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//===-- llvm/MC/MCDisassembler.h - Disassembler interface -------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCDISASSEMBLER_H
#define LLVM_MC_MCDISASSEMBLER_H
#include "llvm-c/Disassembler.h"
#include "llvm/Support/DataTypes.h"
namespace llvm {
class MCInst;
class MCSubtargetInfo;
class MemoryObject;
class raw_ostream;
class MCContext;
/// MCDisassembler - Superclass for all disassemblers. Consumes a memory region
/// and provides an array of assembly instructions.
class MCDisassembler {
public:
/// Ternary decode status. Most backends will just use Fail and
/// Success, however some have a concept of an instruction with
/// understandable semantics but which is architecturally
/// incorrect. An example of this is ARM UNPREDICTABLE instructions
/// which are disassemblable but cause undefined behaviour.
///
/// Because it makes sense to disassemble these instructions, there
/// is a "soft fail" failure mode that indicates the MCInst& is
/// valid but architecturally incorrect.
///
/// The enum numbers are deliberately chosen such that reduction
/// from Success->SoftFail ->Fail can be done with a simple
/// bitwise-AND:
///
/// LEFT & TOP = | Success Unpredictable Fail
/// --------------+-----------------------------------
/// Success | Success Unpredictable Fail
/// Unpredictable | Unpredictable Unpredictable Fail
/// Fail | Fail Fail Fail
///
/// An easy way of encoding this is as 0b11, 0b01, 0b00 for
/// Success, SoftFail, Fail respectively.
enum DecodeStatus {
Fail = 0,
SoftFail = 1,
Success = 3
};
/// Constructor - Performs initial setup for the disassembler.
MCDisassembler(const MCSubtargetInfo &STI) : GetOpInfo(0), SymbolLookUp(0),
DisInfo(0), Ctx(0),
STI(STI), CommentStream(0) {}
virtual ~MCDisassembler();
/// getInstruction - Returns the disassembly of a single instruction.
///
/// @param instr - An MCInst to populate with the contents of the
/// instruction.
/// @param size - A value to populate with the size of the instruction, or
/// the number of bytes consumed while attempting to decode
/// an invalid instruction.
/// @param region - The memory object to use as a source for machine code.
/// @param address - The address, in the memory space of region, of the first
/// byte of the instruction.
/// @param vStream - The stream to print warnings and diagnostic messages on.
/// @param cStream - The stream to print comments and annotations on.
/// @return - MCDisassembler::Success if the instruction is valid,
/// MCDisassembler::SoftFail if the instruction was
/// disassemblable but invalid,
/// MCDisassembler::Fail if the instruction was invalid.
virtual DecodeStatus getInstruction(MCInst& instr,
uint64_t& size,
const MemoryObject ®ion,
uint64_t address,
raw_ostream &vStream,
raw_ostream &cStream) const = 0;
private:
//
// Hooks for symbolic disassembly via the public 'C' interface.
//
// The function to get the symbolic information for operands.
LLVMOpInfoCallback GetOpInfo;
// The function to lookup a symbol name.
LLVMSymbolLookupCallback SymbolLookUp;
// The pointer to the block of symbolic information for above call back.
void *DisInfo;
// The assembly context for creating symbols and MCExprs in place of
// immediate operands when there is symbolic information.
MCContext *Ctx;
protected:
// Subtarget information, for instruction decoding predicates if required.
const MCSubtargetInfo &STI;
public:
void setupForSymbolicDisassembly(LLVMOpInfoCallback getOpInfo,
LLVMSymbolLookupCallback symbolLookUp,
void *disInfo,
MCContext *ctx) {
GetOpInfo = getOpInfo;
SymbolLookUp = symbolLookUp;
DisInfo = disInfo;
Ctx = ctx;
}
LLVMOpInfoCallback getLLVMOpInfoCallback() const { return GetOpInfo; }
LLVMSymbolLookupCallback getLLVMSymbolLookupCallback() const {
return SymbolLookUp;
}
void *getDisInfoBlock() const { return DisInfo; }
MCContext *getMCContext() const { return Ctx; }
// Marked mutable because we cache it inside the disassembler, rather than
// having to pass it around as an argument through all the autogenerated code.
mutable raw_ostream *CommentStream;
};
} // namespace llvm
#endif
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