V);
160 virtual Constant *castToULong(const Constant *V) const {
161 return SubClassName::CastToULong((const ArgType*)V);
163 virtual Constant *castToFloat(const Constant *V) const {
164 return SubClassName::CastToFloat((const ArgType*)V);
166 virtual Constant *castToDouble(const Constant *V) const {
167 return SubClassName::CastToDouble((const ArgType*)V);
169 virtual Constant *castToPointer(const Constant *V,
170 const PointerType *Ty) const {
171 return SubClassName::CastToPointer((const ArgType*)V, Ty);
174 //===--------------------------------------------------------------------===//
175 // Default "noop" implementations
176 //===--------------------------------------------------------------------===//
178 static Constant *Add(const ArgType *V1, const ArgType *V2) { return 0; }
179 static Constant *Sub(const ArgType *V1, const ArgType *V2) { return 0; }
180 static Constant *Mul(const ArgType *V1, const ArgType *V2) { return 0; }
181 static Constant *Div(const ArgType *V1, const ArgType *V2) { return 0; }
182 static Constant *Rem(const ArgType *V1, const ArgType *V2) { return 0; }
183 static Constant *And(const ArgType *V1, const ArgType *V2) { return 0; }
184 static Constant *Or (const ArgType *V1, const ArgType *V2) { return 0; }
185 static Constant *Xor(const ArgType *V1, const ArgType *V2) { return 0; }
186 static Constant *Shl(const ArgType *V1, const ArgType *V2) { return 0; }
187 static Constant *Shr(const ArgType *V1, const ArgType *V2) { return 0; }
188 static Constant *LessThan(const ArgType *V1, const ArgType *V2) {
191 static Constant *EqualTo(const ArgType *V1, const ArgType *V2) {
195 // Casting operators. ick
196 static Constant *CastToBool (const Constant *V) { return 0; }
197 static Constant *CastToSByte (const Constant *V) { return 0; }
198 static Constant *CastToUByte (const Constant *V) { return 0; }
199 static Constant *CastToShort (const Constant *V) { return 0; }
200 static Constant *CastToUShort(const Constant *V) { return 0; }
201 static Constant *CastToInt (const Constant *V) { return 0; }
202 static Constant *CastToUInt (const Constant *V) { return 0; }
203 static Constant *CastToLong (const Constant *V) { return 0; }
204 static Constant *CastToULong (const Constant *V) { return 0; }
205 static Constant *CastToFloat (const Constant *V) { return 0; }
206 static Constant *CastToDouble(const Constant *V) { return 0; }
207 static Constant *CastToPointer(const Constant *,
208 const PointerType *) {return 0;}
211 virtual ~TemplateRules() {}
216 //===----------------------------------------------------------------------===//
218 //===----------------------------------------------------------------------===//
220 // EmptyRules provides a concrete base class of ConstRules that does nothing
222 struct EmptyRules : public TemplateRules<Constant, EmptyRules> {
223 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
224 if (V1 == V2) return ConstantBool::True;
231 //===----------------------------------------------------------------------===//
233 //===----------------------------------------------------------------------===//
235 // BoolRules provides a concrete base class of ConstRules for the 'bool' type.
237 struct BoolRules : public TemplateRules<ConstantBool, BoolRules> {
239 static Constant *LessThan(const ConstantBool *V1, const ConstantBool *V2) {
240 return ConstantBool::get(V1->getValue() < V2->getValue());
243 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
244 return ConstantBool::get(V1 == V2);
247 static Constant *And(const ConstantBool *V1, const ConstantBool *V2) {
248 return ConstantBool::get(V1->getValue() & V2->getValue());
251 static Constant *Or(const ConstantBool *V1, const ConstantBool *V2) {
252 return ConstantBool::get(V1->getValue() | V2->getValue());
255 static Constant *Xor(const ConstantBool *V1, const ConstantBool *V2) {
256 return ConstantBool::get(V1->getValue() ^ V2->getValue());
259 // Casting operators. ick
260 #define DEF_CAST(TYPE, CLASS, CTYPE) \
261 static Constant *CastTo##TYPE (const ConstantBool *V) { \
262 return CLASS::get(Type::TYPE##Ty, (CTYPE)(bool)V->getValue()); \
265 DEF_CAST(Bool , ConstantBool, bool)
266 DEF_CAST(SByte , ConstantSInt, signed char)
267 DEF_CAST(UByte , ConstantUInt, unsigned char)
268 DEF_CAST(Short , ConstantSInt, signed short)
269 DEF_CAST(UShort, ConstantUInt, unsigned short)
270 DEF_CAST(Int , ConstantSInt, signed int)
271 DEF_CAST(UInt , ConstantUInt, unsigned int)
272 DEF_CAST(Long , ConstantSInt, int64_t)
273 DEF_CAST(ULong , ConstantUInt, uint64_t)
274 DEF_CAST(Float , ConstantFP , float)
275 DEF_CAST(Double, ConstantFP , double)
280 //===----------------------------------------------------------------------===//
281 // NullPointerRules Class
282 //===----------------------------------------------------------------------===//
284 // NullPointerRules provides a concrete base class of ConstRules for null
287 struct NullPointerRules : public TemplateRules<ConstantPointerNull,
289 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
290 return ConstantBool::True; // Null pointers are always equal
292 static Constant *CastToBool(const Constant *V) {
293 return ConstantBool::False;
295 static Constant *CastToSByte (const Constant *V) {
296 return ConstantSInt::get(Type::SByteTy, 0);
298 static Constant *CastToUByte (const Constant *V) {
299 return ConstantUInt::get(Type::UByteTy, 0);
301 static Constant *CastToShort (const Constant *V) {
302 return ConstantSInt::get(Type::ShortTy, 0);
304 static Constant *CastToUShort(const Constant *V) {
305 return ConstantUInt::get(Type::UShortTy, 0);
307 static Constant *CastToInt (const Constant *V) {
308 return ConstantSInt::get(Type::IntTy, 0);
310 static Constant *CastToUInt (const Constant *V) {
311 return ConstantUInt::get(Type::UIntTy, 0);
313 static Constant *CastToLong (const Constant *V) {
314 return ConstantSInt::get(Type::LongTy, 0);
316 static Constant *CastToULong (const Constant *V) {
317 return ConstantUInt::get(Type::ULongTy, 0);
319 static Constant *CastToFloat (const Constant *V) {
320 return ConstantFP::get(Type::FloatTy, 0);
322 static Constant *CastToDouble(const Constant *V) {
323 return ConstantFP::get(Type::DoubleTy, 0);
326 static Constant *CastToPointer(const ConstantPointerNull *V,
327 const PointerType *PTy) {
328 return ConstantPointerNull::get(PTy);
332 //===----------------------------------------------------------------------===//
333 // ConstantPackedRules Class
334 //===----------------------------------------------------------------------===//
336 /// DoVectorOp - Given two packed constants and a function pointer, apply the
337 /// function pointer to each element pair, producing a new ConstantPacked
339 static Constant *EvalVectorOp(const ConstantPacked *V1,
340 const ConstantPacked *V2,
341 Constant *(*FP)(Constant*, Constant*)) {
342 std::vector<Constant*> Res;
343 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
344 Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
345 const_cast<Constant*>(V2->getOperand(i))));
346 return ConstantPacked::get(Res);
349 /// PackedTypeRules provides a concrete base class of ConstRules for
350 /// ConstantPacked operands.
352 struct ConstantPackedRules
353 : public TemplateRules<ConstantPacked, ConstantPackedRules> {
355 static Constant *Add(const ConstantPacked *V1, const ConstantPacked *V2) {
356 return EvalVectorOp(V1, V2, ConstantExpr::getAdd);
358 static Constant *Sub(const ConstantPacked *V1, const ConstantPacked *V2) {
359 return EvalVectorOp(V1, V2, ConstantExpr::getSub);
361 static Constant *Mul(const ConstantPacked *V1, const ConstantPacked *V2) {
362 return EvalVectorOp(V1, V2, ConstantExpr::getMul);
364 static Constant *Div(const ConstantPacked *V1, const ConstantPacked *V2) {
365 return EvalVectorOp(V1, V2, ConstantExpr::getDiv);
367 static Constant *Rem(const ConstantPacked *V1, const ConstantPacked *V2) {
368 return EvalVectorOp(V1, V2, ConstantExpr::getRem);
370 static Constant *And(const ConstantPacked *V1, const ConstantPacked *V2) {
371 return EvalVectorOp(V1, V2, ConstantExpr::getAnd);
373 static Constant *Or (const ConstantPacked *V1, const ConstantPacked *V2) {
374 return EvalVectorOp(V1, V2, ConstantExpr::getOr);
376 static Constant *Xor(const ConstantPacked *V1, const ConstantPacked *V2) {
377 return EvalVectorOp(V1, V2, ConstantExpr::getXor);
379 static Constant *Shl(const ConstantPacked *V1, const ConstantPacked *V2) {
380 return EvalVectorOp(V1, V2, ConstantExpr::getShl);
382 static Constant *Shr(const ConstantPacked *V1, const ConstantPacked *V2) {
383 return EvalVectorOp(V1, V2, ConstantExpr::getShr);
385 static Constant *LessThan(const ConstantPacked *V1, const ConstantPacked *V2){
388 static Constant *EqualTo(const ConstantPacked *V1, const ConstantPacked *V2) {
389 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i) {
391 ConstantExpr::getSetEQ(const_cast<Constant*>(V1->getOperand(i)),
392 const_cast<Constant*>(V2->getOperand(i)));
393 if (ConstantBool *CB = dyn_cast<ConstantBool>(C))
396 // Otherwise, could not decide from any element pairs.
402 //===----------------------------------------------------------------------===//
403 // GeneralPackedRules Class
404 //===----------------------------------------------------------------------===//
406 /// GeneralPackedRules provides a concrete base class of ConstRules for
407 /// PackedType operands, where both operands are not ConstantPacked. The usual
408 /// cause for this is that one operand is a ConstantAggregateZero.
410 struct GeneralPackedRules : public TemplateRules<Constant, GeneralPackedRules> {
414 //===----------------------------------------------------------------------===//
416 //===----------------------------------------------------------------------===//
418 // DirectRules provides a concrete base classes of ConstRules for a variety of
419 // different types. This allows the C++ compiler to automatically generate our
420 // constant handling operations in a typesafe and accurate manner.
422 template<class ConstantClass, class BuiltinType, Type **Ty, class SuperClass>
423 struct DirectRules : public TemplateRules<ConstantClass, SuperClass> {
424 static Constant *Add(const ConstantClass *V1, const ConstantClass *V2) {
425 BuiltinType R = (BuiltinType)V1->getValue() + (BuiltinType)V2->getValue();
426 return ConstantClass::get(*Ty, R);
429 static Constant *Sub(const ConstantClass *V1, const ConstantClass *V2) {
430 BuiltinType R = (BuiltinType)V1->getValue() - (BuiltinType)V2->getValue();
431 return ConstantClass::get(*Ty, R);
434 static Constant *Mul(const ConstantClass *V1, const ConstantClass *V2) {
435 BuiltinType R = (BuiltinType)V1->getValue() * (BuiltinType)V2->getValue();
436 return ConstantClass::get(*Ty, R);
439 static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
440 if (V2->isNullValue()) return 0;
441 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
442 return ConstantClass::get(*Ty, R);
445 static Constant *LessThan(const ConstantClass *V1, const ConstantClass *V2) {
446 bool R = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue();
447 return ConstantBool::get(R);
450 static Constant *EqualTo(const ConstantClass *V1, const ConstantClass *V2) {
451 bool R = (BuiltinType)V1->getValue() == (BuiltinType)V2->getValue();
452 return ConstantBool::get(R);
455 static Constant *CastToPointer(const ConstantClass *V,
456 const PointerType *PTy) {
457 if (V->isNullValue()) // Is it a FP or Integral null value?
458 return ConstantPointerNull::get(PTy);
459 return 0; // Can't const prop other types of pointers
462 // Casting operators. ick
463 #define DEF_CAST(TYPE, CLASS, CTYPE) \
464 static Constant *CastTo##TYPE (const ConstantClass *V) { \
465 return CLASS::get(Type::TYPE##Ty, (CTYPE)(BuiltinType)V->getValue()); \
468 DEF_CAST(Bool , ConstantBool, bool)
469 DEF_CAST(SByte , ConstantSInt, signed char)
470 DEF_CAST(UByte , ConstantUInt, unsigned char)
471 DEF_CAST(Short , ConstantSInt, signed short)
472 DEF_CAST(UShort, ConstantUInt, unsigned short)
473 DEF_CAST(Int , ConstantSInt, signed int)
474 DEF_CAST(UInt , ConstantUInt, unsigned int)
475 DEF_CAST(Long , ConstantSInt, int64_t)
476 DEF_CAST(ULong , ConstantUInt, uint64_t)
477 DEF_CAST(Float , ConstantFP , float)
478 DEF_CAST(Double, ConstantFP , double)
483 //===----------------------------------------------------------------------===//
484 // DirectIntRules Class
485 //===----------------------------------------------------------------------===//
487 // DirectIntRules provides implementations of functions that are valid on
488 // integer types, but not all types in general.
490 template <class ConstantClass, class BuiltinType, Type **Ty>
491 struct DirectIntRules
492 : public DirectRules<ConstantClass, BuiltinType, Ty,
493 DirectIntRules<ConstantClass, BuiltinType, Ty> > {
495 static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
496 if (V2->isNullValue()) return 0;
497 if (V2->isAllOnesValue() && // MIN_INT / -1
498 (BuiltinType)V1->getValue() == -(BuiltinType)V1->getValue())
500 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
501 return ConstantClass::get(*Ty, R);
504 static Constant *Rem(const ConstantClass *V1,
505 const ConstantClass *V2) {
506 if (V2->isNullValue()) return 0; // X / 0
507 if (V2->isAllOnesValue() && // MIN_INT / -1
508 (BuiltinType)V1->getValue() == -(BuiltinType)V1->getValue())
510 BuiltinType R = (BuiltinType)V1->getValue() % (BuiltinType)V2->getValue();
511 return ConstantClass::get(*Ty, R);
514 static Constant *And(const ConstantClass *V1, const ConstantClass *V2) {
515 BuiltinType R = (BuiltinType)V1->getValue() & (BuiltinType)V2->getValue();
516 return ConstantClass::get(*Ty, R);
518 static Constant *Or(const ConstantClass *V1, const ConstantClass *V2) {
519 BuiltinType R = (BuiltinType)V1->getValue() | (BuiltinType)V2->getValue();
520 return ConstantClass::get(*Ty, R);
522 static Constant *Xor(const ConstantClass *V1, const ConstantClass *V2) {
523 BuiltinType R = (BuiltinType)V1->getValue() ^ (BuiltinType)V2->getValue();
524 return ConstantClass::get(*Ty, R);
527 static Constant *Shl(const ConstantClass *V1, const ConstantClass *V2) {
528 BuiltinType R = (BuiltinType)V1->getValue() << (BuiltinType)V2->getValue();
529 return ConstantClass::get(*Ty, R);
532 static Constant *Shr(const ConstantClass *V1, const ConstantClass *V2) {
533 BuiltinType R = (BuiltinType)V1->getValue() >> (BuiltinType)V2->getValue();
534 return ConstantClass::get(*Ty, R);
539 //===----------------------------------------------------------------------===//
540 // DirectFPRules Class
541 //===----------------------------------------------------------------------===//
543 /// DirectFPRules provides implementations of functions that are valid on
544 /// floating point types, but not all types in general.
546 template <class ConstantClass, class BuiltinType, Type **Ty>
548 : public DirectRules<ConstantClass, BuiltinType, Ty,
549 DirectFPRules<ConstantClass, BuiltinType, Ty> > {
550 static Constant *Rem(const ConstantClass *V1, const ConstantClass *V2) {
551 if (V2->isNullValue()) return 0;
552 BuiltinType Result = std::fmod((BuiltinType)V1->getValue(),
553 (BuiltinType)V2->getValue());
554 return ConstantClass::get(*Ty, Result);
556 static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
557 BuiltinType inf = std::numeric_limits<BuiltinType>::infinity();
558 if (V2->isExactlyValue(0.0)) return ConstantClass::get(*Ty, inf);
559 if (V2->isExactlyValue(-0.0)) return ConstantClass::get(*Ty, -inf);
560 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
561 return ConstantClass::get(*Ty, R);
566 /// ConstRules::get - This method returns the constant rules implementation that
567 /// implements the semantics of the two specified constants.
568 ConstRules &ConstRules::get(const Constant *V1, const Constant *V2) {
569 static EmptyRules EmptyR;
570 static BoolRules BoolR;
571 static NullPointerRules NullPointerR;
572 static ConstantPackedRules ConstantPackedR;
573 static GeneralPackedRules GeneralPackedR;
574 static DirectIntRules<ConstantSInt, signed char , &Type::SByteTy> SByteR;
575 static DirectIntRules<ConstantUInt, unsigned char , &Type::UByteTy> UByteR;
576 static DirectIntRules<ConstantSInt, signed short, &Type::ShortTy> ShortR;
577 static DirectIntRules<ConstantUInt, unsigned short, &Type::UShortTy> UShortR;
578 static DirectIntRules<ConstantSInt, signed int , &Type::IntTy> IntR;
579 static DirectIntRules<ConstantUInt, unsigned int , &Type::UIntTy> UIntR;
580 static DirectIntRules<ConstantSInt, int64_t , &Type::LongTy> LongR;
581 static DirectIntRules<ConstantUInt, uint64_t , &Type::ULongTy> ULongR;
582 static DirectFPRules <ConstantFP , float , &Type::FloatTy> FloatR;
583 static DirectFPRules <ConstantFP , double , &Type::DoubleTy> DoubleR;
585 if (isa<ConstantExpr>(V1) || isa<ConstantExpr>(V2) ||
586 isa<GlobalValue>(V1) || isa<GlobalValue>(V2) ||
587 isa<UndefValue>(V1) || isa<UndefValue>(V2))
590 switch (V1->getType()->getTypeID()) {
591 default: assert(0 && "Unknown value type for constant folding!");
592 case Type::BoolTyID: return BoolR;
593 case Type::PointerTyID: return NullPointerR;
594 case Type::SByteTyID: return SByteR;
595 case Type::UByteTyID: return UByteR;
596 case Type::ShortTyID: return ShortR;
597 case Type::UShortTyID: return UShortR;
598 case Type::IntTyID: return IntR;
599 case Type::UIntTyID: return UIntR;
600 case Type::LongTyID: return LongR;
601 case Type::ULongTyID: return ULongR;
602 case Type::FloatTyID: return FloatR;
603 case Type::DoubleTyID: return DoubleR;
604 case Type::PackedTyID:
605 if (isa<ConstantPacked>(V1) && isa<ConstantPacked>(V2))
606 return ConstantPackedR;
607 return GeneralPackedR; // Constant folding rules for ConstantAggregateZero.
612 //===----------------------------------------------------------------------===//
613 // ConstantFold*Instruction Implementations
614 //===----------------------------------------------------------------------===//
616 // These methods contain the special case hackery required to symbolically
617 // evaluate some constant expression cases, and use the ConstantRules class to
618 // evaluate normal constants.
620 static unsigned getSize(const Type *Ty) {
621 unsigned S = Ty->getPrimitiveSize();
622 return S ? S : 8; // Treat pointers at 8 bytes
625 /// CastConstantPacked - Convert the specified ConstantPacked node to the
626 /// specified packed type. At this point, we know that the elements of the
627 /// input packed constant are all simple integer or FP values.
628 static Constant *CastConstantPacked(ConstantPacked *CP,
629 const PackedType *DstTy) {
630 unsigned SrcNumElts = CP->getType()->getNumElements();
631 unsigned DstNumElts = DstTy->getNumElements();
632 const Type *SrcEltTy = CP->getType()->getElementType();
633 const Type *DstEltTy = DstTy->getElementType();
635 // If both vectors have the same number of elements (thus, the elements
636 // are the same size), perform the conversion now.
637 if (SrcNumElts == DstNumElts) {
638 std::vector<Constant*> Result;
640 // If the src and dest elements are both integers, just cast each one
641 // which will do the appropriate bit-convert.
642 if (SrcEltTy->isIntegral() && DstEltTy->isIntegral()) {
643 for (unsigned i = 0; i != SrcNumElts; ++i)
644 Result.push_back(ConstantExpr::getCast(CP->getOperand(i),
646 return ConstantPacked::get(Result);
649 if (SrcEltTy->isIntegral()) {
650 // Otherwise, this is an int-to-fp cast.
651 assert(DstEltTy->isFloatingPoint());
652 if (DstEltTy->getTypeID() == Type::DoubleTyID) {
653 for (unsigned i = 0; i != SrcNumElts; ++i) {
655 BitsToDouble(cast<ConstantInt>(CP->getOperand(i))->getRawValue());
656 Result.push_back(ConstantFP::get(Type::DoubleTy, V));
658 return ConstantPacked::get(Result);
660 assert(DstEltTy == Type::FloatTy && "Unknown fp type!");
661 for (unsigned i = 0; i != SrcNumElts; ++i) {
663 BitsToFloat(cast<ConstantInt>(CP->getOperand(i))->getRawValue());
664 Result.push_back(ConstantFP::get(Type::FloatTy, V));
666 return ConstantPacked::get(Result);
669 // Otherwise, this is an fp-to-int cast.
670 assert(SrcEltTy->isFloatingPoint() && DstEltTy->isIntegral());
672 if (SrcEltTy->getTypeID() == Type::DoubleTyID) {
673 for (unsigned i = 0; i != SrcNumElts; ++i) {
675 DoubleToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
676 Constant *C = ConstantUInt::get(Type::ULongTy, V);
677 Result.push_back(ConstantExpr::getCast(C, DstEltTy));
679 return ConstantPacked::get(Result);
682 assert(SrcEltTy->getTypeID() == Type::FloatTyID);
683 for (unsigned i = 0; i != SrcNumElts; ++i) {
684 unsigned V = FloatToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
685 Constant *C = ConstantUInt::get(Type::UIntTy, V);
686 Result.push_back(ConstantExpr::getCast(C, DstEltTy));
688 return ConstantPacked::get(Result);
691 // Otherwise, this is a cast that changes element count and size. Handle
692 // casts which shrink the elements here.
694 // FIXME: We need to know endianness to do this!
700 Constant *llvm::ConstantFoldCastInstruction(const Constant *V,
701 const Type *DestTy) {
702 if (V->getType() == DestTy) return (Constant*)V;
704 // Cast of a global address to boolean is always true.
705 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
706 if (DestTy == Type::BoolTy)
707 // FIXME: When we support 'external weak' references, we have to prevent
708 // this transformation from happening. This code will need to be updated
709 // to ignore external weak symbols when we support it.
710 return ConstantBool::True;
711 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
712 if (CE->getOpcode() == Instruction::Cast) {
713 Constant *Op = const_cast<Constant*>(CE->getOperand(0));
714 // Try to not produce a cast of a cast, which is almost always redundant.
715 if (!Op->getType()->isFloatingPoint() &&
716 !CE->getType()->isFloatingPoint() &&
717 !DestTy->isFloatingPoint()) {
718 unsigned S1 = getSize(Op->getType()), S2 = getSize(CE->getType());
719 unsigned S3 = getSize(DestTy);
720 if (Op->getType() == DestTy && S3 >= S2)
722 if (S1 >= S2 && S2 >= S3)
723 return ConstantExpr::getCast(Op, DestTy);
724 if (S1 <= S2 && S2 >= S3 && S1 <= S3)
725 return ConstantExpr::getCast(Op, DestTy);
727 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
728 // If all of the indexes in the GEP are null values, there is no pointer
729 // adjustment going on. We might as well cast the source pointer.
730 bool isAllNull = true;
731 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
732 if (!CE->getOperand(i)->isNullValue()) {
737 return ConstantExpr::getCast(CE->getOperand(0), DestTy);
739 } else if (isa<UndefValue>(V)) {
740 return UndefValue::get(DestTy);
743 // Check to see if we are casting an pointer to an aggregate to a pointer to
744 // the first element. If so, return the appropriate GEP instruction.
745 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
746 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
747 std::vector<Value*> IdxList;
748 IdxList.push_back(Constant::getNullValue(Type::IntTy));
749 const Type *ElTy = PTy->getElementType();
750 while (ElTy != DPTy->getElementType()) {
751 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
752 if (STy->getNumElements() == 0) break;
753 ElTy = STy->getElementType(0);
754 IdxList.push_back(Constant::getNullValue(Type::UIntTy));
755 } else if (const SequentialType *STy = dyn_cast<SequentialType>(ElTy)) {
756 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
757 ElTy = STy->getElementType();
758 IdxList.push_back(IdxList[0]);
764 if (ElTy == DPTy->getElementType())
765 return ConstantExpr::getGetElementPtr(const_cast<Constant*>(V),IdxList);
768 // Handle casts from one packed constant to another. We know that the src and
769 // dest type have the same size.
770 if (const PackedType *DestPTy = dyn_cast<PackedType>(DestTy)) {
771 if (const PackedType *SrcTy = dyn_cast<PackedType>(V->getType())) {
772 assert(DestPTy->getElementType()->getPrimitiveSizeInBits() *
773 DestPTy->getNumElements() ==
774 SrcTy->getElementType()->getPrimitiveSizeInBits() *
775 SrcTy->getNumElements() && "Not cast between same sized vectors!");
776 if (isa<ConstantAggregateZero>(V))
777 return Constant::getNullValue(DestTy);
778 if (isa<UndefValue>(V))
779 return UndefValue::get(DestTy);
780 if (const ConstantPacked *CP = dyn_cast<ConstantPacked>(V)) {
781 // This is a cast from a ConstantPacked of one type to a ConstantPacked
782 // of another type. Check to see if all elements of the input are
784 bool AllSimpleConstants = true;
785 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
786 if (!isa<ConstantInt>(CP->getOperand(i)) &&
787 !isa<ConstantFP>(CP->getOperand(i))) {
788 AllSimpleConstants = false;
793 // If all of the elements are simple constants, we can fold this.
794 if (AllSimpleConstants)
795 return CastConstantPacked(const_cast<ConstantPacked*>(CP), DestPTy);
800 ConstRules &Rules = ConstRules::get(V, V);
802 switch (DestTy->getTypeID()) {
803 case Type::BoolTyID: return Rules.castToBool(V);
804 case Type::UByteTyID: return Rules.castToUByte(V);
805 case Type::SByteTyID: return Rules.castToSByte(V);
806 case Type::UShortTyID: return Rules.castToUShort(V);
807 case Type::ShortTyID: return Rules.castToShort(V);
808 case Type::UIntTyID: return Rules.castToUInt(V);
809 case Type::IntTyID: return Rules.castToInt(V);
810 case Type::ULongTyID: return Rules.castToULong(V);
811 case Type::LongTyID: return Rules.castToLong(V);
812 case Type::FloatTyID: return Rules.castToFloat(V);
813 case Type::DoubleTyID: return Rules.castToDouble(V);
814 case Type::PointerTyID:
815 return Rules.castToPointer(V, cast<PointerType>(DestTy));
820 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
822 const Constant *V2) {
823 if (Cond == ConstantBool::True)
824 return const_cast<Constant*>(V1);
825 else if (Cond == ConstantBool::False)
826 return const_cast<Constant*>(V2);
828 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
829 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
830 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
831 if (V1 == V2) return const_cast<Constant*>(V1);
835 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
836 const Constant *Idx) {
837 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
838 return UndefValue::get(cast<PackedType>(Val->getType())->getElementType());
839 if (Val->isNullValue()) // ee(zero, x) -> zero
840 return Constant::getNullValue(
841 cast<PackedType>(Val->getType())->getElementType());
843 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
844 if (const ConstantUInt *CIdx = dyn_cast<ConstantUInt>(Idx)) {
845 return const_cast<Constant*>(CVal->getOperand(CIdx->getValue()));
846 } else if (isa<UndefValue>(Idx)) {
847 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
848 return const_cast<Constant*>(CVal->getOperand(0));
854 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
856 const Constant *Idx) {
857 const ConstantUInt *CIdx = dyn_cast<ConstantUInt>(Idx);
859 unsigned idxVal = CIdx->getValue();
860 if (const UndefValue *UVal = dyn_cast<UndefValue>(Val)) {
861 // Insertion of scalar constant into packed undef
862 // Optimize away insertion of undef
863 if (isa<UndefValue>(Elt))
864 return const_cast<Constant*>(Val);
865 // Otherwise break the aggregate undef into multiple undefs and do
868 cast<PackedType>(Val->getType())->getNumElements();
869 std::vector<Constant*> Ops;
871 for (unsigned i = 0; i < numOps; ++i) {
873 (i == idxVal) ? Elt : UndefValue::get(Elt->getType());
874 Ops.push_back(const_cast<Constant*>(Op));
876 return ConstantPacked::get(Ops);
878 if (const ConstantAggregateZero *CVal =
879 dyn_cast<ConstantAggregateZero>(Val)) {
880 // Insertion of scalar constant into packed aggregate zero
881 // Optimize away insertion of zero
882 if (Elt->isNullValue())
883 return const_cast<Constant*>(Val);
884 // Otherwise break the aggregate zero into multiple zeros and do
887 cast<PackedType>(Val->getType())->getNumElements();
888 std::vector<Constant*> Ops;
890 for (unsigned i = 0; i < numOps; ++i) {
892 (i == idxVal) ? Elt : Constant::getNullValue(Elt->getType());
893 Ops.push_back(const_cast<Constant*>(Op));
895 return ConstantPacked::get(Ops);
897 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
898 // Insertion of scalar constant into packed constant
899 std::vector<Constant*> Ops;
900 Ops.reserve(CVal->getNumOperands());
901 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
903 (i == idxVal) ? Elt : cast<Constant>(CVal->getOperand(i));
904 Ops.push_back(const_cast<Constant*>(Op));
906 return ConstantPacked::get(Ops);
911 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
913 const Constant *Mask) {
919 /// isZeroSizedType - This type is zero sized if its an array or structure of
920 /// zero sized types. The only leaf zero sized type is an empty structure.
921 static bool isMaybeZeroSizedType(const Type *Ty) {
922 if (isa<OpaqueType>(Ty)) return true; // Can't say.
923 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
925 // If all of elements have zero size, this does too.
926 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
927 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
930 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
931 return isMaybeZeroSizedType(ATy->getElementType());
936 /// IdxCompare - Compare the two constants as though they were getelementptr
937 /// indices. This allows coersion of the types to be the same thing.
939 /// If the two constants are the "same" (after coersion), return 0. If the
940 /// first is less than the second, return -1, if the second is less than the
941 /// first, return 1. If the constants are not integral, return -2.
943 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
944 if (C1 == C2) return 0;
946 // Ok, we found a different index. Are either of the operands
947 // ConstantExprs? If so, we can't do anything with them.
948 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
949 return -2; // don't know!
951 // Ok, we have two differing integer indices. Sign extend them to be the same
952 // type. Long is always big enough, so we use it.
953 C1 = ConstantExpr::getSignExtend(C1, Type::LongTy);
954 C2 = ConstantExpr::getSignExtend(C2, Type::LongTy);
955 if (C1 == C2) return 0; // Are they just differing types?
957 // If the type being indexed over is really just a zero sized type, there is
958 // no pointer difference being made here.
959 if (isMaybeZeroSizedType(ElTy))
962 // If they are really different, now that they are the same type, then we
963 // found a difference!
964 if (cast<ConstantSInt>(C1)->getValue() < cast<ConstantSInt>(C2)->getValue())
970 /// evaluateRelation - This function determines if there is anything we can
971 /// decide about the two constants provided. This doesn't need to handle simple
972 /// things like integer comparisons, but should instead handle ConstantExprs
973 /// and GlobalValuess. If we can determine that the two constants have a
974 /// particular relation to each other, we should return the corresponding SetCC
975 /// code, otherwise return Instruction::BinaryOpsEnd.
977 /// To simplify this code we canonicalize the relation so that the first
978 /// operand is always the most "complex" of the two. We consider simple
979 /// constants (like ConstantInt) to be the simplest, followed by
980 /// GlobalValues, followed by ConstantExpr's (the most complex).
982 static Instruction::BinaryOps evaluateRelation(Constant *V1, Constant *V2) {
983 assert(V1->getType() == V2->getType() &&
984 "Cannot compare different types of values!");
985 if (V1 == V2) return Instruction::SetEQ;
987 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
988 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
989 // We distilled this down to a simple case, use the standard constant
991 ConstantBool *R = dyn_cast<ConstantBool>(ConstantExpr::getSetEQ(V1, V2));
992 if (R == ConstantBool::True) return Instruction::SetEQ;
993 R = dyn_cast<ConstantBool>(ConstantExpr::getSetLT(V1, V2));
994 if (R == ConstantBool::True) return Instruction::SetLT;
995 R = dyn_cast<ConstantBool>(ConstantExpr::getSetGT(V1, V2));
996 if (R == ConstantBool::True) return Instruction::SetGT;
998 // If we couldn't figure it out, bail.
999 return Instruction::BinaryOpsEnd;
1002 // If the first operand is simple, swap operands.
1003 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
1004 if (SwappedRelation != Instruction::BinaryOpsEnd)
1005 return SetCondInst::getSwappedCondition(SwappedRelation);
1007 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
1008 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
1009 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
1010 if (SwappedRelation != Instruction::BinaryOpsEnd)
1011 return SetCondInst::getSwappedCondition(SwappedRelation);
1013 return Instruction::BinaryOpsEnd;
1016 // Now we know that the RHS is a GlobalValue or simple constant,
1017 // which (since the types must match) means that it's a ConstantPointerNull.
1018 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1019 assert(CPR1 != CPR2 &&
1020 "GVs for the same value exist at different addresses??");
1021 // FIXME: If both globals are external weak, they might both be null!
1022 return Instruction::SetNE;
1024 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
1025 // Global can never be null. FIXME: if we implement external weak
1026 // linkage, this is not necessarily true!
1027 return Instruction::SetNE;
1031 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
1032 // constantexpr, a CPR, or a simple constant.
1033 ConstantExpr *CE1 = cast<ConstantExpr>(V1);
1034 Constant *CE1Op0 = CE1->getOperand(0);
1036 switch (CE1->getOpcode()) {
1037 case Instruction::Cast:
1038 // If the cast is not actually changing bits, and the second operand is a
1039 // null pointer, do the comparison with the pre-casted value.
1040 if (V2->isNullValue() &&
1041 (isa<PointerType>(CE1->getType()) || CE1->getType()->isIntegral()))
1042 return evaluateRelation(CE1Op0,
1043 Constant::getNullValue(CE1Op0->getType()));
1045 // If the dest type is a pointer type, and the RHS is a constantexpr cast
1046 // from the same type as the src of the LHS, evaluate the inputs. This is
1047 // important for things like "seteq (cast 4 to int*), (cast 5 to int*)",
1048 // which happens a lot in compilers with tagged integers.
1049 if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
1050 if (isa<PointerType>(CE1->getType()) &&
1051 CE2->getOpcode() == Instruction::Cast &&
1052 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
1053 CE1->getOperand(0)->getType()->isIntegral()) {
1054 return evaluateRelation(CE1->getOperand(0), CE2->getOperand(0));
1058 case Instruction::GetElementPtr:
1059 // Ok, since this is a getelementptr, we know that the constant has a
1060 // pointer type. Check the various cases.
1061 if (isa<ConstantPointerNull>(V2)) {
1062 // If we are comparing a GEP to a null pointer, check to see if the base
1063 // of the GEP equals the null pointer.
1064 if (isa<GlobalValue>(CE1Op0)) {
1065 // FIXME: this is not true when we have external weak references!
1066 // No offset can go from a global to a null pointer.
1067 return Instruction::SetGT;
1068 } else if (isa<ConstantPointerNull>(CE1Op0)) {
1069 // If we are indexing from a null pointer, check to see if we have any
1070 // non-zero indices.
1071 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
1072 if (!CE1->getOperand(i)->isNullValue())
1073 // Offsetting from null, must not be equal.
1074 return Instruction::SetGT;
1075 // Only zero indexes from null, must still be zero.
1076 return Instruction::SetEQ;
1078 // Otherwise, we can't really say if the first operand is null or not.
1079 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1080 if (isa<ConstantPointerNull>(CE1Op0)) {
1081 // FIXME: This is not true with external weak references.
1082 return Instruction::SetLT;
1083 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
1085 // If this is a getelementptr of the same global, then it must be
1086 // different. Because the types must match, the getelementptr could
1087 // only have at most one index, and because we fold getelementptr's
1088 // with a single zero index, it must be nonzero.
1089 assert(CE1->getNumOperands() == 2 &&
1090 !CE1->getOperand(1)->isNullValue() &&
1091 "Suprising getelementptr!");
1092 return Instruction::SetGT;
1094 // If they are different globals, we don't know what the value is,
1095 // but they can't be equal.
1096 return Instruction::SetNE;
1100 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
1101 const Constant *CE2Op0 = CE2->getOperand(0);
1103 // There are MANY other foldings that we could perform here. They will
1104 // probably be added on demand, as they seem needed.
1105 switch (CE2->getOpcode()) {
1107 case Instruction::GetElementPtr:
1108 // By far the most common case to handle is when the base pointers are
1109 // obviously to the same or different globals.
1110 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
1111 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
1112 return Instruction::SetNE;
1113 // Ok, we know that both getelementptr instructions are based on the
1114 // same global. From this, we can precisely determine the relative
1115 // ordering of the resultant pointers.
1118 // Compare all of the operands the GEP's have in common.
1119 gep_type_iterator GTI = gep_type_begin(CE1);
1120 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
1122 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
1123 GTI.getIndexedType())) {
1124 case -1: return Instruction::SetLT;
1125 case 1: return Instruction::SetGT;
1126 case -2: return Instruction::BinaryOpsEnd;
1129 // Ok, we ran out of things they have in common. If any leftovers
1130 // are non-zero then we have a difference, otherwise we are equal.
1131 for (; i < CE1->getNumOperands(); ++i)
1132 if (!CE1->getOperand(i)->isNullValue())
1133 if (isa<ConstantIntegral>(CE1->getOperand(i)))
1134 return Instruction::SetGT;
1136 return Instruction::BinaryOpsEnd; // Might be equal.
1138 for (; i < CE2->getNumOperands(); ++i)
1139 if (!CE2->getOperand(i)->isNullValue())
1140 if (isa<ConstantIntegral>(CE2->getOperand(i)))
1141 return Instruction::SetLT;
1143 return Instruction::BinaryOpsEnd; // Might be equal.
1144 return Instruction::SetEQ;
1154 return Instruction::BinaryOpsEnd;
1157 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
1159 const Constant *V2) {
1163 case Instruction::Add: C = ConstRules::get(V1, V2).add(V1, V2); break;
1164 case Instruction::Sub: C = ConstRules::get(V1, V2).sub(V1, V2); break;
1165 case Instruction::Mul: C = ConstRules::get(V1, V2).mul(V1, V2); break;
1166 case Instruction::Div: C = ConstRules::get(V1, V2).div(V1, V2); break;
1167 case Instruction::Rem: C = ConstRules::get(V1, V2).rem(V1, V2); break;
1168 case Instruction::And: C = ConstRules::get(V1, V2).op_and(V1, V2); break;
1169 case Instruction::Or: C = ConstRules::get(V1, V2).op_or (V1, V2); break;
1170 case Instruction::Xor: C = ConstRules::get(V1, V2).op_xor(V1, V2); break;
1171 case Instruction::Shl: C = ConstRules::get(V1, V2).shl(V1, V2); break;
1172 case Instruction::Shr: C = ConstRules::get(V1, V2).shr(V1, V2); break;
1173 case Instruction::SetEQ: C = ConstRules::get(V1, V2).equalto(V1, V2); break;
1174 case Instruction::SetLT: C = ConstRules::get(V1, V2).lessthan(V1, V2);break;
1175 case Instruction::SetGT: C = ConstRules::get(V1, V2).lessthan(V2, V1);break;
1176 case Instruction::SetNE: // V1 != V2 === !(V1 == V2)
1177 C = ConstRules::get(V1, V2).equalto(V1, V2);
1178 if (C) return ConstantExpr::getNot(C);
1180 case Instruction::SetLE: // V1 <= V2 === !(V2 < V1)
1181 C = ConstRules::get(V1, V2).lessthan(V2, V1);
1182 if (C) return ConstantExpr::getNot(C);
1184 case Instruction::SetGE: // V1 >= V2 === !(V1 < V2)
1185 C = ConstRules::get(V1, V2).lessthan(V1, V2);
1186 if (C) return ConstantExpr::getNot(C);
1190 // If we successfully folded the expression, return it now.
1193 if (SetCondInst::isRelational(Opcode)) {
1194 if (isa<UndefValue>(V1) || isa<UndefValue>(V2))
1195 return UndefValue::get(Type::BoolTy);
1196 switch (evaluateRelation(const_cast<Constant*>(V1),
1197 const_cast<Constant*>(V2))) {
1198 default: assert(0 && "Unknown relational!");
1199 case Instruction::BinaryOpsEnd:
1200 break; // Couldn't determine anything about these constants.
1201 case Instruction::SetEQ: // We know the constants are equal!
1202 // If we know the constants are equal, we can decide the result of this
1203 // computation precisely.
1204 return ConstantBool::get(Opcode == Instruction::SetEQ ||
1205 Opcode == Instruction::SetLE ||
1206 Opcode == Instruction::SetGE);
1207 case Instruction::SetLT:
1208 // If we know that V1 < V2, we can decide the result of this computation
1210 return ConstantBool::get(Opcode == Instruction::SetLT ||
1211 Opcode == Instruction::SetNE ||
1212 Opcode == Instruction::SetLE);
1213 case Instruction::SetGT:
1214 // If we know that V1 > V2, we can decide the result of this computation
1216 return ConstantBool::get(Opcode == Instruction::SetGT ||
1217 Opcode == Instruction::SetNE ||
1218 Opcode == Instruction::SetGE);
1219 case Instruction::SetLE:
1220 // If we know that V1 <= V2, we can only partially decide this relation.
1221 if (Opcode == Instruction::SetGT) return ConstantBool::False;
1222 if (Opcode == Instruction::SetLT) return ConstantBool::True;
1225 case Instruction::SetGE:
1226 // If we know that V1 >= V2, we can only partially decide this relation.
1227 if (Opcode == Instruction::SetLT) return ConstantBool::False;
1228 if (Opcode == Instruction::SetGT) return ConstantBool::True;
1231 case Instruction::SetNE:
1232 // If we know that V1 != V2, we can only partially decide this relation.
1233 if (Opcode == Instruction::SetEQ) return ConstantBool::False;
1234 if (Opcode == Instruction::SetNE) return ConstantBool::True;
1239 if (isa<UndefValue>(V1) || isa<UndefValue>(V2)) {
1241 case Instruction::Add:
1242 case Instruction::Sub:
1243 case Instruction::Xor:
1244 return UndefValue::get(V1->getType());
1246 case Instruction::Mul:
1247 case Instruction::And:
1248 return Constant::getNullValue(V1->getType());
1249 case Instruction::Div:
1250 case Instruction::Rem:
1251 if (!isa<UndefValue>(V2)) // undef/X -> 0
1252 return Constant::getNullValue(V1->getType());
1253 return const_cast<Constant*>(V2); // X/undef -> undef
1254 case Instruction::Or: // X|undef -> -1
1255 return ConstantInt::getAllOnesValue(V1->getType());
1256 case Instruction::Shr:
1257 if (!isa<UndefValue>(V2)) {
1258 if (V1->getType()->isSigned())
1259 return const_cast<Constant*>(V1); // undef >>s X -> undef
1261 } else if (isa<UndefValue>(V1)) {
1262 return const_cast<Constant*>(V1); // undef >> undef -> undef
1264 if (V1->getType()->isSigned())
1265 return const_cast<Constant*>(V1); // X >>s undef -> X
1268 return Constant::getNullValue(V1->getType());
1270 case Instruction::Shl:
1271 // undef << X -> 0 X << undef -> 0
1272 return Constant::getNullValue(V1->getType());
1276 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(V1)) {
1277 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
1278 // There are many possible foldings we could do here. We should probably
1279 // at least fold add of a pointer with an integer into the appropriate
1280 // getelementptr. This will improve alias analysis a bit.
1286 // Just implement a couple of simple identities.
1288 case Instruction::Add:
1289 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X + 0 == X
1291 case Instruction::Sub:
1292 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X - 0 == X
1294 case Instruction::Mul:
1295 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X * 0 == 0
1296 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1297 if (CI->getRawValue() == 1)
1298 return const_cast<Constant*>(V1); // X * 1 == X
1300 case Instruction::Div:
1301 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1302 if (CI->getRawValue() == 1)
1303 return const_cast<Constant*>(V1); // X / 1 == X
1305 case Instruction::Rem:
1306 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1307 if (CI->getRawValue() == 1)
1308 return Constant::getNullValue(CI->getType()); // X % 1 == 0
1310 case Instruction::And:
1311 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1312 return const_cast<Constant*>(V1); // X & -1 == X
1313 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X & 0 == 0
1314 if (CE1->getOpcode() == Instruction::Cast &&
1315 isa<GlobalValue>(CE1->getOperand(0))) {
1316 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
1318 // Functions are at least 4-byte aligned. If and'ing the address of a
1319 // function with a constant < 4, fold it to zero.
1320 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1321 if (CI->getRawValue() < 4 && isa<Function>(CPR))
1322 return Constant::getNullValue(CI->getType());
1325 case Instruction::Or:
1326 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X | 0 == X
1327 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1328 return const_cast<Constant*>(V2); // X | -1 == -1
1330 case Instruction::Xor:
1331 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X ^ 0 == X
1336 } else if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
1337 // If V2 is a constant expr and V1 isn't, flop them around and fold the
1338 // other way if possible.
1340 case Instruction::Add:
1341 case Instruction::Mul:
1342 case Instruction::And:
1343 case Instruction::Or:
1344 case Instruction::Xor:
1345 case Instruction::SetEQ:
1346 case Instruction::SetNE:
1347 // No change of opcode required.
1348 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1350 case Instruction::SetLT:
1351 case Instruction::SetGT:
1352 case Instruction::SetLE:
1353 case Instruction::SetGE:
1354 // Change the opcode as necessary to swap the operands.
1355 Opcode = SetCondInst::getSwappedCondition((Instruction::BinaryOps)Opcode);
1356 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1358 case Instruction::Shl:
1359 case Instruction::Shr:
1360 case Instruction::Sub:
1361 case Instruction::Div:
1362 case Instruction::Rem:
1363 default: // These instructions cannot be flopped around.
1370 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1371 const std::vector<Value*> &IdxList) {
1372 if (IdxList.size() == 0 ||
1373 (IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
1374 return const_cast<Constant*>(C);
1376 if (isa<UndefValue>(C)) {
1377 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1379 assert(Ty != 0 && "Invalid indices for GEP!");
1380 return UndefValue::get(PointerType::get(Ty));
1383 Constant *Idx0 = cast<Constant>(IdxList[0]);
1384 if (C->isNullValue()) {
1386 for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
1387 if (!cast<Constant>(IdxList[i])->isNullValue()) {
1392 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1394 assert(Ty != 0 && "Invalid indices for GEP!");
1395 return ConstantPointerNull::get(PointerType::get(Ty));
1398 if (IdxList.size() == 1) {
1399 const Type *ElTy = cast<PointerType>(C->getType())->getElementType();
1400 if (unsigned ElSize = ElTy->getPrimitiveSize()) {
1401 // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm
1402 // type, we can statically fold this.
1403 Constant *R = ConstantUInt::get(Type::UIntTy, ElSize);
1404 R = ConstantExpr::getCast(R, Idx0->getType());
1405 R = ConstantExpr::getMul(R, Idx0);
1406 return ConstantExpr::getCast(R, C->getType());
1411 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1412 // Combine Indices - If the source pointer to this getelementptr instruction
1413 // is a getelementptr instruction, combine the indices of the two
1414 // getelementptr instructions into a single instruction.
1416 if (CE->getOpcode() == Instruction::GetElementPtr) {
1417 const Type *LastTy = 0;
1418 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1422 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1423 std::vector<Value*> NewIndices;
1424 NewIndices.reserve(IdxList.size() + CE->getNumOperands());
1425 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1426 NewIndices.push_back(CE->getOperand(i));
1428 // Add the last index of the source with the first index of the new GEP.
1429 // Make sure to handle the case when they are actually different types.
1430 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1431 // Otherwise it must be an array.
1432 if (!Idx0->isNullValue()) {
1433 const Type *IdxTy = Combined->getType();
1434 if (IdxTy != Idx0->getType()) IdxTy = Type::LongTy;
1436 ConstantExpr::get(Instruction::Add,
1437 ConstantExpr::getCast(Idx0, IdxTy),
1438 ConstantExpr::getCast(Combined, IdxTy));
1441 NewIndices.push_back(Combined);
1442 NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
1443 return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
1447 // Implement folding of:
1448 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1450 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1452 if (CE->getOpcode() == Instruction::Cast && IdxList.size() > 1 &&
1453 Idx0->isNullValue())
1454 if (const PointerType *SPT =
1455 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1456 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1457 if (const ArrayType *CAT =
1458 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1459 if (CAT->getElementType() == SAT->getElementType())
1460 return ConstantExpr::getGetElementPtr(
1461 (Constant*)CE->getOperand(0), IdxList);