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