//===-- llvm/CodeGen/JITCodeEmitter.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_JITCODEEMITTER_H
#define LLVM_CODEGEN_JITCODEEMITTER_H
#include <string>
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
#include "llvm/ADT/DenseMap.h"
namespace llvm {
class MachineBasicBlock;
class MachineConstantPool;
class MachineJumpTableInfo;
class MachineFunction;
class MachineModuleInfo;
class MachineRelocation;
class Value;
class GlobalValue;
class Function;
/// JITCodeEmitter - 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 JITCodeEmitter : public MachineCodeEmitter {
public:
virtual ~JITCodeEmitter() {}
/// 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;
/// allocIndirectGV - Allocates and fills storage for an indirect
/// GlobalValue, and returns the address.
virtual void *allocIndirectGV(const GlobalValue *GV,
const uint8_t *Buffer, size_t Size,
unsigned Alignment) = 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) {
*CurBufferPtr++ = (uint8_t)(W >> 0);
*CurBufferPtr++ = (uint8_t)(W >> 8);
*CurBufferPtr++ = (uint8_t)(W >> 16);
*CurBufferPtr++ = (uint8_t)(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.
///
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;
uint8_t *NewPtr = (uint8_t*)RoundUpToAlignment((uintptr_t)CurBufferPtr,
Alignment);
CurBufferPtr = std::min(NewPtr, BufferEnd);
}
/// emitAlignmentWithFill - Similar to emitAlignment, except that the
/// extra bytes are filled with the provided byte.
void emitAlignmentWithFill(unsigned Alignment, uint8_t Fill) {
if (Alignment == 0) Alignment = 1;
uint8_t *NewPtr = (uint8_t*)RoundUpToAlignment((uintptr_t)CurBufferPtr,
Alignment);
// Fail if we don't have room.
if (NewPtr > BufferEnd) {
CurBufferPtr = BufferEnd;
return;
}
while (CurBufferPtr < NewPtr) {
*CurBufferPtr++ = Fill;
}
}
/// emitULEB128Bytes - This callback is invoked when a ULEB128 needs to be
/// written to the output stream.
void emitULEB128Bytes(uint64_t Value, unsigned PadTo = 0) {
do {
uint8_t Byte = Value & 0x7f;
Value >>= 7;
if (Value || PadTo != 0) Byte |= 0x80;
emitByte(Byte);
} while (Value);
if (PadTo) {
do {
uint8_t Byte = (PadTo > 1) ? 0x80 : 0x0;
emitByte(Byte);
} while (--PadTo);
}
}
/// emitSLEB128Bytes - This callback is invoked when a SLEB128 needs to be
/// written to the output stream.
void emitSLEB128Bytes(int64_t Value) {
int32_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(uint32_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;
}
/// 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;
}
/// allocateGlobal - Allocate memory for a global. Unlike allocateSpace,
/// this method does not allocate memory in the current output buffer,
/// because a global may live longer than the current function.
virtual void *allocateGlobal(uintptr_t Size, unsigned Alignment) = 0;
/// 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.
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.
bool earlyResolveAddresses() const { return true; }
/// 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 Label 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;
/// getLabelLocations - Return the label locations map of the label IDs to
/// their address.
virtual DenseMap<MCSymbol*, uintptr_t> *getLabelLocations() { return 0; }
};
} // End llvm namespace
#endif