TargetTransformInfo.h revision d3c965d6251e6d939f7797f8704d4e3a82f7e274
1//===- llvm/Analysis/TargetTransformInfo.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// 10// This pass exposes codegen information to IR-level passes. Every 11// transformation that uses codegen information is broken into three parts: 12// 1. The IR-level analysis pass. 13// 2. The IR-level transformation interface which provides the needed 14// information. 15// 3. Codegen-level implementation which uses target-specific hooks. 16// 17// This file defines #2, which is the interface that IR-level transformations 18// use for querying the codegen. 19// 20//===----------------------------------------------------------------------===// 21 22#ifndef LLVM_ANALYSIS_TARGETTRANSFORMINFO_H 23#define LLVM_ANALYSIS_TARGETTRANSFORMINFO_H 24 25#include "llvm/IR/GlobalValue.h" 26#include "llvm/IR/Intrinsics.h" 27#include "llvm/IR/Type.h" 28#include "llvm/Pass.h" 29#include "llvm/Support/DataTypes.h" 30#include "llvm/CodeGen/ValueTypes.h" 31 32namespace llvm { 33 34/// TargetTransformInfo - This pass provides access to the codegen 35/// interfaces that are needed for IR-level transformations. 36class TargetTransformInfo { 37protected: 38 /// \brief The TTI instance one level down the stack. 39 /// 40 /// This is used to implement the default behavior all of the methods which 41 /// is to delegate up through the stack of TTIs until one can answer the 42 /// query. 43 TargetTransformInfo *PrevTTI; 44 45 /// \brief The top of the stack of TTI analyses available. 46 /// 47 /// This is a convenience routine maintained as TTI analyses become available 48 /// that complements the PrevTTI delegation chain. When one part of an 49 /// analysis pass wants to query another part of the analysis pass it can use 50 /// this to start back at the top of the stack. 51 TargetTransformInfo *TopTTI; 52 53 /// All pass subclasses must in their initializePass routine call 54 /// pushTTIStack with themselves to update the pointers tracking the previous 55 /// TTI instance in the analysis group's stack, and the top of the analysis 56 /// group's stack. 57 void pushTTIStack(Pass *P); 58 59 /// All pass subclasses must in their finalizePass routine call popTTIStack 60 /// to update the pointers tracking the previous TTI instance in the analysis 61 /// group's stack, and the top of the analysis group's stack. 62 void popTTIStack(); 63 64 /// All pass subclasses must call TargetTransformInfo::getAnalysisUsage. 65 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 66 67public: 68 /// This class is intended to be subclassed by real implementations. 69 virtual ~TargetTransformInfo() = 0; 70 71 /// \name Scalar Target Information 72 /// @{ 73 74 /// \brief Flags indicating the kind of support for population count. 75 /// 76 /// Compared to the SW implementation, HW support is supposed to 77 /// significantly boost the performance when the population is dense, and it 78 /// may or may not degrade performance if the population is sparse. A HW 79 /// support is considered as "Fast" if it can outperform, or is on a par 80 /// with, SW implementaion when the population is sparse; otherwise, it is 81 /// considered as "Slow". 82 enum PopcntSupportKind { 83 PSK_Software, 84 PSK_SlowHardware, 85 PSK_FastHardware 86 }; 87 88 /// isLegalAddImmediate - Return true if the specified immediate is legal 89 /// add immediate, that is the target has add instructions which can add 90 /// a register with the immediate without having to materialize the 91 /// immediate into a register. 92 virtual bool isLegalAddImmediate(int64_t Imm) const; 93 94 /// isLegalICmpImmediate - Return true if the specified immediate is legal 95 /// icmp immediate, that is the target has icmp instructions which can compare 96 /// a register against the immediate without having to materialize the 97 /// immediate into a register. 98 virtual bool isLegalICmpImmediate(int64_t Imm) const; 99 100 /// isLegalAddressingMode - Return true if the addressing mode represented by 101 /// AM is legal for this target, for a load/store of the specified type. 102 /// The type may be VoidTy, in which case only return true if the addressing 103 /// mode is legal for a load/store of any legal type. 104 /// TODO: Handle pre/postinc as well. 105 virtual bool isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV, 106 int64_t BaseOffset, bool HasBaseReg, 107 int64_t Scale) const; 108 109 /// isTruncateFree - Return true if it's free to truncate a value of 110 /// type Ty1 to type Ty2. e.g. On x86 it's free to truncate a i32 value in 111 /// register EAX to i16 by referencing its sub-register AX. 112 virtual bool isTruncateFree(Type *Ty1, Type *Ty2) const; 113 114 /// Is this type legal. 115 virtual bool isTypeLegal(Type *Ty) const; 116 117 /// getJumpBufAlignment - returns the target's jmp_buf alignment in bytes 118 virtual unsigned getJumpBufAlignment() const; 119 120 /// getJumpBufSize - returns the target's jmp_buf size in bytes. 121 virtual unsigned getJumpBufSize() const; 122 123 /// shouldBuildLookupTables - Return true if switches should be turned into 124 /// lookup tables for the target. 125 virtual bool shouldBuildLookupTables() const; 126 127 /// getPopcntSupport - Return hardware support for population count. 128 virtual PopcntSupportKind getPopcntSupport(unsigned IntTyWidthInBit) const; 129 130 /// getIntImmCost - Return the expected cost of materializing the given 131 /// integer immediate of the specified type. 132 virtual unsigned getIntImmCost(const APInt &Imm, Type *Ty) const; 133 134 /// @} 135 136 /// \name Vector Target Information 137 /// @{ 138 139 /// \brief The various kinds of shuffle patterns for vector queries. 140 enum ShuffleKind { 141 SK_Broadcast, ///< Broadcast element 0 to all other elements. 142 SK_Reverse, ///< Reverse the order of the vector. 143 SK_InsertSubvector, ///< InsertSubvector. Index indicates start offset. 144 SK_ExtractSubvector ///< ExtractSubvector Index indicates start offset. 145 }; 146 147 /// \return The number of scalar or vector registers that the target has. 148 /// If 'Vectors' is true, it returns the number of vector registers. If it is 149 /// set to false, it returns the number of scalar registers. 150 virtual unsigned getNumberOfRegisters(bool Vector) const; 151 152 /// \return The width of the largest scalar or vector register type. 153 virtual unsigned getRegisterBitWidth(bool Vector) const; 154 155 /// \return The maximum unroll factor that the vectorizer should try to 156 /// perform for this target. This number depends on the level of parallelism 157 /// and the number of execution units in the CPU. 158 virtual unsigned getMaximumUnrollFactor() const; 159 160 /// \return The expected cost of arithmetic ops, such as mul, xor, fsub, etc. 161 virtual unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty) const; 162 163 /// \return The cost of a shuffle instruction of kind Kind and of type Tp. 164 /// The index and subtype parameters are used by the subvector insertion and 165 /// extraction shuffle kinds. 166 virtual unsigned getShuffleCost(ShuffleKind Kind, Type *Tp, int Index = 0, 167 Type *SubTp = 0) const; 168 169 /// \return The expected cost of cast instructions, such as bitcast, trunc, 170 /// zext, etc. 171 virtual unsigned getCastInstrCost(unsigned Opcode, Type *Dst, 172 Type *Src) const; 173 174 /// \return The expected cost of control-flow related instrutctions such as 175 /// Phi, Ret, Br. 176 virtual unsigned getCFInstrCost(unsigned Opcode) const; 177 178 /// \returns The expected cost of compare and select instructions. 179 virtual unsigned getCmpSelInstrCost(unsigned Opcode, Type *ValTy, 180 Type *CondTy = 0) const; 181 182 /// \return The expected cost of vector Insert and Extract. 183 /// Use -1 to indicate that there is no information on the index value. 184 virtual unsigned getVectorInstrCost(unsigned Opcode, Type *Val, 185 unsigned Index = -1) const; 186 187 /// \return The cost of Load and Store instructions. 188 virtual unsigned getMemoryOpCost(unsigned Opcode, Type *Src, 189 unsigned Alignment, 190 unsigned AddressSpace) const; 191 192 /// \returns The cost of Intrinsic instructions. 193 virtual unsigned getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy, 194 ArrayRef<Type *> Tys) const; 195 196 /// \returns The number of pieces into which the provided type must be 197 /// split during legalization. Zero is returned when the answer is unknown. 198 virtual unsigned getNumberOfParts(Type *Tp) const; 199 200 /// @} 201 202 /// Analysis group identification. 203 static char ID; 204}; 205 206/// \brief Create the base case instance of a pass in the TTI analysis group. 207/// 208/// This class provides the base case for the stack of TTI analyses. It doesn't 209/// delegate to anything and uses the STTI and VTTI objects passed in to 210/// satisfy the queries. 211ImmutablePass *createNoTargetTransformInfoPass(); 212 213//======================================= COST TABLES == 214 215/// \brief An entry in a cost table 216/// 217/// Use it as a static array and call the CostTable below to 218/// iterate through it and find the elements you're looking for. 219/// 220/// Leaving Types with fixed size to avoid complications during 221/// static destruction. 222struct CostTableEntry { 223 int ISD; // instruction ID 224 MVT Types[2]; // Types { dest, source } 225 unsigned Cost; // ideal cost 226}; 227 228/// \brief Cost table, containing one or more costs for different instructions 229/// 230/// This class implement the cost table lookup, to simplify 231/// how targets declare their own costs. 232class CostTable { 233 const CostTableEntry *table; 234 const size_t size; 235 const unsigned numTypes; 236 237protected: 238 /// Searches for costs on the table 239 unsigned _findCost(int ISD, MVT *Types) const; 240 241 // We don't want to expose a multi-type cost table, since types are not 242 // sequential by nature. If you need more cost table types, implement 243 // them below. 244 CostTable(const CostTableEntry *table, const size_t size, unsigned numTypes); 245 246public: 247 /// Cost Not found while searching 248 static const unsigned COST_NOT_FOUND = -1; 249}; 250 251/// Specialisation for one-type cost table 252class UnaryCostTable : public CostTable { 253public: 254 UnaryCostTable(const CostTableEntry *table, const size_t size); 255 unsigned findCost(int ISD, MVT Type) const; 256}; 257 258/// Specialisation for two-type cost table 259class BinaryCostTable : public CostTable { 260public: 261 BinaryCostTable(const CostTableEntry *table, const size_t size); 262 unsigned findCost(int ISD, MVT Type, MVT SrcType) const; 263}; 264 265} // End llvm namespace 266 267#endif 268