X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FCodeGen%2FMachineCodeEmitter.h;h=018c5e5a3a6b701bf2d3e29aad3a7d4d5cc4afff;hb=80a75bfae980df96f969f1c05b0c4a80ce975240;hp=cddadb2661e69b0d49368eb1d8eff150cb024521;hpb=8562d4ec7ce4719df7e106a3d27e4549e2cc8054;p=oota-llvm.git diff --git a/include/llvm/CodeGen/MachineCodeEmitter.h b/include/llvm/CodeGen/MachineCodeEmitter.h index cddadb2661e..018c5e5a3a6 100644 --- a/include/llvm/CodeGen/MachineCodeEmitter.h +++ b/include/llvm/CodeGen/MachineCodeEmitter.h @@ -1,46 +1,200 @@ //===-- 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 // emission framework to output the code. This allows machine code emission to -// be seperated from concerns such as resolution of call targets, and where the +// 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_MACHINE_CODE_EMITTER_H -#define LLVM_CODEGEN_MACHINE_CODE_EMITTER_H +#ifndef LLVM_CODEGEN_MACHINECODEEMITTER_H +#define LLVM_CODEGEN_MACHINECODEEMITTER_H + +#include "llvm/Support/DataTypes.h" +#include + +namespace llvm { -class MachineFunction; class MachineBasicBlock; +class MachineConstantPool; +class MachineJumpTableInfo; +class MachineFunction; +class MachineRelocation; class Value; +class GlobalValue; +class Function; -struct MachineCodeEmitter { +/// 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 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 emitByte*/emitWord* + /// methods. /// - virtual void finishFunction(MachineFunction &F) {} + virtual void startFunctionStub(unsigned StubSize, unsigned Alignment = 1) = 0; - /// startBasicBlock - This callback is invoked when a new basic block is about - /// to be emitted. + /// finishFunctionStub - This callback is invoked to terminate a function + /// stub. /// - virtual void startBasicBlock(MachineBasicBlock &BB) {} + 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; + } - /// emitPCRelativeDisp - This callback is invoked when we need to write out a - /// PC relative displacement for the specified Value*. This is used for call - /// and jump instructions typically. + /// emitWordLE - This callback is invoked when a 32-bit word needs to be + /// written to the output stream in little-endian format. + /// + 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 emitPCRelativeDisp(Value *V) {} + 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 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. + 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; + + + /// 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 intptr_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 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. + /// + virtual intptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const= 0; }; +} // End llvm namespace + #endif