JITCodeEmitter.h revision 186c670e15828327960d05a652ec43ae768c9b8e
1//===-- llvm/CodeGen/JITCodeEmitter.h - Code emission ----------*- 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 an abstract interface that is used by the machine code 11// emission framework to output the code. This allows machine code emission to 12// be separated from concerns such as resolution of call targets, and where the 13// machine code will be written (memory or disk, f.e.). 14// 15//===----------------------------------------------------------------------===// 16 17#ifndef LLVM_CODEGEN_JITCODEEMITTER_H 18#define LLVM_CODEGEN_JITCODEEMITTER_H 19 20#include <string> 21#include "llvm/Support/DataTypes.h" 22#include "llvm/Support/Streams.h" 23#include "llvm/CodeGen/MachineCodeEmitter.h" 24 25using namespace std; 26 27namespace llvm { 28 29class MachineBasicBlock; 30class MachineConstantPool; 31class MachineJumpTableInfo; 32class MachineFunction; 33class MachineModuleInfo; 34class MachineRelocation; 35class Value; 36class GlobalValue; 37class Function; 38 39/// JITCodeEmitter - This class defines two sorts of methods: those for 40/// emitting the actual bytes of machine code, and those for emitting auxillary 41/// structures, such as jump tables, relocations, etc. 42/// 43/// Emission of machine code is complicated by the fact that we don't (in 44/// general) know the size of the machine code that we're about to emit before 45/// we emit it. As such, we preallocate a certain amount of memory, and set the 46/// BufferBegin/BufferEnd pointers to the start and end of the buffer. As we 47/// emit machine instructions, we advance the CurBufferPtr to indicate the 48/// location of the next byte to emit. In the case of a buffer overflow (we 49/// need to emit more machine code than we have allocated space for), the 50/// CurBufferPtr will saturate to BufferEnd and ignore stores. Once the entire 51/// function has been emitted, the overflow condition is checked, and if it has 52/// occurred, more memory is allocated, and we reemit the code into it. 53/// 54class JITCodeEmitter : public MachineCodeEmitter { 55public: 56 virtual ~JITCodeEmitter() {} 57 58 /// startFunction - This callback is invoked when the specified function is 59 /// about to be code generated. This initializes the BufferBegin/End/Ptr 60 /// fields. 61 /// 62 virtual void startFunction(MachineFunction &F) = 0; 63 64 /// finishFunction - This callback is invoked when the specified function has 65 /// finished code generation. If a buffer overflow has occurred, this method 66 /// returns true (the callee is required to try again), otherwise it returns 67 /// false. 68 /// 69 virtual bool finishFunction(MachineFunction &F) = 0; 70 71 /// startGVStub - This callback is invoked when the JIT needs the 72 /// address of a GV (e.g. function) that has not been code generated yet. 73 /// The StubSize specifies the total size required by the stub. 74 /// 75 virtual void startGVStub(const GlobalValue* GV, unsigned StubSize, 76 unsigned Alignment = 1) = 0; 77 78 /// startGVStub - This callback is invoked when the JIT needs the address of a 79 /// GV (e.g. function) that has not been code generated yet. Buffer points to 80 /// memory already allocated for this stub. 81 /// 82 virtual void startGVStub(const GlobalValue* GV, void *Buffer, 83 unsigned StubSize) = 0; 84 85 /// finishGVStub - This callback is invoked to terminate a GV stub. 86 /// 87 virtual void *finishGVStub(const GlobalValue* F) = 0; 88 89 /// emitByte - This callback is invoked when a byte needs to be written to the 90 /// output stream. 91 /// 92 void emitByte(uint8_t B) { 93 if (CurBufferPtr != BufferEnd) 94 *CurBufferPtr++ = B; 95 } 96 97 /// emitWordLE - This callback is invoked when a 32-bit word needs to be 98 /// written to the output stream in little-endian format. 99 /// 100 void emitWordLE(unsigned W) { 101 if (4 <= BufferEnd-CurBufferPtr) { 102 *CurBufferPtr++ = (uint8_t)(W >> 0); 103 *CurBufferPtr++ = (uint8_t)(W >> 8); 104 *CurBufferPtr++ = (uint8_t)(W >> 16); 105 *CurBufferPtr++ = (uint8_t)(W >> 24); 106 } else { 107 CurBufferPtr = BufferEnd; 108 } 109 } 110 111 /// emitWordBE - This callback is invoked when a 32-bit word needs to be 112 /// written to the output stream in big-endian format. 113 /// 114 void emitWordBE(unsigned W) { 115 if (4 <= BufferEnd-CurBufferPtr) { 116 *CurBufferPtr++ = (uint8_t)(W >> 24); 117 *CurBufferPtr++ = (uint8_t)(W >> 16); 118 *CurBufferPtr++ = (uint8_t)(W >> 8); 119 *CurBufferPtr++ = (uint8_t)(W >> 0); 120 } else { 121 CurBufferPtr = BufferEnd; 122 } 123 } 124 125 /// emitDWordLE - This callback is invoked when a 64-bit word needs to be 126 /// written to the output stream in little-endian format. 127 /// 128 void emitDWordLE(uint64_t W) { 129 if (8 <= BufferEnd-CurBufferPtr) { 130 *CurBufferPtr++ = (uint8_t)(W >> 0); 131 *CurBufferPtr++ = (uint8_t)(W >> 8); 132 *CurBufferPtr++ = (uint8_t)(W >> 16); 133 *CurBufferPtr++ = (uint8_t)(W >> 24); 134 *CurBufferPtr++ = (uint8_t)(W >> 32); 135 *CurBufferPtr++ = (uint8_t)(W >> 40); 136 *CurBufferPtr++ = (uint8_t)(W >> 48); 137 *CurBufferPtr++ = (uint8_t)(W >> 56); 138 } else { 139 CurBufferPtr = BufferEnd; 140 } 141 } 142 143 /// emitDWordBE - This callback is invoked when a 64-bit word needs to be 144 /// written to the output stream in big-endian format. 145 /// 146 void emitDWordBE(uint64_t W) { 147 if (8 <= BufferEnd-CurBufferPtr) { 148 *CurBufferPtr++ = (uint8_t)(W >> 56); 149 *CurBufferPtr++ = (uint8_t)(W >> 48); 150 *CurBufferPtr++ = (uint8_t)(W >> 40); 151 *CurBufferPtr++ = (uint8_t)(W >> 32); 152 *CurBufferPtr++ = (uint8_t)(W >> 24); 153 *CurBufferPtr++ = (uint8_t)(W >> 16); 154 *CurBufferPtr++ = (uint8_t)(W >> 8); 155 *CurBufferPtr++ = (uint8_t)(W >> 0); 156 } else { 157 CurBufferPtr = BufferEnd; 158 } 159 } 160 161 /// emitAlignment - Move the CurBufferPtr pointer up the the specified 162 /// alignment (saturated to BufferEnd of course). 163 void emitAlignment(unsigned Alignment) { 164 if (Alignment == 0) Alignment = 1; 165 166 if(Alignment <= (uintptr_t)(BufferEnd-CurBufferPtr)) { 167 // Move the current buffer ptr up to the specified alignment. 168 CurBufferPtr = 169 (uint8_t*)(((uintptr_t)CurBufferPtr+Alignment-1) & 170 ~(uintptr_t)(Alignment-1)); 171 } else { 172 CurBufferPtr = BufferEnd; 173 } 174 } 175 176 177 /// emitULEB128Bytes - This callback is invoked when a ULEB128 needs to be 178 /// written to the output stream. 179 void emitULEB128Bytes(unsigned Value) { 180 do { 181 uint8_t Byte = Value & 0x7f; 182 Value >>= 7; 183 if (Value) Byte |= 0x80; 184 emitByte(Byte); 185 } while (Value); 186 } 187 188 /// emitSLEB128Bytes - This callback is invoked when a SLEB128 needs to be 189 /// written to the output stream. 190 void emitSLEB128Bytes(int32_t Value) { 191 int32_t Sign = Value >> (8 * sizeof(Value) - 1); 192 bool IsMore; 193 194 do { 195 uint8_t Byte = Value & 0x7f; 196 Value >>= 7; 197 IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0; 198 if (IsMore) Byte |= 0x80; 199 emitByte(Byte); 200 } while (IsMore); 201 } 202 203 /// emitString - This callback is invoked when a String needs to be 204 /// written to the output stream. 205 void emitString(const std::string &String) { 206 for (unsigned i = 0, N = static_cast<unsigned>(String.size()); 207 i < N; ++i) { 208 uint8_t C = String[i]; 209 emitByte(C); 210 } 211 emitByte(0); 212 } 213 214 /// emitInt32 - Emit a int32 directive. 215 void emitInt32(int32_t Value) { 216 if (4 <= BufferEnd-CurBufferPtr) { 217 *((uint32_t*)CurBufferPtr) = Value; 218 CurBufferPtr += 4; 219 } else { 220 CurBufferPtr = BufferEnd; 221 } 222 } 223 224 /// emitInt64 - Emit a int64 directive. 225 void emitInt64(uint64_t Value) { 226 if (8 <= BufferEnd-CurBufferPtr) { 227 *((uint64_t*)CurBufferPtr) = Value; 228 CurBufferPtr += 8; 229 } else { 230 CurBufferPtr = BufferEnd; 231 } 232 } 233 234 /// emitInt32At - Emit the Int32 Value in Addr. 235 void emitInt32At(uintptr_t *Addr, uintptr_t Value) { 236 if (Addr >= (uintptr_t*)BufferBegin && Addr < (uintptr_t*)BufferEnd) 237 (*(uint32_t*)Addr) = (uint32_t)Value; 238 } 239 240 /// emitInt64At - Emit the Int64 Value in Addr. 241 void emitInt64At(uintptr_t *Addr, uintptr_t Value) { 242 if (Addr >= (uintptr_t*)BufferBegin && Addr < (uintptr_t*)BufferEnd) 243 (*(uint64_t*)Addr) = (uint64_t)Value; 244 } 245 246 247 /// emitLabel - Emits a label 248 virtual void emitLabel(uint64_t LabelID) = 0; 249 250 /// allocateSpace - Allocate a block of space in the current output buffer, 251 /// returning null (and setting conditions to indicate buffer overflow) on 252 /// failure. Alignment is the alignment in bytes of the buffer desired. 253 virtual void *allocateSpace(uintptr_t Size, unsigned Alignment) { 254 emitAlignment(Alignment); 255 void *Result; 256 257 // Check for buffer overflow. 258 if (Size >= (uintptr_t)(BufferEnd-CurBufferPtr)) { 259 CurBufferPtr = BufferEnd; 260 Result = 0; 261 } else { 262 // Allocate the space. 263 Result = CurBufferPtr; 264 CurBufferPtr += Size; 265 } 266 267 return Result; 268 } 269 270 /// StartMachineBasicBlock - This should be called by the target when a new 271 /// basic block is about to be emitted. This way the MCE knows where the 272 /// start of the block is, and can implement getMachineBasicBlockAddress. 273 virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) = 0; 274 275 /// getCurrentPCValue - This returns the address that the next emitted byte 276 /// will be output to. 277 /// 278 virtual uintptr_t getCurrentPCValue() const { 279 return (uintptr_t)CurBufferPtr; 280 } 281 282 /// getCurrentPCOffset - Return the offset from the start of the emitted 283 /// buffer that we are currently writing to. 284 uintptr_t getCurrentPCOffset() const { 285 return CurBufferPtr-BufferBegin; 286 } 287 288 /// addRelocation - Whenever a relocatable address is needed, it should be 289 /// noted with this interface. 290 virtual void addRelocation(const MachineRelocation &MR) = 0; 291 292 /// FIXME: These should all be handled with relocations! 293 294 /// getConstantPoolEntryAddress - Return the address of the 'Index' entry in 295 /// the constant pool that was last emitted with the emitConstantPool method. 296 /// 297 virtual uintptr_t getConstantPoolEntryAddress(unsigned Index) const = 0; 298 299 /// getJumpTableEntryAddress - Return the address of the jump table with index 300 /// 'Index' in the function that last called initJumpTableInfo. 301 /// 302 virtual uintptr_t getJumpTableEntryAddress(unsigned Index) const = 0; 303 304 /// getMachineBasicBlockAddress - Return the address of the specified 305 /// MachineBasicBlock, only usable after the label for the MBB has been 306 /// emitted. 307 /// 308 virtual uintptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const= 0; 309 310 /// getLabelAddress - Return the address of the specified LabelID, only usable 311 /// after the LabelID has been emitted. 312 /// 313 virtual uintptr_t getLabelAddress(uint64_t LabelID) const = 0; 314 315 /// Specifies the MachineModuleInfo object. This is used for exception handling 316 /// purposes. 317 virtual void setModuleInfo(MachineModuleInfo* Info) = 0; 318}; 319 320} // End llvm namespace 321 322#endif 323