1 //===- llvm/Analysis/TargetTransformInfo.cpp ------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #define DEBUG_TYPE "tti"
11 #include "llvm/Analysis/TargetTransformInfo.h"
12 #include "llvm/IR/CallSite.h"
13 #include "llvm/IR/DataLayout.h"
14 #include "llvm/IR/Instruction.h"
15 #include "llvm/IR/Instructions.h"
16 #include "llvm/IR/IntrinsicInst.h"
17 #include "llvm/IR/Operator.h"
18 #include "llvm/Support/ErrorHandling.h"
19 
20 using namespace llvm;
21 
22 // Setup the analysis group to manage the TargetTransformInfo passes.
23 INITIALIZE_ANALYSIS_GROUP(TargetTransformInfo, "Target Information", NoTTI)
24 char TargetTransformInfo::ID = 0;
25 
26 TargetTransformInfo::~TargetTransformInfo() {
27 }
28 
29 void TargetTransformInfo::pushTTIStack(Pass *P) {
30   TopTTI = this;
31   PrevTTI = &P->getAnalysis<TargetTransformInfo>();
32 
33   // Walk up the chain and update the top TTI pointer.
34   for (TargetTransformInfo *PTTI = PrevTTI; PTTI; PTTI = PTTI->PrevTTI)
35     PTTI->TopTTI = this;
36 }
37 
38 void TargetTransformInfo::getAnalysisUsage(AnalysisUsage &AU) const {
39   AU.addRequired<TargetTransformInfo>();
40 }
41 
42 unsigned TargetTransformInfo::getOperationCost(unsigned Opcode, Type *Ty,
43                                                Type *OpTy) const {
44   return PrevTTI->getOperationCost(Opcode, Ty, OpTy);
45 }
46 
47 unsigned TargetTransformInfo::getGEPCost(
48     const Value *Ptr, ArrayRef<const Value *> Operands) const {
49   return PrevTTI->getGEPCost(Ptr, Operands);
50 }
51 
52 unsigned TargetTransformInfo::getCallCost(FunctionType *FTy,
53                                           int NumArgs) const {
54   return PrevTTI->getCallCost(FTy, NumArgs);
55 }
56 
57 unsigned TargetTransformInfo::getCallCost(const Function *F,
58                                           int NumArgs) const {
59   return PrevTTI->getCallCost(F, NumArgs);
60 }
61 
62 unsigned TargetTransformInfo::getCallCost(
63     const Function *F, ArrayRef<const Value *> Arguments) const {
64   return PrevTTI->getCallCost(F, Arguments);
65 }
66 
67 unsigned TargetTransformInfo::getIntrinsicCost(
68     Intrinsic::ID IID, Type *RetTy, ArrayRef<Type *> ParamTys) const {
69   return PrevTTI->getIntrinsicCost(IID, RetTy, ParamTys);
70 }
71 
72 unsigned TargetTransformInfo::getIntrinsicCost(
73     Intrinsic::ID IID, Type *RetTy, ArrayRef<const Value *> Arguments) const {
74   return PrevTTI->getIntrinsicCost(IID, RetTy, Arguments);
75 }
76 
77 unsigned TargetTransformInfo::getUserCost(const User *U) const {
78   return PrevTTI->getUserCost(U);
79 }
80 
81 bool TargetTransformInfo::hasBranchDivergence() const {
82   return PrevTTI->hasBranchDivergence();
83 }
84 
85 bool TargetTransformInfo::isLoweredToCall(const Function *F) const {
86   return PrevTTI->isLoweredToCall(F);
87 }
88 
89 void TargetTransformInfo::getUnrollingPreferences(Loop *L,
90                             UnrollingPreferences &UP) const {
91   PrevTTI->getUnrollingPreferences(L, UP);
92 }
93 
94 bool TargetTransformInfo::isLegalAddImmediate(int64_t Imm) const {
95   return PrevTTI->isLegalAddImmediate(Imm);
96 }
97 
98 bool TargetTransformInfo::isLegalICmpImmediate(int64_t Imm) const {
99   return PrevTTI->isLegalICmpImmediate(Imm);
100 }
101 
102 bool TargetTransformInfo::isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV,
103                                                 int64_t BaseOffset,
104                                                 bool HasBaseReg,
105                                                 int64_t Scale) const {
106   return PrevTTI->isLegalAddressingMode(Ty, BaseGV, BaseOffset, HasBaseReg,
107                                         Scale);
108 }
109 
110 int TargetTransformInfo::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
111                                               int64_t BaseOffset,
112                                               bool HasBaseReg,
113                                               int64_t Scale) const {
114   return PrevTTI->getScalingFactorCost(Ty, BaseGV, BaseOffset, HasBaseReg,
115                                        Scale);
116 }
117 
118 bool TargetTransformInfo::isTruncateFree(Type *Ty1, Type *Ty2) const {
119   return PrevTTI->isTruncateFree(Ty1, Ty2);
120 }
121 
122 bool TargetTransformInfo::isTypeLegal(Type *Ty) const {
123   return PrevTTI->isTypeLegal(Ty);
124 }
125 
126 unsigned TargetTransformInfo::getJumpBufAlignment() const {
127   return PrevTTI->getJumpBufAlignment();
128 }
129 
130 unsigned TargetTransformInfo::getJumpBufSize() const {
131   return PrevTTI->getJumpBufSize();
132 }
133 
134 bool TargetTransformInfo::shouldBuildLookupTables() const {
135   return PrevTTI->shouldBuildLookupTables();
136 }
137 
138 TargetTransformInfo::PopcntSupportKind
139 TargetTransformInfo::getPopcntSupport(unsigned IntTyWidthInBit) const {
140   return PrevTTI->getPopcntSupport(IntTyWidthInBit);
141 }
142 
143 bool TargetTransformInfo::haveFastSqrt(Type *Ty) const {
144   return PrevTTI->haveFastSqrt(Ty);
145 }
146 
147 unsigned TargetTransformInfo::getIntImmCost(const APInt &Imm, Type *Ty) const {
148   return PrevTTI->getIntImmCost(Imm, Ty);
149 }
150 
151 unsigned TargetTransformInfo::getIntImmCost(unsigned Opcode, const APInt &Imm,
152                                             Type *Ty) const {
153   return PrevTTI->getIntImmCost(Opcode, Imm, Ty);
154 }
155 
156 unsigned TargetTransformInfo::getIntImmCost(Intrinsic::ID IID, const APInt &Imm,
157                                             Type *Ty) const {
158   return PrevTTI->getIntImmCost(IID, Imm, Ty);
159 }
160 
161 unsigned TargetTransformInfo::getNumberOfRegisters(bool Vector) const {
162   return PrevTTI->getNumberOfRegisters(Vector);
163 }
164 
165 unsigned TargetTransformInfo::getRegisterBitWidth(bool Vector) const {
166   return PrevTTI->getRegisterBitWidth(Vector);
167 }
168 
169 unsigned TargetTransformInfo::getMaximumUnrollFactor() const {
170   return PrevTTI->getMaximumUnrollFactor();
171 }
172 
173 unsigned TargetTransformInfo::getArithmeticInstrCost(unsigned Opcode,
174                                                 Type *Ty,
175                                                 OperandValueKind Op1Info,
176                                                 OperandValueKind Op2Info) const {
177   return PrevTTI->getArithmeticInstrCost(Opcode, Ty, Op1Info, Op2Info);
178 }
179 
180 unsigned TargetTransformInfo::getShuffleCost(ShuffleKind Kind, Type *Tp,
181                                              int Index, Type *SubTp) const {
182   return PrevTTI->getShuffleCost(Kind, Tp, Index, SubTp);
183 }
184 
185 unsigned TargetTransformInfo::getCastInstrCost(unsigned Opcode, Type *Dst,
186                                                Type *Src) const {
187   return PrevTTI->getCastInstrCost(Opcode, Dst, Src);
188 }
189 
190 unsigned TargetTransformInfo::getCFInstrCost(unsigned Opcode) const {
191   return PrevTTI->getCFInstrCost(Opcode);
192 }
193 
194 unsigned TargetTransformInfo::getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
195                                                  Type *CondTy) const {
196   return PrevTTI->getCmpSelInstrCost(Opcode, ValTy, CondTy);
197 }
198 
199 unsigned TargetTransformInfo::getVectorInstrCost(unsigned Opcode, Type *Val,
200                                                  unsigned Index) const {
201   return PrevTTI->getVectorInstrCost(Opcode, Val, Index);
202 }
203 
204 unsigned TargetTransformInfo::getMemoryOpCost(unsigned Opcode, Type *Src,
205                                               unsigned Alignment,
206                                               unsigned AddressSpace) const {
207   return PrevTTI->getMemoryOpCost(Opcode, Src, Alignment, AddressSpace);
208   ;
209 }
210 
211 unsigned
212 TargetTransformInfo::getIntrinsicInstrCost(Intrinsic::ID ID,
213                                            Type *RetTy,
214                                            ArrayRef<Type *> Tys) const {
215   return PrevTTI->getIntrinsicInstrCost(ID, RetTy, Tys);
216 }
217 
218 unsigned TargetTransformInfo::getNumberOfParts(Type *Tp) const {
219   return PrevTTI->getNumberOfParts(Tp);
220 }
221 
222 unsigned TargetTransformInfo::getAddressComputationCost(Type *Tp,
223                                                         bool IsComplex) const {
224   return PrevTTI->getAddressComputationCost(Tp, IsComplex);
225 }
226 
227 unsigned TargetTransformInfo::getReductionCost(unsigned Opcode, Type *Ty,
228                                                bool IsPairwise) const {
229   return PrevTTI->getReductionCost(Opcode, Ty, IsPairwise);
230 }
231 
232 namespace {
233 
234 struct NoTTI final : ImmutablePass, TargetTransformInfo {
235   const DataLayout *DL;
236 
237   NoTTI() : ImmutablePass(ID), DL(0) {
238     initializeNoTTIPass(*PassRegistry::getPassRegistry());
239   }
240 
241   virtual void initializePass() override {
242     // Note that this subclass is special, and must *not* call initializeTTI as
243     // it does not chain.
244     TopTTI = this;
245     PrevTTI = 0;
246     DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
247     DL = DLP ? &DLP->getDataLayout() : 0;
248   }
249 
250   virtual void getAnalysisUsage(AnalysisUsage &AU) const override {
251     // Note that this subclass is special, and must *not* call
252     // TTI::getAnalysisUsage as it breaks the recursion.
253   }
254 
255   /// Pass identification.
256   static char ID;
257 
258   /// Provide necessary pointer adjustments for the two base classes.
259   virtual void *getAdjustedAnalysisPointer(const void *ID) override {
260     if (ID == &TargetTransformInfo::ID)
261       return (TargetTransformInfo*)this;
262     return this;
263   }
264 
265   unsigned getOperationCost(unsigned Opcode, Type *Ty,
266                             Type *OpTy) const override {
267     switch (Opcode) {
268     default:
269       // By default, just classify everything as 'basic'.
270       return TCC_Basic;
271 
272     case Instruction::GetElementPtr:
273       llvm_unreachable("Use getGEPCost for GEP operations!");
274 
275     case Instruction::BitCast:
276       assert(OpTy && "Cast instructions must provide the operand type");
277       if (Ty == OpTy || (Ty->isPointerTy() && OpTy->isPointerTy()))
278         // Identity and pointer-to-pointer casts are free.
279         return TCC_Free;
280 
281       // Otherwise, the default basic cost is used.
282       return TCC_Basic;
283 
284     case Instruction::IntToPtr: {
285       if (!DL)
286         return TCC_Basic;
287 
288       // An inttoptr cast is free so long as the input is a legal integer type
289       // which doesn't contain values outside the range of a pointer.
290       unsigned OpSize = OpTy->getScalarSizeInBits();
291       if (DL->isLegalInteger(OpSize) &&
292           OpSize <= DL->getPointerTypeSizeInBits(Ty))
293         return TCC_Free;
294 
295       // Otherwise it's not a no-op.
296       return TCC_Basic;
297     }
298     case Instruction::PtrToInt: {
299       if (!DL)
300         return TCC_Basic;
301 
302       // A ptrtoint cast is free so long as the result is large enough to store
303       // the pointer, and a legal integer type.
304       unsigned DestSize = Ty->getScalarSizeInBits();
305       if (DL->isLegalInteger(DestSize) &&
306           DestSize >= DL->getPointerTypeSizeInBits(OpTy))
307         return TCC_Free;
308 
309       // Otherwise it's not a no-op.
310       return TCC_Basic;
311     }
312     case Instruction::Trunc:
313       // trunc to a native type is free (assuming the target has compare and
314       // shift-right of the same width).
315       if (DL && DL->isLegalInteger(DL->getTypeSizeInBits(Ty)))
316         return TCC_Free;
317 
318       return TCC_Basic;
319     }
320   }
321 
322   unsigned getGEPCost(const Value *Ptr,
323                       ArrayRef<const Value *> Operands) const override {
324     // In the basic model, we just assume that all-constant GEPs will be folded
325     // into their uses via addressing modes.
326     for (unsigned Idx = 0, Size = Operands.size(); Idx != Size; ++Idx)
327       if (!isa<Constant>(Operands[Idx]))
328         return TCC_Basic;
329 
330     return TCC_Free;
331   }
332 
333   unsigned getCallCost(FunctionType *FTy, int NumArgs = -1) const override
334   {
335     assert(FTy && "FunctionType must be provided to this routine.");
336 
337     // The target-independent implementation just measures the size of the
338     // function by approximating that each argument will take on average one
339     // instruction to prepare.
340 
341     if (NumArgs < 0)
342       // Set the argument number to the number of explicit arguments in the
343       // function.
344       NumArgs = FTy->getNumParams();
345 
346     return TCC_Basic * (NumArgs + 1);
347   }
348 
349   unsigned getCallCost(const Function *F, int NumArgs = -1) const override
350   {
351     assert(F && "A concrete function must be provided to this routine.");
352 
353     if (NumArgs < 0)
354       // Set the argument number to the number of explicit arguments in the
355       // function.
356       NumArgs = F->arg_size();
357 
358     if (Intrinsic::ID IID = (Intrinsic::ID)F->getIntrinsicID()) {
359       FunctionType *FTy = F->getFunctionType();
360       SmallVector<Type *, 8> ParamTys(FTy->param_begin(), FTy->param_end());
361       return TopTTI->getIntrinsicCost(IID, FTy->getReturnType(), ParamTys);
362     }
363 
364     if (!TopTTI->isLoweredToCall(F))
365       return TCC_Basic; // Give a basic cost if it will be lowered directly.
366 
367     return TopTTI->getCallCost(F->getFunctionType(), NumArgs);
368   }
369 
370   unsigned getCallCost(const Function *F,
371                        ArrayRef<const Value *> Arguments) const override {
372     // Simply delegate to generic handling of the call.
373     // FIXME: We should use instsimplify or something else to catch calls which
374     // will constant fold with these arguments.
375     return TopTTI->getCallCost(F, Arguments.size());
376   }
377 
378   unsigned getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
379                             ArrayRef<Type *> ParamTys) const override {
380     switch (IID) {
381     default:
382       // Intrinsics rarely (if ever) have normal argument setup constraints.
383       // Model them as having a basic instruction cost.
384       // FIXME: This is wrong for libc intrinsics.
385       return TCC_Basic;
386 
387     case Intrinsic::dbg_declare:
388     case Intrinsic::dbg_value:
389     case Intrinsic::invariant_start:
390     case Intrinsic::invariant_end:
391     case Intrinsic::lifetime_start:
392     case Intrinsic::lifetime_end:
393     case Intrinsic::objectsize:
394     case Intrinsic::ptr_annotation:
395     case Intrinsic::var_annotation:
396       // These intrinsics don't actually represent code after lowering.
397       return TCC_Free;
398     }
399   }
400 
401   unsigned
402   getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
403                    ArrayRef<const Value *> Arguments) const override {
404     // Delegate to the generic intrinsic handling code. This mostly provides an
405     // opportunity for targets to (for example) special case the cost of
406     // certain intrinsics based on constants used as arguments.
407     SmallVector<Type *, 8> ParamTys;
408     ParamTys.reserve(Arguments.size());
409     for (unsigned Idx = 0, Size = Arguments.size(); Idx != Size; ++Idx)
410       ParamTys.push_back(Arguments[Idx]->getType());
411     return TopTTI->getIntrinsicCost(IID, RetTy, ParamTys);
412   }
413 
414   unsigned getUserCost(const User *U) const override {
415     if (isa<PHINode>(U))
416       return TCC_Free; // Model all PHI nodes as free.
417 
418     if (const GEPOperator *GEP = dyn_cast<GEPOperator>(U))
419       // In the basic model we just assume that all-constant GEPs will be
420       // folded into their uses via addressing modes.
421       return GEP->hasAllConstantIndices() ? TCC_Free : TCC_Basic;
422 
423     if (ImmutableCallSite CS = U) {
424       const Function *F = CS.getCalledFunction();
425       if (!F) {
426         // Just use the called value type.
427         Type *FTy = CS.getCalledValue()->getType()->getPointerElementType();
428         return TopTTI->getCallCost(cast<FunctionType>(FTy), CS.arg_size());
429       }
430 
431       SmallVector<const Value *, 8> Arguments(CS.arg_begin(), CS.arg_end());
432       return TopTTI->getCallCost(F, Arguments);
433     }
434 
435     if (const CastInst *CI = dyn_cast<CastInst>(U)) {
436       // Result of a cmp instruction is often extended (to be used by other
437       // cmp instructions, logical or return instructions). These are usually
438       // nop on most sane targets.
439       if (isa<CmpInst>(CI->getOperand(0)))
440         return TCC_Free;
441     }
442 
443     // Otherwise delegate to the fully generic implementations.
444     return getOperationCost(Operator::getOpcode(U), U->getType(),
445                             U->getNumOperands() == 1 ?
446                                 U->getOperand(0)->getType() : 0);
447   }
448 
449   bool hasBranchDivergence() const override { return false; }
450 
451   bool isLoweredToCall(const Function *F) const override {
452     // FIXME: These should almost certainly not be handled here, and instead
453     // handled with the help of TLI or the target itself. This was largely
454     // ported from existing analysis heuristics here so that such refactorings
455     // can take place in the future.
456 
457     if (F->isIntrinsic())
458       return false;
459 
460     if (F->hasLocalLinkage() || !F->hasName())
461       return true;
462 
463     StringRef Name = F->getName();
464 
465     // These will all likely lower to a single selection DAG node.
466     if (Name == "copysign" || Name == "copysignf" || Name == "copysignl" ||
467         Name == "fabs" || Name == "fabsf" || Name == "fabsl" || Name == "sin" ||
468         Name == "sinf" || Name == "sinl" || Name == "cos" || Name == "cosf" ||
469         Name == "cosl" || Name == "sqrt" || Name == "sqrtf" || Name == "sqrtl")
470       return false;
471 
472     // These are all likely to be optimized into something smaller.
473     if (Name == "pow" || Name == "powf" || Name == "powl" || Name == "exp2" ||
474         Name == "exp2l" || Name == "exp2f" || Name == "floor" || Name ==
475         "floorf" || Name == "ceil" || Name == "round" || Name == "ffs" ||
476         Name == "ffsl" || Name == "abs" || Name == "labs" || Name == "llabs")
477       return false;
478 
479     return true;
480   }
481 
482   void getUnrollingPreferences(Loop *, UnrollingPreferences &) const override {
483   }
484 
485   bool isLegalAddImmediate(int64_t Imm) const override {
486     return false;
487   }
488 
489   bool isLegalICmpImmediate(int64_t Imm) const override {
490     return false;
491   }
492 
493   bool isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset,
494                              bool HasBaseReg, int64_t Scale) const override
495   {
496     // Guess that reg+reg addressing is allowed. This heuristic is taken from
497     // the implementation of LSR.
498     return !BaseGV && BaseOffset == 0 && Scale <= 1;
499   }
500 
501   int getScalingFactorCost(Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset,
502                            bool HasBaseReg, int64_t Scale) const override {
503     // Guess that all legal addressing mode are free.
504     if(isLegalAddressingMode(Ty, BaseGV, BaseOffset, HasBaseReg, Scale))
505       return 0;
506     return -1;
507   }
508 
509   bool isTruncateFree(Type *Ty1, Type *Ty2) const override {
510     return false;
511   }
512 
513   bool isTypeLegal(Type *Ty) const override {
514     return false;
515   }
516 
517   unsigned getJumpBufAlignment() const override {
518     return 0;
519   }
520 
521   unsigned getJumpBufSize() const override {
522     return 0;
523   }
524 
525   bool shouldBuildLookupTables() const override {
526     return true;
527   }
528 
529   PopcntSupportKind
530   getPopcntSupport(unsigned IntTyWidthInBit) const override {
531     return PSK_Software;
532   }
533 
534   bool haveFastSqrt(Type *Ty) const override {
535     return false;
536   }
537 
538   unsigned getIntImmCost(const APInt &Imm, Type *Ty) const override {
539     return TCC_Basic;
540   }
541 
542   unsigned getIntImmCost(unsigned Opcode, const APInt &Imm,
543                          Type *Ty) const override {
544     return TCC_Free;
545   }
546 
547   unsigned getIntImmCost(Intrinsic::ID IID, const APInt &Imm,
548                          Type *Ty) const override {
549     return TCC_Free;
550   }
551 
552   unsigned getNumberOfRegisters(bool Vector) const override {
553     return 8;
554   }
555 
556   unsigned  getRegisterBitWidth(bool Vector) const override {
557     return 32;
558   }
559 
560   unsigned getMaximumUnrollFactor() const override {
561     return 1;
562   }
563 
564   unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty, OperandValueKind,
565                                   OperandValueKind) const override {
566     return 1;
567   }
568 
569   unsigned getShuffleCost(ShuffleKind Kind, Type *Ty,
570                           int Index = 0, Type *SubTp = 0) const override {
571     return 1;
572   }
573 
574   unsigned getCastInstrCost(unsigned Opcode, Type *Dst,
575                             Type *Src) const override {
576     return 1;
577   }
578 
579   unsigned getCFInstrCost(unsigned Opcode) const override {
580     return 1;
581   }
582 
583   unsigned getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
584                               Type *CondTy = 0) const override {
585     return 1;
586   }
587 
588   unsigned getVectorInstrCost(unsigned Opcode, Type *Val,
589                               unsigned Index = -1) const override {
590     return 1;
591   }
592 
593   unsigned getMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
594                            unsigned AddressSpace) const override {
595     return 1;
596   }
597 
598   unsigned getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy,
599                                  ArrayRef<Type*> Tys) const override {
600     return 1;
601   }
602 
603   unsigned getNumberOfParts(Type *Tp) const override {
604     return 0;
605   }
606 
607   unsigned getAddressComputationCost(Type *Tp, bool) const override {
608     return 0;
609   }
610 
611   unsigned getReductionCost(unsigned, Type *, bool) const override {
612     return 1;
613   }
614 };
615 
616 } // end anonymous namespace
617 
618 INITIALIZE_AG_PASS(NoTTI, TargetTransformInfo, "notti",
619                    "No target information", true, true, true)
620 char NoTTI::ID = 0;
621 
622 ImmutablePass *llvm::createNoTargetTransformInfoPass() {
623   return new NoTTI();
624 }
625