1193323Sed//===-- llvm/CodeGen/MachineCodeEmitter.h - Code emission -------*- C++ -*-===// 2193323Sed// 3193323Sed// The LLVM Compiler Infrastructure 4193323Sed// 5193323Sed// This file is distributed under the University of Illinois Open Source 6193323Sed// License. See LICENSE.TXT for details. 7193323Sed// 8193323Sed//===----------------------------------------------------------------------===// 9193323Sed// 10193323Sed// This file defines an abstract interface that is used by the machine code 11193323Sed// emission framework to output the code. This allows machine code emission to 12193323Sed// be separated from concerns such as resolution of call targets, and where the 13193323Sed// machine code will be written (memory or disk, f.e.). 14193323Sed// 15193323Sed//===----------------------------------------------------------------------===// 16193323Sed 17193323Sed#ifndef LLVM_CODEGEN_MACHINECODEEMITTER_H 18193323Sed#define LLVM_CODEGEN_MACHINECODEEMITTER_H 19193323Sed 20218893Sdim#include "llvm/Support/DataTypes.h" 21198090Srdivacky#include "llvm/Support/DebugLoc.h" 22234353Sdim#include <string> 23234353Sdim 24193323Sednamespace llvm { 25193323Sed 26193323Sedclass MachineBasicBlock; 27193323Sedclass MachineConstantPool; 28193323Sedclass MachineJumpTableInfo; 29193323Sedclass MachineFunction; 30193323Sedclass MachineModuleInfo; 31193323Sedclass MachineRelocation; 32193323Sedclass Value; 33193323Sedclass GlobalValue; 34193323Sedclass Function; 35205218Srdivackyclass MCSymbol; 36193323Sed 37193323Sed/// MachineCodeEmitter - This class defines two sorts of methods: those for 38221345Sdim/// emitting the actual bytes of machine code, and those for emitting auxiliary 39193323Sed/// structures, such as jump tables, relocations, etc. 40193323Sed/// 41193323Sed/// Emission of machine code is complicated by the fact that we don't (in 42193323Sed/// general) know the size of the machine code that we're about to emit before 43193323Sed/// we emit it. As such, we preallocate a certain amount of memory, and set the 44193323Sed/// BufferBegin/BufferEnd pointers to the start and end of the buffer. As we 45193323Sed/// emit machine instructions, we advance the CurBufferPtr to indicate the 46193323Sed/// location of the next byte to emit. In the case of a buffer overflow (we 47193323Sed/// need to emit more machine code than we have allocated space for), the 48193323Sed/// CurBufferPtr will saturate to BufferEnd and ignore stores. Once the entire 49193323Sed/// function has been emitted, the overflow condition is checked, and if it has 50193323Sed/// occurred, more memory is allocated, and we reemit the code into it. 51193323Sed/// 52193323Sedclass MachineCodeEmitter { 53234353Sdim virtual void anchor(); 54193323Sedprotected: 55201360Srdivacky /// BufferBegin/BufferEnd - Pointers to the start and end of the memory 56201360Srdivacky /// allocated for this code buffer. 57201360Srdivacky uint8_t *BufferBegin, *BufferEnd; 58201360Srdivacky /// CurBufferPtr - Pointer to the next byte of memory to fill when emitting 59221345Sdim /// code. This is guaranteed to be in the range [BufferBegin,BufferEnd]. If 60201360Srdivacky /// this pointer is at BufferEnd, it will never move due to code emission, and 61201360Srdivacky /// all code emission requests will be ignored (this is the buffer overflow 62201360Srdivacky /// condition). 63201360Srdivacky uint8_t *CurBufferPtr; 64193323Sed 65193323Sedpublic: 66193323Sed virtual ~MachineCodeEmitter() {} 67193323Sed 68193323Sed /// startFunction - This callback is invoked when the specified function is 69193323Sed /// about to be code generated. This initializes the BufferBegin/End/Ptr 70193323Sed /// fields. 71193323Sed /// 72193323Sed virtual void startFunction(MachineFunction &F) = 0; 73193323Sed 74193323Sed /// finishFunction - This callback is invoked when the specified function has 75193323Sed /// finished code generation. If a buffer overflow has occurred, this method 76193323Sed /// returns true (the callee is required to try again), otherwise it returns 77193323Sed /// false. 78193323Sed /// 79193323Sed virtual bool finishFunction(MachineFunction &F) = 0; 80193323Sed 81193323Sed /// emitByte - This callback is invoked when a byte needs to be written to the 82193323Sed /// output stream. 83193323Sed /// 84193574Sed void emitByte(uint8_t B) { 85193323Sed if (CurBufferPtr != BufferEnd) 86193323Sed *CurBufferPtr++ = B; 87193323Sed } 88193323Sed 89193323Sed /// emitWordLE - This callback is invoked when a 32-bit word needs to be 90193323Sed /// written to the output stream in little-endian format. 91193323Sed /// 92194178Sed void emitWordLE(uint32_t W) { 93193323Sed if (4 <= BufferEnd-CurBufferPtr) { 94201360Srdivacky emitWordLEInto(CurBufferPtr, W); 95193323Sed } else { 96193323Sed CurBufferPtr = BufferEnd; 97193323Sed } 98193323Sed } 99201360Srdivacky 100201360Srdivacky /// emitWordLEInto - This callback is invoked when a 32-bit word needs to be 101201360Srdivacky /// written to an arbitrary buffer in little-endian format. Buf must have at 102201360Srdivacky /// least 4 bytes of available space. 103201360Srdivacky /// 104201360Srdivacky static void emitWordLEInto(uint8_t *&Buf, uint32_t W) { 105201360Srdivacky *Buf++ = (uint8_t)(W >> 0); 106201360Srdivacky *Buf++ = (uint8_t)(W >> 8); 107201360Srdivacky *Buf++ = (uint8_t)(W >> 16); 108201360Srdivacky *Buf++ = (uint8_t)(W >> 24); 109201360Srdivacky } 110201360Srdivacky 111193323Sed /// emitWordBE - This callback is invoked when a 32-bit word needs to be 112193323Sed /// written to the output stream in big-endian format. 113193323Sed /// 114194178Sed void emitWordBE(uint32_t W) { 115193323Sed if (4 <= BufferEnd-CurBufferPtr) { 116193574Sed *CurBufferPtr++ = (uint8_t)(W >> 24); 117193574Sed *CurBufferPtr++ = (uint8_t)(W >> 16); 118193574Sed *CurBufferPtr++ = (uint8_t)(W >> 8); 119193574Sed *CurBufferPtr++ = (uint8_t)(W >> 0); 120193323Sed } else { 121193323Sed CurBufferPtr = BufferEnd; 122193323Sed } 123193323Sed } 124193323Sed 125193323Sed /// emitDWordLE - This callback is invoked when a 64-bit word needs to be 126193323Sed /// written to the output stream in little-endian format. 127193323Sed /// 128193323Sed void emitDWordLE(uint64_t W) { 129193323Sed if (8 <= BufferEnd-CurBufferPtr) { 130193574Sed *CurBufferPtr++ = (uint8_t)(W >> 0); 131193574Sed *CurBufferPtr++ = (uint8_t)(W >> 8); 132193574Sed *CurBufferPtr++ = (uint8_t)(W >> 16); 133193574Sed *CurBufferPtr++ = (uint8_t)(W >> 24); 134193574Sed *CurBufferPtr++ = (uint8_t)(W >> 32); 135193574Sed *CurBufferPtr++ = (uint8_t)(W >> 40); 136193574Sed *CurBufferPtr++ = (uint8_t)(W >> 48); 137193574Sed *CurBufferPtr++ = (uint8_t)(W >> 56); 138193323Sed } else { 139193323Sed CurBufferPtr = BufferEnd; 140193323Sed } 141193323Sed } 142193323Sed 143193323Sed /// emitDWordBE - This callback is invoked when a 64-bit word needs to be 144193323Sed /// written to the output stream in big-endian format. 145193323Sed /// 146193323Sed void emitDWordBE(uint64_t W) { 147193323Sed if (8 <= BufferEnd-CurBufferPtr) { 148193574Sed *CurBufferPtr++ = (uint8_t)(W >> 56); 149193574Sed *CurBufferPtr++ = (uint8_t)(W >> 48); 150193574Sed *CurBufferPtr++ = (uint8_t)(W >> 40); 151193574Sed *CurBufferPtr++ = (uint8_t)(W >> 32); 152193574Sed *CurBufferPtr++ = (uint8_t)(W >> 24); 153193574Sed *CurBufferPtr++ = (uint8_t)(W >> 16); 154193574Sed *CurBufferPtr++ = (uint8_t)(W >> 8); 155193574Sed *CurBufferPtr++ = (uint8_t)(W >> 0); 156193323Sed } else { 157193323Sed CurBufferPtr = BufferEnd; 158193323Sed } 159193323Sed } 160193323Sed 161203954Srdivacky /// emitAlignment - Move the CurBufferPtr pointer up to the specified 162193323Sed /// alignment (saturated to BufferEnd of course). 163193323Sed void emitAlignment(unsigned Alignment) { 164193323Sed if (Alignment == 0) Alignment = 1; 165193323Sed 166193323Sed if(Alignment <= (uintptr_t)(BufferEnd-CurBufferPtr)) { 167193323Sed // Move the current buffer ptr up to the specified alignment. 168193323Sed CurBufferPtr = 169193574Sed (uint8_t*)(((uintptr_t)CurBufferPtr+Alignment-1) & 170193574Sed ~(uintptr_t)(Alignment-1)); 171193323Sed } else { 172193323Sed CurBufferPtr = BufferEnd; 173193323Sed } 174193323Sed } 175193323Sed 176193323Sed 177193323Sed /// emitULEB128Bytes - This callback is invoked when a ULEB128 needs to be 178193323Sed /// written to the output stream. 179194178Sed void emitULEB128Bytes(uint64_t Value) { 180193323Sed do { 181193574Sed uint8_t Byte = Value & 0x7f; 182193323Sed Value >>= 7; 183193323Sed if (Value) Byte |= 0x80; 184193323Sed emitByte(Byte); 185193323Sed } while (Value); 186193323Sed } 187193323Sed 188193323Sed /// emitSLEB128Bytes - This callback is invoked when a SLEB128 needs to be 189193323Sed /// written to the output stream. 190194178Sed void emitSLEB128Bytes(uint64_t Value) { 191194178Sed uint64_t Sign = Value >> (8 * sizeof(Value) - 1); 192193323Sed bool IsMore; 193193323Sed 194193323Sed do { 195193574Sed uint8_t Byte = Value & 0x7f; 196193323Sed Value >>= 7; 197193323Sed IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0; 198193323Sed if (IsMore) Byte |= 0x80; 199193323Sed emitByte(Byte); 200193323Sed } while (IsMore); 201193323Sed } 202193323Sed 203193323Sed /// emitString - This callback is invoked when a String needs to be 204193323Sed /// written to the output stream. 205193323Sed void emitString(const std::string &String) { 206193323Sed for (unsigned i = 0, N = static_cast<unsigned>(String.size()); 207193323Sed i < N; ++i) { 208193574Sed uint8_t C = String[i]; 209193323Sed emitByte(C); 210193323Sed } 211193323Sed emitByte(0); 212193323Sed } 213193323Sed 214193323Sed /// emitInt32 - Emit a int32 directive. 215193574Sed void emitInt32(int32_t Value) { 216193323Sed if (4 <= BufferEnd-CurBufferPtr) { 217193323Sed *((uint32_t*)CurBufferPtr) = Value; 218193323Sed CurBufferPtr += 4; 219193323Sed } else { 220193323Sed CurBufferPtr = BufferEnd; 221193323Sed } 222193323Sed } 223193323Sed 224193323Sed /// emitInt64 - Emit a int64 directive. 225193323Sed void emitInt64(uint64_t Value) { 226193323Sed if (8 <= BufferEnd-CurBufferPtr) { 227193323Sed *((uint64_t*)CurBufferPtr) = Value; 228193323Sed CurBufferPtr += 8; 229193323Sed } else { 230193323Sed CurBufferPtr = BufferEnd; 231193323Sed } 232193323Sed } 233193323Sed 234193323Sed /// emitInt32At - Emit the Int32 Value in Addr. 235193323Sed void emitInt32At(uintptr_t *Addr, uintptr_t Value) { 236193323Sed if (Addr >= (uintptr_t*)BufferBegin && Addr < (uintptr_t*)BufferEnd) 237193323Sed (*(uint32_t*)Addr) = (uint32_t)Value; 238193323Sed } 239193323Sed 240193323Sed /// emitInt64At - Emit the Int64 Value in Addr. 241193323Sed void emitInt64At(uintptr_t *Addr, uintptr_t Value) { 242193323Sed if (Addr >= (uintptr_t*)BufferBegin && Addr < (uintptr_t*)BufferEnd) 243193323Sed (*(uint64_t*)Addr) = (uint64_t)Value; 244193323Sed } 245193323Sed 246198090Srdivacky /// processDebugLoc - Records debug location information about a 247198090Srdivacky /// MachineInstruction. This is called before emitting any bytes associated 248198090Srdivacky /// with the instruction. Even if successive instructions have the same debug 249198090Srdivacky /// location, this method will be called for each one. 250198090Srdivacky virtual void processDebugLoc(DebugLoc DL, bool BeforePrintintInsn) {} 251198090Srdivacky 252193323Sed /// emitLabel - Emits a label 253205218Srdivacky virtual void emitLabel(MCSymbol *Label) = 0; 254193323Sed 255193323Sed /// allocateSpace - Allocate a block of space in the current output buffer, 256193323Sed /// returning null (and setting conditions to indicate buffer overflow) on 257193323Sed /// failure. Alignment is the alignment in bytes of the buffer desired. 258193323Sed virtual void *allocateSpace(uintptr_t Size, unsigned Alignment) { 259193323Sed emitAlignment(Alignment); 260193323Sed void *Result; 261193323Sed 262193323Sed // Check for buffer overflow. 263193323Sed if (Size >= (uintptr_t)(BufferEnd-CurBufferPtr)) { 264193323Sed CurBufferPtr = BufferEnd; 265193323Sed Result = 0; 266193323Sed } else { 267193323Sed // Allocate the space. 268193323Sed Result = CurBufferPtr; 269193323Sed CurBufferPtr += Size; 270193323Sed } 271193323Sed 272193323Sed return Result; 273193323Sed } 274193323Sed 275193323Sed /// StartMachineBasicBlock - This should be called by the target when a new 276193323Sed /// basic block is about to be emitted. This way the MCE knows where the 277193323Sed /// start of the block is, and can implement getMachineBasicBlockAddress. 278193323Sed virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) = 0; 279193323Sed 280193323Sed /// getCurrentPCValue - This returns the address that the next emitted byte 281193323Sed /// will be output to. 282193323Sed /// 283193323Sed virtual uintptr_t getCurrentPCValue() const { 284193323Sed return (uintptr_t)CurBufferPtr; 285193323Sed } 286193323Sed 287193323Sed /// getCurrentPCOffset - Return the offset from the start of the emitted 288193323Sed /// buffer that we are currently writing to. 289198090Srdivacky virtual uintptr_t getCurrentPCOffset() const { 290193323Sed return CurBufferPtr-BufferBegin; 291193323Sed } 292193323Sed 293198090Srdivacky /// earlyResolveAddresses - True if the code emitter can use symbol addresses 294198090Srdivacky /// during code emission time. The JIT is capable of doing this because it 295198090Srdivacky /// creates jump tables or constant pools in memory on the fly while the 296198090Srdivacky /// object code emitters rely on a linker to have real addresses and should 297198090Srdivacky /// use relocations instead. 298198090Srdivacky virtual bool earlyResolveAddresses() const = 0; 299198090Srdivacky 300193323Sed /// addRelocation - Whenever a relocatable address is needed, it should be 301193323Sed /// noted with this interface. 302193323Sed virtual void addRelocation(const MachineRelocation &MR) = 0; 303193323Sed 304193323Sed /// FIXME: These should all be handled with relocations! 305193323Sed 306193323Sed /// getConstantPoolEntryAddress - Return the address of the 'Index' entry in 307193323Sed /// the constant pool that was last emitted with the emitConstantPool method. 308193323Sed /// 309193323Sed virtual uintptr_t getConstantPoolEntryAddress(unsigned Index) const = 0; 310193323Sed 311193323Sed /// getJumpTableEntryAddress - Return the address of the jump table with index 312193323Sed /// 'Index' in the function that last called initJumpTableInfo. 313193323Sed /// 314193323Sed virtual uintptr_t getJumpTableEntryAddress(unsigned Index) const = 0; 315193323Sed 316193323Sed /// getMachineBasicBlockAddress - Return the address of the specified 317193323Sed /// MachineBasicBlock, only usable after the label for the MBB has been 318193323Sed /// emitted. 319193323Sed /// 320193323Sed virtual uintptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const= 0; 321193323Sed 322205218Srdivacky /// getLabelAddress - Return the address of the specified Label, only usable 323193323Sed /// after the LabelID has been emitted. 324193323Sed /// 325205218Srdivacky virtual uintptr_t getLabelAddress(MCSymbol *Label) const = 0; 326193323Sed 327193323Sed /// Specifies the MachineModuleInfo object. This is used for exception handling 328193323Sed /// purposes. 329193323Sed virtual void setModuleInfo(MachineModuleInfo* Info) = 0; 330193323Sed}; 331193323Sed 332193323Sed} // End llvm namespace 333193323Sed 334193323Sed#endif 335