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"
34 struct VISIBILITY_HIDDEN ConstRules {
36 virtual ~ConstRules() {}
38 // Binary Operators...
39 virtual Constant *add(const Constant *V1, const Constant *V2) const = 0;
40 virtual Constant *sub(const Constant *V1, const Constant *V2) const = 0;
41 virtual Constant *mul(const Constant *V1, const Constant *V2) const = 0;
42 virtual Constant *urem(const Constant *V1, const Constant *V2) const = 0;
43 virtual Constant *srem(const Constant *V1, const Constant *V2) const = 0;
44 virtual Constant *frem(const Constant *V1, const Constant *V2) const = 0;
45 virtual Constant *udiv(const Constant *V1, const Constant *V2) const = 0;
46 virtual Constant *sdiv(const Constant *V1, const Constant *V2) const = 0;
47 virtual Constant *fdiv(const Constant *V1, const Constant *V2) const = 0;
48 virtual Constant *op_and(const Constant *V1, const Constant *V2) const = 0;
49 virtual Constant *op_or (const Constant *V1, const Constant *V2) const = 0;
50 virtual Constant *op_xor(const Constant *V1, const Constant *V2) const = 0;
51 virtual Constant *shl(const Constant *V1, const Constant *V2) const = 0;
52 virtual Constant *lshr(const Constant *V1, const Constant *V2) const = 0;
53 virtual Constant *ashr(const Constant *V1, const Constant *V2) const = 0;
54 virtual Constant *lessthan(const Constant *V1, const Constant *V2) const =0;
55 virtual Constant *equalto(const Constant *V1, const Constant *V2) const = 0;
57 // ConstRules::get - Return an instance of ConstRules for the specified
60 static ConstRules &get(const Constant *V1, const Constant *V2);
62 ConstRules(const ConstRules &); // Do not implement
63 ConstRules &operator=(const ConstRules &); // Do not implement
68 //===----------------------------------------------------------------------===//
69 // TemplateRules Class
70 //===----------------------------------------------------------------------===//
72 // TemplateRules - Implement a subclass of ConstRules that provides all
73 // operations as noops. All other rules classes inherit from this class so
74 // that if functionality is needed in the future, it can simply be added here
75 // and to ConstRules without changing anything else...
77 // This class also provides subclasses with typesafe implementations of methods
78 // so that don't have to do type casting.
81 template<class ArgType, class SubClassName>
82 class VISIBILITY_HIDDEN TemplateRules : public ConstRules {
85 //===--------------------------------------------------------------------===//
86 // Redirecting functions that cast to the appropriate types
87 //===--------------------------------------------------------------------===//
89 virtual Constant *add(const Constant *V1, const Constant *V2) const {
90 return SubClassName::Add((const ArgType *)V1, (const ArgType *)V2);
92 virtual Constant *sub(const Constant *V1, const Constant *V2) const {
93 return SubClassName::Sub((const ArgType *)V1, (const ArgType *)V2);
95 virtual Constant *mul(const Constant *V1, const Constant *V2) const {
96 return SubClassName::Mul((const ArgType *)V1, (const ArgType *)V2);
98 virtual Constant *udiv(const Constant *V1, const Constant *V2) const {
99 return SubClassName::UDiv((const ArgType *)V1, (const ArgType *)V2);
101 virtual Constant *sdiv(const Constant *V1, const Constant *V2) const {
102 return SubClassName::SDiv((const ArgType *)V1, (const ArgType *)V2);
104 virtual Constant *fdiv(const Constant *V1, const Constant *V2) const {
105 return SubClassName::FDiv((const ArgType *)V1, (const ArgType *)V2);
107 virtual Constant *urem(const Constant *V1, const Constant *V2) const {
108 return SubClassName::URem((const ArgType *)V1, (const ArgType *)V2);
110 virtual Constant *srem(const Constant *V1, const Constant *V2) const {
111 return SubClassName::SRem((const ArgType *)V1, (const ArgType *)V2);
113 virtual Constant *frem(const Constant *V1, const Constant *V2) const {
114 return SubClassName::FRem((const ArgType *)V1, (const ArgType *)V2);
116 virtual Constant *op_and(const Constant *V1, const Constant *V2) const {
117 return SubClassName::And((const ArgType *)V1, (const ArgType *)V2);
119 virtual Constant *op_or(const Constant *V1, const Constant *V2) const {
120 return SubClassName::Or((const ArgType *)V1, (const ArgType *)V2);
122 virtual Constant *op_xor(const Constant *V1, const Constant *V2) const {
123 return SubClassName::Xor((const ArgType *)V1, (const ArgType *)V2);
125 virtual Constant *shl(const Constant *V1, const Constant *V2) const {
126 return SubClassName::Shl((const ArgType *)V1, (const ArgType *)V2);
128 virtual Constant *lshr(const Constant *V1, const Constant *V2) const {
129 return SubClassName::LShr((const ArgType *)V1, (const ArgType *)V2);
131 virtual Constant *ashr(const Constant *V1, const Constant *V2) const {
132 return SubClassName::AShr((const ArgType *)V1, (const ArgType *)V2);
135 virtual Constant *lessthan(const Constant *V1, const Constant *V2) const {
136 return SubClassName::LessThan((const ArgType *)V1, (const ArgType *)V2);
138 virtual Constant *equalto(const Constant *V1, const Constant *V2) const {
139 return SubClassName::EqualTo((const ArgType *)V1, (const ArgType *)V2);
143 //===--------------------------------------------------------------------===//
144 // Default "noop" implementations
145 //===--------------------------------------------------------------------===//
147 static Constant *Add (const ArgType *V1, const ArgType *V2) { return 0; }
148 static Constant *Sub (const ArgType *V1, const ArgType *V2) { return 0; }
149 static Constant *Mul (const ArgType *V1, const ArgType *V2) { return 0; }
150 static Constant *SDiv(const ArgType *V1, const ArgType *V2) { return 0; }
151 static Constant *UDiv(const ArgType *V1, const ArgType *V2) { return 0; }
152 static Constant *FDiv(const ArgType *V1, const ArgType *V2) { return 0; }
153 static Constant *URem(const ArgType *V1, const ArgType *V2) { return 0; }
154 static Constant *SRem(const ArgType *V1, const ArgType *V2) { return 0; }
155 static Constant *FRem(const ArgType *V1, const ArgType *V2) { return 0; }
156 static Constant *And (const ArgType *V1, const ArgType *V2) { return 0; }
157 static Constant *Or (const ArgType *V1, const ArgType *V2) { return 0; }
158 static Constant *Xor (const ArgType *V1, const ArgType *V2) { return 0; }
159 static Constant *Shl (const ArgType *V1, const ArgType *V2) { return 0; }
160 static Constant *LShr(const ArgType *V1, const ArgType *V2) { return 0; }
161 static Constant *AShr(const ArgType *V1, const ArgType *V2) { return 0; }
162 static Constant *LessThan(const ArgType *V1, const ArgType *V2) {
165 static Constant *EqualTo(const ArgType *V1, const ArgType *V2) {
170 virtual ~TemplateRules() {}
172 } // end anonymous namespace
175 //===----------------------------------------------------------------------===//
177 //===----------------------------------------------------------------------===//
179 // EmptyRules provides a concrete base class of ConstRules that does nothing
182 struct VISIBILITY_HIDDEN EmptyRules
183 : public TemplateRules<Constant, EmptyRules> {
184 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
185 if (V1 == V2) return ConstantBool::getTrue();
189 } // end anonymous namespace
193 //===----------------------------------------------------------------------===//
195 //===----------------------------------------------------------------------===//
197 // BoolRules provides a concrete base class of ConstRules for the 'bool' type.
200 struct VISIBILITY_HIDDEN BoolRules
201 : public TemplateRules<ConstantBool, BoolRules> {
203 static Constant *LessThan(const ConstantBool *V1, const ConstantBool *V2) {
204 return ConstantBool::get(V1->getValue() < V2->getValue());
207 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
208 return ConstantBool::get(V1 == V2);
211 static Constant *And(const ConstantBool *V1, const ConstantBool *V2) {
212 return ConstantBool::get(V1->getValue() & V2->getValue());
215 static Constant *Or(const ConstantBool *V1, const ConstantBool *V2) {
216 return ConstantBool::get(V1->getValue() | V2->getValue());
219 static Constant *Xor(const ConstantBool *V1, const ConstantBool *V2) {
220 return ConstantBool::get(V1->getValue() ^ V2->getValue());
223 } // end anonymous namespace
226 //===----------------------------------------------------------------------===//
227 // NullPointerRules Class
228 //===----------------------------------------------------------------------===//
230 // NullPointerRules provides a concrete base class of ConstRules for null
234 struct VISIBILITY_HIDDEN NullPointerRules
235 : public TemplateRules<ConstantPointerNull, NullPointerRules> {
236 static Constant *EqualTo(const Constant *V1, const Constant *V2) {
237 return ConstantBool::getTrue(); // Null pointers are always equal
240 } // end anonymous namespace
242 //===----------------------------------------------------------------------===//
243 // ConstantPackedRules Class
244 //===----------------------------------------------------------------------===//
246 /// DoVectorOp - Given two packed constants and a function pointer, apply the
247 /// function pointer to each element pair, producing a new ConstantPacked
249 static Constant *EvalVectorOp(const ConstantPacked *V1,
250 const ConstantPacked *V2,
251 Constant *(*FP)(Constant*, Constant*)) {
252 std::vector<Constant*> Res;
253 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
254 Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
255 const_cast<Constant*>(V2->getOperand(i))));
256 return ConstantPacked::get(Res);
259 /// PackedTypeRules provides a concrete base class of ConstRules for
260 /// ConstantPacked operands.
263 struct VISIBILITY_HIDDEN ConstantPackedRules
264 : public TemplateRules<ConstantPacked, ConstantPackedRules> {
266 static Constant *Add(const ConstantPacked *V1, const ConstantPacked *V2) {
267 return EvalVectorOp(V1, V2, ConstantExpr::getAdd);
269 static Constant *Sub(const ConstantPacked *V1, const ConstantPacked *V2) {
270 return EvalVectorOp(V1, V2, ConstantExpr::getSub);
272 static Constant *Mul(const ConstantPacked *V1, const ConstantPacked *V2) {
273 return EvalVectorOp(V1, V2, ConstantExpr::getMul);
275 static Constant *UDiv(const ConstantPacked *V1, const ConstantPacked *V2) {
276 return EvalVectorOp(V1, V2, ConstantExpr::getUDiv);
278 static Constant *SDiv(const ConstantPacked *V1, const ConstantPacked *V2) {
279 return EvalVectorOp(V1, V2, ConstantExpr::getSDiv);
281 static Constant *FDiv(const ConstantPacked *V1, const ConstantPacked *V2) {
282 return EvalVectorOp(V1, V2, ConstantExpr::getFDiv);
284 static Constant *URem(const ConstantPacked *V1, const ConstantPacked *V2) {
285 return EvalVectorOp(V1, V2, ConstantExpr::getURem);
287 static Constant *SRem(const ConstantPacked *V1, const ConstantPacked *V2) {
288 return EvalVectorOp(V1, V2, ConstantExpr::getSRem);
290 static Constant *FRem(const ConstantPacked *V1, const ConstantPacked *V2) {
291 return EvalVectorOp(V1, V2, ConstantExpr::getFRem);
293 static Constant *And(const ConstantPacked *V1, const ConstantPacked *V2) {
294 return EvalVectorOp(V1, V2, ConstantExpr::getAnd);
296 static Constant *Or (const ConstantPacked *V1, const ConstantPacked *V2) {
297 return EvalVectorOp(V1, V2, ConstantExpr::getOr);
299 static Constant *Xor(const ConstantPacked *V1, const ConstantPacked *V2) {
300 return EvalVectorOp(V1, V2, ConstantExpr::getXor);
302 static Constant *LessThan(const ConstantPacked *V1, const ConstantPacked *V2){
305 static Constant *EqualTo(const ConstantPacked *V1, const ConstantPacked *V2) {
306 for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i) {
308 ConstantExpr::getSetEQ(const_cast<Constant*>(V1->getOperand(i)),
309 const_cast<Constant*>(V2->getOperand(i)));
310 if (ConstantBool *CB = dyn_cast<ConstantBool>(C))
313 // Otherwise, could not decide from any element pairs.
317 } // end anonymous namespace
320 //===----------------------------------------------------------------------===//
321 // GeneralPackedRules Class
322 //===----------------------------------------------------------------------===//
324 /// GeneralPackedRules provides a concrete base class of ConstRules for
325 /// PackedType operands, where both operands are not ConstantPacked. The usual
326 /// cause for this is that one operand is a ConstantAggregateZero.
329 struct VISIBILITY_HIDDEN GeneralPackedRules
330 : public TemplateRules<Constant, GeneralPackedRules> {
332 } // end anonymous namespace
335 //===----------------------------------------------------------------------===//
336 // DirectIntRules Class
337 //===----------------------------------------------------------------------===//
339 // DirectIntRules provides implementations of functions that are valid on
340 // integer types, but not all types in general.
343 template <class BuiltinType, Type **Ty>
344 struct VISIBILITY_HIDDEN DirectIntRules
345 : public TemplateRules<ConstantInt, DirectIntRules<BuiltinType, Ty> > {
347 static Constant *Add(const ConstantInt *V1, const ConstantInt *V2) {
348 BuiltinType R = (BuiltinType)V1->getZExtValue() +
349 (BuiltinType)V2->getZExtValue();
350 return ConstantInt::get(*Ty, R);
353 static Constant *Sub(const ConstantInt *V1, const ConstantInt *V2) {
354 BuiltinType R = (BuiltinType)V1->getZExtValue() -
355 (BuiltinType)V2->getZExtValue();
356 return ConstantInt::get(*Ty, R);
359 static Constant *Mul(const ConstantInt *V1, const ConstantInt *V2) {
360 BuiltinType R = (BuiltinType)V1->getZExtValue() *
361 (BuiltinType)V2->getZExtValue();
362 return ConstantInt::get(*Ty, R);
365 static Constant *LessThan(const ConstantInt *V1, const ConstantInt *V2) {
366 bool R = (BuiltinType)V1->getZExtValue() < (BuiltinType)V2->getZExtValue();
367 return ConstantBool::get(R);
370 static Constant *EqualTo(const ConstantInt *V1, const ConstantInt *V2) {
371 bool R = (BuiltinType)V1->getZExtValue() == (BuiltinType)V2->getZExtValue();
372 return ConstantBool::get(R);
375 static Constant *UDiv(const ConstantInt *V1, const ConstantInt *V2) {
376 if (V2->isNullValue()) // X / 0
378 BuiltinType R = (BuiltinType)(V1->getZExtValue() / V2->getZExtValue());
379 return ConstantInt::get(*Ty, R);
382 static Constant *SDiv(const ConstantInt *V1, const ConstantInt *V2) {
383 if (V2->isNullValue()) // X / 0
385 if (V2->isAllOnesValue() && // MIN_INT / -1
386 (BuiltinType)V1->getSExtValue() == -(BuiltinType)V1->getSExtValue())
388 BuiltinType R = (BuiltinType)(V1->getSExtValue() / V2->getSExtValue());
389 return ConstantInt::get(*Ty, R);
392 static Constant *URem(const ConstantInt *V1,
393 const ConstantInt *V2) {
394 if (V2->isNullValue()) return 0; // X / 0
395 BuiltinType R = (BuiltinType)(V1->getZExtValue() % V2->getZExtValue());
396 return ConstantInt::get(*Ty, R);
399 static Constant *SRem(const ConstantInt *V1,
400 const ConstantInt *V2) {
401 if (V2->isNullValue()) return 0; // X % 0
402 if (V2->isAllOnesValue() && // MIN_INT % -1
403 (BuiltinType)V1->getSExtValue() == -(BuiltinType)V1->getSExtValue())
405 BuiltinType R = (BuiltinType)(V1->getSExtValue() % V2->getSExtValue());
406 return ConstantInt::get(*Ty, R);
409 static Constant *And(const ConstantInt *V1, const ConstantInt *V2) {
411 (BuiltinType)V1->getZExtValue() & (BuiltinType)V2->getZExtValue();
412 return ConstantInt::get(*Ty, R);
414 static Constant *Or(const ConstantInt *V1, const ConstantInt *V2) {
416 (BuiltinType)V1->getZExtValue() | (BuiltinType)V2->getZExtValue();
417 return ConstantInt::get(*Ty, R);
419 static Constant *Xor(const ConstantInt *V1, const ConstantInt *V2) {
421 (BuiltinType)V1->getZExtValue() ^ (BuiltinType)V2->getZExtValue();
422 return ConstantInt::get(*Ty, R);
425 static Constant *Shl(const ConstantInt *V1, const ConstantInt *V2) {
427 (BuiltinType)V1->getZExtValue() << (BuiltinType)V2->getZExtValue();
428 return ConstantInt::get(*Ty, R);
431 static Constant *LShr(const ConstantInt *V1, const ConstantInt *V2) {
432 BuiltinType R = BuiltinType(V1->getZExtValue() >> V2->getZExtValue());
433 return ConstantInt::get(*Ty, R);
436 static Constant *AShr(const ConstantInt *V1, const ConstantInt *V2) {
437 BuiltinType R = BuiltinType(V1->getSExtValue() >> V2->getZExtValue());
438 return ConstantInt::get(*Ty, R);
441 } // end anonymous namespace
444 //===----------------------------------------------------------------------===//
445 // DirectFPRules Class
446 //===----------------------------------------------------------------------===//
448 /// DirectFPRules provides implementations of functions that are valid on
449 /// floating point types, but not all types in general.
452 template <class BuiltinType, Type **Ty>
453 struct VISIBILITY_HIDDEN DirectFPRules
454 : public TemplateRules<ConstantFP, DirectFPRules<BuiltinType, Ty> > {
456 static Constant *Add(const ConstantFP *V1, const ConstantFP *V2) {
457 BuiltinType R = (BuiltinType)V1->getValue() +
458 (BuiltinType)V2->getValue();
459 return ConstantFP::get(*Ty, R);
462 static Constant *Sub(const ConstantFP *V1, const ConstantFP *V2) {
463 BuiltinType R = (BuiltinType)V1->getValue() - (BuiltinType)V2->getValue();
464 return ConstantFP::get(*Ty, R);
467 static Constant *Mul(const ConstantFP *V1, const ConstantFP *V2) {
468 BuiltinType R = (BuiltinType)V1->getValue() * (BuiltinType)V2->getValue();
469 return ConstantFP::get(*Ty, R);
472 static Constant *LessThan(const ConstantFP *V1, const ConstantFP *V2) {
473 bool R = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue();
474 return ConstantBool::get(R);
477 static Constant *EqualTo(const ConstantFP *V1, const ConstantFP *V2) {
478 bool R = (BuiltinType)V1->getValue() == (BuiltinType)V2->getValue();
479 return ConstantBool::get(R);
482 static Constant *FRem(const ConstantFP *V1, const ConstantFP *V2) {
483 if (V2->isNullValue()) return 0;
484 BuiltinType Result = std::fmod((BuiltinType)V1->getValue(),
485 (BuiltinType)V2->getValue());
486 return ConstantFP::get(*Ty, Result);
488 static Constant *FDiv(const ConstantFP *V1, const ConstantFP *V2) {
489 BuiltinType inf = std::numeric_limits<BuiltinType>::infinity();
490 if (V2->isExactlyValue(0.0)) return ConstantFP::get(*Ty, inf);
491 if (V2->isExactlyValue(-0.0)) return ConstantFP::get(*Ty, -inf);
492 BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
493 return ConstantFP::get(*Ty, R);
496 } // end anonymous namespace
498 static ManagedStatic<EmptyRules> EmptyR;
499 static ManagedStatic<BoolRules> BoolR;
500 static ManagedStatic<NullPointerRules> NullPointerR;
501 static ManagedStatic<ConstantPackedRules> ConstantPackedR;
502 static ManagedStatic<GeneralPackedRules> GeneralPackedR;
503 static ManagedStatic<DirectIntRules<signed char , &Type::SByteTy> > SByteR;
504 static ManagedStatic<DirectIntRules<unsigned char , &Type::UByteTy> > UByteR;
505 static ManagedStatic<DirectIntRules<signed short , &Type::ShortTy> > ShortR;
506 static ManagedStatic<DirectIntRules<unsigned short, &Type::UShortTy> > UShortR;
507 static ManagedStatic<DirectIntRules<signed int , &Type::IntTy> > IntR;
508 static ManagedStatic<DirectIntRules<unsigned int , &Type::UIntTy> > UIntR;
509 static ManagedStatic<DirectIntRules<int64_t , &Type::LongTy> > LongR;
510 static ManagedStatic<DirectIntRules<uint64_t , &Type::ULongTy> > ULongR;
511 static ManagedStatic<DirectFPRules <float , &Type::FloatTy> > FloatR;
512 static ManagedStatic<DirectFPRules <double , &Type::DoubleTy> > DoubleR;
514 /// ConstRules::get - This method returns the constant rules implementation that
515 /// implements the semantics of the two specified constants.
516 ConstRules &ConstRules::get(const Constant *V1, const Constant *V2) {
517 if (isa<ConstantExpr>(V1) || isa<ConstantExpr>(V2) ||
518 isa<GlobalValue>(V1) || isa<GlobalValue>(V2) ||
519 isa<UndefValue>(V1) || isa<UndefValue>(V2))
522 switch (V1->getType()->getTypeID()) {
523 default: assert(0 && "Unknown value type for constant folding!");
524 case Type::BoolTyID: return *BoolR;
525 case Type::PointerTyID: return *NullPointerR;
526 case Type::SByteTyID: return *SByteR;
527 case Type::UByteTyID: return *UByteR;
528 case Type::ShortTyID: return *ShortR;
529 case Type::UShortTyID: return *UShortR;
530 case Type::IntTyID: return *IntR;
531 case Type::UIntTyID: return *UIntR;
532 case Type::LongTyID: return *LongR;
533 case Type::ULongTyID: return *ULongR;
534 case Type::FloatTyID: return *FloatR;
535 case Type::DoubleTyID: return *DoubleR;
536 case Type::PackedTyID:
537 if (isa<ConstantPacked>(V1) && isa<ConstantPacked>(V2))
538 return *ConstantPackedR;
539 return *GeneralPackedR; // Constant folding rules for ConstantAggregateZero.
544 //===----------------------------------------------------------------------===//
545 // ConstantFold*Instruction Implementations
546 //===----------------------------------------------------------------------===//
548 /// CastConstantPacked - Convert the specified ConstantPacked node to the
549 /// specified packed type. At this point, we know that the elements of the
550 /// input packed constant are all simple integer or FP values.
551 static Constant *CastConstantPacked(ConstantPacked *CP,
552 const PackedType *DstTy) {
553 unsigned SrcNumElts = CP->getType()->getNumElements();
554 unsigned DstNumElts = DstTy->getNumElements();
555 const Type *SrcEltTy = CP->getType()->getElementType();
556 const Type *DstEltTy = DstTy->getElementType();
558 // If both vectors have the same number of elements (thus, the elements
559 // are the same size), perform the conversion now.
560 if (SrcNumElts == DstNumElts) {
561 std::vector<Constant*> Result;
563 // If the src and dest elements are both integers, or both floats, we can
564 // just BitCast each element because the elements are the same size.
565 if ((SrcEltTy->isIntegral() && DstEltTy->isIntegral()) ||
566 (SrcEltTy->isFloatingPoint() && DstEltTy->isFloatingPoint())) {
567 for (unsigned i = 0; i != SrcNumElts; ++i)
569 ConstantExpr::getBitCast(CP->getOperand(i), DstEltTy));
570 return ConstantPacked::get(Result);
573 // If this is an int-to-fp cast ..
574 if (SrcEltTy->isIntegral()) {
575 // Ensure that it is int-to-fp cast
576 assert(DstEltTy->isFloatingPoint());
577 if (DstEltTy->getTypeID() == Type::DoubleTyID) {
578 for (unsigned i = 0; i != SrcNumElts; ++i) {
580 BitsToDouble(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
581 Result.push_back(ConstantFP::get(Type::DoubleTy, V));
583 return ConstantPacked::get(Result);
585 assert(DstEltTy == Type::FloatTy && "Unknown fp type!");
586 for (unsigned i = 0; i != SrcNumElts; ++i) {
588 BitsToFloat(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
589 Result.push_back(ConstantFP::get(Type::FloatTy, V));
591 return ConstantPacked::get(Result);
594 // Otherwise, this is an fp-to-int cast.
595 assert(SrcEltTy->isFloatingPoint() && DstEltTy->isIntegral());
597 if (SrcEltTy->getTypeID() == Type::DoubleTyID) {
598 for (unsigned i = 0; i != SrcNumElts; ++i) {
600 DoubleToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
601 Constant *C = ConstantInt::get(Type::ULongTy, V);
602 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy ));
604 return ConstantPacked::get(Result);
607 assert(SrcEltTy->getTypeID() == Type::FloatTyID);
608 for (unsigned i = 0; i != SrcNumElts; ++i) {
609 uint32_t V = FloatToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
610 Constant *C = ConstantInt::get(Type::UIntTy, V);
611 Result.push_back(ConstantExpr::getBitCast(C, DstEltTy));
613 return ConstantPacked::get(Result);
616 // Otherwise, this is a cast that changes element count and size. Handle
617 // casts which shrink the elements here.
619 // FIXME: We need to know endianness to do this!
624 /// This function determines which opcode to use to fold two constant cast
625 /// expressions together. It uses CastInst::isEliminableCastPair to determine
626 /// the opcode. Consequently its just a wrapper around that function.
627 /// @Determine if it is valid to fold a cast of a cast
629 foldConstantCastPair(
630 unsigned opc, ///< opcode of the second cast constant expression
631 const ConstantExpr*Op, ///< the first cast constant expression
632 const Type *DstTy ///< desintation type of the first cast
634 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
635 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
636 assert(CastInst::isCast(opc) && "Invalid cast opcode");
638 // The the types and opcodes for the two Cast constant expressions
639 const Type *SrcTy = Op->getOperand(0)->getType();
640 const Type *MidTy = Op->getType();
641 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
642 Instruction::CastOps secondOp = Instruction::CastOps(opc);
644 // Let CastInst::isEliminableCastPair do the heavy lifting.
645 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
649 Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
650 const Type *DestTy) {
651 const Type *SrcTy = V->getType();
653 if (isa<UndefValue>(V))
654 return UndefValue::get(DestTy);
656 // If the cast operand is a constant expression, there's a few things we can
657 // do to try to simplify it.
658 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
660 // Try hard to fold cast of cast because they are often eliminable.
661 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
662 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
663 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
664 // If all of the indexes in the GEP are null values, there is no pointer
665 // adjustment going on. We might as well cast the source pointer.
666 bool isAllNull = true;
667 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
668 if (!CE->getOperand(i)->isNullValue()) {
673 // This is casting one pointer type to another, always BitCast
674 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
678 // We actually have to do a cast now. Perform the cast according to the
681 case Instruction::FPTrunc:
682 case Instruction::FPExt:
683 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V))
684 return ConstantFP::get(DestTy, FPC->getValue());
685 return 0; // Can't fold.
686 case Instruction::FPToUI:
687 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V))
688 return ConstantIntegral::get(DestTy,(uint64_t) FPC->getValue());
689 return 0; // Can't fold.
690 case Instruction::FPToSI:
691 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V))
692 return ConstantIntegral::get(DestTy,(int64_t) FPC->getValue());
693 return 0; // Can't fold.
694 case Instruction::IntToPtr: //always treated as unsigned
695 if (V->isNullValue()) // Is it an integral null value?
696 return ConstantPointerNull::get(cast<PointerType>(DestTy));
697 return 0; // Other pointer types cannot be casted
698 case Instruction::PtrToInt: // always treated as unsigned
699 if (V->isNullValue()) // is it a null pointer value?
700 return ConstantIntegral::get(DestTy, 0);
701 return 0; // Other pointer types cannot be casted
702 case Instruction::UIToFP:
703 if (const ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
704 return ConstantFP::get(DestTy, double(CI->getZExtValue()));
706 case Instruction::SIToFP:
707 if (const ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
708 return ConstantFP::get(DestTy, double(CI->getSExtValue()));
710 case Instruction::ZExt:
711 if (const ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
712 return ConstantInt::get(DestTy, CI->getZExtValue());
714 case Instruction::SExt:
715 if (const ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
716 return ConstantInt::get(DestTy, CI->getSExtValue());
718 case Instruction::Trunc:
719 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) // Can't trunc a bool
720 return ConstantIntegral::get(DestTy, CI->getZExtValue());
722 case Instruction::BitCast:
724 return (Constant*)V; // no-op cast
726 // Check to see if we are casting a pointer to an aggregate to a pointer to
727 // the first element. If so, return the appropriate GEP instruction.
728 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
729 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
730 std::vector<Value*> IdxList;
731 IdxList.push_back(Constant::getNullValue(Type::IntTy));
732 const Type *ElTy = PTy->getElementType();
733 while (ElTy != DPTy->getElementType()) {
734 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
735 if (STy->getNumElements() == 0) break;
736 ElTy = STy->getElementType(0);
737 IdxList.push_back(Constant::getNullValue(Type::UIntTy));
738 } else if (const SequentialType *STy =
739 dyn_cast<SequentialType>(ElTy)) {
740 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
741 ElTy = STy->getElementType();
742 IdxList.push_back(IdxList[0]);
748 if (ElTy == DPTy->getElementType())
749 return ConstantExpr::getGetElementPtr(
750 const_cast<Constant*>(V),IdxList);
753 // Handle casts from one packed constant to another. We know that the src
754 // and dest type have the same size (otherwise its an illegal cast).
755 if (const PackedType *DestPTy = dyn_cast<PackedType>(DestTy)) {
756 if (const PackedType *SrcTy = dyn_cast<PackedType>(V->getType())) {
757 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
758 "Not cast between same sized vectors!");
759 // First, check for null and undef
760 if (isa<ConstantAggregateZero>(V))
761 return Constant::getNullValue(DestTy);
762 if (isa<UndefValue>(V))
763 return UndefValue::get(DestTy);
765 if (const ConstantPacked *CP = dyn_cast<ConstantPacked>(V)) {
766 // This is a cast from a ConstantPacked of one type to a
767 // ConstantPacked of another type. Check to see if all elements of
768 // the input are simple.
769 bool AllSimpleConstants = true;
770 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
771 if (!isa<ConstantInt>(CP->getOperand(i)) &&
772 !isa<ConstantFP>(CP->getOperand(i))) {
773 AllSimpleConstants = false;
778 // If all of the elements are simple constants, we can fold this.
779 if (AllSimpleConstants)
780 return CastConstantPacked(const_cast<ConstantPacked*>(CP), DestPTy);
785 // Finally, implement bitcast folding now. The code below doesn't handle
787 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
788 return ConstantPointerNull::get(cast<PointerType>(DestTy));
790 // Handle integral constant input.
791 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
792 // Integral -> Integral, must be changing sign.
793 if (DestTy->isIntegral())
794 return ConstantInt::get(DestTy, CI->getZExtValue());
796 if (DestTy->isFloatingPoint()) {
797 if (DestTy == Type::FloatTy)
798 return ConstantFP::get(DestTy, BitsToFloat(CI->getZExtValue()));
799 assert(DestTy == Type::DoubleTy && "Unknown FP type!");
800 return ConstantFP::get(DestTy, BitsToDouble(CI->getZExtValue()));
802 // Otherwise, can't fold this (packed?)
806 // Handle ConstantFP input.
807 if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
809 if (DestTy->isIntegral()) {
810 if (DestTy == Type::IntTy || DestTy == Type::UIntTy)
811 return ConstantInt::get(DestTy, FloatToBits(FP->getValue()));
812 assert((DestTy == Type::LongTy || DestTy == Type::ULongTy)
813 && "Incorrect integer type for bitcast!");
814 return ConstantInt::get(DestTy, DoubleToBits(FP->getValue()));
819 assert(!"Invalid CE CastInst opcode");
823 assert(0 && "Failed to cast constant expression");
827 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
829 const Constant *V2) {
830 if (const ConstantBool *CB = dyn_cast<ConstantBool>(Cond))
831 return const_cast<Constant*>(CB->getValue() ? V1 : V2);
833 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
834 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
835 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
836 if (V1 == V2) return const_cast<Constant*>(V1);
840 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
841 const Constant *Idx) {
842 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
843 return UndefValue::get(cast<PackedType>(Val->getType())->getElementType());
844 if (Val->isNullValue()) // ee(zero, x) -> zero
845 return Constant::getNullValue(
846 cast<PackedType>(Val->getType())->getElementType());
848 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
849 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
850 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue()));
851 } else if (isa<UndefValue>(Idx)) {
852 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
853 return const_cast<Constant*>(CVal->getOperand(0));
859 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
861 const Constant *Idx) {
862 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
864 uint64_t idxVal = CIdx->getZExtValue();
865 if (isa<UndefValue>(Val)) {
866 // Insertion of scalar constant into packed undef
867 // Optimize away insertion of undef
868 if (isa<UndefValue>(Elt))
869 return const_cast<Constant*>(Val);
870 // Otherwise break the aggregate undef into multiple undefs and do
873 cast<PackedType>(Val->getType())->getNumElements();
874 std::vector<Constant*> Ops;
876 for (unsigned i = 0; i < numOps; ++i) {
878 (i == idxVal) ? Elt : UndefValue::get(Elt->getType());
879 Ops.push_back(const_cast<Constant*>(Op));
881 return ConstantPacked::get(Ops);
883 if (isa<ConstantAggregateZero>(Val)) {
884 // Insertion of scalar constant into packed aggregate zero
885 // Optimize away insertion of zero
886 if (Elt->isNullValue())
887 return const_cast<Constant*>(Val);
888 // Otherwise break the aggregate zero into multiple zeros and do
891 cast<PackedType>(Val->getType())->getNumElements();
892 std::vector<Constant*> Ops;
894 for (unsigned i = 0; i < numOps; ++i) {
896 (i == idxVal) ? Elt : Constant::getNullValue(Elt->getType());
897 Ops.push_back(const_cast<Constant*>(Op));
899 return ConstantPacked::get(Ops);
901 if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
902 // Insertion of scalar constant into packed constant
903 std::vector<Constant*> Ops;
904 Ops.reserve(CVal->getNumOperands());
905 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
907 (i == idxVal) ? Elt : cast<Constant>(CVal->getOperand(i));
908 Ops.push_back(const_cast<Constant*>(Op));
910 return ConstantPacked::get(Ops);
915 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
917 const Constant *Mask) {
923 /// isZeroSizedType - This type is zero sized if its an array or structure of
924 /// zero sized types. The only leaf zero sized type is an empty structure.
925 static bool isMaybeZeroSizedType(const Type *Ty) {
926 if (isa<OpaqueType>(Ty)) return true; // Can't say.
927 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
929 // If all of elements have zero size, this does too.
930 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
931 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
934 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
935 return isMaybeZeroSizedType(ATy->getElementType());
940 /// IdxCompare - Compare the two constants as though they were getelementptr
941 /// indices. This allows coersion of the types to be the same thing.
943 /// If the two constants are the "same" (after coersion), return 0. If the
944 /// first is less than the second, return -1, if the second is less than the
945 /// first, return 1. If the constants are not integral, return -2.
947 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
948 if (C1 == C2) return 0;
950 // Ok, we found a different index. Are either of the operands ConstantExprs?
951 // If so, we can't do anything with them.
952 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
953 return -2; // don't know!
955 // Ok, we have two differing integer indices. Sign extend them to be the same
956 // type. Long is always big enough, so we use it.
957 if (C1->getType() != Type::LongTy && C1->getType() != Type::ULongTy)
958 C1 = ConstantExpr::getSExt(C1, Type::LongTy);
960 C1 = ConstantExpr::getBitCast(C1, Type::LongTy);
961 if (C2->getType() != Type::LongTy && C1->getType() != Type::ULongTy)
962 C2 = ConstantExpr::getSExt(C2, Type::LongTy);
964 C2 = ConstantExpr::getBitCast(C2, Type::LongTy);
966 if (C1 == C2) return 0; // Are they just differing types?
968 // If the type being indexed over is really just a zero sized type, there is
969 // no pointer difference being made here.
970 if (isMaybeZeroSizedType(ElTy))
973 // If they are really different, now that they are the same type, then we
974 // found a difference!
975 if (cast<ConstantInt>(C1)->getSExtValue() <
976 cast<ConstantInt>(C2)->getSExtValue())
982 /// evaluateRelation - This function determines if there is anything we can
983 /// decide about the two constants provided. This doesn't need to handle simple
984 /// things like integer comparisons, but should instead handle ConstantExprs
985 /// and GlobalValues. If we can determine that the two constants have a
986 /// particular relation to each other, we should return the corresponding SetCC
987 /// code, otherwise return Instruction::BinaryOpsEnd.
989 /// To simplify this code we canonicalize the relation so that the first
990 /// operand is always the most "complex" of the two. We consider simple
991 /// constants (like ConstantInt) to be the simplest, followed by
992 /// GlobalValues, followed by ConstantExpr's (the most complex).
994 static Instruction::BinaryOps evaluateRelation(Constant *V1, Constant *V2) {
995 assert(V1->getType() == V2->getType() &&
996 "Cannot compare different types of values!");
997 if (V1 == V2) return Instruction::SetEQ;
999 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
1000 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
1001 // We distilled this down to a simple case, use the standard constant
1003 ConstantBool *R = dyn_cast<ConstantBool>(ConstantExpr::getSetEQ(V1, V2));
1004 if (R && R->getValue()) return Instruction::SetEQ;
1005 R = dyn_cast<ConstantBool>(ConstantExpr::getSetLT(V1, V2));
1006 if (R && R->getValue()) return Instruction::SetLT;
1007 R = dyn_cast<ConstantBool>(ConstantExpr::getSetGT(V1, V2));
1008 if (R && R->getValue()) return Instruction::SetGT;
1010 // If we couldn't figure it out, bail.
1011 return Instruction::BinaryOpsEnd;
1014 // If the first operand is simple, swap operands.
1015 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
1016 if (SwappedRelation != Instruction::BinaryOpsEnd)
1017 return SetCondInst::getSwappedCondition(SwappedRelation);
1019 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
1020 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
1021 Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
1022 if (SwappedRelation != Instruction::BinaryOpsEnd)
1023 return SetCondInst::getSwappedCondition(SwappedRelation);
1025 return Instruction::BinaryOpsEnd;
1028 // Now we know that the RHS is a GlobalValue or simple constant,
1029 // which (since the types must match) means that it's a ConstantPointerNull.
1030 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1031 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
1032 return Instruction::SetNE;
1034 // GlobalVals can never be null.
1035 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
1036 if (!CPR1->hasExternalWeakLinkage())
1037 return Instruction::SetNE;
1040 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
1041 // constantexpr, a CPR, or a simple constant.
1042 ConstantExpr *CE1 = cast<ConstantExpr>(V1);
1043 Constant *CE1Op0 = CE1->getOperand(0);
1045 switch (CE1->getOpcode()) {
1046 case Instruction::Trunc:
1047 case Instruction::FPTrunc:
1048 case Instruction::FPExt:
1049 case Instruction::FPToUI:
1050 case Instruction::FPToSI:
1051 break; // We don't do anything with floating point.
1052 case Instruction::ZExt:
1053 case Instruction::SExt:
1054 case Instruction::UIToFP:
1055 case Instruction::SIToFP:
1056 case Instruction::PtrToInt:
1057 case Instruction::IntToPtr:
1058 case Instruction::BitCast:
1059 // If the cast is not actually changing bits, and the second operand is a
1060 // null pointer, do the comparison with the pre-casted value.
1061 if (V2->isNullValue() &&
1062 (isa<PointerType>(CE1->getType()) || CE1->getType()->isIntegral()))
1063 return evaluateRelation(CE1Op0,
1064 Constant::getNullValue(CE1Op0->getType()));
1066 // If the dest type is a pointer type, and the RHS is a constantexpr cast
1067 // from the same type as the src of the LHS, evaluate the inputs. This is
1068 // important for things like "seteq (cast 4 to int*), (cast 5 to int*)",
1069 // which happens a lot in compilers with tagged integers.
1070 if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
1071 if (isa<PointerType>(CE1->getType()) && CE2->isCast() &&
1072 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
1073 CE1->getOperand(0)->getType()->isIntegral()) {
1074 return evaluateRelation(CE1->getOperand(0), CE2->getOperand(0));
1078 case Instruction::GetElementPtr:
1079 // Ok, since this is a getelementptr, we know that the constant has a
1080 // pointer type. Check the various cases.
1081 if (isa<ConstantPointerNull>(V2)) {
1082 // If we are comparing a GEP to a null pointer, check to see if the base
1083 // of the GEP equals the null pointer.
1084 if (GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
1085 if (GV->hasExternalWeakLinkage())
1086 // Weak linkage GVals could be zero or not. We're comparing that
1087 // to null pointer so its greater-or-equal
1088 return Instruction::SetGE;
1090 // If its not weak linkage, the GVal must have a non-zero address
1091 // so the result is greater-than
1092 return Instruction::SetGT;
1093 } else if (isa<ConstantPointerNull>(CE1Op0)) {
1094 // If we are indexing from a null pointer, check to see if we have any
1095 // non-zero indices.
1096 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
1097 if (!CE1->getOperand(i)->isNullValue())
1098 // Offsetting from null, must not be equal.
1099 return Instruction::SetGT;
1100 // Only zero indexes from null, must still be zero.
1101 return Instruction::SetEQ;
1103 // Otherwise, we can't really say if the first operand is null or not.
1104 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1105 if (isa<ConstantPointerNull>(CE1Op0)) {
1106 if (CPR2->hasExternalWeakLinkage())
1107 // Weak linkage GVals could be zero or not. We're comparing it to
1108 // a null pointer, so its less-or-equal
1109 return Instruction::SetLE;
1111 // If its not weak linkage, the GVal must have a non-zero address
1112 // so the result is less-than
1113 return Instruction::SetLT;
1114 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
1116 // If this is a getelementptr of the same global, then it must be
1117 // different. Because the types must match, the getelementptr could
1118 // only have at most one index, and because we fold getelementptr's
1119 // with a single zero index, it must be nonzero.
1120 assert(CE1->getNumOperands() == 2 &&
1121 !CE1->getOperand(1)->isNullValue() &&
1122 "Suprising getelementptr!");
1123 return Instruction::SetGT;
1125 // If they are different globals, we don't know what the value is,
1126 // but they can't be equal.
1127 return Instruction::SetNE;
1131 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
1132 const Constant *CE2Op0 = CE2->getOperand(0);
1134 // There are MANY other foldings that we could perform here. They will
1135 // probably be added on demand, as they seem needed.
1136 switch (CE2->getOpcode()) {
1138 case Instruction::GetElementPtr:
1139 // By far the most common case to handle is when the base pointers are
1140 // obviously to the same or different globals.
1141 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
1142 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
1143 return Instruction::SetNE;
1144 // Ok, we know that both getelementptr instructions are based on the
1145 // same global. From this, we can precisely determine the relative
1146 // ordering of the resultant pointers.
1149 // Compare all of the operands the GEP's have in common.
1150 gep_type_iterator GTI = gep_type_begin(CE1);
1151 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
1153 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
1154 GTI.getIndexedType())) {
1155 case -1: return Instruction::SetLT;
1156 case 1: return Instruction::SetGT;
1157 case -2: return Instruction::BinaryOpsEnd;
1160 // Ok, we ran out of things they have in common. If any leftovers
1161 // are non-zero then we have a difference, otherwise we are equal.
1162 for (; i < CE1->getNumOperands(); ++i)
1163 if (!CE1->getOperand(i)->isNullValue())
1164 if (isa<ConstantIntegral>(CE1->getOperand(i)))
1165 return Instruction::SetGT;
1167 return Instruction::BinaryOpsEnd; // Might be equal.
1169 for (; i < CE2->getNumOperands(); ++i)
1170 if (!CE2->getOperand(i)->isNullValue())
1171 if (isa<ConstantIntegral>(CE2->getOperand(i)))
1172 return Instruction::SetLT;
1174 return Instruction::BinaryOpsEnd; // Might be equal.
1175 return Instruction::SetEQ;
1185 return Instruction::BinaryOpsEnd;
1188 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
1190 const Constant *V2) {
1194 case Instruction::Add: C = ConstRules::get(V1, V2).add(V1, V2); break;
1195 case Instruction::Sub: C = ConstRules::get(V1, V2).sub(V1, V2); break;
1196 case Instruction::Mul: C = ConstRules::get(V1, V2).mul(V1, V2); break;
1197 case Instruction::UDiv: C = ConstRules::get(V1, V2).udiv(V1, V2); break;
1198 case Instruction::SDiv: C = ConstRules::get(V1, V2).sdiv(V1, V2); break;
1199 case Instruction::FDiv: C = ConstRules::get(V1, V2).fdiv(V1, V2); break;
1200 case Instruction::URem: C = ConstRules::get(V1, V2).urem(V1, V2); break;
1201 case Instruction::SRem: C = ConstRules::get(V1, V2).srem(V1, V2); break;
1202 case Instruction::FRem: C = ConstRules::get(V1, V2).frem(V1, V2); break;
1203 case Instruction::And: C = ConstRules::get(V1, V2).op_and(V1, V2); break;
1204 case Instruction::Or: C = ConstRules::get(V1, V2).op_or (V1, V2); break;
1205 case Instruction::Xor: C = ConstRules::get(V1, V2).op_xor(V1, V2); break;
1206 case Instruction::Shl: C = ConstRules::get(V1, V2).shl(V1, V2); break;
1207 case Instruction::LShr: C = ConstRules::get(V1, V2).lshr(V1, V2); break;
1208 case Instruction::AShr: C = ConstRules::get(V1, V2).ashr(V1, V2); break;
1209 case Instruction::SetEQ:
1210 // SetEQ(null,GV) -> false
1211 if (V1->isNullValue()) {
1212 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V2))
1213 if (!GV->hasExternalWeakLinkage())
1214 return ConstantBool::getFalse();
1215 // SetEQ(GV,null) -> false
1216 } else if (V2->isNullValue()) {
1217 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1))
1218 if (!GV->hasExternalWeakLinkage())
1219 return ConstantBool::getFalse();
1221 C = ConstRules::get(V1, V2).equalto(V1, V2);
1223 case Instruction::SetLT: C = ConstRules::get(V1, V2).lessthan(V1, V2);break;
1224 case Instruction::SetGT: C = ConstRules::get(V1, V2).lessthan(V2, V1);break;
1225 case Instruction::SetNE:
1226 // SetNE(null,GV) -> true
1227 if (V1->isNullValue()) {
1228 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V2))
1229 if (!GV->hasExternalWeakLinkage())
1230 return ConstantBool::getTrue();
1231 // SetNE(GV,null) -> true
1232 } else if (V2->isNullValue()) {
1233 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1))
1234 if (!GV->hasExternalWeakLinkage())
1235 return ConstantBool::getTrue();
1237 // V1 != V2 === !(V1 == V2)
1238 C = ConstRules::get(V1, V2).equalto(V1, V2);
1239 if (C) return ConstantExpr::getNot(C);
1241 case Instruction::SetLE: // V1 <= V2 === !(V2 < V1)
1242 C = ConstRules::get(V1, V2).lessthan(V2, V1);
1243 if (C) return ConstantExpr::getNot(C);
1245 case Instruction::SetGE: // V1 >= V2 === !(V1 < V2)
1246 C = ConstRules::get(V1, V2).lessthan(V1, V2);
1247 if (C) return ConstantExpr::getNot(C);
1251 // If we successfully folded the expression, return it now.
1254 if (SetCondInst::isComparison(Opcode)) {
1255 if (isa<UndefValue>(V1) || isa<UndefValue>(V2))
1256 return UndefValue::get(Type::BoolTy);
1257 switch (evaluateRelation(const_cast<Constant*>(V1),
1258 const_cast<Constant*>(V2))) {
1259 default: assert(0 && "Unknown relational!");
1260 case Instruction::BinaryOpsEnd:
1261 break; // Couldn't determine anything about these constants.
1262 case Instruction::SetEQ: // We know the constants are equal!
1263 // If we know the constants are equal, we can decide the result of this
1264 // computation precisely.
1265 return ConstantBool::get(Opcode == Instruction::SetEQ ||
1266 Opcode == Instruction::SetLE ||
1267 Opcode == Instruction::SetGE);
1268 case Instruction::SetLT:
1269 // If we know that V1 < V2, we can decide the result of this computation
1271 return ConstantBool::get(Opcode == Instruction::SetLT ||
1272 Opcode == Instruction::SetNE ||
1273 Opcode == Instruction::SetLE);
1274 case Instruction::SetGT:
1275 // If we know that V1 > V2, we can decide the result of this computation
1277 return ConstantBool::get(Opcode == Instruction::SetGT ||
1278 Opcode == Instruction::SetNE ||
1279 Opcode == Instruction::SetGE);
1280 case Instruction::SetLE:
1281 // If we know that V1 <= V2, we can only partially decide this relation.
1282 if (Opcode == Instruction::SetGT) return ConstantBool::getFalse();
1283 if (Opcode == Instruction::SetLT) return ConstantBool::getTrue();
1286 case Instruction::SetGE:
1287 // If we know that V1 >= V2, we can only partially decide this relation.
1288 if (Opcode == Instruction::SetLT) return ConstantBool::getFalse();
1289 if (Opcode == Instruction::SetGT) return ConstantBool::getTrue();
1292 case Instruction::SetNE:
1293 // If we know that V1 != V2, we can only partially decide this relation.
1294 if (Opcode == Instruction::SetEQ) return ConstantBool::getFalse();
1295 if (Opcode == Instruction::SetNE) return ConstantBool::getTrue();
1300 if (isa<UndefValue>(V1) || isa<UndefValue>(V2)) {
1302 case Instruction::Add:
1303 case Instruction::Sub:
1304 case Instruction::Xor:
1305 return UndefValue::get(V1->getType());
1307 case Instruction::Mul:
1308 case Instruction::And:
1309 return Constant::getNullValue(V1->getType());
1310 case Instruction::UDiv:
1311 case Instruction::SDiv:
1312 case Instruction::FDiv:
1313 case Instruction::URem:
1314 case Instruction::SRem:
1315 case Instruction::FRem:
1316 if (!isa<UndefValue>(V2)) // undef / X -> 0
1317 return Constant::getNullValue(V1->getType());
1318 return const_cast<Constant*>(V2); // X / undef -> undef
1319 case Instruction::Or: // X | undef -> -1
1320 return ConstantInt::getAllOnesValue(V1->getType());
1321 case Instruction::LShr:
1322 if (isa<UndefValue>(V2) && isa<UndefValue>(V1))
1323 return const_cast<Constant*>(V1); // undef lshr undef -> undef
1324 return Constant::getNullValue(V1->getType()); // X lshr undef -> 0
1325 // undef lshr X -> 0
1326 case Instruction::AShr:
1327 if (!isa<UndefValue>(V2))
1328 return const_cast<Constant*>(V1); // undef ashr X --> undef
1329 else if (isa<UndefValue>(V1))
1330 return const_cast<Constant*>(V1); // undef ashr undef -> undef
1332 return const_cast<Constant*>(V1); // X ashr undef --> X
1333 case Instruction::Shl:
1334 // undef << X -> 0 or X << undef -> 0
1335 return Constant::getNullValue(V1->getType());
1339 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(V1)) {
1340 if (isa<ConstantExpr>(V2)) {
1341 // There are many possible foldings we could do here. We should probably
1342 // at least fold add of a pointer with an integer into the appropriate
1343 // getelementptr. This will improve alias analysis a bit.
1345 // Just implement a couple of simple identities.
1347 case Instruction::Add:
1348 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X + 0 == X
1350 case Instruction::Sub:
1351 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X - 0 == X
1353 case Instruction::Mul:
1354 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X * 0 == 0
1355 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1356 if (CI->getZExtValue() == 1)
1357 return const_cast<Constant*>(V1); // X * 1 == X
1359 case Instruction::UDiv:
1360 case Instruction::SDiv:
1361 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1362 if (CI->getZExtValue() == 1)
1363 return const_cast<Constant*>(V1); // X / 1 == X
1365 case Instruction::URem:
1366 case Instruction::SRem:
1367 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1368 if (CI->getZExtValue() == 1)
1369 return Constant::getNullValue(CI->getType()); // X % 1 == 0
1371 case Instruction::And:
1372 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1373 return const_cast<Constant*>(V1); // X & -1 == X
1374 if (V2->isNullValue()) return const_cast<Constant*>(V2); // X & 0 == 0
1375 if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
1376 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
1378 // Functions are at least 4-byte aligned. If and'ing the address of a
1379 // function with a constant < 4, fold it to zero.
1380 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
1381 if (CI->getZExtValue() < 4 && isa<Function>(CPR))
1382 return Constant::getNullValue(CI->getType());
1385 case Instruction::Or:
1386 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X | 0 == X
1387 if (cast<ConstantIntegral>(V2)->isAllOnesValue())
1388 return const_cast<Constant*>(V2); // X | -1 == -1
1390 case Instruction::Xor:
1391 if (V2->isNullValue()) return const_cast<Constant*>(V1); // X ^ 0 == X
1396 } else if (isa<ConstantExpr>(V2)) {
1397 // If V2 is a constant expr and V1 isn't, flop them around and fold the
1398 // other way if possible.
1400 case Instruction::Add:
1401 case Instruction::Mul:
1402 case Instruction::And:
1403 case Instruction::Or:
1404 case Instruction::Xor:
1405 case Instruction::SetEQ:
1406 case Instruction::SetNE:
1407 // No change of opcode required.
1408 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1410 case Instruction::SetLT:
1411 case Instruction::SetGT:
1412 case Instruction::SetLE:
1413 case Instruction::SetGE:
1414 // Change the opcode as necessary to swap the operands.
1415 Opcode = SetCondInst::getSwappedCondition((Instruction::BinaryOps)Opcode);
1416 return ConstantFoldBinaryInstruction(Opcode, V2, V1);
1418 case Instruction::Shl:
1419 case Instruction::LShr:
1420 case Instruction::AShr:
1421 case Instruction::Sub:
1422 case Instruction::SDiv:
1423 case Instruction::UDiv:
1424 case Instruction::FDiv:
1425 case Instruction::URem:
1426 case Instruction::SRem:
1427 case Instruction::FRem:
1428 default: // These instructions cannot be flopped around.
1435 Constant *llvm::ConstantFoldCompare(
1436 unsigned opcode, Constant *C1, Constant *C2, unsigned short predicate)
1438 // Place holder for future folding of ICmp and FCmp instructions
1442 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1443 const std::vector<Value*> &IdxList) {
1444 if (IdxList.size() == 0 ||
1445 (IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
1446 return const_cast<Constant*>(C);
1448 if (isa<UndefValue>(C)) {
1449 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1451 assert(Ty != 0 && "Invalid indices for GEP!");
1452 return UndefValue::get(PointerType::get(Ty));
1455 Constant *Idx0 = cast<Constant>(IdxList[0]);
1456 if (C->isNullValue()) {
1458 for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
1459 if (!cast<Constant>(IdxList[i])->isNullValue()) {
1464 const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1466 assert(Ty != 0 && "Invalid indices for GEP!");
1467 return ConstantPointerNull::get(PointerType::get(Ty));
1470 if (IdxList.size() == 1) {
1471 const Type *ElTy = cast<PointerType>(C->getType())->getElementType();
1472 if (uint32_t ElSize = ElTy->getPrimitiveSize()) {
1473 // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm
1474 // type, we can statically fold this.
1475 Constant *R = ConstantInt::get(Type::UIntTy, ElSize);
1476 // We know R is unsigned, Idx0 is signed because it must be an index
1477 // through a sequential type (gep pointer operand) which is always
1479 R = ConstantExpr::getSExtOrBitCast(R, Idx0->getType());
1480 R = ConstantExpr::getMul(R, Idx0); // signed multiply
1481 // R is a signed integer, C is the GEP pointer so -> IntToPtr
1482 return ConstantExpr::getIntToPtr(R, C->getType());
1487 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1488 // Combine Indices - If the source pointer to this getelementptr instruction
1489 // is a getelementptr instruction, combine the indices of the two
1490 // getelementptr instructions into a single instruction.
1492 if (CE->getOpcode() == Instruction::GetElementPtr) {
1493 const Type *LastTy = 0;
1494 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1498 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1499 std::vector<Value*> NewIndices;
1500 NewIndices.reserve(IdxList.size() + CE->getNumOperands());
1501 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1502 NewIndices.push_back(CE->getOperand(i));
1504 // Add the last index of the source with the first index of the new GEP.
1505 // Make sure to handle the case when they are actually different types.
1506 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1507 // Otherwise it must be an array.
1508 if (!Idx0->isNullValue()) {
1509 const Type *IdxTy = Combined->getType();
1510 if (IdxTy != Idx0->getType()) {
1511 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::LongTy);
1512 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
1514 Combined = ConstantExpr::get(Instruction::Add, C1, C2);
1517 ConstantExpr::get(Instruction::Add, Idx0, Combined);
1521 NewIndices.push_back(Combined);
1522 NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
1523 return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
1527 // Implement folding of:
1528 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1530 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1532 if (CE->isCast() && IdxList.size() > 1 && Idx0->isNullValue())
1533 if (const PointerType *SPT =
1534 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1535 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1536 if (const ArrayType *CAT =
1537 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1538 if (CAT->getElementType() == SAT->getElementType())
1539 return ConstantExpr::getGetElementPtr(
1540 (Constant*)CE->getOperand(0), IdxList);