X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FCodeGen%2FMachineCodeEmitter.h;h=018c5e5a3a6b701bf2d3e29aad3a7d4d5cc4afff;hb=80a75bfae980df96f969f1c05b0c4a80ce975240;hp=c8a088213859e829990968662d30af203f1b0d08;hpb=ec45c2388f65a5f52a91e7cbaf0a43d56ddd30ca;p=oota-llvm.git diff --git a/include/llvm/CodeGen/MachineCodeEmitter.h b/include/llvm/CodeGen/MachineCodeEmitter.h index c8a08821385..018c5e5a3a6 100644 --- a/include/llvm/CodeGen/MachineCodeEmitter.h +++ b/include/llvm/CodeGen/MachineCodeEmitter.h @@ -1,10 +1,10 @@ //===-- llvm/CodeGen/MachineCodeEmitter.h - Code emission -------*- C++ -*-===// -// +// // The LLVM Compiler Infrastructure // // This file was developed by the LLVM research group and 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 @@ -18,110 +18,181 @@ #define LLVM_CODEGEN_MACHINECODEEMITTER_H #include "llvm/Support/DataTypes.h" +#include namespace llvm { class MachineBasicBlock; class MachineConstantPool; +class MachineJumpTableInfo; class MachineFunction; class MachineRelocation; class Value; class GlobalValue; class Function; +/// MachineCodeEmitter - This class defines two sorts of methods: those for +/// emitting the actual bytes of machine code, and those for emitting auxillary +/// 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 { +protected: + /// BufferBegin/BufferEnd - Pointers to the start and end of the memory + /// allocated for this code buffer. + unsigned char *BufferBegin, *BufferEnd; + + /// CurBufferPtr - Pointer to the next byte of memory to fill when emitting + /// code. This is guranteed 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). + unsigned char *CurBufferPtr; public: virtual ~MachineCodeEmitter() {} /// startFunction - This callback is invoked when the specified function is - /// about to be code generated. + /// about to be code generated. This initializes the BufferBegin/End/Ptr + /// fields. /// - virtual void startFunction(MachineFunction &F) {} - + virtual void startFunction(MachineFunction &F) = 0; + /// finishFunction - This callback is invoked when the specified function has - /// finished code generation. + /// 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 void finishFunction(MachineFunction &F) {} - - /// emitConstantPool - This callback is invoked to output the constant pool - /// for the function. - virtual void emitConstantPool(MachineConstantPool *MCP) {} - + virtual bool finishFunction(MachineFunction &F) = 0; + /// startFunctionStub - This callback is invoked when the JIT needs the /// address of a function that has not been code generated yet. The StubSize /// specifies the total size required by the stub. Stubs are not allowed to - /// have constant pools, the can only use the other emit* methods. + /// have constant pools, the can only use the other emitByte*/emitWord* + /// methods. /// - virtual void startFunctionStub(unsigned StubSize) {} + virtual void startFunctionStub(unsigned StubSize, unsigned Alignment = 1) = 0; /// finishFunctionStub - This callback is invoked to terminate a function /// stub. /// - virtual void *finishFunctionStub(const Function *F) { return 0; } + virtual void *finishFunctionStub(const Function *F) = 0; /// emitByte - This callback is invoked when a byte needs to be written to the /// output stream. /// - virtual void emitByte(unsigned char B) {} + void emitByte(unsigned char B) { + if (CurBufferPtr != BufferEnd) + *CurBufferPtr++ = B; + } - /// emitWordAt - This callback is invoked when a word needs to be written to - /// the output stream at a different position than the current PC (for - /// instance, when performing relocations). + /// emitWordLE - This callback is invoked when a 32-bit word needs to be + /// written to the output stream in little-endian format. /// - virtual void emitWordAt(unsigned W, unsigned *Ptr) {} - - /// emitWord - This callback is invoked when a word needs to be written to the - /// output stream. + void emitWordLE(unsigned W) { + if (CurBufferPtr+4 <= BufferEnd) { + *CurBufferPtr++ = (unsigned char)(W >> 0); + *CurBufferPtr++ = (unsigned char)(W >> 8); + *CurBufferPtr++ = (unsigned char)(W >> 16); + *CurBufferPtr++ = (unsigned char)(W >> 24); + } else { + CurBufferPtr = BufferEnd; + } + } + + /// emitWordBE - This callback is invoked when a 32-bit word needs to be + /// written to the output stream in big-endian format. /// - virtual void emitWord(unsigned W) = 0; - + void emitWordBE(unsigned W) { + if (CurBufferPtr+4 <= BufferEnd) { + *CurBufferPtr++ = (unsigned char)(W >> 24); + *CurBufferPtr++ = (unsigned char)(W >> 16); + *CurBufferPtr++ = (unsigned char)(W >> 8); + *CurBufferPtr++ = (unsigned char)(W >> 0); + } else { + CurBufferPtr = BufferEnd; + } + } + + /// emitAlignment - Move the CurBufferPtr pointer up the the specified + /// alignment (saturated to BufferEnd of course). + void emitAlignment(unsigned Alignment) { + if (Alignment == 0) Alignment = 1; + // Move the current buffer ptr up to the specified alignment. + CurBufferPtr = + (unsigned char*)(((intptr_t)CurBufferPtr+Alignment-1) & + ~(intptr_t)(Alignment-1)); + if (CurBufferPtr > BufferEnd) + CurBufferPtr = BufferEnd; + } + + /// 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. + void *allocateSpace(intptr_t Size, unsigned Alignment) { + emitAlignment(Alignment); + void *Result = CurBufferPtr; + + // Allocate the space. + CurBufferPtr += Size; + + // Check for buffer overflow. + if (CurBufferPtr >= BufferEnd) { + CurBufferPtr = BufferEnd; + Result = 0; + } + 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 uint64_t getCurrentPCValue() = 0; - + virtual intptr_t getCurrentPCValue() const { + return (intptr_t)CurBufferPtr; + } /// getCurrentPCOffset - Return the offset from the start of the emitted /// buffer that we are currently writing to. - virtual uint64_t getCurrentPCOffset() = 0; + intptr_t getCurrentPCOffset() const { + return CurBufferPtr-BufferBegin; + } /// addRelocation - Whenever a relocatable address is needed, it should be /// noted with this interface. virtual void addRelocation(const MachineRelocation &MR) = 0; + - /// getGlobalValueAddress - This method is used to get the address of the - /// specified global value. In some cases, however, the address may not yet - /// be known at the point that the method is called (for example, getting the - /// address of a function which has not yet been code generated). If this is - /// the case, the function returns zero, and the callee has to be able to - /// handle the situation. - /// - virtual uint64_t getGlobalValueAddress(GlobalValue *V) = 0; - virtual uint64_t getGlobalValueAddress(const char *SymName) = 0; - - // getConstantPoolEntryAddress - Return the address of the 'Index' entry in - // the constant pool that was last emitted with the 'emitConstantPool' method. - // - virtual uint64_t getConstantPoolEntryAddress(unsigned Index) = 0; - - // forceCompilationOf - Force the compilation of the specified function, and - // return its address, because we REALLY need the address now. - // - // FIXME: This is JIT specific! - // - virtual uint64_t forceCompilationOf(Function *F) = 0; + /// FIXME: These should all be handled with relocations! - /// createDebugEmitter - Return a dynamically allocated machine - /// code emitter, which just prints the opcodes and fields out the cout. This - /// can be used for debugging users of the MachineCodeEmitter interface. + /// getConstantPoolEntryAddress - Return the address of the 'Index' entry in + /// the constant pool that was last emitted with the emitConstantPool method. /// - static MachineCodeEmitter *createDebugEmitter(); + virtual intptr_t getConstantPoolEntryAddress(unsigned Index) const = 0; - /// createFilePrinterEmitter - Return a dynamically allocated - /// machine code emitter, which prints binary code to a file. This - /// can be used for debugging users of the MachineCodeEmitter interface. + /// getJumpTableEntryAddress - Return the address of the jump table with index + /// 'Index' in the function that last called initJumpTableInfo. + /// + virtual intptr_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. /// - static MachineCodeEmitter *createFilePrinterEmitter(MachineCodeEmitter&); + virtual intptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const= 0; }; } // End llvm namespace