//===-- 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 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
#ifndef LLVM_CODEGEN_MACHINECODEEMITTER_H
#define LLVM_CODEGEN_MACHINECODEEMITTER_H
-#include "llvm/Support/DataTypes.h"
+#include "llvm/System/DataTypes.h"
+#include "llvm/Support/DebugLoc.h"
namespace llvm {
class MachineBasicBlock;
class MachineConstantPool;
+class MachineJumpTableInfo;
class MachineFunction;
+class MachineModuleInfo;
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.
+ uint8_t *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).
+ uint8_t *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) {}
+ virtual bool finishFunction(MachineFunction &F) = 0;
- /// emitConstantPool - This callback is invoked to output the constant pool
- /// for the function.
- virtual void emitConstantPool(MachineConstantPool *MCP) {}
-
- /// 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.
+ /// emitByte - This callback is invoked when a byte needs to be written to the
+ /// output stream.
///
- virtual void startFunctionStub(unsigned StubSize) {}
+ void emitByte(uint8_t B) {
+ if (CurBufferPtr != BufferEnd)
+ *CurBufferPtr++ = B;
+ }
- /// finishFunctionStub - This callback is invoked to terminate a function
- /// stub.
+ /// emitWordLE - This callback is invoked when a 32-bit word needs to be
+ /// written to the output stream in little-endian format.
///
- virtual void *finishFunctionStub(const Function *F) { return 0; }
+ void emitWordLE(uint32_t W) {
+ if (4 <= BufferEnd-CurBufferPtr) {
+ emitWordLEInto(CurBufferPtr, W);
+ } else {
+ CurBufferPtr = BufferEnd;
+ }
+ }
- /// emitByte - This callback is invoked when a byte needs to be written to the
- /// output stream.
+ /// 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.
///
- virtual void emitByte(unsigned char B) {}
+ 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);
+ }
- /// 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).
+ /// emitWordBE - This callback is invoked when a 32-bit word needs to be
+ /// written to the output stream in big-endian format.
///
- virtual void emitWordAt(unsigned W, unsigned *Ptr) {}
+ 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;
+ }
+ }
- /// emitWord - This callback is invoked when a word needs to be written to the
- /// output stream.
+ /// emitDWordLE - This callback is invoked when a 64-bit word needs to be
+ /// written to the output stream in little-endian format.
///
- virtual void emitWord(unsigned W) = 0;
+ 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 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(uint64_t LabelID) = 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 uint64_t getCurrentPCValue() = 0;
-
+ 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 uint64_t getCurrentPCOffset() = 0;
+ 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;
- // 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!
+
+ /// 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;
- /// 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.
+ /// getMachineBasicBlockAddress - Return the address of the specified
+ /// MachineBasicBlock, only usable after the label for the MBB has been
+ /// emitted.
///
- static MachineCodeEmitter *createDebugEmitter();
+ virtual uintptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) 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.
+ /// getLabelAddress - Return the address of the specified LabelID, only usable
+ /// after the LabelID has been emitted.
///
- static MachineCodeEmitter *createFilePrinterEmitter(MachineCodeEmitter&);
+ virtual uintptr_t getLabelAddress(uint64_t LabelID) const = 0;
+
+ /// Specifies the MachineModuleInfo object. This is used for exception handling
+ /// purposes.
+ virtual void setModuleInfo(MachineModuleInfo* Info) = 0;
};
} // End llvm namespace
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