1 //===-- ConstantFolding.cpp - Analyze constant folding possibilities ------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This family of functions determines the possibility of performing constant
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Analysis/ConstantFolding.h"
16 #include "llvm/Constants.h"
17 #include "llvm/DerivedTypes.h"
18 #include "llvm/Function.h"
19 #include "llvm/Instructions.h"
20 #include "llvm/Intrinsics.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/StringMap.h"
23 #include "llvm/Target/TargetData.h"
24 #include "llvm/Support/GetElementPtrTypeIterator.h"
25 #include "llvm/Support/MathExtras.h"
30 //===----------------------------------------------------------------------===//
31 // Constant Folding internal helper functions
32 //===----------------------------------------------------------------------===//
34 /// IsConstantOffsetFromGlobal - If this constant is actually a constant offset
35 /// from a global, return the global and the constant. Because of
36 /// constantexprs, this function is recursive.
37 static bool IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV,
38 int64_t &Offset, const TargetData &TD) {
39 // Trivial case, constant is the global.
40 if ((GV = dyn_cast<GlobalValue>(C))) {
45 // Otherwise, if this isn't a constant expr, bail out.
46 ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
47 if (!CE) return false;
49 // Look through ptr->int and ptr->ptr casts.
50 if (CE->getOpcode() == Instruction::PtrToInt ||
51 CE->getOpcode() == Instruction::BitCast)
52 return IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD);
54 // i32* getelementptr ([5 x i32]* @a, i32 0, i32 5)
55 if (CE->getOpcode() == Instruction::GetElementPtr) {
56 // Cannot compute this if the element type of the pointer is missing size
58 if (!cast<PointerType>(CE->getOperand(0)->getType())
59 ->getElementType()->isSized())
62 // If the base isn't a global+constant, we aren't either.
63 if (!IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD))
66 // Otherwise, add any offset that our operands provide.
67 gep_type_iterator GTI = gep_type_begin(CE);
68 for (User::const_op_iterator i = CE->op_begin() + 1, e = CE->op_end();
70 ConstantInt *CI = dyn_cast<ConstantInt>(*i);
71 if (!CI) return false; // Index isn't a simple constant?
72 if (CI->getZExtValue() == 0) continue; // Not adding anything.
74 if (const StructType *ST = dyn_cast<StructType>(*GTI)) {
76 Offset += TD.getStructLayout(ST)->getElementOffset(CI->getZExtValue());
78 const SequentialType *SQT = cast<SequentialType>(*GTI);
79 Offset += TD.getTypePaddedSize(SQT->getElementType())*CI->getSExtValue();
89 /// SymbolicallyEvaluateBinop - One of Op0/Op1 is a constant expression.
90 /// Attempt to symbolically evaluate the result of a binary operator merging
91 /// these together. If target data info is available, it is provided as TD,
92 /// otherwise TD is null.
93 static Constant *SymbolicallyEvaluateBinop(unsigned Opc, Constant *Op0,
94 Constant *Op1, const TargetData *TD){
97 // Fold (and 0xffffffff00000000, (shl x, 32)) -> shl.
98 // Fold (lshr (or X, Y), 32) -> (lshr [X/Y], 32) if one doesn't contribute
102 // If the constant expr is something like &A[123] - &A[4].f, fold this into a
103 // constant. This happens frequently when iterating over a global array.
104 if (Opc == Instruction::Sub && TD) {
105 GlobalValue *GV1, *GV2;
106 int64_t Offs1, Offs2;
108 if (IsConstantOffsetFromGlobal(Op0, GV1, Offs1, *TD))
109 if (IsConstantOffsetFromGlobal(Op1, GV2, Offs2, *TD) &&
111 // (&GV+C1) - (&GV+C2) -> C1-C2, pointer arithmetic cannot overflow.
112 return ConstantInt::get(Op0->getType(), Offs1-Offs2);
119 /// SymbolicallyEvaluateGEP - If we can symbolically evaluate the specified GEP
120 /// constant expression, do so.
121 static Constant *SymbolicallyEvaluateGEP(Constant* const* Ops, unsigned NumOps,
122 const Type *ResultTy,
123 const TargetData *TD) {
124 Constant *Ptr = Ops[0];
125 if (!TD || !cast<PointerType>(Ptr->getType())->getElementType()->isSized())
128 uint64_t BasePtr = 0;
129 if (!Ptr->isNullValue()) {
130 // If this is a inttoptr from a constant int, we can fold this as the base,
131 // otherwise we can't.
132 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
133 if (CE->getOpcode() == Instruction::IntToPtr)
134 if (ConstantInt *Base = dyn_cast<ConstantInt>(CE->getOperand(0)))
135 BasePtr = Base->getZExtValue();
141 // If this is a constant expr gep that is effectively computing an
142 // "offsetof", fold it into 'cast int Size to T*' instead of 'gep 0, 0, 12'
143 for (unsigned i = 1; i != NumOps; ++i)
144 if (!isa<ConstantInt>(Ops[i]))
147 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
148 (Value**)Ops+1, NumOps-1);
149 Constant *C = ConstantInt::get(TD->getIntPtrType(), Offset+BasePtr);
150 return ConstantExpr::getIntToPtr(C, ResultTy);
153 /// FoldBitCast - Constant fold bitcast, symbolically evaluating it with
154 /// targetdata. Return 0 if unfoldable.
155 static Constant *FoldBitCast(Constant *C, const Type *DestTy,
156 const TargetData &TD) {
157 // If this is a bitcast from constant vector -> vector, fold it.
158 if (ConstantVector *CV = dyn_cast<ConstantVector>(C)) {
159 if (const VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
160 // If the element types match, VMCore can fold it.
161 unsigned NumDstElt = DestVTy->getNumElements();
162 unsigned NumSrcElt = CV->getNumOperands();
163 if (NumDstElt == NumSrcElt)
166 const Type *SrcEltTy = CV->getType()->getElementType();
167 const Type *DstEltTy = DestVTy->getElementType();
169 // Otherwise, we're changing the number of elements in a vector, which
170 // requires endianness information to do the right thing. For example,
171 // bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
172 // folds to (little endian):
173 // <4 x i32> <i32 0, i32 0, i32 1, i32 0>
174 // and to (big endian):
175 // <4 x i32> <i32 0, i32 0, i32 0, i32 1>
177 // First thing is first. We only want to think about integer here, so if
178 // we have something in FP form, recast it as integer.
179 if (DstEltTy->isFloatingPoint()) {
180 // Fold to an vector of integers with same size as our FP type.
181 unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
182 const Type *DestIVTy = VectorType::get(IntegerType::get(FPWidth),
184 // Recursively handle this integer conversion, if possible.
185 C = FoldBitCast(C, DestIVTy, TD);
188 // Finally, VMCore can handle this now that #elts line up.
189 return ConstantExpr::getBitCast(C, DestTy);
192 // Okay, we know the destination is integer, if the input is FP, convert
193 // it to integer first.
194 if (SrcEltTy->isFloatingPoint()) {
195 unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
196 const Type *SrcIVTy = VectorType::get(IntegerType::get(FPWidth),
198 // Ask VMCore to do the conversion now that #elts line up.
199 C = ConstantExpr::getBitCast(C, SrcIVTy);
200 CV = dyn_cast<ConstantVector>(C);
201 if (!CV) return 0; // If VMCore wasn't able to fold it, bail out.
204 // Now we know that the input and output vectors are both integer vectors
205 // of the same size, and that their #elements is not the same. Do the
206 // conversion here, which depends on whether the input or output has
208 bool isLittleEndian = TD.isLittleEndian();
210 SmallVector<Constant*, 32> Result;
211 if (NumDstElt < NumSrcElt) {
212 // Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
213 Constant *Zero = Constant::getNullValue(DstEltTy);
214 unsigned Ratio = NumSrcElt/NumDstElt;
215 unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
217 for (unsigned i = 0; i != NumDstElt; ++i) {
218 // Build each element of the result.
219 Constant *Elt = Zero;
220 unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
221 for (unsigned j = 0; j != Ratio; ++j) {
222 Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(SrcElt++));
223 if (!Src) return 0; // Reject constantexpr elements.
225 // Zero extend the element to the right size.
226 Src = ConstantExpr::getZExt(Src, Elt->getType());
228 // Shift it to the right place, depending on endianness.
229 Src = ConstantExpr::getShl(Src,
230 ConstantInt::get(Src->getType(), ShiftAmt));
231 ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
234 Elt = ConstantExpr::getOr(Elt, Src);
236 Result.push_back(Elt);
239 // Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
240 unsigned Ratio = NumDstElt/NumSrcElt;
241 unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits();
243 // Loop over each source value, expanding into multiple results.
244 for (unsigned i = 0; i != NumSrcElt; ++i) {
245 Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(i));
246 if (!Src) return 0; // Reject constantexpr elements.
248 unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
249 for (unsigned j = 0; j != Ratio; ++j) {
250 // Shift the piece of the value into the right place, depending on
252 Constant *Elt = ConstantExpr::getLShr(Src,
253 ConstantInt::get(Src->getType(), ShiftAmt));
254 ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
256 // Truncate and remember this piece.
257 Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
262 return ConstantVector::get(&Result[0], Result.size());
270 //===----------------------------------------------------------------------===//
271 // Constant Folding public APIs
272 //===----------------------------------------------------------------------===//
275 /// ConstantFoldInstruction - Attempt to constant fold the specified
276 /// instruction. If successful, the constant result is returned, if not, null
277 /// is returned. Note that this function can only fail when attempting to fold
278 /// instructions like loads and stores, which have no constant expression form.
280 Constant *llvm::ConstantFoldInstruction(Instruction *I, const TargetData *TD) {
281 if (PHINode *PN = dyn_cast<PHINode>(I)) {
282 if (PN->getNumIncomingValues() == 0)
283 return UndefValue::get(PN->getType());
285 Constant *Result = dyn_cast<Constant>(PN->getIncomingValue(0));
286 if (Result == 0) return 0;
288 // Handle PHI nodes specially here...
289 for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
290 if (PN->getIncomingValue(i) != Result && PN->getIncomingValue(i) != PN)
291 return 0; // Not all the same incoming constants...
293 // If we reach here, all incoming values are the same constant.
297 // Scan the operand list, checking to see if they are all constants, if so,
298 // hand off to ConstantFoldInstOperands.
299 SmallVector<Constant*, 8> Ops;
300 for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i)
301 if (Constant *Op = dyn_cast<Constant>(*i))
304 return 0; // All operands not constant!
306 if (const CmpInst *CI = dyn_cast<CmpInst>(I))
307 return ConstantFoldCompareInstOperands(CI->getPredicate(),
308 &Ops[0], Ops.size(), TD);
310 return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
311 &Ops[0], Ops.size(), TD);
314 /// ConstantFoldConstantExpression - Attempt to fold the constant expression
315 /// using the specified TargetData. If successful, the constant result is
316 /// result is returned, if not, null is returned.
317 Constant *llvm::ConstantFoldConstantExpression(ConstantExpr *CE,
318 const TargetData *TD) {
319 assert(TD && "ConstantFoldConstantExpression requires a valid TargetData.");
321 SmallVector<Constant*, 8> Ops;
322 for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i)
323 Ops.push_back(cast<Constant>(*i));
326 return ConstantFoldCompareInstOperands(CE->getPredicate(),
327 &Ops[0], Ops.size(), TD);
329 return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(),
330 &Ops[0], Ops.size(), TD);
333 /// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
334 /// specified opcode and operands. If successful, the constant result is
335 /// returned, if not, null is returned. Note that this function can fail when
336 /// attempting to fold instructions like loads and stores, which have no
337 /// constant expression form.
339 Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
340 Constant* const* Ops, unsigned NumOps,
341 const TargetData *TD) {
342 // Handle easy binops first.
343 if (Instruction::isBinaryOp(Opcode)) {
344 if (isa<ConstantExpr>(Ops[0]) || isa<ConstantExpr>(Ops[1]))
345 if (Constant *C = SymbolicallyEvaluateBinop(Opcode, Ops[0], Ops[1], TD))
348 return ConstantExpr::get(Opcode, Ops[0], Ops[1]);
353 case Instruction::Call:
354 if (Function *F = dyn_cast<Function>(Ops[0]))
355 if (canConstantFoldCallTo(F))
356 return ConstantFoldCall(F, Ops+1, NumOps-1);
358 case Instruction::ICmp:
359 case Instruction::FCmp:
360 case Instruction::VICmp:
361 case Instruction::VFCmp:
362 assert(0 &&"This function is invalid for compares: no predicate specified");
363 case Instruction::PtrToInt:
364 // If the input is a inttoptr, eliminate the pair. This requires knowing
365 // the width of a pointer, so it can't be done in ConstantExpr::getCast.
366 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0])) {
367 if (TD && CE->getOpcode() == Instruction::IntToPtr) {
368 Constant *Input = CE->getOperand(0);
369 unsigned InWidth = Input->getType()->getPrimitiveSizeInBits();
370 if (TD->getPointerSizeInBits() < InWidth) {
372 ConstantInt::get(APInt::getLowBitsSet(InWidth,
373 TD->getPointerSizeInBits()));
374 Input = ConstantExpr::getAnd(Input, Mask);
376 // Do a zext or trunc to get to the dest size.
377 return ConstantExpr::getIntegerCast(Input, DestTy, false);
380 return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
381 case Instruction::IntToPtr:
382 // If the input is a ptrtoint, turn the pair into a ptr to ptr bitcast if
383 // the int size is >= the ptr size. This requires knowing the width of a
384 // pointer, so it can't be done in ConstantExpr::getCast.
385 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0])) {
386 if (TD && CE->getOpcode() == Instruction::PtrToInt &&
387 TD->getPointerSizeInBits() <=
388 CE->getType()->getPrimitiveSizeInBits()) {
389 Constant *Input = CE->getOperand(0);
390 Constant *C = FoldBitCast(Input, DestTy, *TD);
391 return C ? C : ConstantExpr::getBitCast(Input, DestTy);
394 return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
395 case Instruction::Trunc:
396 case Instruction::ZExt:
397 case Instruction::SExt:
398 case Instruction::FPTrunc:
399 case Instruction::FPExt:
400 case Instruction::UIToFP:
401 case Instruction::SIToFP:
402 case Instruction::FPToUI:
403 case Instruction::FPToSI:
404 return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
405 case Instruction::BitCast:
407 if (Constant *C = FoldBitCast(Ops[0], DestTy, *TD))
409 return ConstantExpr::getBitCast(Ops[0], DestTy);
410 case Instruction::Select:
411 return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
412 case Instruction::ExtractElement:
413 return ConstantExpr::getExtractElement(Ops[0], Ops[1]);
414 case Instruction::InsertElement:
415 return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]);
416 case Instruction::ShuffleVector:
417 return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]);
418 case Instruction::GetElementPtr:
419 if (Constant *C = SymbolicallyEvaluateGEP(Ops, NumOps, DestTy, TD))
422 return ConstantExpr::getGetElementPtr(Ops[0], Ops+1, NumOps-1);
426 /// ConstantFoldCompareInstOperands - Attempt to constant fold a compare
427 /// instruction (icmp/fcmp) with the specified operands. If it fails, it
428 /// returns a constant expression of the specified operands.
430 Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate,
431 Constant*const * Ops,
433 const TargetData *TD) {
434 // fold: icmp (inttoptr x), null -> icmp x, 0
435 // fold: icmp (ptrtoint x), 0 -> icmp x, null
436 // fold: icmp (inttoptr x), (inttoptr y) -> icmp trunc/zext x, trunc/zext y
437 // fold: icmp (ptrtoint x), (ptrtoint y) -> icmp x, y
439 // ConstantExpr::getCompare cannot do this, because it doesn't have TD
440 // around to know if bit truncation is happening.
441 if (ConstantExpr *CE0 = dyn_cast<ConstantExpr>(Ops[0])) {
442 if (TD && Ops[1]->isNullValue()) {
443 const Type *IntPtrTy = TD->getIntPtrType();
444 if (CE0->getOpcode() == Instruction::IntToPtr) {
445 // Convert the integer value to the right size to ensure we get the
446 // proper extension or truncation.
447 Constant *C = ConstantExpr::getIntegerCast(CE0->getOperand(0),
449 Constant *NewOps[] = { C, Constant::getNullValue(C->getType()) };
450 return ConstantFoldCompareInstOperands(Predicate, NewOps, 2, TD);
453 // Only do this transformation if the int is intptrty in size, otherwise
454 // there is a truncation or extension that we aren't modeling.
455 if (CE0->getOpcode() == Instruction::PtrToInt &&
456 CE0->getType() == IntPtrTy) {
457 Constant *C = CE0->getOperand(0);
458 Constant *NewOps[] = { C, Constant::getNullValue(C->getType()) };
460 return ConstantFoldCompareInstOperands(Predicate, NewOps, 2, TD);
464 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(Ops[1])) {
465 if (TD && CE0->getOpcode() == CE1->getOpcode()) {
466 const Type *IntPtrTy = TD->getIntPtrType();
468 if (CE0->getOpcode() == Instruction::IntToPtr) {
469 // Convert the integer value to the right size to ensure we get the
470 // proper extension or truncation.
471 Constant *C0 = ConstantExpr::getIntegerCast(CE0->getOperand(0),
473 Constant *C1 = ConstantExpr::getIntegerCast(CE1->getOperand(0),
475 Constant *NewOps[] = { C0, C1 };
476 return ConstantFoldCompareInstOperands(Predicate, NewOps, 2, TD);
479 // Only do this transformation if the int is intptrty in size, otherwise
480 // there is a truncation or extension that we aren't modeling.
481 if ((CE0->getOpcode() == Instruction::PtrToInt &&
482 CE0->getType() == IntPtrTy &&
483 CE0->getOperand(0)->getType() == CE1->getOperand(0)->getType())) {
484 Constant *NewOps[] = {
485 CE0->getOperand(0), CE1->getOperand(0)
487 return ConstantFoldCompareInstOperands(Predicate, NewOps, 2, TD);
492 return ConstantExpr::getCompare(Predicate, Ops[0], Ops[1]);
496 /// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a
497 /// getelementptr constantexpr, return the constant value being addressed by the
498 /// constant expression, or null if something is funny and we can't decide.
499 Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
501 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
502 return 0; // Do not allow stepping over the value!
504 // Loop over all of the operands, tracking down which value we are
506 gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
507 for (++I; I != E; ++I)
508 if (const StructType *STy = dyn_cast<StructType>(*I)) {
509 ConstantInt *CU = cast<ConstantInt>(I.getOperand());
510 assert(CU->getZExtValue() < STy->getNumElements() &&
511 "Struct index out of range!");
512 unsigned El = (unsigned)CU->getZExtValue();
513 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
514 C = CS->getOperand(El);
515 } else if (isa<ConstantAggregateZero>(C)) {
516 C = Constant::getNullValue(STy->getElementType(El));
517 } else if (isa<UndefValue>(C)) {
518 C = UndefValue::get(STy->getElementType(El));
522 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
523 if (const ArrayType *ATy = dyn_cast<ArrayType>(*I)) {
524 if (CI->getZExtValue() >= ATy->getNumElements())
526 if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
527 C = CA->getOperand(CI->getZExtValue());
528 else if (isa<ConstantAggregateZero>(C))
529 C = Constant::getNullValue(ATy->getElementType());
530 else if (isa<UndefValue>(C))
531 C = UndefValue::get(ATy->getElementType());
534 } else if (const VectorType *PTy = dyn_cast<VectorType>(*I)) {
535 if (CI->getZExtValue() >= PTy->getNumElements())
537 if (ConstantVector *CP = dyn_cast<ConstantVector>(C))
538 C = CP->getOperand(CI->getZExtValue());
539 else if (isa<ConstantAggregateZero>(C))
540 C = Constant::getNullValue(PTy->getElementType());
541 else if (isa<UndefValue>(C))
542 C = UndefValue::get(PTy->getElementType());
555 //===----------------------------------------------------------------------===//
556 // Constant Folding for Calls
559 /// canConstantFoldCallTo - Return true if its even possible to fold a call to
560 /// the specified function.
562 llvm::canConstantFoldCallTo(const Function *F) {
563 switch (F->getIntrinsicID()) {
564 case Intrinsic::sqrt:
565 case Intrinsic::powi:
566 case Intrinsic::bswap:
567 case Intrinsic::ctpop:
568 case Intrinsic::ctlz:
569 case Intrinsic::cttz:
574 const ValueName *NameVal = F->getValueName();
575 if (NameVal == 0) return false;
576 const char *Str = NameVal->getKeyData();
577 unsigned Len = NameVal->getKeyLength();
579 // In these cases, the check of the length is required. We don't want to
580 // return true for a name like "cos\0blah" which strcmp would return equal to
581 // "cos", but has length 8.
583 default: return false;
586 return !strcmp(Str, "acos") || !strcmp(Str, "asin") ||
587 !strcmp(Str, "atan");
589 return !strcmp(Str, "atan2");
593 return !strcmp(Str, "cos");
595 return !strcmp(Str, "ceil") || !strcmp(Str, "cosf") ||
596 !strcmp(Str, "cosh");
600 return !strcmp(Str, "exp");
604 return !strcmp(Str, "fabs") || !strcmp(Str, "fmod");
606 return !strcmp(Str, "floor");
610 if (Len == 3 && !strcmp(Str, "log"))
612 if (Len == 5 && !strcmp(Str, "log10"))
616 if (Len == 3 && !strcmp(Str, "pow"))
621 return !strcmp(Str, "sin");
623 return !strcmp(Str, "sinh") || !strcmp(Str, "sqrt") ||
624 !strcmp(Str, "sinf");
626 return !strcmp(Str, "sqrtf");
629 if (Len == 3 && !strcmp(Str, "tan"))
631 else if (Len == 4 && !strcmp(Str, "tanh"))
637 static Constant *ConstantFoldFP(double (*NativeFP)(double), double V,
646 if (Ty == Type::FloatTy)
647 return ConstantFP::get(APFloat((float)V));
648 if (Ty == Type::DoubleTy)
649 return ConstantFP::get(APFloat(V));
650 assert(0 && "Can only constant fold float/double");
651 return 0; // dummy return to suppress warning
654 static Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double),
664 if (Ty == Type::FloatTy)
665 return ConstantFP::get(APFloat((float)V));
666 if (Ty == Type::DoubleTy)
667 return ConstantFP::get(APFloat(V));
668 assert(0 && "Can only constant fold float/double");
669 return 0; // dummy return to suppress warning
672 /// ConstantFoldCall - Attempt to constant fold a call to the specified function
673 /// with the specified arguments, returning null if unsuccessful.
676 llvm::ConstantFoldCall(Function *F,
677 Constant* const* Operands, unsigned NumOperands) {
678 const ValueName *NameVal = F->getValueName();
679 if (NameVal == 0) return 0;
680 const char *Str = NameVal->getKeyData();
681 unsigned Len = NameVal->getKeyLength();
683 const Type *Ty = F->getReturnType();
684 if (NumOperands == 1) {
685 if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) {
686 if (Ty!=Type::FloatTy && Ty!=Type::DoubleTy)
688 /// Currently APFloat versions of these functions do not exist, so we use
689 /// the host native double versions. Float versions are not called
690 /// directly but for all these it is true (float)(f((double)arg)) ==
691 /// f(arg). Long double not supported yet.
692 double V = Ty==Type::FloatTy ? (double)Op->getValueAPF().convertToFloat():
693 Op->getValueAPF().convertToDouble();
696 if (Len == 4 && !strcmp(Str, "acos"))
697 return ConstantFoldFP(acos, V, Ty);
698 else if (Len == 4 && !strcmp(Str, "asin"))
699 return ConstantFoldFP(asin, V, Ty);
700 else if (Len == 4 && !strcmp(Str, "atan"))
701 return ConstantFoldFP(atan, V, Ty);
704 if (Len == 4 && !strcmp(Str, "ceil"))
705 return ConstantFoldFP(ceil, V, Ty);
706 else if (Len == 3 && !strcmp(Str, "cos"))
707 return ConstantFoldFP(cos, V, Ty);
708 else if (Len == 4 && !strcmp(Str, "cosh"))
709 return ConstantFoldFP(cosh, V, Ty);
710 else if (Len == 4 && !strcmp(Str, "cosf"))
711 return ConstantFoldFP(cos, V, Ty);
714 if (Len == 3 && !strcmp(Str, "exp"))
715 return ConstantFoldFP(exp, V, Ty);
718 if (Len == 4 && !strcmp(Str, "fabs"))
719 return ConstantFoldFP(fabs, V, Ty);
720 else if (Len == 5 && !strcmp(Str, "floor"))
721 return ConstantFoldFP(floor, V, Ty);
724 if (Len == 3 && !strcmp(Str, "log") && V > 0)
725 return ConstantFoldFP(log, V, Ty);
726 else if (Len == 5 && !strcmp(Str, "log10") && V > 0)
727 return ConstantFoldFP(log10, V, Ty);
728 else if (!strcmp(Str, "llvm.sqrt.f32") ||
729 !strcmp(Str, "llvm.sqrt.f64")) {
731 return ConstantFoldFP(sqrt, V, Ty);
733 return Constant::getNullValue(Ty);
737 if (Len == 3 && !strcmp(Str, "sin"))
738 return ConstantFoldFP(sin, V, Ty);
739 else if (Len == 4 && !strcmp(Str, "sinh"))
740 return ConstantFoldFP(sinh, V, Ty);
741 else if (Len == 4 && !strcmp(Str, "sqrt") && V >= 0)
742 return ConstantFoldFP(sqrt, V, Ty);
743 else if (Len == 5 && !strcmp(Str, "sqrtf") && V >= 0)
744 return ConstantFoldFP(sqrt, V, Ty);
745 else if (Len == 4 && !strcmp(Str, "sinf"))
746 return ConstantFoldFP(sin, V, Ty);
749 if (Len == 3 && !strcmp(Str, "tan"))
750 return ConstantFoldFP(tan, V, Ty);
751 else if (Len == 4 && !strcmp(Str, "tanh"))
752 return ConstantFoldFP(tanh, V, Ty);
757 } else if (ConstantInt *Op = dyn_cast<ConstantInt>(Operands[0])) {
758 if (Len > 11 && !memcmp(Str, "llvm.bswap", 10))
759 return ConstantInt::get(Op->getValue().byteSwap());
760 else if (Len > 11 && !memcmp(Str, "llvm.ctpop", 10))
761 return ConstantInt::get(Ty, Op->getValue().countPopulation());
762 else if (Len > 10 && !memcmp(Str, "llvm.cttz", 9))
763 return ConstantInt::get(Ty, Op->getValue().countTrailingZeros());
764 else if (Len > 10 && !memcmp(Str, "llvm.ctlz", 9))
765 return ConstantInt::get(Ty, Op->getValue().countLeadingZeros());
767 } else if (NumOperands == 2) {
768 if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
769 if (Ty!=Type::FloatTy && Ty!=Type::DoubleTy)
771 double Op1V = Ty==Type::FloatTy ?
772 (double)Op1->getValueAPF().convertToFloat():
773 Op1->getValueAPF().convertToDouble();
774 if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
775 double Op2V = Ty==Type::FloatTy ?
776 (double)Op2->getValueAPF().convertToFloat():
777 Op2->getValueAPF().convertToDouble();
779 if (Len == 3 && !strcmp(Str, "pow")) {
780 return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
781 } else if (Len == 4 && !strcmp(Str, "fmod")) {
782 return ConstantFoldBinaryFP(fmod, Op1V, Op2V, Ty);
783 } else if (Len == 5 && !strcmp(Str, "atan2")) {
784 return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty);
786 } else if (ConstantInt *Op2C = dyn_cast<ConstantInt>(Operands[1])) {
787 if (!strcmp(Str, "llvm.powi.f32")) {
788 return ConstantFP::get(APFloat((float)std::pow((float)Op1V,
789 (int)Op2C->getZExtValue())));
790 } else if (!strcmp(Str, "llvm.powi.f64")) {
791 return ConstantFP::get(APFloat((double)std::pow((double)Op1V,
792 (int)Op2C->getZExtValue())));