MachineRelocation.h revision 199481
1//===-- llvm/CodeGen/MachineRelocation.h - Target Relocation ----*- 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 file defines the MachineRelocation class. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_CODEGEN_MACHINERELOCATION_H 15#define LLVM_CODEGEN_MACHINERELOCATION_H 16 17#include "llvm/System/DataTypes.h" 18#include <cassert> 19 20namespace llvm { 21class GlobalValue; 22class MachineBasicBlock; 23 24/// MachineRelocation - This represents a target-specific relocation value, 25/// produced by the code emitter. This relocation is resolved after the has 26/// been emitted, either to an object file or to memory, when the target of the 27/// relocation can be resolved. 28/// 29/// A relocation is made up of the following logical portions: 30/// 1. An offset in the machine code buffer, the location to modify. 31/// 2. A target specific relocation type (a number from 0 to 63). 32/// 3. A symbol being referenced, either as a GlobalValue* or as a string. 33/// 4. An optional constant value to be added to the reference. 34/// 5. A bit, CanRewrite, which indicates to the JIT that a function stub is 35/// not needed for the relocation. 36/// 6. An index into the GOT, if the target uses a GOT 37/// 38class MachineRelocation { 39 enum AddressType { 40 isResult, // Relocation has be transformed into its result pointer. 41 isGV, // The Target.GV field is valid. 42 isIndirectSym, // Relocation of an indirect symbol. 43 isBB, // Relocation of BB address. 44 isExtSym, // The Target.ExtSym field is valid. 45 isConstPool, // Relocation of constant pool address. 46 isJumpTable, // Relocation of jump table address. 47 isGOTIndex // The Target.GOTIndex field is valid. 48 }; 49 50 /// Offset - This is the offset from the start of the code buffer of the 51 /// relocation to perform. 52 uintptr_t Offset; 53 54 /// ConstantVal - A field that may be used by the target relocation type. 55 intptr_t ConstantVal; 56 57 union { 58 void *Result; // If this has been resolved to a resolved pointer 59 GlobalValue *GV; // If this is a pointer to a GV or an indirect ref. 60 MachineBasicBlock *MBB; // If this is a pointer to a LLVM BB 61 const char *ExtSym; // If this is a pointer to a named symbol 62 unsigned Index; // Constant pool / jump table index 63 unsigned GOTIndex; // Index in the GOT of this symbol/global 64 } Target; 65 66 unsigned TargetReloType : 6; // The target relocation ID 67 AddressType AddrType : 4; // The field of Target to use 68 bool MayNeedFarStub : 1; // True if this relocation may require a far-stub 69 bool GOTRelative : 1; // Should this relocation be relative to the GOT? 70 bool TargetResolve : 1; // True if target should resolve the address 71 72public: 73 // Relocation types used in a generic implementation. Currently, relocation 74 // entries for all things use the generic VANILLA type until they are refined 75 // into target relocation types. 76 enum RelocationType { 77 VANILLA 78 }; 79 80 /// MachineRelocation::getGV - Return a relocation entry for a GlobalValue. 81 /// 82 static MachineRelocation getGV(uintptr_t offset, unsigned RelocationType, 83 GlobalValue *GV, intptr_t cst = 0, 84 bool MayNeedFarStub = 0, 85 bool GOTrelative = 0) { 86 assert((RelocationType & ~63) == 0 && "Relocation type too large!"); 87 MachineRelocation Result; 88 Result.Offset = offset; 89 Result.ConstantVal = cst; 90 Result.TargetReloType = RelocationType; 91 Result.AddrType = isGV; 92 Result.MayNeedFarStub = MayNeedFarStub; 93 Result.GOTRelative = GOTrelative; 94 Result.TargetResolve = false; 95 Result.Target.GV = GV; 96 return Result; 97 } 98 99 /// MachineRelocation::getIndirectSymbol - Return a relocation entry for an 100 /// indirect symbol. 101 static MachineRelocation getIndirectSymbol(uintptr_t offset, 102 unsigned RelocationType, 103 GlobalValue *GV, intptr_t cst = 0, 104 bool MayNeedFarStub = 0, 105 bool GOTrelative = 0) { 106 assert((RelocationType & ~63) == 0 && "Relocation type too large!"); 107 MachineRelocation Result; 108 Result.Offset = offset; 109 Result.ConstantVal = cst; 110 Result.TargetReloType = RelocationType; 111 Result.AddrType = isIndirectSym; 112 Result.MayNeedFarStub = MayNeedFarStub; 113 Result.GOTRelative = GOTrelative; 114 Result.TargetResolve = false; 115 Result.Target.GV = GV; 116 return Result; 117 } 118 119 /// MachineRelocation::getBB - Return a relocation entry for a BB. 120 /// 121 static MachineRelocation getBB(uintptr_t offset,unsigned RelocationType, 122 MachineBasicBlock *MBB, intptr_t cst = 0) { 123 assert((RelocationType & ~63) == 0 && "Relocation type too large!"); 124 MachineRelocation Result; 125 Result.Offset = offset; 126 Result.ConstantVal = cst; 127 Result.TargetReloType = RelocationType; 128 Result.AddrType = isBB; 129 Result.MayNeedFarStub = false; 130 Result.GOTRelative = false; 131 Result.TargetResolve = false; 132 Result.Target.MBB = MBB; 133 return Result; 134 } 135 136 /// MachineRelocation::getExtSym - Return a relocation entry for an external 137 /// symbol, like "free". 138 /// 139 static MachineRelocation getExtSym(uintptr_t offset, unsigned RelocationType, 140 const char *ES, intptr_t cst = 0, 141 bool GOTrelative = 0) { 142 assert((RelocationType & ~63) == 0 && "Relocation type too large!"); 143 MachineRelocation Result; 144 Result.Offset = offset; 145 Result.ConstantVal = cst; 146 Result.TargetReloType = RelocationType; 147 Result.AddrType = isExtSym; 148 Result.MayNeedFarStub = true; 149 Result.GOTRelative = GOTrelative; 150 Result.TargetResolve = false; 151 Result.Target.ExtSym = ES; 152 return Result; 153 } 154 155 /// MachineRelocation::getConstPool - Return a relocation entry for a constant 156 /// pool entry. 157 /// 158 static MachineRelocation getConstPool(uintptr_t offset,unsigned RelocationType, 159 unsigned CPI, intptr_t cst = 0, 160 bool letTargetResolve = false) { 161 assert((RelocationType & ~63) == 0 && "Relocation type too large!"); 162 MachineRelocation Result; 163 Result.Offset = offset; 164 Result.ConstantVal = cst; 165 Result.TargetReloType = RelocationType; 166 Result.AddrType = isConstPool; 167 Result.MayNeedFarStub = false; 168 Result.GOTRelative = false; 169 Result.TargetResolve = letTargetResolve; 170 Result.Target.Index = CPI; 171 return Result; 172 } 173 174 /// MachineRelocation::getJumpTable - Return a relocation entry for a jump 175 /// table entry. 176 /// 177 static MachineRelocation getJumpTable(uintptr_t offset,unsigned RelocationType, 178 unsigned JTI, intptr_t cst = 0, 179 bool letTargetResolve = false) { 180 assert((RelocationType & ~63) == 0 && "Relocation type too large!"); 181 MachineRelocation Result; 182 Result.Offset = offset; 183 Result.ConstantVal = cst; 184 Result.TargetReloType = RelocationType; 185 Result.AddrType = isJumpTable; 186 Result.MayNeedFarStub = false; 187 Result.GOTRelative = false; 188 Result.TargetResolve = letTargetResolve; 189 Result.Target.Index = JTI; 190 return Result; 191 } 192 193 /// getMachineCodeOffset - Return the offset into the code buffer that the 194 /// relocation should be performed. 195 intptr_t getMachineCodeOffset() const { 196 return Offset; 197 } 198 199 /// getRelocationType - Return the target-specific relocation ID for this 200 /// relocation. 201 unsigned getRelocationType() const { 202 return TargetReloType; 203 } 204 205 /// getConstantVal - Get the constant value associated with this relocation. 206 /// This is often an offset from the symbol. 207 /// 208 intptr_t getConstantVal() const { 209 return ConstantVal; 210 } 211 212 /// setConstantVal - Set the constant value associated with this relocation. 213 /// This is often an offset from the symbol. 214 /// 215 void setConstantVal(intptr_t val) { 216 ConstantVal = val; 217 } 218 219 /// isGlobalValue - Return true if this relocation is a GlobalValue, as 220 /// opposed to a constant string. 221 bool isGlobalValue() const { 222 return AddrType == isGV; 223 } 224 225 /// isIndirectSymbol - Return true if this relocation is the address an 226 /// indirect symbol 227 bool isIndirectSymbol() const { 228 return AddrType == isIndirectSym; 229 } 230 231 /// isBasicBlock - Return true if this relocation is a basic block reference. 232 /// 233 bool isBasicBlock() const { 234 return AddrType == isBB; 235 } 236 237 /// isExternalSymbol - Return true if this is a constant string. 238 /// 239 bool isExternalSymbol() const { 240 return AddrType == isExtSym; 241 } 242 243 /// isConstantPoolIndex - Return true if this is a constant pool reference. 244 /// 245 bool isConstantPoolIndex() const { 246 return AddrType == isConstPool; 247 } 248 249 /// isJumpTableIndex - Return true if this is a jump table reference. 250 /// 251 bool isJumpTableIndex() const { 252 return AddrType == isJumpTable; 253 } 254 255 /// isGOTRelative - Return true the target wants the index into the GOT of 256 /// the symbol rather than the address of the symbol. 257 bool isGOTRelative() const { 258 return GOTRelative; 259 } 260 261 /// mayNeedFarStub - This function returns true if the JIT for this target may 262 /// need either a stub function or an indirect global-variable load to handle 263 /// the relocated GlobalValue reference. For example, the x86-64 call 264 /// instruction can only call functions within +/-2GB of the call site. 265 /// Anything farther away needs a longer mov+call sequence, which can't just 266 /// be written on top of the existing call. 267 bool mayNeedFarStub() const { 268 return MayNeedFarStub; 269 } 270 271 /// letTargetResolve - Return true if the target JITInfo is usually 272 /// responsible for resolving the address of this relocation. 273 bool letTargetResolve() const { 274 return TargetResolve; 275 } 276 277 /// getGlobalValue - If this is a global value reference, return the 278 /// referenced global. 279 GlobalValue *getGlobalValue() const { 280 assert((isGlobalValue() || isIndirectSymbol()) && 281 "This is not a global value reference!"); 282 return Target.GV; 283 } 284 285 MachineBasicBlock *getBasicBlock() const { 286 assert(isBasicBlock() && "This is not a basic block reference!"); 287 return Target.MBB; 288 } 289 290 /// getString - If this is a string value, return the string reference. 291 /// 292 const char *getExternalSymbol() const { 293 assert(isExternalSymbol() && "This is not an external symbol reference!"); 294 return Target.ExtSym; 295 } 296 297 /// getConstantPoolIndex - If this is a const pool reference, return 298 /// the index into the constant pool. 299 unsigned getConstantPoolIndex() const { 300 assert(isConstantPoolIndex() && "This is not a constant pool reference!"); 301 return Target.Index; 302 } 303 304 /// getJumpTableIndex - If this is a jump table reference, return 305 /// the index into the jump table. 306 unsigned getJumpTableIndex() const { 307 assert(isJumpTableIndex() && "This is not a jump table reference!"); 308 return Target.Index; 309 } 310 311 /// getResultPointer - Once this has been resolved to point to an actual 312 /// address, this returns the pointer. 313 void *getResultPointer() const { 314 assert(AddrType == isResult && "Result pointer isn't set yet!"); 315 return Target.Result; 316 } 317 318 /// setResultPointer - Set the result to the specified pointer value. 319 /// 320 void setResultPointer(void *Ptr) { 321 Target.Result = Ptr; 322 AddrType = isResult; 323 } 324 325 /// setGOTIndex - Set the GOT index to a specific value. 326 void setGOTIndex(unsigned idx) { 327 AddrType = isGOTIndex; 328 Target.GOTIndex = idx; 329 } 330 331 /// getGOTIndex - Once this has been resolved to an entry in the GOT, 332 /// this returns that index. The index is from the lowest address entry 333 /// in the GOT. 334 unsigned getGOTIndex() const { 335 assert(AddrType == isGOTIndex); 336 return Target.GOTIndex; 337 } 338}; 339} 340 341#endif 342