1 //===- ConstantFolding.cpp - LLVM constant folder -------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements folding of constants for LLVM. This implements the
11 // (internal) ConstantFolding.h interface, which is used by the
12 // ConstantExpr::get* methods to automatically fold constants when possible.
14 // The current constant folding implementation is implemented in two pieces: the
15 // template-based folder for simple primitive constants like ConstantInt, and
16 // the special case hackery that we use to symbolically evaluate expressions
17 // that use ConstantExprs.
19 //===----------------------------------------------------------------------===//
21 #include "ConstantFolding.h"
22 #include "llvm/Constants.h"
23 #include "llvm/Instructions.h"
24 #include "llvm/DerivedTypes.h"
25 #include "llvm/Function.h"
26 #include "llvm/Support/Compiler.h"
27 #include "llvm/Support/GetElementPtrTypeIterator.h"
28 #include "llvm/Support/ManagedStatic.h"
29 #include "llvm/Support/MathExtras.h"
35 struct VISIBILITY_HIDDEN ConstRules {
37 virtual ~ConstRules() {}
39 // Binary Operators...
40 virtual Constant *add(const Constant *V1, const Constant *V2) const = 0;
41 virtual Constant *sub(const Constant *V1, const Constant *V2) const = 0;
42 virtual Constant *mul(const Constant *V1, const Constant *V2) const = 0;
43 virtual Constant *urem(const Constant *V1, const Constant *V2) const = 0;
44 virtual Constant *srem(const Constant *V1, const Constant *V2) const = 0;
45 virtual Constant *frem(const Constant *V1, const Constant *V2) const = 0;
46 virtual Constant *udiv(const Constant *V1, const Constant *V2) const = 0;
47 virtual Constant *sdiv(const Constant *V1, const Constant *V2) const = 0;
48 virtual Constant *fdiv(const Constant *V1, const Constant *V2) const = 0;
49 virtual Constant *op_and(const Constant *V1, const Constant *V2) const = 0;
50 virtual Constant *op_or (const Constant *V1, const Constant *V2) const = 0;
51 virtual Constant *op_xor(const Constant *V1, const Constant *V2) const = 0;
52 virtual Constant *shl(const Constant *V1, const Constant *V2) const = 0;
53 virtual Constant *lshr(const Constant *V1, const Constant *V2) const = 0;
54 virtual Constant *ashr(const Constant *V1, const Constant *V2) const = 0;
55 virtual Constant *lessthan(const Constant *V1, const Constant *V2) const =0;
56 virtual Constant *equalto(const Constant *V1, const Constant *V2) const = 0;
59 virtual Constant *castToBool (const Constant *V) const = 0;
60 virtual Constant *castToSByte (const Constant *V) const = 0;
61 virtual Constant *castToUByte (const Constant *V) const = 0;
62 virtual Constant *castToShort (const Constant *V) const = 0;
63 virtual Constant *castToUShort(const Constant *V) const = 0;
64 virtual Constant *castToInt (const Constant *V) const = 0;
65 virtual Constant *castToUInt (const Constant *V) const = 0;
66 virtual Constant *castToLong (const Constant *V) const = 0;
67 virtual Constant *castToULong (const Constant *V) const = 0;
68 virtual Constant *castToFloat (const Constant *V) const = 0;
69 virtual Constant *castToDouble(const Constant *V) const = 0;
70 virtual Constant *castToPointer(const Constant *V,
71 const PointerType *Ty) const = 0;
73 // ConstRules::get - Return an instance of ConstRules for the specified
76 static ConstRules &get(const Constant *V1, const Constant *V2);
78 ConstRules(const ConstRules &); // Do not implement
79 ConstRules &operator=(const ConstRules &); // Do not implement
84 //===----------------------------------------------------------------------===//
85 // TemplateRules Class
86 //===----------------------------------------------------------------------===//
88 // TemplateRules - Implement a subclass of ConstRules that provides all
89 // operations as noops. All other rules classes inherit from this class so
90 // that if functionality is needed in the future, it can simply be added here
91 // and to ConstRules without changing anything else...
93 // This class also provides subclasses with typesafe implementations of methods
94 // so that don't have to do type casting.
97 template<class ArgType, class SubClassName>
98 class VISIBILITY_HIDDEN TemplateRules : public ConstRules {
101 //===--------------------------------------------------------------------===//
102 // Redirecting functions that cast to the appropriate types
103 //===--------------------------------------------------------------------===//
105 virtual Constant *add(const Constant *V1, const Constant *V2) const {
106 return SubClassName::Add((const ArgType *)V1, (const ArgType *)V2);
108 virtual Constant *sub(const Constant *V1, const Constant *V2) const {
109 return SubClassName::Sub((const ArgType *)V1, (const ArgType *)V2);
111 virtual Constant *mul(const Constant *V1, const Constant *V2) const {
112 return SubClassName::Mul((const ArgType *)V1, (const ArgType *)V2);
114 virtual Constant *udiv(const Constant *V1, const Constant *V2) const {
115 return SubClassName::UDiv((const ArgType *)V1, (const ArgType *)V2);
117 virtual Constant *sdiv(const Constant *V1, const Constant *V2) const {
118 return SubClassName::SDiv((const ArgType *)V1, (const ArgType *)V2);
120 virtual Constant *fdiv(const Constant *V1, const Constant *V2) const {
121 return SubClassName::FDiv((const ArgType *)V1, (const ArgType *)V2);
123 virtual Constant *urem(const Constant *V1, const Constant *V2) const {
124 return SubClassName::URem((const ArgType *)V1, (const ArgType *)V2);
126 virtual Constant *srem(const Constant *V1, const Constant *V2) const {
127 return SubClassName::SRem((const ArgType *)V1, (const ArgType *)V2);
129 virtual Constant *frem(const Constant *V1, const Constant *V2) const {
130 return SubClassName::FRem((const ArgType *)V1, (const ArgType *)V2);
132 virtual Constant *op_and(const Constant *V1, const Constant *V2) const {
133 return SubClassName::And((const ArgType *)V1, (const ArgType *)V2);
135 virtual Constant *op_or(const Constant *V1, const Constant *V2) const {
136 return SubClassName::Or((const ArgType *)V1, (const ArgType *)V2);
138 virtual Constant *op_xor(const Constant *V1, const Constant *V2) const {
139 return SubClassName::Xor((const ArgType *)V1, (const ArgType *)V2);
141 virtual Constant *shl(const Constant *V1, const Constant *V2) const {
142 return SubClassName::Shl((const ArgType *)V1, (const ArgType *)V2);
144 virtual Constant *lshr(const Constant *V1, const Constant *V2) const {
145 return SubClassName::LShr((const ArgType *)V1, (const ArgType *)V2);
147 virtual Constant *ashr(const Constant *V1, const Constant *V2) const {
148 return SubClassName::AShr((const ArgType *)V1, (const ArgType *)V2);
151 virtual Constant *lessthan(const Constant *V1, const Constant *V2) const {
152 return SubClassName::LessThan((const ArgType *)V1, (const ArgType *)V2);
154 virtual Constant *equalto(const Constant *V1, const Constant *V2) const {
155 return SubClassName::EqualTo((const ArgType *)V1, (const ArgType *)V2);
158 // Casting operators. ick
159 virtual Constant *castToBool(const Constant *V) const {
160 return SubClassName::CastToBool((const ArgType*)V);
162 virtual Constant *castToSByte(const Constant *V) const {
163 return SubClassName::CastToSByte((const ArgType*)V);
165 virtual Constant *castToUByte(const Constant *V) const {
166 return SubClassName::CastToUByte((const ArgType*)V);
168 virtual Constant *castToShort(const Constant *V) const {
169 return SubClassName::CastToShort((const ArgType*)V);
171 virtual Constant *castToUShort(const Constant *V) const {
172 return SubClassName::CastToUShort((const ArgType*)V);
174 virtual Constant *castToInt(const Constant *V) const {
175 return SubClassName::CastToInt((const ArgType*)V);
177 virtual Constant *castToUInt(const Constant *V) const {
178 return SubClassName::CastToUInt((const ArgType*)V);
180 virtual Constant *castToLong(const Constant *V) const {
181 return SubClassName::CastToLong((const ArgType*)V);
183 virtual Constant *castToULong(const Constant *V) const {
184 return SubClassName::CastToULong((const ArgType*)V);
186 virtual Constant *castToFloat(const Constant *V) const {
187 return SubClassName::CastToFloat((const ArgType*)V);
189 virtual Constant *castToDouble(const Constant *V) const {
190 return SubClassName::CastToDouble((const ArgType*)V);
192 virtual Constant *castToPointer(const Constant *V,
193 const PointerType *Ty) const {
194 return SubClassName::CastToPointer((const ArgType*)V, Ty);
197 //===--------------------------------------------------------------------===//
198 // Default "noop" implementations
199 //===--------------------------------------------------------------------===//
201 static Constant *Add (const ArgType *V1, const ArgType *V2) { return 0; }
202 static Constant *Sub (const ArgType *V1, const ArgType *V2) { return 0; }
203 static Constant *Mul (const ArgType *V1, const ArgType *V2) { return 0; }
204 static Constant *SDiv(const ArgType *V1, const ArgType *V2) { return 0; }
205 static Constant *UDiv(const ArgType *V1, const ArgType *V2) { return 0; }
206 static Constant *FDiv(const ArgType *V1, const ArgType *V2) { return 0; }
207 static Constant *URem(const ArgType *V1, const ArgType *V2) { return 0; }
208 static Constant *SRem(const ArgType *V1, const ArgType *V2) { return 0; }
209 static Constant *FRem(const ArgType *V1, const ArgType *V2) { return 0; }
210 static Constant *And (const ArgType *V1, const ArgType *V2) { return 0; }
211 static Constant *Or (const ArgType *V1, const ArgType *V2) { return 0; }
212 static Constant *Xor (const ArgType *V1, const ArgType *V2) { return 0; }
213 static Constant *Shl (const ArgType *V1, const ArgType *V2) { return 0; }
214 static Constant *LShr(const ArgType *V1, const ArgType *V2) { return 0; }
215 static Constant *AShr(const ArgType *V1, const ArgType *V2) { return 0; }
216 static Constant *LessThan(const ArgType *V1, const ArgType *V2) {
219 static Constant *EqualTo(const ArgType *V1, const ArgType *V2) {
223 // Casting operators. ick
224 static Constant *CastToBool (const Constant *V) { return 0; }
225 static Constant *CastToSByte (const Constant *V) { return 0; }
226 static Constant *CastToUByte (const Constant *V) { return 0; }
227 static Constant *CastToShort (const Constant *V) { return 0; }
228 static Constant *CastToUShort(const Constant *V) { return 0; }
229 static Constant *CastToInt (const Constant *V) { return 0; }
230 static Constant *CastToUInt (const Constant *V) { return 0; }
231 static Constant *CastToLong (const Constant *V) { return 0; }
232 static Constant *CastToULong (const Constant *V) { return 0; }
233 static Constant *CastToFloat (const Constant *V) { return 0; }
234 static Constant *CastToDouble(const Constant *V) { return 0; }
235 static Constant *CastToPointer(const Constant *,
236 const PointerType *) {return 0;}
239 virtual ~TemplateRules() {}
241 } // end anonymous namespace
244 //===----------------------------------------------------------------------===//
246 //===----------------------------------------------------------------------===//
248 // EmptyRules provides a concrete base class of ConstRules that does nothing
251 struct VISIBILITY_HIDDEN EmptyRules
252 : public TemplateRules<Constant, EmptyRules> {
253 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
254 if (V1 == V2) return ConstantBool::getTrue();
258 } // end anonymous namespace
262 //===----------------------------------------------------------------------===//
264 //===----------------------------------------------------------------------===//
266 // BoolRules provides a concrete base class of ConstRules for the 'bool' type.
269 struct VISIBILITY_HIDDEN BoolRules
270 : public TemplateRules<ConstantBool, BoolRules> {
272 static Constant *LessThan(const ConstantBool *V1, const ConstantBool *V2) {
273 return ConstantBool::get(V1->getValue() < V2->getValue());
276 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
277 return ConstantBool::get(V1 == V2);
280 static Constant *And(const ConstantBool *V1, const ConstantBool *V2) {
281 return ConstantBool::get(V1->getValue() & V2->getValue());
284 static Constant *Or(const ConstantBool *V1, const ConstantBool *V2) {
285 return ConstantBool::get(V1->getValue() | V2->getValue());
288 static Constant *Xor(const ConstantBool *V1, const ConstantBool *V2) {
289 return ConstantBool::get(V1->getValue() ^ V2->getValue());
292 // Casting operators. ick
293 #define DEF_CAST(TYPE, CLASS, CTYPE) \
294 static Constant *CastTo##TYPE (const ConstantBool *V) { \
295 return CLASS::get(Type::TYPE##Ty, (CTYPE)(bool)V->getValue()); \
298 DEF_CAST(Bool , ConstantBool, bool)
299 DEF_CAST(SByte , ConstantInt, signed char)
300 DEF_CAST(UByte , ConstantInt, unsigned char)
301 DEF_CAST(Short , ConstantInt, signed short)
302 DEF_CAST(UShort, ConstantInt, unsigned short)
303 DEF_CAST(Int , ConstantInt, signed int)
304 DEF_CAST(UInt , ConstantInt, unsigned int)
305 DEF_CAST(Long , ConstantInt, int64_t)
306 DEF_CAST(ULong , ConstantInt, uint64_t)
307 DEF_CAST(Float , ConstantFP , float)
308 DEF_CAST(Double, ConstantFP , double)
311 } // end anonymous namespace
314 //===----------------------------------------------------------------------===//
315 // NullPointerRules Class
316 //===----------------------------------------------------------------------===//
318 // NullPointerRules provides a concrete base class of ConstRules for null
322 struct VISIBILITY_HIDDEN NullPointerRules
323 : public TemplateRules<ConstantPointerNull, NullPointerRules> {
324 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
325 return ConstantBool::getTrue(); // Null pointers are always equal
327 static Constant *CastToBool(const Constant *V) {
328 return ConstantBool::getFalse();
330 static Constant *CastToSByte (const Constant *V) {
331 return ConstantInt::get(Type::SByteTy, 0);
333 static Constant *CastToUByte (const Constant *V) {
334 return ConstantInt::get(Type::UByteTy, 0);
336 static Constant *CastToShort (const Constant *V) {
337 return ConstantInt::get(Type::ShortTy, 0);
339 static Constant *CastToUShort(const Constant *V) {
340 return ConstantInt::get(Type::UShortTy, 0);
342 static Constant *CastToInt (const Constant *V) {
343 return ConstantInt::get(Type::IntTy, 0);
345 static Constant *CastToUInt (const Constant *V) {
346 return ConstantInt::get(Type::UIntTy, 0);
348 static Constant *CastToLong (const Constant *V) {
349 return ConstantInt::get(Type::LongTy, 0);
351 static Constant *CastToULong (const Constant *V) {
352 return ConstantInt::get(Type::ULongTy, 0);
354 static Constant *CastToFloat (const Constant *V) {
355 return ConstantFP::get(Type::FloatTy, 0);
357 static Constant *CastToDouble(const Constant *V) {
358 return ConstantFP::get(Type::DoubleTy, 0);
361 static Constant *CastToPointer(const ConstantPointerNull *V,
362 const PointerType *PTy) {
363 return ConstantPointerNull::get(PTy);
366 } // end anonymous namespace
368 //===----------------------------------------------------------------------===//
369 // ConstantPackedRules Class
370 //===----------------------------------------------------------------------===//
372 /// DoVectorOp - Given two packed constants and a function pointer, apply the
373 /// function pointer to each element pair, producing a new ConstantPacked
375 static Constant *EvalVectorOp(const ConstantPacked *V1,
376 const ConstantPacked *V2,
377 Constant *(*FP)(Constant*, Constant*)) {
378 std::vector<Constant*> Res;
379 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
380 Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
381 const_cast<Constant*>(V2->getOperand(i))));
382 return ConstantPacked::get(Res);
385 /// PackedTypeRules provides a concrete base class of ConstRules for
386 /// ConstantPacked operands.
389 struct VISIBILITY_HIDDEN ConstantPackedRules
390 : public TemplateRules<ConstantPacked, ConstantPackedRules> {
392 static Constant *Add(const ConstantPacked *V1, const ConstantPacked *V2) {
393 return EvalVectorOp(V1, V2, ConstantExpr::getAdd);
395 static Constant *Sub(const ConstantPacked *V1, const ConstantPacked *V2) {
396 return EvalVectorOp(V1, V2, ConstantExpr::getSub);
398 static Constant *Mul(const ConstantPacked *V1, const ConstantPacked *V2) {
399 return EvalVectorOp(V1, V2, ConstantExpr::getMul);
401 static Constant *UDiv(const ConstantPacked *V1, const ConstantPacked *V2) {
402 return EvalVectorOp(V1, V2, ConstantExpr::getUDiv);
404 static Constant *SDiv(const ConstantPacked *V1, const ConstantPacked *V2) {
405 return EvalVectorOp(V1, V2, ConstantExpr::getSDiv);
407 static Constant *FDiv(const ConstantPacked *V1, const ConstantPacked *V2) {
408 return EvalVectorOp(V1, V2, ConstantExpr::getFDiv);
410 static Constant *URem(const ConstantPacked *V1, const ConstantPacked *V2) {
411 return EvalVectorOp(V1, V2, ConstantExpr::getURem);
413 static Constant *SRem(const ConstantPacked *V1, const ConstantPacked *V2) {
414 return EvalVectorOp(V1, V2, ConstantExpr::getSRem);
416 static Constant *FRem(const ConstantPacked *V1, const ConstantPacked *V2) {
417 return EvalVectorOp(V1, V2, ConstantExpr::getFRem);
419 static Constant *And(const ConstantPacked *V1, const ConstantPacked *V2) {
420 return EvalVectorOp(V1, V2, ConstantExpr::getAnd);
422 static Constant *Or (const ConstantPacked *V1, const ConstantPacked *V2) {
423 return EvalVectorOp(V1, V2, ConstantExpr::getOr);
425 static Constant *Xor(const ConstantPacked *V1, const ConstantPacked *V2) {
426 return EvalVectorOp(V1, V2, ConstantExpr::getXor);
428 static Constant *LessThan(const ConstantPacked *V1, const ConstantPacked *V2){
431 static Constant *EqualTo(const ConstantPacked *V1, const ConstantPacked *V2) {
432 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i) {
434 ConstantExpr::getSetEQ(const_cast<Constant*>(V1->getOperand(i)),
435 const_cast<Constant*>(V2->getOperand(i)));
436 if (ConstantBool *CB = dyn_cast<ConstantBool>(C))
439 // Otherwise, could not decide from any element pairs.
443 } // end anonymous namespace
446 //===----------------------------------------------------------------------===//
447 // GeneralPackedRules Class
448 //===----------------------------------------------------------------------===//
450 /// GeneralPackedRules provides a concrete base class of ConstRules for
451 /// PackedType operands, where both operands are not ConstantPacked. The usual
452 /// cause for this is that one operand is a ConstantAggregateZero.
455 struct VISIBILITY_HIDDEN GeneralPackedRules
456 : public TemplateRules<Constant, GeneralPackedRules> {
458 } // end anonymous namespace
461 //===----------------------------------------------------------------------===//
462 // DirectIntRules Class
463 //===----------------------------------------------------------------------===//
465 // DirectIntRules provides implementations of functions that are valid on
466 // integer types, but not all types in general.
469 template <class BuiltinType, Type **Ty>
470 struct VISIBILITY_HIDDEN DirectIntRules
471 : public TemplateRules<ConstantInt, DirectIntRules<BuiltinType, Ty> > {
473 static Constant *Add(const ConstantInt *V1, const ConstantInt *V2) {
474 BuiltinType R = (BuiltinType)V1->getZExtValue() +
475 (BuiltinType)V2->getZExtValue();
476 return ConstantInt::get(*Ty, R);
479 static Constant *Sub(const ConstantInt *V1, const ConstantInt *V2) {
480 BuiltinType R = (BuiltinType)V1->getZExtValue() -
481 (BuiltinType)V2->getZExtValue();
482 return ConstantInt::get(*Ty, R);
485 static Constant *Mul(const ConstantInt *V1, const ConstantInt *V2) {
486 BuiltinType R = (BuiltinType)V1->getZExtValue() *
487 (BuiltinType)V2->getZExtValue();
488 return ConstantInt::get(*Ty, R);
491 static Constant *LessThan(const ConstantInt *V1, const ConstantInt *V2) {
492 bool R = (BuiltinType)V1->getZExtValue() < (BuiltinType)V2->getZExtValue();
493 return ConstantBool::get(R);
496 static Constant *EqualTo(const ConstantInt *V1, const ConstantInt *V2) {
497 bool R = (BuiltinType)V1->getZExtValue() == (BuiltinType)V2->getZExtValue();
498 return ConstantBool::get(R);
501 static Constant *CastToPointer(const ConstantInt *V,
502 const PointerType *PTy) {
503 if (V->isNullValue()) // Is it a FP or Integral null value?
504 return ConstantPointerNull::get(PTy);
505 return 0; // Can't const prop other types of pointers
508 // Casting operators. ick
509 #define DEF_CAST(TYPE, CLASS, CTYPE) \
510 static Constant *CastTo##TYPE (const ConstantInt *V) { \
511 return CLASS::get(Type::TYPE##Ty, (CTYPE)(BuiltinType)V->getZExtValue()); \
514 DEF_CAST(Bool , ConstantBool, bool)
515 DEF_CAST(SByte , ConstantInt, signed char)
516 DEF_CAST(UByte , ConstantInt, unsigned char)
517 DEF_CAST(Short , ConstantInt, signed short)
518 DEF_CAST(UShort, ConstantInt, unsigned short)
519 DEF_CAST(Int , ConstantInt, signed int)
520 DEF_CAST(UInt , ConstantInt, unsigned int)
521 DEF_CAST(Long , ConstantInt, int64_t)
522 DEF_CAST(ULong , ConstantInt, uint64_t)
523 DEF_CAST(Float , ConstantFP , float)
524 DEF_CAST(Double, ConstantFP , double)
527 static Constant *UDiv(const ConstantInt *V1, const ConstantInt *V2) {
528 if (V2->isNullValue()) // X / 0
530 BuiltinType R = (BuiltinType)(V1->getZExtValue() / V2->getZExtValue());
531 return ConstantInt::get(*Ty, R);
534 static Constant *SDiv(const ConstantInt *V1, const ConstantInt *V2) {
535 if (V2->isNullValue()) // X / 0
537 if (V2->isAllOnesValue() && // MIN_INT / -1
538 (BuiltinType)V1->getSExtValue() == -(BuiltinType)V1->getSExtValue())
540 BuiltinType R = (BuiltinType)(V1->getSExtValue() / V2->getSExtValue());
541 return ConstantInt::get(*Ty, R);
544 static Constant *URem(const ConstantInt *V1,
545 const ConstantInt *V2) {
546 if (V2->isNullValue()) return 0; // X / 0
547 BuiltinType R = (BuiltinType)(V1->getZExtValue() % V2->getZExtValue());
548 return ConstantInt::get(*Ty, R);
551 static Constant *SRem(const ConstantInt *V1,
552 const ConstantInt *V2) {
553 if (V2->isNullValue()) return 0; // X % 0
554 if (V2->isAllOnesValue() && // MIN_INT % -1
555 (BuiltinType)V1->getSExtValue() == -(BuiltinType)V1->getSExtValue())
557 BuiltinType R = (BuiltinType)(V1->getSExtValue() % V2->getSExtValue());
558 return ConstantInt::get(*Ty, R);
561 static Constant *And(const ConstantInt *V1, const ConstantInt *V2) {
563 (BuiltinType)V1->getZExtValue() & (BuiltinType)V2->getZExtValue();
564 return ConstantInt::get(*Ty, R);
566 static Constant *Or(const ConstantInt *V1, const ConstantInt *V2) {
568 (BuiltinType)V1->getZExtValue() | (BuiltinType)V2->getZExtValue();
569 return ConstantInt::get(*Ty, R);
571 static Constant *Xor(const ConstantInt *V1, const ConstantInt *V2) {
573 (BuiltinType)V1->getZExtValue() ^ (BuiltinType)V2->getZExtValue();
574 return ConstantInt::get(*Ty, R);
577 static Constant *Shl(const ConstantInt *V1, const ConstantInt *V2) {
579 (BuiltinType)V1->getZExtValue() << (BuiltinType)V2->getZExtValue();
580 return ConstantInt::get(*Ty, R);
583 static Constant *LShr(const ConstantInt *V1, const ConstantInt *V2) {
584 BuiltinType R = BuiltinType(V1->getZExtValue() >> V2->getZExtValue());
585 return ConstantInt::get(*Ty, R);
588 static Constant *AShr(const ConstantInt *V1, const ConstantInt *V2) {
589 BuiltinType R = BuiltinType(V1->getSExtValue() >> V2->getZExtValue());
590 return ConstantInt::get(*Ty, R);
593 } // end anonymous namespace
596 //===----------------------------------------------------------------------===//
597 // DirectFPRules Class
598 //===----------------------------------------------------------------------===//
600 /// DirectFPRules provides implementations of functions that are valid on
601 /// floating point types, but not all types in general.
604 template <class BuiltinType, Type **Ty>
605 struct VISIBILITY_HIDDEN DirectFPRules
606 : public TemplateRules<ConstantFP, DirectFPRules<BuiltinType, Ty> > {
608 static Constant *Add(const ConstantFP *V1, const ConstantFP *V2) {
609 BuiltinType R = (BuiltinType)V1->getValue() +
610 (BuiltinType)V2->getValue();
611 return ConstantFP::get(*Ty, R);
614 static Constant *Sub(const ConstantFP *V1, const ConstantFP *V2) {
615 BuiltinType R = (BuiltinType)V1->getValue() - (BuiltinType)V2->getValue();
616 return ConstantFP::get(*Ty, R);
619 static Constant *Mul(const ConstantFP *V1, const ConstantFP *V2) {
620 BuiltinType R = (BuiltinType)V1->getValue() * (BuiltinType)V2->getValue();
621 return ConstantFP::get(*Ty, R);
624 static Constant *LessThan(const ConstantFP *V1, const ConstantFP *V2) {
625 bool R = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue();
626 return ConstantBool::get(R);
629 static Constant *EqualTo(const ConstantFP *V1, const ConstantFP *V2) {
630 bool R = (BuiltinType)V1->getValue() == (BuiltinType)V2->getValue();
631 return ConstantBool::get(R);
634 static Constant *CastToPointer(const ConstantFP *V,
635 const PointerType *PTy) {
636 if (V->isNullValue()) // Is it a FP or Integral null value?
637 return ConstantPointerNull::get(PTy);
638 return 0; // Can't const prop other types of pointers
641 // Casting operators. ick
642 #define DEF_CAST(TYPE, CLASS, CTYPE) \
643 static Constant *CastTo##TYPE (const ConstantFP *V) { \
644 return CLASS::get(Type::TYPE##Ty, (CTYPE)(BuiltinType)V->getValue()); \
647 DEF_CAST(Bool , ConstantBool, bool)
648 DEF_CAST(SByte , ConstantInt, signed char)
649 DEF_CAST(UByte , ConstantInt, unsigned char)
650 DEF_CAST(Short , ConstantInt, signed short)
651 DEF_CAST(UShort, ConstantInt, unsigned short)
652 DEF_CAST(Int , ConstantInt, signed int)
653 DEF_CAST(UInt , ConstantInt, unsigned int)
654 DEF_CAST(Long , ConstantInt, int64_t)
655 DEF_CAST(ULong , ConstantInt, uint64_t)
656 DEF_CAST(Float , ConstantFP , float)
657 DEF_CAST(Double, ConstantFP , double)
660 static Constant *FRem(const ConstantFP *V1, const ConstantFP *V2) {
661 if (V2->isNullValue()) return 0;
662 BuiltinType Result = std::fmod((BuiltinType)V1->getValue(),
663 (BuiltinType)V2->getValue());
664 return ConstantFP::get(*Ty, Result);
666 static Constant *FDiv(const ConstantFP *V1, const ConstantFP *V2) {
667 BuiltinType inf = std::numeric_limits<BuiltinType>::infinity();
668 if (V2->isExactlyValue(0.0)) return ConstantFP::get(*Ty, inf);
669 if (V2->isExactlyValue(-0.0)) return ConstantFP::get(*Ty, -inf);
670 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
671 return ConstantFP::get(*Ty, R);
674 } // end anonymous namespace
676 static ManagedStatic<EmptyRules> EmptyR;
677 static ManagedStatic<BoolRules> BoolR;
678 static ManagedStatic<NullPointerRules> NullPointerR;
679 static ManagedStatic<ConstantPackedRules> ConstantPackedR;
680 static ManagedStatic<GeneralPackedRules> GeneralPackedR;
681 static ManagedStatic<DirectIntRules<signed char , &Type::SByteTy> > SByteR;
682 static ManagedStatic<DirectIntRules<unsigned char , &Type::UByteTy> > UByteR;
683 static ManagedStatic<DirectIntRules<signed short , &Type::ShortTy> > ShortR;
684 static ManagedStatic<DirectIntRules<unsigned short, &Type::UShortTy> > UShortR;
685 static ManagedStatic<DirectIntRules<signed int , &Type::IntTy> > IntR;
686 static ManagedStatic<DirectIntRules<unsigned int , &Type::UIntTy> > UIntR;
687 static ManagedStatic<DirectIntRules<int64_t , &Type::LongTy> > LongR;
688 static ManagedStatic<DirectIntRules<uint64_t , &Type::ULongTy> > ULongR;
689 static ManagedStatic<DirectFPRules <float , &Type::FloatTy> > FloatR;
690 static ManagedStatic<DirectFPRules <double , &Type::DoubleTy> > DoubleR;
692 /// ConstRules::get - This method returns the constant rules implementation that
693 /// implements the semantics of the two specified constants.
694 ConstRules &ConstRules::get(const Constant *V1, const Constant *V2) {
695 if (isa<ConstantExpr>(V1) || isa<ConstantExpr>(V2) ||
696 isa<GlobalValue>(V1) || isa<GlobalValue>(V2) ||
697 isa<UndefValue>(V1) || isa<UndefValue>(V2))
700 switch (V1->getType()->getTypeID()) {
701 default: assert(0 && "Unknown value type for constant folding!");
702 case Type::BoolTyID: return *BoolR;
703 case Type::PointerTyID: return *NullPointerR;
704 case Type::SByteTyID: return *SByteR;
705 case Type::UByteTyID: return *UByteR;
706 case Type::ShortTyID: return *ShortR;
707 case Type::UShortTyID: return *UShortR;
708 case Type::IntTyID: return *IntR;
709 case Type::UIntTyID: return *UIntR;
710 case Type::LongTyID: return *LongR;
711 case Type::ULongTyID: return *ULongR;
712 case Type::FloatTyID: return *FloatR;
713 case Type::DoubleTyID: return *DoubleR;
714 case Type::PackedTyID:
715 if (isa<ConstantPacked>(V1) && isa<ConstantPacked>(V2))
716 return *ConstantPackedR;
717 return *GeneralPackedR; // Constant folding rules for ConstantAggregateZero.
722 //===----------------------------------------------------------------------===//
723 // ConstantFold*Instruction Implementations
724 //===----------------------------------------------------------------------===//
726 // These methods contain the special case hackery required to symbolically
727 // evaluate some constant expression cases, and use the ConstantRules class to
728 // evaluate normal constants.
730 static unsigned getSize(const Type *Ty) {
731 unsigned S = Ty->getPrimitiveSize();
732 return S ? S : 8; // Treat pointers at 8 bytes
735 /// CastConstantPacked - Convert the specified ConstantPacked node to the
736 /// specified packed type. At this point, we know that the elements of the
737 /// input packed constant are all simple integer or FP values.
738 static Constant *CastConstantPacked(ConstantPacked *CP,
739 const PackedType *DstTy) {
740 unsigned SrcNumElts = CP->getType()->getNumElements();
741 unsigned DstNumElts = DstTy->getNumElements();
742 const Type *SrcEltTy = CP->getType()->getElementType();
743 const Type *DstEltTy = DstTy->getElementType();
745 // If both vectors have the same number of elements (thus, the elements
746 // are the same size), perform the conversion now.
747 if (SrcNumElts == DstNumElts) {
748 std::vector<Constant*> Result;
750 // If the src and dest elements are both integers, just cast each one
751 // which will do the appropriate bit-convert.
752 if (SrcEltTy->isIntegral() && DstEltTy->isIntegral()) {
753 for (unsigned i = 0; i != SrcNumElts; ++i)
754 Result.push_back(ConstantExpr::getCast(CP->getOperand(i),
756 return ConstantPacked::get(Result);
759 if (SrcEltTy->isIntegral()) {
760 // Otherwise, this is an int-to-fp cast.
761 assert(DstEltTy->isFloatingPoint());
762 if (DstEltTy->getTypeID() == Type::DoubleTyID) {
763 for (unsigned i = 0; i != SrcNumElts; ++i) {
765 BitsToDouble(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
766 Result.push_back(ConstantFP::get(Type::DoubleTy, V));
768 return ConstantPacked::get(Result);
770 assert(DstEltTy == Type::FloatTy && "Unknown fp type!");
771 for (unsigned i = 0; i != SrcNumElts; ++i) {
773 BitsToFloat(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
774 Result.push_back(ConstantFP::get(Type::FloatTy, V));
776 return ConstantPacked::get(Result);
779 // Otherwise, this is an fp-to-int cast.
780 assert(SrcEltTy->isFloatingPoint() && DstEltTy->isIntegral());
782 if (SrcEltTy->getTypeID() == Type::DoubleTyID) {
783 for (unsigned i = 0; i != SrcNumElts; ++i) {
785 DoubleToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
786 Constant *C = ConstantInt::get(Type::ULongTy, V);
787 Result.push_back(ConstantExpr::getCast(C, DstEltTy));
789 return ConstantPacked::get(Result);
792 assert(SrcEltTy->getTypeID() == Type::FloatTyID);
793 for (unsigned i = 0; i != SrcNumElts; ++i) {
794 uint32_t V = FloatToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
795 Constant *C = ConstantInt::get(Type::UIntTy, V);
796 Result.push_back(ConstantExpr::getCast(C, DstEltTy));
798 return ConstantPacked::get(Result);
801 // Otherwise, this is a cast that changes element count and size. Handle
802 // casts which shrink the elements here.
804 // FIXME: We need to know endianness to do this!
810 Constant *llvm::ConstantFoldCastInstruction(const Constant *V,
811 const Type *DestTy) {
812 if (V->getType() == DestTy) return (Constant*)V;
814 // Cast of a global address to boolean is always true.
815 if (isa<GlobalValue>(V)) {
816 if (DestTy == Type::BoolTy)
817 // FIXME: When we support 'external weak' references, we have to prevent
818 // this transformation from happening. This code will need to be updated
819 // to ignore external weak symbols when we support it.
820 return ConstantBool::getTrue();
821 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
822 if (CE->getOpcode() == Instruction::Cast) {
823 Constant *Op = const_cast<Constant*>(CE->getOperand(0));
824 // Try to not produce a cast of a cast, which is almost always redundant.
825 if (!Op->getType()->isFloatingPoint() &&
826 !CE->getType()->isFloatingPoint() &&
827 !DestTy->isFloatingPoint()) {
828 unsigned S1 = getSize(Op->getType()), S2 = getSize(CE->getType());
829 unsigned S3 = getSize(DestTy);
830 if (Op->getType() == DestTy && S3 >= S2)
832 if (S1 >= S2 && S2 >= S3)
833 return ConstantExpr::getCast(Op, DestTy);
834 if (S1 <= S2 && S2 >= S3 && S1 <= S3)
835 return ConstantExpr::getCast(Op, DestTy);
837 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
838 // If all of the indexes in the GEP are null values, there is no pointer
839 // adjustment going on. We might as well cast the source pointer.
840 bool isAllNull = true;
841 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
842 if (!CE->getOperand(i)->isNullValue()) {
847 return ConstantExpr::getCast(CE->getOperand(0), DestTy);
849 } else if (isa<UndefValue>(V)) {
850 return UndefValue::get(DestTy);
853 // Check to see if we are casting an pointer to an aggregate to a pointer to
854 // the first element. If so, return the appropriate GEP instruction.
855 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
856 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
857 std::vector<Value*> IdxList;
858 IdxList.push_back(Constant::getNullValue(Type::IntTy));
859 const Type *ElTy = PTy->getElementType();
860 while (ElTy != DPTy->getElementType()) {
861 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
862 if (STy->getNumElements() == 0) break;
863 ElTy = STy->getElementType(0);
864 IdxList.push_back(Constant::getNullValue(Type::UIntTy));
865 } else if (const SequentialType *STy = dyn_cast<SequentialType>(ElTy)) {
866 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
867 ElTy = STy->getElementType();
868 IdxList.push_back(IdxList[0]);
874 if (ElTy == DPTy->getElementType())
875 return ConstantExpr::getGetElementPtr(const_cast<Constant*>(V),IdxList);
878 // Handle casts from one packed constant to another. We know that the src and
879 // dest type have the same size.
880 if (const PackedType *DestPTy = dyn_cast<PackedType>(DestTy)) {
881 if (const PackedType *SrcTy = dyn_cast<PackedType>(V->getType())) {
882 assert(DestPTy->getElementType()->getPrimitiveSizeInBits() *
883 DestPTy->getNumElements() ==
884 SrcTy->getElementType()->getPrimitiveSizeInBits() *
885 SrcTy->getNumElements() && "Not cast between same sized vectors!");
886 if (isa<ConstantAggregateZero>(V))
887 return Constant::getNullValue(DestTy);
888 if (isa<UndefValue>(V))
889 return UndefValue::get(DestTy);
890 if (const ConstantPacked *CP = dyn_cast<ConstantPacked>(V)) {
891 // This is a cast from a ConstantPacked of one type to a ConstantPacked
892 // of another type. Check to see if all elements of the input are
894 bool AllSimpleConstants = true;
895 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
896 if (!isa<ConstantInt>(CP->getOperand(i)) &&
897 !isa<ConstantFP>(CP->getOperand(i))) {
898 AllSimpleConstants = false;
903 // If all of the elements are simple constants, we can fold this.
904 if (AllSimpleConstants)
905 return CastConstantPacked(const_cast<ConstantPacked*>(CP), DestPTy);
910 ConstRules &Rules = ConstRules::get(V, V);
912 switch (DestTy->getTypeID()) {
913 case Type::BoolTyID: return Rules.castToBool(V);
914 case Type::UByteTyID: return Rules.castToUByte(V);
915 case Type::SByteTyID: return Rules.castToSByte(V);
916 case Type::UShortTyID: return Rules.castToUShort(V);
917 case Type::ShortTyID: return Rules.castToShort(V);
918 case Type::UIntTyID: return Rules.castToUInt(V);
919 case Type::IntTyID: return Rules.castToInt(V);
920 case Type::ULongTyID: return Rules.castToULong(V);
921 case Type::LongTyID: return Rules.castToLong(V);
922 case Type::FloatTyID: return Rules.castToFloat(V);
923 case Type::DoubleTyID: return Rules.castToDouble(V);
924 case Type::PointerTyID:
925 return Rules.castToPointer(V, cast<PointerType>(DestTy));
930 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
932 const Constant *V2) {
933 if (const ConstantBool *CB = dyn_cast<ConstantBool>(Cond))
934 return const_cast<Constant*>(CB->getValue() ? V1 : V2);
936 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
937 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
938 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
939 if (V1 == V2) return const_cast<Constant*>(V1);
943 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
944 const Constant *Idx) {
945 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
946 return UndefValue::get(cast<PackedType>(Val->getType())->getElementType());
947 if (Val->isNullValue()) // ee(zero, x) -> zero
948 return Constant::getNullValue(
949 cast<PackedType>(Val->getType())->getElementType());
951 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
952 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
953 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue()));
954 } else if (isa<UndefValue>(Idx)) {
955 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
956 return const_cast<Constant*>(CVal->getOperand(0));
962 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
964 const Constant *Idx) {
965 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
967 uint64_t idxVal = CIdx->getZExtValue();
968 if (isa<UndefValue>(Val)) {
969 // Insertion of scalar constant into packed undef
970 // Optimize away insertion of undef
971 if (isa<UndefValue>(Elt))
972 return const_cast<Constant*>(Val);
973 // Otherwise break the aggregate undef into multiple undefs and do
976 cast<PackedType>(Val->getType())->getNumElements();
977 std::vector<Constant*> Ops;
979 for (unsigned i = 0; i < numOps; ++i) {
981 (i == idxVal) ? Elt : UndefValue::get(Elt->getType());
982 Ops.push_back(const_cast<Constant*>(Op));
984 return ConstantPacked::get(Ops);
986 if (isa<ConstantAggregateZero>(Val)) {
987 // Insertion of scalar constant into packed aggregate zero
988 // Optimize away insertion of zero
989 if (Elt->isNullValue())
990 return const_cast<Constant*>(Val);
991 // Otherwise break the aggregate zero into multiple zeros and do
994 cast<PackedType>(Val->getType())->getNumElements();
995 std::vector<Constant*> Ops;
997 for (unsigned i = 0; i < numOps; ++i) {
999 (i == idxVal) ? Elt : Constant::getNullValue(Elt->getType());
1000 Ops.push_back(const_cast<Constant*>(Op));
1002 return ConstantPacked::get(Ops);
1004 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
1005 // Insertion of scalar constant into packed constant
1006 std::vector<Constant*> Ops;
1007 Ops.reserve(CVal->getNumOperands());
1008 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
1009 const Constant *Op =
1010 (i == idxVal) ? Elt : cast<Constant>(CVal->getOperand(i));
1011 Ops.push_back(const_cast<Constant*>(Op));
1013 return ConstantPacked::get(Ops);
1018 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
1020 const Constant *Mask) {
1026 /// isZeroSizedType - This type is zero sized if its an array or structure of
1027 /// zero sized types. The only leaf zero sized type is an empty structure.
1028 static bool isMaybeZeroSizedType(const Type *Ty) {
1029 if (isa<OpaqueType>(Ty)) return true; // Can't say.
1030 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
1032 // If all of elements have zero size, this does too.
1033 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
1034 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
1037 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
1038 return isMaybeZeroSizedType(ATy->getElementType());
1043 /// IdxCompare - Compare the two constants as though they were getelementptr
1044 /// indices. This allows coersion of the types to be the same thing.
1046 /// If the two constants are the "same" (after coersion), return 0. If the
1047 /// first is less than the second, return -1, if the second is less than the
1048 /// first, return 1. If the constants are not integral, return -2.
1050 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
1051 if (C1 == C2) return 0;
1053 // Ok, we found a different index. Are either of the operands
1054 // ConstantExprs? If so, we can't do anything with them.
1055 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
1056 return -2; // don't know!
1058 // Ok, we have two differing integer indices. Sign extend them to be the same
1059 // type. Long is always big enough, so we use it.
1060 C1 = ConstantExpr::getSignExtend(C1, Type::LongTy);
1061 C2 = ConstantExpr::getSignExtend(C2, Type::LongTy);
1062 if (C1 == C2) return 0; // Are they just differing types?
1064 // If the type being indexed over is really just a zero sized type, there is
1065 // no pointer difference being made here.
1066 if (isMaybeZeroSizedType(ElTy))
1067 return -2; // dunno.
1069 // If they are really different, now that they are the same type, then we
1070 // found a difference!
1071 if (cast<ConstantInt>(C1)->getSExtValue() <
1072 cast<ConstantInt>(C2)->getSExtValue())
1078 /// evaluateRelation - This function determines if there is anything we can
1079 /// decide about the two constants provided. This doesn't need to handle simple
1080 /// things like integer comparisons, but should instead handle ConstantExprs
1081 /// and GlobalValuess. If we can determine that the two constants have a
1082 /// particular relation to each other, we should return the corresponding SetCC
1083 /// code, otherwise return Instruction::BinaryOpsEnd.
1085 /// To simplify this code we canonicalize the relation so that the first
1086 /// operand is always the most "complex" of the two. We consider simple
1087 /// constants (like ConstantInt) to be the simplest, followed by
1088 /// GlobalValues, followed by ConstantExpr's (the most complex).
1090 static Instruction::BinaryOps evaluateRelation(Constant *V1, Constant *V2) {
1091 assert(V1->getType() == V2->getType() &&
1092 "Cannot compare different types of values!");
1093 if (V1 == V2) return Instruction::SetEQ;
1095 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
1096 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
1097 // We distilled this down to a simple case, use the standard constant
1099 ConstantBool *R = dyn_cast<ConstantBool>(ConstantExpr::getSetEQ(V1, V2));
1100 if (R && R->getValue()) return Instruction::SetEQ;
1101 R = dyn_cast<ConstantBool>(ConstantExpr::getSetLT(V1, V2));
1102 if (R && R->getValue()) return Instruction::SetLT;
1103 R = dyn_cast<ConstantBool>(ConstantExpr::getSetGT(V1, V2));
1104 if (R && R->getValue()) return Instruction::SetGT;
1106 // If we couldn't figure it out, bail.
1107 return Instruction::BinaryOpsEnd;
1110 // If the first operand is simple, swap operands.
1111 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
1112 if (SwappedRelation != Instruction::BinaryOpsEnd)
1113 return SetCondInst::getSwappedCondition(SwappedRelation);
1115 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
1116 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
1117 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
1118 if (SwappedRelation != Instruction::BinaryOpsEnd)
1119 return SetCondInst::getSwappedCondition(SwappedRelation);
1121 return Instruction::BinaryOpsEnd;
1124 // Now we know that the RHS is a GlobalValue or simple constant,
1125 // which (since the types must match) means that it's a ConstantPointerNull.
1126 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1127 assert(CPR1 != CPR2 &&
1128 "GVs for the same value exist at different addresses??");
1129 // FIXME: If both globals are external weak, they might both be null!
1130 return Instruction::SetNE;
1132 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
1133 // Global can never be null. FIXME: if we implement external weak
1134 // linkage, this is not necessarily true!
1135 return Instruction::SetNE;
1139 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
1140 // constantexpr, a CPR, or a simple constant.
1141 ConstantExpr *CE1 = cast<ConstantExpr>(V1);
1142 Constant *CE1Op0 = CE1->getOperand(0);
1144 switch (CE1->getOpcode()) {
1145 case Instruction::Cast:
1146 // If the cast is not actually changing bits, and the second operand is a
1147 // null pointer, do the comparison with the pre-casted value.
1148 if (V2->isNullValue() &&
1149 (isa<PointerType>(CE1->getType()) || CE1->getType()->isIntegral()))
1150 return evaluateRelation(CE1Op0,
1151 Constant::getNullValue(CE1Op0->getType()));
1153 // If the dest type is a pointer type, and the RHS is a constantexpr cast
1154 // from the same type as the src of the LHS, evaluate the inputs. This is
1155 // important for things like "seteq (cast 4 to int*), (cast 5 to int*)",
1156 // which happens a lot in compilers with tagged integers.
1157 if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
1158 if (isa<PointerType>(CE1->getType()) &&
1159 CE2->getOpcode() == Instruction::Cast &&
1160 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
1161 CE1->getOperand(0)->getType()->isIntegral()) {
1162 return evaluateRelation(CE1->getOperand(0), CE2->getOperand(0));
1166 case Instruction::GetElementPtr:
1167 // Ok, since this is a getelementptr, we know that the constant has a
1168 // pointer type. Check the various cases.
1169 if (isa<ConstantPointerNull>(V2)) {
1170 // If we are comparing a GEP to a null pointer, check to see if the base
1171 // of the GEP equals the null pointer.
1172 if (isa<GlobalValue>(CE1Op0)) {
1173 // FIXME: this is not true when we have external weak references!
1174 // No offset can go from a global to a null pointer.
1175 return Instruction::SetGT;
1176 } else if (isa<ConstantPointerNull>(CE1Op0)) {
1177 // If we are indexing from a null pointer, check to see if we have any
1178 // non-zero indices.
1179 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
1180 if (!CE1->getOperand(i)->isNullValue())
1181 // Offsetting from null, must not be equal.
1182 return Instruction::SetGT;
1183 // Only zero indexes from null, must still be zero.
1184 return Instruction::SetEQ;
1186 // Otherwise, we can't really say if the first operand is null or not.
1187 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1188 if (isa<ConstantPointerNull>(CE1Op0)) {
1189 // FIXME: This is not true with external weak references.
1190 return Instruction::SetLT;
1191 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
1193 // If this is a getelementptr of the same global, then it must be
1194 // different. Because the types must match, the getelementptr could
1195 // only have at most one index, and because we fold getelementptr's
1196 // with a single zero index, it must be nonzero.
1197 assert(CE1->getNumOperands() == 2 &&
1198 !CE1->getOperand(1)->isNullValue() &&
1199 "Suprising getelementptr!");
1200 return Instruction::SetGT;
1202 // If they are different globals, we don't know what the value is,
1203 // but they can't be equal.
1204 return Instruction::SetNE;
1208 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
1209 const Constant *CE2Op0 = CE2->getOperand(0);
1211 // There are MANY other foldings that we could perform here. They will
1212 // probably be added on demand, as they seem needed.
1213 switch (CE2->getOpcode()) {
1215 case Instruction::GetElementPtr:
1216 // By far the most common case to handle is when the base pointers are
1217 // obviously to the same or different globals.
1218 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
1219 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
1220 return Instruction::SetNE;
1221 // Ok, we know that both getelementptr instructions are based on the
1222 // same global. From this, we can precisely determine the relative
1223 // ordering of the resultant pointers.
1226 // Compare all of the operands the GEP's have in common.
1227 gep_type_iterator GTI = gep_type_begin(CE1);
1228 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
1230 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
1231 GTI.getIndexedType())) {
1232 case -1: return Instruction::SetLT;
1233 case 1: return Instruction::SetGT;
1234 case -2: return Instruction::BinaryOpsEnd;
1237 // Ok, we ran out of things they have in common. If any leftovers
1238 // are non-zero then we have a difference, otherwise we are equal.
1239 for (; i < CE1->getNumOperands(); ++i)
1240 if (!CE1->getOperand(i)->isNullValue())
1241 if (isa<ConstantIntegral>(CE1->getOperand(i)))
1242 return Instruction::SetGT;
1244 return Instruction::BinaryOpsEnd; // Might be equal.
1246 for (; i < CE2->getNumOperands(); ++i)
1247 if (!CE2->getOperand(i)->isNullValue())
1248 if (isa<ConstantIntegral>(CE2->getOperand(i)))
1249 return Instruction::SetLT;
1251 return Instruction::BinaryOpsEnd; // Might be equal.
1252 return Instruction::SetEQ;
1262 return Instruction::BinaryOpsEnd;
1265 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
1267 const Constant *V2) {
1271 case Instruction::Add: C = ConstRules::get(V1, V2).add(V1, V2); break;
1272 case Instruction::Sub: C = ConstRules::get(V1, V2).sub(V1, V2); break;
1273 case Instruction::Mul: C = ConstRules::get(V1, V2).mul(V1, V2); break;
1274 case Instruction::UDiv: C = ConstRules::get(V1, V2).udiv(V1, V2); break;
1275 case Instruction::SDiv: C = ConstRules::get(V1, V2).sdiv(V1, V2); break;
1276 case Instruction::FDiv: C = ConstRules::get(V1, V2).fdiv(V1, V2); break;
1277 case Instruction::URem: C = ConstRules::get(V1, V2).urem(V1, V2); break;
1278 case Instruction::SRem: C = ConstRules::get(V1, V2).srem(V1, V2); break;
1279 case Instruction::FRem: C = ConstRules::get(V1, V2).frem(V1, V2); break;
1280 case Instruction::And: C = ConstRules::get(V1, V2).op_and(V1, V2); break;
1281 case Instruction::Or: C = ConstRules::get(V1, V2).op_or (V1, V2); break;
1282 case Instruction::Xor: C = ConstRules::get(V1, V2).op_xor(V1, V2); break;
1283 case Instruction::Shl: C = ConstRules::get(V1, V2).shl(V1, V2); break;
1284 case Instruction::LShr: C = ConstRules::get(V1, V2).lshr(V1, V2); break;
1285 case Instruction::AShr: C = ConstRules::get(V1, V2).ashr(V1, V2); break;
1286 case Instruction::SetEQ: C = ConstRules::get(V1, V2).equalto(V1, V2); break;
1287 case Instruction::SetLT: C = ConstRules::get(V1, V2).lessthan(V1, V2);break;
1288 case Instruction::SetGT: C = ConstRules::get(V1, V2).lessthan(V2, V1);break;
1289 case Instruction::SetNE: // V1 != V2 === !(V1 == V2)
1290 C = ConstRules::get(V1, V2).equalto(V1, V2);
1291 if (C) return ConstantExpr::getNot(C);
1293 case Instruction::SetLE: // V1 <= V2 === !(V2 < V1)
1294 C = ConstRules::get(V1, V2).lessthan(V2, V1);
1295 if (C) return ConstantExpr::getNot(C);
1297 case Instruction::SetGE: // V1 >= V2 === !(V1 < V2)
1298 C = ConstRules::get(V1, V2).lessthan(V1, V2);
1299 if (C) return ConstantExpr::getNot(C);
1303 // If we successfully folded the expression, return it now.
1306 if (SetCondInst::isComparison(Opcode)) {
1307 if (isa<UndefValue>(V1) || isa<UndefValue>(V2))
1308 return UndefValue::get(Type::BoolTy);
1309 switch (evaluateRelation(const_cast<Constant*>(V1),
1310 const_cast<Constant*>(V2))) {
1311 default: assert(0 && "Unknown relational!");
1312 case Instruction::BinaryOpsEnd:
1313 break; // Couldn't determine anything about these constants.
1314 case Instruction::SetEQ: // We know the constants are equal!
1315 // If we know the constants are equal, we can decide the result of this
1316 // computation precisely.
1317 return ConstantBool::get(Opcode == Instruction::SetEQ ||
1318 Opcode == Instruction::SetLE ||
1319 Opcode == Instruction::SetGE);
1320 case Instruction::SetLT:
1321 // If we know that V1 < V2, we can decide the result of this computation
1323 return ConstantBool::get(Opcode == Instruction::SetLT ||
1324 Opcode == Instruction::SetNE ||
1325 Opcode == Instruction::SetLE);
1326 case Instruction::SetGT:
1327 // If we know that V1 > V2, we can decide the result of this computation
1329 return ConstantBool::get(Opcode == Instruction::SetGT ||
1330 Opcode == Instruction::SetNE ||
1331 Opcode == Instruction::SetGE);
1332 case Instruction::SetLE:
1333 // If we know that V1 <= V2, we can only partially decide this relation.
1334 if (Opcode == Instruction::SetGT) return ConstantBool::getFalse();
1335 if (Opcode == Instruction::SetLT) return ConstantBool::getTrue();
1338 case Instruction::SetGE:
1339 // If we know that V1 >= V2, we can only partially decide this relation.
1340 if (Opcode == Instruction::SetLT) return ConstantBool::getFalse();
1341 if (Opcode == Instruction::SetGT) return ConstantBool::getTrue();
1344 case Instruction::SetNE:
1345 // If we know that V1 != V2, we can only partially decide this relation.
1346 if (Opcode == Instruction::SetEQ) return ConstantBool::getFalse();
1347 if (Opcode == Instruction::SetNE) return ConstantBool::getTrue();
1352 if (isa<UndefValue>(V1) || isa<UndefValue>(V2)) {
1354 case Instruction::Add:
1355 case Instruction::Sub:
1356 case Instruction::Xor:
1357 return UndefValue::get(V1->getType());
1359 case Instruction::Mul:
1360 case Instruction::And:
1361 return Constant::getNullValue(V1->getType());
1362 case Instruction::UDiv:
1363 case Instruction::SDiv:
1364 case Instruction::FDiv:
1365 case Instruction::URem:
1366 case Instruction::SRem:
1367 case Instruction::FRem:
1368 if (!isa<UndefValue>(V2)) // undef / X -> 0
1369 return Constant::getNullValue(V1->getType());
1370 return const_cast<Constant*>(V2); // X / undef -> undef
1371 case Instruction::Or: // X | undef -> -1
1372 return ConstantInt::getAllOnesValue(V1->getType());
1373 case Instruction::LShr:
1374 if (isa<UndefValue>(V2) && isa<UndefValue>(V1))
1375 return const_cast<Constant*>(V1); // undef lshr undef -> undef
1376 return Constant::getNullValue(V1->getType()); // X lshr undef -> 0
1377 // undef lshr X -> 0
1378 case Instruction::AShr:
1379 if (!isa<UndefValue>(V2))
1380 return const_cast<Constant*>(V1); // undef ashr X --> undef
1381 else if (isa<UndefValue>(V1))
1382 return const_cast<Constant*>(V1); // undef ashr undef -> undef
1384 return const_cast<Constant*>(V1); // X ashr undef --> X
1385 case Instruction::Shl:
1386 // undef << X -> 0 or X << undef -> 0
1387 return Constant::getNullValue(V1->getType());
1391 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(V1)) {
1392 if (isa<ConstantExpr>(V2)) {
1393 // There are many possible foldings we could do here. We should probably
1394 // at least fold add of a pointer with an integer into the appropriate
1395 // getelementptr. This will improve alias analysis a bit.
1397 // Just implement a couple of simple identities.
1399 case Instruction::Add:
1400 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X + 0 == X
1402 case Instruction::Sub:
1403 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X - 0 == X
1405 case Instruction::Mul:
1406 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X * 0 == 0
1407 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1408 if (CI->getZExtValue() == 1)
1409 return const_cast<Constant*>(V1); // X * 1 == X
1411 case Instruction::UDiv:
1412 case Instruction::SDiv:
1413 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1414 if (CI->getZExtValue() == 1)
1415 return const_cast<Constant*>(V1); // X / 1 == X
1417 case Instruction::URem:
1418 case Instruction::SRem:
1419 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1420 if (CI->getZExtValue() == 1)
1421 return Constant::getNullValue(CI->getType()); // X % 1 == 0
1423 case Instruction::And:
1424 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1425 return const_cast<Constant*>(V1); // X & -1 == X
1426 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X & 0 == 0
1427 if (CE1->getOpcode() == Instruction::Cast &&
1428 isa<GlobalValue>(CE1->getOperand(0))) {
1429 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
1431 // Functions are at least 4-byte aligned. If and'ing the address of a
1432 // function with a constant < 4, fold it to zero.
1433 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1434 if (CI->getZExtValue() < 4 && isa<Function>(CPR))
1435 return Constant::getNullValue(CI->getType());
1438 case Instruction::Or:
1439 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X | 0 == X
1440 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1441 return const_cast<Constant*>(V2); // X | -1 == -1
1443 case Instruction::Xor:
1444 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X ^ 0 == X
1449 } else if (isa<ConstantExpr>(V2)) {
1450 // If V2 is a constant expr and V1 isn't, flop them around and fold the
1451 // other way if possible.
1453 case Instruction::Add:
1454 case Instruction::Mul:
1455 case Instruction::And:
1456 case Instruction::Or:
1457 case Instruction::Xor:
1458 case Instruction::SetEQ:
1459 case Instruction::SetNE:
1460 // No change of opcode required.
1461 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1463 case Instruction::SetLT:
1464 case Instruction::SetGT:
1465 case Instruction::SetLE:
1466 case Instruction::SetGE:
1467 // Change the opcode as necessary to swap the operands.
1468 Opcode = SetCondInst::getSwappedCondition((Instruction::BinaryOps)Opcode);
1469 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1471 case Instruction::Shl:
1472 case Instruction::LShr:
1473 case Instruction::AShr:
1474 case Instruction::Sub:
1475 case Instruction::SDiv:
1476 case Instruction::UDiv:
1477 case Instruction::FDiv:
1478 case Instruction::URem:
1479 case Instruction::SRem:
1480 case Instruction::FRem:
1481 default: // These instructions cannot be flopped around.
1488 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1489 const std::vector<Value*> &IdxList) {
1490 if (IdxList.size() == 0 ||
1491 (IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
1492 return const_cast<Constant*>(C);
1494 if (isa<UndefValue>(C)) {
1495 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1497 assert(Ty != 0 && "Invalid indices for GEP!");
1498 return UndefValue::get(PointerType::get(Ty));
1501 Constant *Idx0 = cast<Constant>(IdxList[0]);
1502 if (C->isNullValue()) {
1504 for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
1505 if (!cast<Constant>(IdxList[i])->isNullValue()) {
1510 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1512 assert(Ty != 0 && "Invalid indices for GEP!");
1513 return ConstantPointerNull::get(PointerType::get(Ty));
1516 if (IdxList.size() == 1) {
1517 const Type *ElTy = cast<PointerType>(C->getType())->getElementType();
1518 if (uint32_t ElSize = ElTy->getPrimitiveSize()) {
1519 // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm
1520 // type, we can statically fold this.
1521 Constant *R = ConstantInt::get(Type::UIntTy, ElSize);
1522 R = ConstantExpr::getCast(R, Idx0->getType());
1523 R = ConstantExpr::getMul(R, Idx0);
1524 return ConstantExpr::getCast(R, C->getType());
1529 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1530 // Combine Indices - If the source pointer to this getelementptr instruction
1531 // is a getelementptr instruction, combine the indices of the two
1532 // getelementptr instructions into a single instruction.
1534 if (CE->getOpcode() == Instruction::GetElementPtr) {
1535 const Type *LastTy = 0;
1536 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1540 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1541 std::vector<Value*> NewIndices;
1542 NewIndices.reserve(IdxList.size() + CE->getNumOperands());
1543 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1544 NewIndices.push_back(CE->getOperand(i));
1546 // Add the last index of the source with the first index of the new GEP.
1547 // Make sure to handle the case when they are actually different types.
1548 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1549 // Otherwise it must be an array.
1550 if (!Idx0->isNullValue()) {
1551 const Type *IdxTy = Combined->getType();
1552 if (IdxTy != Idx0->getType()) IdxTy = Type::LongTy;
1554 ConstantExpr::get(Instruction::Add,
1555 ConstantExpr::getCast(Idx0, IdxTy),
1556 ConstantExpr::getCast(Combined, IdxTy));
1559 NewIndices.push_back(Combined);
1560 NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
1561 return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
1565 // Implement folding of:
1566 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1568 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1570 if (CE->getOpcode() == Instruction::Cast && IdxList.size() > 1 &&
1571 Idx0->isNullValue())
1572 if (const PointerType *SPT =
1573 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1574 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1575 if (const ArrayType *CAT =
1576 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1577 if (CAT->getElementType() == SAT->getElementType())
1578 return ConstantExpr::getGetElementPtr(
1579 (Constant*)CE->getOperand(0), IdxList);