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());
840 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
841 if (const ConstantUInt *CIdx = dyn_cast<ConstantUInt>(Idx)) {
842 return const_cast<Constant*>(CVal->getOperand(CIdx->getValue()));
843 } else if (isa<UndefValue>(Idx)) {
844 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
845 return const_cast<Constant*>(CVal->getOperand(0));
851 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
853 const Constant *Idx) {
854 const ConstantUInt *CIdx = dyn_cast<ConstantUInt>(Idx);
856 unsigned idxVal = CIdx->getValue();
857 if (const UndefValue *UVal = dyn_cast<UndefValue>(Val)) {
858 // Insertion of scalar constant into packed undef
859 // Optimize away insertion of undef
860 if (isa<UndefValue>(Elt))
861 return const_cast<Constant*>(Val);
862 // Otherwise break the aggregate undef into multiple undefs and do
865 cast<PackedType>(Val->getType())->getNumElements();
866 std::vector<Constant*> Ops;
868 for (unsigned i = 0; i < numOps; ++i) {
870 (i == idxVal) ? Elt : UndefValue::get(Elt->getType());
871 Ops.push_back(const_cast<Constant*>(Op));
873 return ConstantPacked::get(Ops);
875 if (const ConstantAggregateZero *CVal =
876 dyn_cast<ConstantAggregateZero>(Val)) {
877 // Insertion of scalar constant into packed aggregate zero
878 // Optimize away insertion of zero
879 if (Elt->isNullValue())
880 return const_cast<Constant*>(Val);
881 // Otherwise break the aggregate zero into multiple zeros and do
884 cast<PackedType>(Val->getType())->getNumElements();
885 std::vector<Constant*> Ops;
887 for (unsigned i = 0; i < numOps; ++i) {
889 (i == idxVal) ? Elt : Constant::getNullValue(Elt->getType());
890 Ops.push_back(const_cast<Constant*>(Op));
892 return ConstantPacked::get(Ops);
894 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
895 // Insertion of scalar constant into packed constant
896 std::vector<Constant*> Ops;
897 Ops.reserve(CVal->getNumOperands());
898 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
900 (i == idxVal) ? Elt : cast<Constant>(CVal->getOperand(i));
901 Ops.push_back(const_cast<Constant*>(Op));
903 return ConstantPacked::get(Ops);
908 /// isZeroSizedType - This type is zero sized if its an array or structure of
909 /// zero sized types. The only leaf zero sized type is an empty structure.
910 static bool isMaybeZeroSizedType(const Type *Ty) {
911 if (isa<OpaqueType>(Ty)) return true; // Can't say.
912 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
914 // If all of elements have zero size, this does too.
915 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
916 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
919 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
920 return isMaybeZeroSizedType(ATy->getElementType());
925 /// IdxCompare - Compare the two constants as though they were getelementptr
926 /// indices. This allows coersion of the types to be the same thing.
928 /// If the two constants are the "same" (after coersion), return 0. If the
929 /// first is less than the second, return -1, if the second is less than the
930 /// first, return 1. If the constants are not integral, return -2.
932 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
933 if (C1 == C2) return 0;
935 // Ok, we found a different index. Are either of the operands
936 // ConstantExprs? If so, we can't do anything with them.
937 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
938 return -2; // don't know!
940 // Ok, we have two differing integer indices. Sign extend them to be the same
941 // type. Long is always big enough, so we use it.
942 C1 = ConstantExpr::getSignExtend(C1, Type::LongTy);
943 C2 = ConstantExpr::getSignExtend(C2, Type::LongTy);
944 if (C1 == C2) return 0; // Are they just differing types?
946 // If the type being indexed over is really just a zero sized type, there is
947 // no pointer difference being made here.
948 if (isMaybeZeroSizedType(ElTy))
951 // If they are really different, now that they are the same type, then we
952 // found a difference!
953 if (cast<ConstantSInt>(C1)->getValue() < cast<ConstantSInt>(C2)->getValue())
959 /// evaluateRelation - This function determines if there is anything we can
960 /// decide about the two constants provided. This doesn't need to handle simple
961 /// things like integer comparisons, but should instead handle ConstantExprs
962 /// and GlobalValuess. If we can determine that the two constants have a
963 /// particular relation to each other, we should return the corresponding SetCC
964 /// code, otherwise return Instruction::BinaryOpsEnd.
966 /// To simplify this code we canonicalize the relation so that the first
967 /// operand is always the most "complex" of the two. We consider simple
968 /// constants (like ConstantInt) to be the simplest, followed by
969 /// GlobalValues, followed by ConstantExpr's (the most complex).
971 static Instruction::BinaryOps evaluateRelation(Constant *V1, Constant *V2) {
972 assert(V1->getType() == V2->getType() &&
973 "Cannot compare different types of values!");
974 if (V1 == V2) return Instruction::SetEQ;
976 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
977 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
978 // We distilled this down to a simple case, use the standard constant
980 ConstantBool *R = dyn_cast<ConstantBool>(ConstantExpr::getSetEQ(V1, V2));
981 if (R == ConstantBool::True) return Instruction::SetEQ;
982 R = dyn_cast<ConstantBool>(ConstantExpr::getSetLT(V1, V2));
983 if (R == ConstantBool::True) return Instruction::SetLT;
984 R = dyn_cast<ConstantBool>(ConstantExpr::getSetGT(V1, V2));
985 if (R == ConstantBool::True) return Instruction::SetGT;
987 // If we couldn't figure it out, bail.
988 return Instruction::BinaryOpsEnd;
991 // If the first operand is simple, swap operands.
992 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
993 if (SwappedRelation != Instruction::BinaryOpsEnd)
994 return SetCondInst::getSwappedCondition(SwappedRelation);
996 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
997 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
998 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
999 if (SwappedRelation != Instruction::BinaryOpsEnd)
1000 return SetCondInst::getSwappedCondition(SwappedRelation);
1002 return Instruction::BinaryOpsEnd;
1005 // Now we know that the RHS is a GlobalValue or simple constant,
1006 // which (since the types must match) means that it's a ConstantPointerNull.
1007 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1008 assert(CPR1 != CPR2 &&
1009 "GVs for the same value exist at different addresses??");
1010 // FIXME: If both globals are external weak, they might both be null!
1011 return Instruction::SetNE;
1013 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
1014 // Global can never be null. FIXME: if we implement external weak
1015 // linkage, this is not necessarily true!
1016 return Instruction::SetNE;
1020 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
1021 // constantexpr, a CPR, or a simple constant.
1022 ConstantExpr *CE1 = cast<ConstantExpr>(V1);
1023 Constant *CE1Op0 = CE1->getOperand(0);
1025 switch (CE1->getOpcode()) {
1026 case Instruction::Cast:
1027 // If the cast is not actually changing bits, and the second operand is a
1028 // null pointer, do the comparison with the pre-casted value.
1029 if (V2->isNullValue() &&
1030 (isa<PointerType>(CE1->getType()) || CE1->getType()->isIntegral()))
1031 return evaluateRelation(CE1Op0,
1032 Constant::getNullValue(CE1Op0->getType()));
1034 // If the dest type is a pointer type, and the RHS is a constantexpr cast
1035 // from the same type as the src of the LHS, evaluate the inputs. This is
1036 // important for things like "seteq (cast 4 to int*), (cast 5 to int*)",
1037 // which happens a lot in compilers with tagged integers.
1038 if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
1039 if (isa<PointerType>(CE1->getType()) &&
1040 CE2->getOpcode() == Instruction::Cast &&
1041 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
1042 CE1->getOperand(0)->getType()->isIntegral()) {
1043 return evaluateRelation(CE1->getOperand(0), CE2->getOperand(0));
1047 case Instruction::GetElementPtr:
1048 // Ok, since this is a getelementptr, we know that the constant has a
1049 // pointer type. Check the various cases.
1050 if (isa<ConstantPointerNull>(V2)) {
1051 // If we are comparing a GEP to a null pointer, check to see if the base
1052 // of the GEP equals the null pointer.
1053 if (isa<GlobalValue>(CE1Op0)) {
1054 // FIXME: this is not true when we have external weak references!
1055 // No offset can go from a global to a null pointer.
1056 return Instruction::SetGT;
1057 } else if (isa<ConstantPointerNull>(CE1Op0)) {
1058 // If we are indexing from a null pointer, check to see if we have any
1059 // non-zero indices.
1060 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
1061 if (!CE1->getOperand(i)->isNullValue())
1062 // Offsetting from null, must not be equal.
1063 return Instruction::SetGT;
1064 // Only zero indexes from null, must still be zero.
1065 return Instruction::SetEQ;
1067 // Otherwise, we can't really say if the first operand is null or not.
1068 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1069 if (isa<ConstantPointerNull>(CE1Op0)) {
1070 // FIXME: This is not true with external weak references.
1071 return Instruction::SetLT;
1072 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
1074 // If this is a getelementptr of the same global, then it must be
1075 // different. Because the types must match, the getelementptr could
1076 // only have at most one index, and because we fold getelementptr's
1077 // with a single zero index, it must be nonzero.
1078 assert(CE1->getNumOperands() == 2 &&
1079 !CE1->getOperand(1)->isNullValue() &&
1080 "Suprising getelementptr!");
1081 return Instruction::SetGT;
1083 // If they are different globals, we don't know what the value is,
1084 // but they can't be equal.
1085 return Instruction::SetNE;
1089 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
1090 const Constant *CE2Op0 = CE2->getOperand(0);
1092 // There are MANY other foldings that we could perform here. They will
1093 // probably be added on demand, as they seem needed.
1094 switch (CE2->getOpcode()) {
1096 case Instruction::GetElementPtr:
1097 // By far the most common case to handle is when the base pointers are
1098 // obviously to the same or different globals.
1099 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
1100 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
1101 return Instruction::SetNE;
1102 // Ok, we know that both getelementptr instructions are based on the
1103 // same global. From this, we can precisely determine the relative
1104 // ordering of the resultant pointers.
1107 // Compare all of the operands the GEP's have in common.
1108 gep_type_iterator GTI = gep_type_begin(CE1);
1109 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
1111 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
1112 GTI.getIndexedType())) {
1113 case -1: return Instruction::SetLT;
1114 case 1: return Instruction::SetGT;
1115 case -2: return Instruction::BinaryOpsEnd;
1118 // Ok, we ran out of things they have in common. If any leftovers
1119 // are non-zero then we have a difference, otherwise we are equal.
1120 for (; i < CE1->getNumOperands(); ++i)
1121 if (!CE1->getOperand(i)->isNullValue())
1122 if (isa<ConstantIntegral>(CE1->getOperand(i)))
1123 return Instruction::SetGT;
1125 return Instruction::BinaryOpsEnd; // Might be equal.
1127 for (; i < CE2->getNumOperands(); ++i)
1128 if (!CE2->getOperand(i)->isNullValue())
1129 if (isa<ConstantIntegral>(CE2->getOperand(i)))
1130 return Instruction::SetLT;
1132 return Instruction::BinaryOpsEnd; // Might be equal.
1133 return Instruction::SetEQ;
1143 return Instruction::BinaryOpsEnd;
1146 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
1148 const Constant *V2) {
1152 case Instruction::Add: C = ConstRules::get(V1, V2).add(V1, V2); break;
1153 case Instruction::Sub: C = ConstRules::get(V1, V2).sub(V1, V2); break;
1154 case Instruction::Mul: C = ConstRules::get(V1, V2).mul(V1, V2); break;
1155 case Instruction::Div: C = ConstRules::get(V1, V2).div(V1, V2); break;
1156 case Instruction::Rem: C = ConstRules::get(V1, V2).rem(V1, V2); break;
1157 case Instruction::And: C = ConstRules::get(V1, V2).op_and(V1, V2); break;
1158 case Instruction::Or: C = ConstRules::get(V1, V2).op_or (V1, V2); break;
1159 case Instruction::Xor: C = ConstRules::get(V1, V2).op_xor(V1, V2); break;
1160 case Instruction::Shl: C = ConstRules::get(V1, V2).shl(V1, V2); break;
1161 case Instruction::Shr: C = ConstRules::get(V1, V2).shr(V1, V2); break;
1162 case Instruction::SetEQ: C = ConstRules::get(V1, V2).equalto(V1, V2); break;
1163 case Instruction::SetLT: C = ConstRules::get(V1, V2).lessthan(V1, V2);break;
1164 case Instruction::SetGT: C = ConstRules::get(V1, V2).lessthan(V2, V1);break;
1165 case Instruction::SetNE: // V1 != V2 === !(V1 == V2)
1166 C = ConstRules::get(V1, V2).equalto(V1, V2);
1167 if (C) return ConstantExpr::getNot(C);
1169 case Instruction::SetLE: // V1 <= V2 === !(V2 < V1)
1170 C = ConstRules::get(V1, V2).lessthan(V2, V1);
1171 if (C) return ConstantExpr::getNot(C);
1173 case Instruction::SetGE: // V1 >= V2 === !(V1 < V2)
1174 C = ConstRules::get(V1, V2).lessthan(V1, V2);
1175 if (C) return ConstantExpr::getNot(C);
1179 // If we successfully folded the expression, return it now.
1182 if (SetCondInst::isRelational(Opcode)) {
1183 if (isa<UndefValue>(V1) || isa<UndefValue>(V2))
1184 return UndefValue::get(Type::BoolTy);
1185 switch (evaluateRelation(const_cast<Constant*>(V1),
1186 const_cast<Constant*>(V2))) {
1187 default: assert(0 && "Unknown relational!");
1188 case Instruction::BinaryOpsEnd:
1189 break; // Couldn't determine anything about these constants.
1190 case Instruction::SetEQ: // We know the constants are equal!
1191 // If we know the constants are equal, we can decide the result of this
1192 // computation precisely.
1193 return ConstantBool::get(Opcode == Instruction::SetEQ ||
1194 Opcode == Instruction::SetLE ||
1195 Opcode == Instruction::SetGE);
1196 case Instruction::SetLT:
1197 // If we know that V1 < V2, we can decide the result of this computation
1199 return ConstantBool::get(Opcode == Instruction::SetLT ||
1200 Opcode == Instruction::SetNE ||
1201 Opcode == Instruction::SetLE);
1202 case Instruction::SetGT:
1203 // If we know that V1 > V2, we can decide the result of this computation
1205 return ConstantBool::get(Opcode == Instruction::SetGT ||
1206 Opcode == Instruction::SetNE ||
1207 Opcode == Instruction::SetGE);
1208 case Instruction::SetLE:
1209 // If we know that V1 <= V2, we can only partially decide this relation.
1210 if (Opcode == Instruction::SetGT) return ConstantBool::False;
1211 if (Opcode == Instruction::SetLT) return ConstantBool::True;
1214 case Instruction::SetGE:
1215 // If we know that V1 >= V2, we can only partially decide this relation.
1216 if (Opcode == Instruction::SetLT) return ConstantBool::False;
1217 if (Opcode == Instruction::SetGT) return ConstantBool::True;
1220 case Instruction::SetNE:
1221 // If we know that V1 != V2, we can only partially decide this relation.
1222 if (Opcode == Instruction::SetEQ) return ConstantBool::False;
1223 if (Opcode == Instruction::SetNE) return ConstantBool::True;
1228 if (isa<UndefValue>(V1) || isa<UndefValue>(V2)) {
1230 case Instruction::Add:
1231 case Instruction::Sub:
1232 case Instruction::Xor:
1233 return UndefValue::get(V1->getType());
1235 case Instruction::Mul:
1236 case Instruction::And:
1237 return Constant::getNullValue(V1->getType());
1238 case Instruction::Div:
1239 case Instruction::Rem:
1240 if (!isa<UndefValue>(V2)) // undef/X -> 0
1241 return Constant::getNullValue(V1->getType());
1242 return const_cast<Constant*>(V2); // X/undef -> undef
1243 case Instruction::Or: // X|undef -> -1
1244 return ConstantInt::getAllOnesValue(V1->getType());
1245 case Instruction::Shr:
1246 if (!isa<UndefValue>(V2)) {
1247 if (V1->getType()->isSigned())
1248 return const_cast<Constant*>(V1); // undef >>s X -> undef
1250 } else if (isa<UndefValue>(V1)) {
1251 return const_cast<Constant*>(V1); // undef >> undef -> undef
1253 if (V1->getType()->isSigned())
1254 return const_cast<Constant*>(V1); // X >>s undef -> X
1257 return Constant::getNullValue(V1->getType());
1259 case Instruction::Shl:
1260 // undef << X -> 0 X << undef -> 0
1261 return Constant::getNullValue(V1->getType());
1265 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(V1)) {
1266 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
1267 // There are many possible foldings we could do here. We should probably
1268 // at least fold add of a pointer with an integer into the appropriate
1269 // getelementptr. This will improve alias analysis a bit.
1275 // Just implement a couple of simple identities.
1277 case Instruction::Add:
1278 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X + 0 == X
1280 case Instruction::Sub:
1281 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X - 0 == X
1283 case Instruction::Mul:
1284 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X * 0 == 0
1285 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1286 if (CI->getRawValue() == 1)
1287 return const_cast<Constant*>(V1); // X * 1 == X
1289 case Instruction::Div:
1290 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1291 if (CI->getRawValue() == 1)
1292 return const_cast<Constant*>(V1); // X / 1 == X
1294 case Instruction::Rem:
1295 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1296 if (CI->getRawValue() == 1)
1297 return Constant::getNullValue(CI->getType()); // X % 1 == 0
1299 case Instruction::And:
1300 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1301 return const_cast<Constant*>(V1); // X & -1 == X
1302 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X & 0 == 0
1303 if (CE1->getOpcode() == Instruction::Cast &&
1304 isa<GlobalValue>(CE1->getOperand(0))) {
1305 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
1307 // Functions are at least 4-byte aligned. If and'ing the address of a
1308 // function with a constant < 4, fold it to zero.
1309 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1310 if (CI->getRawValue() < 4 && isa<Function>(CPR))
1311 return Constant::getNullValue(CI->getType());
1314 case Instruction::Or:
1315 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X | 0 == X
1316 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1317 return const_cast<Constant*>(V2); // X | -1 == -1
1319 case Instruction::Xor:
1320 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X ^ 0 == X
1325 } else if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
1326 // If V2 is a constant expr and V1 isn't, flop them around and fold the
1327 // other way if possible.
1329 case Instruction::Add:
1330 case Instruction::Mul:
1331 case Instruction::And:
1332 case Instruction::Or:
1333 case Instruction::Xor:
1334 case Instruction::SetEQ:
1335 case Instruction::SetNE:
1336 // No change of opcode required.
1337 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1339 case Instruction::SetLT:
1340 case Instruction::SetGT:
1341 case Instruction::SetLE:
1342 case Instruction::SetGE:
1343 // Change the opcode as necessary to swap the operands.
1344 Opcode = SetCondInst::getSwappedCondition((Instruction::BinaryOps)Opcode);
1345 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1347 case Instruction::Shl:
1348 case Instruction::Shr:
1349 case Instruction::Sub:
1350 case Instruction::Div:
1351 case Instruction::Rem:
1352 default: // These instructions cannot be flopped around.
1359 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1360 const std::vector<Value*> &IdxList) {
1361 if (IdxList.size() == 0 ||
1362 (IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
1363 return const_cast<Constant*>(C);
1365 if (isa<UndefValue>(C)) {
1366 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1368 assert(Ty != 0 && "Invalid indices for GEP!");
1369 return UndefValue::get(PointerType::get(Ty));
1372 Constant *Idx0 = cast<Constant>(IdxList[0]);
1373 if (C->isNullValue()) {
1375 for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
1376 if (!cast<Constant>(IdxList[i])->isNullValue()) {
1381 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1383 assert(Ty != 0 && "Invalid indices for GEP!");
1384 return ConstantPointerNull::get(PointerType::get(Ty));
1387 if (IdxList.size() == 1) {
1388 const Type *ElTy = cast<PointerType>(C->getType())->getElementType();
1389 if (unsigned ElSize = ElTy->getPrimitiveSize()) {
1390 // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm
1391 // type, we can statically fold this.
1392 Constant *R = ConstantUInt::get(Type::UIntTy, ElSize);
1393 R = ConstantExpr::getCast(R, Idx0->getType());
1394 R = ConstantExpr::getMul(R, Idx0);
1395 return ConstantExpr::getCast(R, C->getType());
1400 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1401 // Combine Indices - If the source pointer to this getelementptr instruction
1402 // is a getelementptr instruction, combine the indices of the two
1403 // getelementptr instructions into a single instruction.
1405 if (CE->getOpcode() == Instruction::GetElementPtr) {
1406 const Type *LastTy = 0;
1407 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1411 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1412 std::vector<Value*> NewIndices;
1413 NewIndices.reserve(IdxList.size() + CE->getNumOperands());
1414 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1415 NewIndices.push_back(CE->getOperand(i));
1417 // Add the last index of the source with the first index of the new GEP.
1418 // Make sure to handle the case when they are actually different types.
1419 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1420 // Otherwise it must be an array.
1421 if (!Idx0->isNullValue()) {
1422 const Type *IdxTy = Combined->getType();
1423 if (IdxTy != Idx0->getType()) IdxTy = Type::LongTy;
1425 ConstantExpr::get(Instruction::Add,
1426 ConstantExpr::getCast(Idx0, IdxTy),
1427 ConstantExpr::getCast(Combined, IdxTy));
1430 NewIndices.push_back(Combined);
1431 NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
1432 return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
1436 // Implement folding of:
1437 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1439 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1441 if (CE->getOpcode() == Instruction::Cast && IdxList.size() > 1 &&
1442 Idx0->isNullValue())
1443 if (const PointerType *SPT =
1444 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1445 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1446 if (const ArrayType *CAT =
1447 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1448 if (CAT->getElementType() == SAT->getElementType())
1449 return ConstantExpr::getGetElementPtr(
1450 (Constant*)CE->getOperand(0), IdxList);