lib/MC/MCDisassembler/Disassembler.cpp

   1 //===-- lib/MC/Disassembler.cpp - Disassembler Public C Interface -*- C -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "Disassembler.h"
  11 #include "llvm-c/Disassembler.h"
  12
  13 #include "llvm/MC/MCAsmInfo.h"
  14 #include "llvm/MC/MCDisassembler.h"
  15 #include "llvm/MC/MCInst.h"
  16 #include "llvm/MC/MCInstPrinter.h"
  17 #include "llvm/MC/MCContext.h"
  18 #include "llvm/Target/TargetRegistry.h"
  19 #include "llvm/Target/TargetAsmInfo.h"  // FIXME.
  20 #include "llvm/Target/TargetMachine.h"  // FIXME.
  21 #include "llvm/Target/TargetSelect.h"
  22 #include "llvm/Support/MemoryObject.h"
  23
  24 namespace llvm {
  25 class Target;
  26 } // namespace llvm
  27 using namespace llvm;
  28
  29 // LLVMCreateDisasm() creates a disassembler for the TripleName.  Symbolic
  30 // disassembly is supported by passing a block of information in the DisInfo
  31 // parameter and specifying the TagType and callback functions as described in
  32 // the header llvm-c/Disassembler.h .  The pointer to the block and the
  33 // functions can all be passed as NULL.  If successful, this returns a
  34 // disassembler context.  If not, it returns NULL.
  35 //
  36 LLVMDisasmContextRef LLVMCreateDisasm(const char *TripleName, void *DisInfo,
  37                                       int TagType, LLVMOpInfoCallback GetOpInfo,
  38                                       LLVMSymbolLookupCallback SymbolLookUp) {
  39   // Initialize targets and assembly printers/parsers.
  40   llvm::InitializeAllTargetInfos();
  41   // FIXME: We shouldn't need to initialize the Target(Machine)s.
  42   llvm::InitializeAllTargets();
  43   llvm::InitializeAllAsmPrinters();
  44   llvm::InitializeAllAsmParsers();
  45   llvm::InitializeAllDisassemblers();
  46
  47   // Get the target.
  48   std::string Error;
  49   const Target *TheTarget = TargetRegistry::lookupTarget(TripleName, Error);
  50   assert(TheTarget && "Unable to create target!");
  51
  52   // Get the assembler info needed to setup the MCContext.
  53   const MCAsmInfo *MAI = TheTarget->createAsmInfo(TripleName);
  54   assert(MAI && "Unable to create target asm info!");
  55
  56   // Package up features to be passed to target/subtarget
  57   std::string FeaturesStr;
  58   std::string CPU;
  59
  60   // FIXME: We shouldn't need to do this (and link in codegen).
  61   //        When we split this out, we should do it in a way that makes
  62   //        it straightforward to switch subtargets on the fly.
  63   TargetMachine *TM = TheTarget->createTargetMachine(TripleName, CPU,
  64                                                      FeaturesStr);
  65   assert(TM && "Unable to create target machine!");
  66
  67   // Get the target assembler info needed to setup the context.
  68   const TargetAsmInfo *tai = new TargetAsmInfo(*TM);
  69   assert(tai && "Unable to create target assembler!");
  70
  71   // Set up the MCContext for creating symbols and MCExpr's.
  72   MCContext *Ctx = new MCContext(*MAI, tai);
  73   assert(Ctx && "Unable to create MCContext!");
  74
  75   // Set up disassembler.
  76   MCDisassembler *DisAsm = TheTarget->createMCDisassembler();
  77   assert(DisAsm && "Unable to create disassembler!");
  78   DisAsm->setupForSymbolicDisassembly(GetOpInfo, DisInfo, Ctx);
  79
  80   // Set up the instruction printer.
  81   int AsmPrinterVariant = MAI->getAssemblerDialect();
  82   MCInstPrinter *IP = TheTarget->createMCInstPrinter(AsmPrinterVariant,
  83                                                      *MAI);
  84   assert(IP && "Unable to create instruction printer!");
  85
  86   LLVMDisasmContext *DC = new LLVMDisasmContext(TripleName, DisInfo, TagType,
  87                                                 GetOpInfo, SymbolLookUp,
  88                                                 TheTarget, MAI, TM, tai, Ctx,
  89                                                 DisAsm, IP);
  90   assert(DC && "Allocation failure!");
  91   return DC;
  92 }
  93
  94 //
  95 // LLVMDisasmDispose() disposes of the disassembler specified by the context.
  96 //
  97 void LLVMDisasmDispose(LLVMDisasmContextRef DCR){
  98   LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
  99   delete DC;
 100 }
 101
 102 namespace {
 103 //
 104 // The memory object created by LLVMDisasmInstruction().
 105 //
 106 class DisasmMemoryObject : public MemoryObject {
 107   uint8_t *Bytes;
 108   uint64_t Size;
 109   uint64_t BasePC;
 110 public:
 111   DisasmMemoryObject(uint8_t *bytes, uint64_t size, uint64_t basePC) :
 112                      Bytes(bytes), Size(size), BasePC(basePC) {}
 113
 114   uint64_t getBase() const { return BasePC; }
 115   uint64_t getExtent() const { return Size; }
 116
 117   int readByte(uint64_t Addr, uint8_t *Byte) const {
 118     if (Addr - BasePC >= Size)
 119       return -1;
 120     *Byte = Bytes[Addr - BasePC];
 121     return 0;
 122   }
 123 };
 124 } // end anonymous namespace
 125
 126 //
 127 // LLVMDisasmInstruction() disassembles a single instruction using the
 128 // disassembler context specified in the parameter DC.  The bytes of the
 129 // instruction are specified in the parameter Bytes, and contains at least
 130 // BytesSize number of bytes.  The instruction is at the address specified by
 131 // the PC parameter.  If a valid instruction can be disassembled its string is
 132 // returned indirectly in OutString which whos size is specified in the
 133 // parameter OutStringSize.  This function returns the number of bytes in the
 134 // instruction or zero if there was no valid instruction.  If this function
 135 // returns zero the caller will have to pick how many bytes they want to step
 136 // over by printing a .byte, .long etc. to continue.
 137 //
 138 size_t LLVMDisasmInstruction(LLVMDisasmContextRef DCR, uint8_t *Bytes,
 139                              uint64_t BytesSize, uint64_t PC, char *OutString,
 140                              size_t OutStringSize){
 141   LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
 142   // Wrap the pointer to the Bytes, BytesSize and PC in a MemoryObject.
 143   DisasmMemoryObject MemoryObject(Bytes, BytesSize, PC);
 144
 145   uint64_t Size;
 146   MCInst Inst;
 147   const MCDisassembler *DisAsm = DC->getDisAsm();
 148   MCInstPrinter *IP = DC->getIP();
 149   if (!DisAsm->getInstruction(Inst, Size, MemoryObject, PC, /*REMOVE*/ nulls()))
 150     return 0;
 151
 152   SmallVector<char, 64> InsnStr;
 153   raw_svector_ostream OS(InsnStr);
 154   IP->printInst(&Inst, OS);
 155   OS.flush();
 156
 157   assert(OutStringSize != 0 && "Output buffer cannot be zero size");
 158   size_t OutputSize = std::min(OutStringSize-1, InsnStr.size());
 159   std::memcpy(OutString, InsnStr.data(), OutputSize);
 160   OutString[OutputSize] = '\0'; // Terminate string.
 161
 162   return Size;
 163 }