| //===-- llvm/CodeGen/MachineCodeEmitter.h - Code emission -------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines an abstract interface that is used by the machine code |
| // emission framework to output the code. This allows machine code emission to |
| // be separated from concerns such as resolution of call targets, and where the |
| // machine code will be written (memory or disk, f.e.). |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_CODEGEN_MACHINECODEEMITTER_H |
| #define LLVM_CODEGEN_MACHINECODEEMITTER_H |
| |
| #include "llvm/Support/DataTypes.h" |
| #include "llvm/Support/DebugLoc.h" |
| |
| #include <string> |
| |
| namespace llvm { |
| |
| class MachineBasicBlock; |
| class MachineConstantPool; |
| class MachineJumpTableInfo; |
| class MachineFunction; |
| class MachineModuleInfo; |
| class MachineRelocation; |
| class Value; |
| class GlobalValue; |
| class Function; |
| class MCSymbol; |
| |
| /// MachineCodeEmitter - This class defines two sorts of methods: those for |
| /// emitting the actual bytes of machine code, and those for emitting auxiliary |
| /// structures, such as jump tables, relocations, etc. |
| /// |
| /// Emission of machine code is complicated by the fact that we don't (in |
| /// general) know the size of the machine code that we're about to emit before |
| /// we emit it. As such, we preallocate a certain amount of memory, and set the |
| /// BufferBegin/BufferEnd pointers to the start and end of the buffer. As we |
| /// emit machine instructions, we advance the CurBufferPtr to indicate the |
| /// location of the next byte to emit. In the case of a buffer overflow (we |
| /// need to emit more machine code than we have allocated space for), the |
| /// CurBufferPtr will saturate to BufferEnd and ignore stores. Once the entire |
| /// function has been emitted, the overflow condition is checked, and if it has |
| /// occurred, more memory is allocated, and we reemit the code into it. |
| /// |
| class MachineCodeEmitter { |
| virtual void anchor(); |
| protected: |
| /// BufferBegin/BufferEnd - Pointers to the start and end of the memory |
| /// allocated for this code buffer. |
| uint8_t *BufferBegin, *BufferEnd; |
| /// CurBufferPtr - Pointer to the next byte of memory to fill when emitting |
| /// code. This is guaranteed to be in the range [BufferBegin,BufferEnd]. If |
| /// this pointer is at BufferEnd, it will never move due to code emission, and |
| /// all code emission requests will be ignored (this is the buffer overflow |
| /// condition). |
| uint8_t *CurBufferPtr; |
| |
| public: |
| virtual ~MachineCodeEmitter() {} |
| |
| /// startFunction - This callback is invoked when the specified function is |
| /// about to be code generated. This initializes the BufferBegin/End/Ptr |
| /// fields. |
| /// |
| virtual void startFunction(MachineFunction &F) = 0; |
| |
| /// finishFunction - This callback is invoked when the specified function has |
| /// finished code generation. If a buffer overflow has occurred, this method |
| /// returns true (the callee is required to try again), otherwise it returns |
| /// false. |
| /// |
| virtual bool finishFunction(MachineFunction &F) = 0; |
| |
| /// emitByte - This callback is invoked when a byte needs to be written to the |
| /// output stream. |
| /// |
| void emitByte(uint8_t B) { |
| if (CurBufferPtr != BufferEnd) |
| *CurBufferPtr++ = B; |
| } |
| |
| /// emitWordLE - This callback is invoked when a 32-bit word needs to be |
| /// written to the output stream in little-endian format. |
| /// |
| void emitWordLE(uint32_t W) { |
| if (4 <= BufferEnd-CurBufferPtr) { |
| emitWordLEInto(CurBufferPtr, W); |
| } else { |
| CurBufferPtr = BufferEnd; |
| } |
| } |
| |
| /// emitWordLEInto - This callback is invoked when a 32-bit word needs to be |
| /// written to an arbitrary buffer in little-endian format. Buf must have at |
| /// least 4 bytes of available space. |
| /// |
| static void emitWordLEInto(uint8_t *&Buf, uint32_t W) { |
| *Buf++ = (uint8_t)(W >> 0); |
| *Buf++ = (uint8_t)(W >> 8); |
| *Buf++ = (uint8_t)(W >> 16); |
| *Buf++ = (uint8_t)(W >> 24); |
| } |
| |
| /// emitWordBE - This callback is invoked when a 32-bit word needs to be |
| /// written to the output stream in big-endian format. |
| /// |
| void emitWordBE(uint32_t W) { |
| if (4 <= BufferEnd-CurBufferPtr) { |
| *CurBufferPtr++ = (uint8_t)(W >> 24); |
| *CurBufferPtr++ = (uint8_t)(W >> 16); |
| *CurBufferPtr++ = (uint8_t)(W >> 8); |
| *CurBufferPtr++ = (uint8_t)(W >> 0); |
| } else { |
| CurBufferPtr = BufferEnd; |
| } |
| } |
| |
| /// emitDWordLE - This callback is invoked when a 64-bit word needs to be |
| /// written to the output stream in little-endian format. |
| /// |
| void emitDWordLE(uint64_t W) { |
| if (8 <= BufferEnd-CurBufferPtr) { |
| *CurBufferPtr++ = (uint8_t)(W >> 0); |
| *CurBufferPtr++ = (uint8_t)(W >> 8); |
| *CurBufferPtr++ = (uint8_t)(W >> 16); |
| *CurBufferPtr++ = (uint8_t)(W >> 24); |
| *CurBufferPtr++ = (uint8_t)(W >> 32); |
| *CurBufferPtr++ = (uint8_t)(W >> 40); |
| *CurBufferPtr++ = (uint8_t)(W >> 48); |
| *CurBufferPtr++ = (uint8_t)(W >> 56); |
| } else { |
| CurBufferPtr = BufferEnd; |
| } |
| } |
| |
| /// emitDWordBE - This callback is invoked when a 64-bit word needs to be |
| /// written to the output stream in big-endian format. |
| /// |
| void emitDWordBE(uint64_t W) { |
| if (8 <= BufferEnd-CurBufferPtr) { |
| *CurBufferPtr++ = (uint8_t)(W >> 56); |
| *CurBufferPtr++ = (uint8_t)(W >> 48); |
| *CurBufferPtr++ = (uint8_t)(W >> 40); |
| *CurBufferPtr++ = (uint8_t)(W >> 32); |
| *CurBufferPtr++ = (uint8_t)(W >> 24); |
| *CurBufferPtr++ = (uint8_t)(W >> 16); |
| *CurBufferPtr++ = (uint8_t)(W >> 8); |
| *CurBufferPtr++ = (uint8_t)(W >> 0); |
| } else { |
| CurBufferPtr = BufferEnd; |
| } |
| } |
| |
| /// emitAlignment - Move the CurBufferPtr pointer up to the specified |
| /// alignment (saturated to BufferEnd of course). |
| void emitAlignment(unsigned Alignment) { |
| if (Alignment == 0) Alignment = 1; |
| |
| if(Alignment <= (uintptr_t)(BufferEnd-CurBufferPtr)) { |
| // Move the current buffer ptr up to the specified alignment. |
| CurBufferPtr = |
| (uint8_t*)(((uintptr_t)CurBufferPtr+Alignment-1) & |
| ~(uintptr_t)(Alignment-1)); |
| } else { |
| CurBufferPtr = BufferEnd; |
| } |
| } |
| |
| |
| /// emitULEB128Bytes - This callback is invoked when a ULEB128 needs to be |
| /// written to the output stream. |
| void emitULEB128Bytes(uint64_t Value) { |
| do { |
| uint8_t Byte = Value & 0x7f; |
| Value >>= 7; |
| if (Value) Byte |= 0x80; |
| emitByte(Byte); |
| } while (Value); |
| } |
| |
| /// emitSLEB128Bytes - This callback is invoked when a SLEB128 needs to be |
| /// written to the output stream. |
| void emitSLEB128Bytes(uint64_t Value) { |
| uint64_t Sign = Value >> (8 * sizeof(Value) - 1); |
| bool IsMore; |
| |
| do { |
| uint8_t Byte = Value & 0x7f; |
| Value >>= 7; |
| IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0; |
| if (IsMore) Byte |= 0x80; |
| emitByte(Byte); |
| } while (IsMore); |
| } |
| |
| /// emitString - This callback is invoked when a String needs to be |
| /// written to the output stream. |
| void emitString(const std::string &String) { |
| for (unsigned i = 0, N = static_cast<unsigned>(String.size()); |
| i < N; ++i) { |
| uint8_t C = String[i]; |
| emitByte(C); |
| } |
| emitByte(0); |
| } |
| |
| /// emitInt32 - Emit a int32 directive. |
| void emitInt32(int32_t Value) { |
| if (4 <= BufferEnd-CurBufferPtr) { |
| *((uint32_t*)CurBufferPtr) = Value; |
| CurBufferPtr += 4; |
| } else { |
| CurBufferPtr = BufferEnd; |
| } |
| } |
| |
| /// emitInt64 - Emit a int64 directive. |
| void emitInt64(uint64_t Value) { |
| if (8 <= BufferEnd-CurBufferPtr) { |
| *((uint64_t*)CurBufferPtr) = Value; |
| CurBufferPtr += 8; |
| } else { |
| CurBufferPtr = BufferEnd; |
| } |
| } |
| |
| /// emitInt32At - Emit the Int32 Value in Addr. |
| void emitInt32At(uintptr_t *Addr, uintptr_t Value) { |
| if (Addr >= (uintptr_t*)BufferBegin && Addr < (uintptr_t*)BufferEnd) |
| (*(uint32_t*)Addr) = (uint32_t)Value; |
| } |
| |
| /// emitInt64At - Emit the Int64 Value in Addr. |
| void emitInt64At(uintptr_t *Addr, uintptr_t Value) { |
| if (Addr >= (uintptr_t*)BufferBegin && Addr < (uintptr_t*)BufferEnd) |
| (*(uint64_t*)Addr) = (uint64_t)Value; |
| } |
| |
| /// processDebugLoc - Records debug location information about a |
| /// MachineInstruction. This is called before emitting any bytes associated |
| /// with the instruction. Even if successive instructions have the same debug |
| /// location, this method will be called for each one. |
| virtual void processDebugLoc(DebugLoc DL, bool BeforePrintintInsn) {} |
| |
| /// emitLabel - Emits a label |
| virtual void emitLabel(MCSymbol *Label) = 0; |
| |
| /// allocateSpace - Allocate a block of space in the current output buffer, |
| /// returning null (and setting conditions to indicate buffer overflow) on |
| /// failure. Alignment is the alignment in bytes of the buffer desired. |
| virtual void *allocateSpace(uintptr_t Size, unsigned Alignment) { |
| emitAlignment(Alignment); |
| void *Result; |
| |
| // Check for buffer overflow. |
| if (Size >= (uintptr_t)(BufferEnd-CurBufferPtr)) { |
| CurBufferPtr = BufferEnd; |
| Result = 0; |
| } else { |
| // Allocate the space. |
| Result = CurBufferPtr; |
| CurBufferPtr += Size; |
| } |
| |
| return Result; |
| } |
| |
| /// StartMachineBasicBlock - This should be called by the target when a new |
| /// basic block is about to be emitted. This way the MCE knows where the |
| /// start of the block is, and can implement getMachineBasicBlockAddress. |
| virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) = 0; |
| |
| /// getCurrentPCValue - This returns the address that the next emitted byte |
| /// will be output to. |
| /// |
| virtual uintptr_t getCurrentPCValue() const { |
| return (uintptr_t)CurBufferPtr; |
| } |
| |
| /// getCurrentPCOffset - Return the offset from the start of the emitted |
| /// buffer that we are currently writing to. |
| virtual uintptr_t getCurrentPCOffset() const { |
| return CurBufferPtr-BufferBegin; |
| } |
| |
| /// earlyResolveAddresses - True if the code emitter can use symbol addresses |
| /// during code emission time. The JIT is capable of doing this because it |
| /// creates jump tables or constant pools in memory on the fly while the |
| /// object code emitters rely on a linker to have real addresses and should |
| /// use relocations instead. |
| virtual bool earlyResolveAddresses() const = 0; |
| |
| /// addRelocation - Whenever a relocatable address is needed, it should be |
| /// noted with this interface. |
| virtual void addRelocation(const MachineRelocation &MR) = 0; |
| |
| /// FIXME: These should all be handled with relocations! |
| |
| /// getConstantPoolEntryAddress - Return the address of the 'Index' entry in |
| /// the constant pool that was last emitted with the emitConstantPool method. |
| /// |
| virtual uintptr_t getConstantPoolEntryAddress(unsigned Index) const = 0; |
| |
| /// getJumpTableEntryAddress - Return the address of the jump table with index |
| /// 'Index' in the function that last called initJumpTableInfo. |
| /// |
| virtual uintptr_t getJumpTableEntryAddress(unsigned Index) const = 0; |
| |
| /// getMachineBasicBlockAddress - Return the address of the specified |
| /// MachineBasicBlock, only usable after the label for the MBB has been |
| /// emitted. |
| /// |
| virtual uintptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const= 0; |
| |
| /// getLabelAddress - Return the address of the specified Label, only usable |
| /// after the LabelID has been emitted. |
| /// |
| virtual uintptr_t getLabelAddress(MCSymbol *Label) const = 0; |
| |
| /// Specifies the MachineModuleInfo object. This is used for exception handling |
| /// purposes. |
| virtual void setModuleInfo(MachineModuleInfo* Info) = 0; |
| }; |
| |
| } // End llvm namespace |
| |
| #endif |