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      1 //===- TargetTransformInfoImpl.h --------------------------------*- C++ -*-===//
      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 /// \file
     10 /// This file provides helpers for the implementation of
     11 /// a TargetTransformInfo-conforming class.
     12 ///
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_ANALYSIS_TARGETTRANSFORMINFOIMPL_H
     16 #define LLVM_ANALYSIS_TARGETTRANSFORMINFOIMPL_H
     17 
     18 #include "llvm/Analysis/TargetTransformInfo.h"
     19 #include "llvm/IR/CallSite.h"
     20 #include "llvm/IR/DataLayout.h"
     21 #include "llvm/IR/Function.h"
     22 #include "llvm/IR/Operator.h"
     23 #include "llvm/IR/Type.h"
     24 
     25 namespace llvm {
     26 
     27 /// \brief Base class for use as a mix-in that aids implementing
     28 /// a TargetTransformInfo-compatible class.
     29 class TargetTransformInfoImplBase {
     30 protected:
     31   typedef TargetTransformInfo TTI;
     32 
     33   const DataLayout *DL;
     34 
     35   explicit TargetTransformInfoImplBase(const DataLayout *DL)
     36       : DL(DL) {}
     37 
     38 public:
     39   // Provide value semantics. MSVC requires that we spell all of these out.
     40   TargetTransformInfoImplBase(const TargetTransformInfoImplBase &Arg)
     41       : DL(Arg.DL) {}
     42   TargetTransformInfoImplBase(TargetTransformInfoImplBase &&Arg)
     43       : DL(std::move(Arg.DL)) {}
     44   TargetTransformInfoImplBase &
     45   operator=(const TargetTransformInfoImplBase &RHS) {
     46     DL = RHS.DL;
     47     return *this;
     48   }
     49   TargetTransformInfoImplBase &operator=(TargetTransformInfoImplBase &&RHS) {
     50     DL = std::move(RHS.DL);
     51     return *this;
     52   }
     53 
     54   unsigned getOperationCost(unsigned Opcode, Type *Ty, Type *OpTy) {
     55     switch (Opcode) {
     56     default:
     57       // By default, just classify everything as 'basic'.
     58       return TTI::TCC_Basic;
     59 
     60     case Instruction::GetElementPtr:
     61       llvm_unreachable("Use getGEPCost for GEP operations!");
     62 
     63     case Instruction::BitCast:
     64       assert(OpTy && "Cast instructions must provide the operand type");
     65       if (Ty == OpTy || (Ty->isPointerTy() && OpTy->isPointerTy()))
     66         // Identity and pointer-to-pointer casts are free.
     67         return TTI::TCC_Free;
     68 
     69       // Otherwise, the default basic cost is used.
     70       return TTI::TCC_Basic;
     71 
     72     case Instruction::IntToPtr: {
     73       if (!DL)
     74         return TTI::TCC_Basic;
     75 
     76       // An inttoptr cast is free so long as the input is a legal integer type
     77       // which doesn't contain values outside the range of a pointer.
     78       unsigned OpSize = OpTy->getScalarSizeInBits();
     79       if (DL->isLegalInteger(OpSize) &&
     80           OpSize <= DL->getPointerTypeSizeInBits(Ty))
     81         return TTI::TCC_Free;
     82 
     83       // Otherwise it's not a no-op.
     84       return TTI::TCC_Basic;
     85     }
     86     case Instruction::PtrToInt: {
     87       if (!DL)
     88         return TTI::TCC_Basic;
     89 
     90       // A ptrtoint cast is free so long as the result is large enough to store
     91       // the pointer, and a legal integer type.
     92       unsigned DestSize = Ty->getScalarSizeInBits();
     93       if (DL->isLegalInteger(DestSize) &&
     94           DestSize >= DL->getPointerTypeSizeInBits(OpTy))
     95         return TTI::TCC_Free;
     96 
     97       // Otherwise it's not a no-op.
     98       return TTI::TCC_Basic;
     99     }
    100     case Instruction::Trunc:
    101       // trunc to a native type is free (assuming the target has compare and
    102       // shift-right of the same width).
    103       if (DL && DL->isLegalInteger(DL->getTypeSizeInBits(Ty)))
    104         return TTI::TCC_Free;
    105 
    106       return TTI::TCC_Basic;
    107     }
    108   }
    109 
    110   unsigned getGEPCost(const Value *Ptr, ArrayRef<const Value *> Operands) {
    111     // In the basic model, we just assume that all-constant GEPs will be folded
    112     // into their uses via addressing modes.
    113     for (unsigned Idx = 0, Size = Operands.size(); Idx != Size; ++Idx)
    114       if (!isa<Constant>(Operands[Idx]))
    115         return TTI::TCC_Basic;
    116 
    117     return TTI::TCC_Free;
    118   }
    119 
    120   unsigned getCallCost(FunctionType *FTy, int NumArgs) {
    121     assert(FTy && "FunctionType must be provided to this routine.");
    122 
    123     // The target-independent implementation just measures the size of the
    124     // function by approximating that each argument will take on average one
    125     // instruction to prepare.
    126 
    127     if (NumArgs < 0)
    128       // Set the argument number to the number of explicit arguments in the
    129       // function.
    130       NumArgs = FTy->getNumParams();
    131 
    132     return TTI::TCC_Basic * (NumArgs + 1);
    133   }
    134 
    135   unsigned getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
    136                             ArrayRef<Type *> ParamTys) {
    137     switch (IID) {
    138     default:
    139       // Intrinsics rarely (if ever) have normal argument setup constraints.
    140       // Model them as having a basic instruction cost.
    141       // FIXME: This is wrong for libc intrinsics.
    142       return TTI::TCC_Basic;
    143 
    144     case Intrinsic::annotation:
    145     case Intrinsic::assume:
    146     case Intrinsic::dbg_declare:
    147     case Intrinsic::dbg_value:
    148     case Intrinsic::invariant_start:
    149     case Intrinsic::invariant_end:
    150     case Intrinsic::lifetime_start:
    151     case Intrinsic::lifetime_end:
    152     case Intrinsic::objectsize:
    153     case Intrinsic::ptr_annotation:
    154     case Intrinsic::var_annotation:
    155     case Intrinsic::experimental_gc_result_int:
    156     case Intrinsic::experimental_gc_result_float:
    157     case Intrinsic::experimental_gc_result_ptr:
    158     case Intrinsic::experimental_gc_result:
    159     case Intrinsic::experimental_gc_relocate:
    160       // These intrinsics don't actually represent code after lowering.
    161       return TTI::TCC_Free;
    162     }
    163   }
    164 
    165   bool hasBranchDivergence() { return false; }
    166 
    167   bool isSourceOfDivergence(const Value *V) { return false; }
    168 
    169   bool isLoweredToCall(const Function *F) {
    170     // FIXME: These should almost certainly not be handled here, and instead
    171     // handled with the help of TLI or the target itself. This was largely
    172     // ported from existing analysis heuristics here so that such refactorings
    173     // can take place in the future.
    174 
    175     if (F->isIntrinsic())
    176       return false;
    177 
    178     if (F->hasLocalLinkage() || !F->hasName())
    179       return true;
    180 
    181     StringRef Name = F->getName();
    182 
    183     // These will all likely lower to a single selection DAG node.
    184     if (Name == "copysign" || Name == "copysignf" || Name == "copysignl" ||
    185         Name == "fabs" || Name == "fabsf" || Name == "fabsl" || Name == "sin" ||
    186         Name == "fmin" || Name == "fminf" || Name == "fminl" ||
    187         Name == "fmax" || Name == "fmaxf" || Name == "fmaxl" ||
    188         Name == "sinf" || Name == "sinl" || Name == "cos" || Name == "cosf" ||
    189         Name == "cosl" || Name == "sqrt" || Name == "sqrtf" || Name == "sqrtl")
    190       return false;
    191 
    192     // These are all likely to be optimized into something smaller.
    193     if (Name == "pow" || Name == "powf" || Name == "powl" || Name == "exp2" ||
    194         Name == "exp2l" || Name == "exp2f" || Name == "floor" ||
    195         Name == "floorf" || Name == "ceil" || Name == "round" ||
    196         Name == "ffs" || Name == "ffsl" || Name == "abs" || Name == "labs" ||
    197         Name == "llabs")
    198       return false;
    199 
    200     return true;
    201   }
    202 
    203   void getUnrollingPreferences(Loop *, TTI::UnrollingPreferences &) {}
    204 
    205   bool isLegalAddImmediate(int64_t Imm) { return false; }
    206 
    207   bool isLegalICmpImmediate(int64_t Imm) { return false; }
    208 
    209   bool isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset,
    210                              bool HasBaseReg, int64_t Scale) {
    211     // Guess that reg+reg addressing is allowed. This heuristic is taken from
    212     // the implementation of LSR.
    213     return !BaseGV && BaseOffset == 0 && Scale <= 1;
    214   }
    215 
    216   bool isLegalMaskedStore(Type *DataType, int Consecutive) { return false; }
    217 
    218   bool isLegalMaskedLoad(Type *DataType, int Consecutive) { return false; }
    219 
    220   int getScalingFactorCost(Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset,
    221                            bool HasBaseReg, int64_t Scale) {
    222     // Guess that all legal addressing mode are free.
    223     if (isLegalAddressingMode(Ty, BaseGV, BaseOffset, HasBaseReg, Scale))
    224       return 0;
    225     return -1;
    226   }
    227 
    228   bool isTruncateFree(Type *Ty1, Type *Ty2) { return false; }
    229 
    230   bool isProfitableToHoist(Instruction *I) { return true; }
    231 
    232   bool isTypeLegal(Type *Ty) { return false; }
    233 
    234   unsigned getJumpBufAlignment() { return 0; }
    235 
    236   unsigned getJumpBufSize() { return 0; }
    237 
    238   bool shouldBuildLookupTables() { return true; }
    239 
    240   bool enableAggressiveInterleaving(bool LoopHasReductions) { return false; }
    241 
    242   TTI::PopcntSupportKind getPopcntSupport(unsigned IntTyWidthInBit) {
    243     return TTI::PSK_Software;
    244   }
    245 
    246   bool haveFastSqrt(Type *Ty) { return false; }
    247 
    248   unsigned getFPOpCost(Type *Ty) { return TargetTransformInfo::TCC_Basic; }
    249 
    250   unsigned getIntImmCost(const APInt &Imm, Type *Ty) { return TTI::TCC_Basic; }
    251 
    252   unsigned getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm,
    253                          Type *Ty) {
    254     return TTI::TCC_Free;
    255   }
    256 
    257   unsigned getIntImmCost(Intrinsic::ID IID, unsigned Idx, const APInt &Imm,
    258                          Type *Ty) {
    259     return TTI::TCC_Free;
    260   }
    261 
    262   unsigned getNumberOfRegisters(bool Vector) { return 8; }
    263 
    264   unsigned getRegisterBitWidth(bool Vector) { return 32; }
    265 
    266   unsigned getMaxInterleaveFactor() { return 1; }
    267 
    268   unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty,
    269                                   TTI::OperandValueKind Opd1Info,
    270                                   TTI::OperandValueKind Opd2Info,
    271                                   TTI::OperandValueProperties Opd1PropInfo,
    272                                   TTI::OperandValueProperties Opd2PropInfo) {
    273     return 1;
    274   }
    275 
    276   unsigned getShuffleCost(TTI::ShuffleKind Kind, Type *Ty, int Index,
    277                           Type *SubTp) {
    278     return 1;
    279   }
    280 
    281   unsigned getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src) { return 1; }
    282 
    283   unsigned getCFInstrCost(unsigned Opcode) { return 1; }
    284 
    285   unsigned getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy) {
    286     return 1;
    287   }
    288 
    289   unsigned getVectorInstrCost(unsigned Opcode, Type *Val, unsigned Index) {
    290     return 1;
    291   }
    292 
    293   unsigned getMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
    294                            unsigned AddressSpace) {
    295     return 1;
    296   }
    297 
    298   unsigned getMaskedMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
    299                                  unsigned AddressSpace) {
    300     return 1;
    301   }
    302 
    303   unsigned getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy,
    304                                  ArrayRef<Type *> Tys) {
    305     return 1;
    306   }
    307 
    308   unsigned getCallInstrCost(Function *F, Type *RetTy, ArrayRef<Type *> Tys) {
    309     return 1;
    310   }
    311 
    312   unsigned getNumberOfParts(Type *Tp) { return 0; }
    313 
    314   unsigned getAddressComputationCost(Type *Tp, bool) { return 0; }
    315 
    316   unsigned getReductionCost(unsigned, Type *, bool) { return 1; }
    317 
    318   unsigned getCostOfKeepingLiveOverCall(ArrayRef<Type *> Tys) { return 0; }
    319 
    320   bool getTgtMemIntrinsic(IntrinsicInst *Inst, MemIntrinsicInfo &Info) {
    321     return false;
    322   }
    323 
    324   Value *getOrCreateResultFromMemIntrinsic(IntrinsicInst *Inst,
    325                                            Type *ExpectedType) {
    326     return nullptr;
    327   }
    328 };
    329 
    330 /// \brief CRTP base class for use as a mix-in that aids implementing
    331 /// a TargetTransformInfo-compatible class.
    332 template <typename T>
    333 class TargetTransformInfoImplCRTPBase : public TargetTransformInfoImplBase {
    334 private:
    335   typedef TargetTransformInfoImplBase BaseT;
    336 
    337 protected:
    338   explicit TargetTransformInfoImplCRTPBase(const DataLayout *DL)
    339       : BaseT(DL) {}
    340 
    341 public:
    342   // Provide value semantics. MSVC requires that we spell all of these out.
    343   TargetTransformInfoImplCRTPBase(const TargetTransformInfoImplCRTPBase &Arg)
    344       : BaseT(static_cast<const BaseT &>(Arg)) {}
    345   TargetTransformInfoImplCRTPBase(TargetTransformInfoImplCRTPBase &&Arg)
    346       : BaseT(std::move(static_cast<BaseT &>(Arg))) {}
    347   TargetTransformInfoImplCRTPBase &
    348   operator=(const TargetTransformInfoImplCRTPBase &RHS) {
    349     BaseT::operator=(static_cast<const BaseT &>(RHS));
    350     return *this;
    351   }
    352   TargetTransformInfoImplCRTPBase &
    353   operator=(TargetTransformInfoImplCRTPBase &&RHS) {
    354     BaseT::operator=(std::move(static_cast<BaseT &>(RHS)));
    355     return *this;
    356   }
    357 
    358   using BaseT::getCallCost;
    359 
    360   unsigned getCallCost(const Function *F, int NumArgs) {
    361     assert(F && "A concrete function must be provided to this routine.");
    362 
    363     if (NumArgs < 0)
    364       // Set the argument number to the number of explicit arguments in the
    365       // function.
    366       NumArgs = F->arg_size();
    367 
    368     if (Intrinsic::ID IID = (Intrinsic::ID)F->getIntrinsicID()) {
    369       FunctionType *FTy = F->getFunctionType();
    370       SmallVector<Type *, 8> ParamTys(FTy->param_begin(), FTy->param_end());
    371       return static_cast<T *>(this)
    372           ->getIntrinsicCost(IID, FTy->getReturnType(), ParamTys);
    373     }
    374 
    375     if (!static_cast<T *>(this)->isLoweredToCall(F))
    376       return TTI::TCC_Basic; // Give a basic cost if it will be lowered
    377                              // directly.
    378 
    379     return static_cast<T *>(this)->getCallCost(F->getFunctionType(), NumArgs);
    380   }
    381 
    382   unsigned getCallCost(const Function *F, ArrayRef<const Value *> Arguments) {
    383     // Simply delegate to generic handling of the call.
    384     // FIXME: We should use instsimplify or something else to catch calls which
    385     // will constant fold with these arguments.
    386     return static_cast<T *>(this)->getCallCost(F, Arguments.size());
    387   }
    388 
    389   using BaseT::getIntrinsicCost;
    390 
    391   unsigned getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
    392                             ArrayRef<const Value *> Arguments) {
    393     // Delegate to the generic intrinsic handling code. This mostly provides an
    394     // opportunity for targets to (for example) special case the cost of
    395     // certain intrinsics based on constants used as arguments.
    396     SmallVector<Type *, 8> ParamTys;
    397     ParamTys.reserve(Arguments.size());
    398     for (unsigned Idx = 0, Size = Arguments.size(); Idx != Size; ++Idx)
    399       ParamTys.push_back(Arguments[Idx]->getType());
    400     return static_cast<T *>(this)->getIntrinsicCost(IID, RetTy, ParamTys);
    401   }
    402 
    403   unsigned getUserCost(const User *U) {
    404     if (isa<PHINode>(U))
    405       return TTI::TCC_Free; // Model all PHI nodes as free.
    406 
    407     if (const GEPOperator *GEP = dyn_cast<GEPOperator>(U)) {
    408       SmallVector<const Value *, 4> Indices(GEP->idx_begin(), GEP->idx_end());
    409       return static_cast<T *>(this)
    410           ->getGEPCost(GEP->getPointerOperand(), Indices);
    411     }
    412 
    413     if (auto CS = ImmutableCallSite(U)) {
    414       const Function *F = CS.getCalledFunction();
    415       if (!F) {
    416         // Just use the called value type.
    417         Type *FTy = CS.getCalledValue()->getType()->getPointerElementType();
    418         return static_cast<T *>(this)
    419             ->getCallCost(cast<FunctionType>(FTy), CS.arg_size());
    420       }
    421 
    422       SmallVector<const Value *, 8> Arguments(CS.arg_begin(), CS.arg_end());
    423       return static_cast<T *>(this)->getCallCost(F, Arguments);
    424     }
    425 
    426     if (const CastInst *CI = dyn_cast<CastInst>(U)) {
    427       // Result of a cmp instruction is often extended (to be used by other
    428       // cmp instructions, logical or return instructions). These are usually
    429       // nop on most sane targets.
    430       if (isa<CmpInst>(CI->getOperand(0)))
    431         return TTI::TCC_Free;
    432     }
    433 
    434     return static_cast<T *>(this)->getOperationCost(
    435         Operator::getOpcode(U), U->getType(),
    436         U->getNumOperands() == 1 ? U->getOperand(0)->getType() : nullptr);
    437   }
    438 };
    439 }
    440 
    441 #endif
    442