1//===-- lib/MC/Disassembler.cpp - Disassembler Public C Interface ---------===//
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/MCContext.h"
15#include "llvm/MC/MCDisassembler.h"
16#include "llvm/MC/MCInst.h"
17#include "llvm/MC/MCInstPrinter.h"
18#include "llvm/MC/MCRegisterInfo.h"
19#include "llvm/Support/MemoryObject.h"
20#include "llvm/Support/TargetRegistry.h"
21#include "llvm/Support/TargetSelect.h"
22
23namespace llvm {
24class Target;
25} // namespace llvm
26using namespace llvm;
27
28// LLVMCreateDisasm() creates a disassembler for the TripleName.  Symbolic
29// disassembly is supported by passing a block of information in the DisInfo
30// parameter and specifying the TagType and callback functions as described in
31// the header llvm-c/Disassembler.h .  The pointer to the block and the
32// functions can all be passed as NULL.  If successful, this returns a
33// disassembler context.  If not, it returns NULL.
34//
35LLVMDisasmContextRef LLVMCreateDisasm(const char *TripleName, void *DisInfo,
36                                      int TagType, LLVMOpInfoCallback GetOpInfo,
37                                      LLVMSymbolLookupCallback SymbolLookUp) {
38  // Initialize targets and assembly printers/parsers.
39  llvm::InitializeAllTargetInfos();
40  llvm::InitializeAllTargetMCs();
41  llvm::InitializeAllAsmParsers();
42  llvm::InitializeAllDisassemblers();
43
44  // Get the target.
45  std::string Error;
46  const Target *TheTarget = TargetRegistry::lookupTarget(TripleName, Error);
47  assert(TheTarget && "Unable to create target!");
48
49  // Get the assembler info needed to setup the MCContext.
50  const MCAsmInfo *MAI = TheTarget->createMCAsmInfo(TripleName);
51  assert(MAI && "Unable to create target asm info!");
52
53  const MCRegisterInfo *MRI = TheTarget->createMCRegInfo(TripleName);
54  assert(MRI && "Unable to create target register info!");
55
56  // Package up features to be passed to target/subtarget
57  std::string FeaturesStr;
58  std::string CPU;
59
60  const MCSubtargetInfo *STI = TheTarget->createMCSubtargetInfo(TripleName, CPU,
61                                                                FeaturesStr);
62  assert(STI && "Unable to create subtarget info!");
63
64  // Set up the MCContext for creating symbols and MCExpr's.
65  MCContext *Ctx = new MCContext(*MAI, *MRI, 0);
66  assert(Ctx && "Unable to create MCContext!");
67
68  // Set up disassembler.
69  MCDisassembler *DisAsm = TheTarget->createMCDisassembler(*STI);
70  assert(DisAsm && "Unable to create disassembler!");
71  DisAsm->setupForSymbolicDisassembly(GetOpInfo, SymbolLookUp, DisInfo, Ctx);
72
73  // Set up the instruction printer.
74  int AsmPrinterVariant = MAI->getAssemblerDialect();
75  MCInstPrinter *IP = TheTarget->createMCInstPrinter(AsmPrinterVariant,
76                                                     *MAI, *STI);
77  assert(IP && "Unable to create instruction printer!");
78
79  LLVMDisasmContext *DC = new LLVMDisasmContext(TripleName, DisInfo, TagType,
80                                                GetOpInfo, SymbolLookUp,
81                                                TheTarget, MAI, MRI,
82                                                Ctx, DisAsm, IP);
83  assert(DC && "Allocation failure!");
84
85  return DC;
86}
87
88//
89// LLVMDisasmDispose() disposes of the disassembler specified by the context.
90//
91void LLVMDisasmDispose(LLVMDisasmContextRef DCR){
92  LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
93  delete DC;
94}
95
96namespace {
97//
98// The memory object created by LLVMDisasmInstruction().
99//
100class DisasmMemoryObject : public MemoryObject {
101  uint8_t *Bytes;
102  uint64_t Size;
103  uint64_t BasePC;
104public:
105  DisasmMemoryObject(uint8_t *bytes, uint64_t size, uint64_t basePC) :
106                     Bytes(bytes), Size(size), BasePC(basePC) {}
107
108  uint64_t getBase() const { return BasePC; }
109  uint64_t getExtent() const { return Size; }
110
111  int readByte(uint64_t Addr, uint8_t *Byte) const {
112    if (Addr - BasePC >= Size)
113      return -1;
114    *Byte = Bytes[Addr - BasePC];
115    return 0;
116  }
117};
118} // end anonymous namespace
119
120//
121// LLVMDisasmInstruction() disassembles a single instruction using the
122// disassembler context specified in the parameter DC.  The bytes of the
123// instruction are specified in the parameter Bytes, and contains at least
124// BytesSize number of bytes.  The instruction is at the address specified by
125// the PC parameter.  If a valid instruction can be disassembled its string is
126// returned indirectly in OutString which whos size is specified in the
127// parameter OutStringSize.  This function returns the number of bytes in the
128// instruction or zero if there was no valid instruction.  If this function
129// returns zero the caller will have to pick how many bytes they want to step
130// over by printing a .byte, .long etc. to continue.
131//
132size_t LLVMDisasmInstruction(LLVMDisasmContextRef DCR, uint8_t *Bytes,
133                             uint64_t BytesSize, uint64_t PC, char *OutString,
134                             size_t OutStringSize){
135  LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
136  // Wrap the pointer to the Bytes, BytesSize and PC in a MemoryObject.
137  DisasmMemoryObject MemoryObject(Bytes, BytesSize, PC);
138
139  uint64_t Size;
140  MCInst Inst;
141  const MCDisassembler *DisAsm = DC->getDisAsm();
142  MCInstPrinter *IP = DC->getIP();
143  MCDisassembler::DecodeStatus S;
144  S = DisAsm->getInstruction(Inst, Size, MemoryObject, PC,
145                             /*REMOVE*/ nulls(), DC->CommentStream);
146  switch (S) {
147  case MCDisassembler::Fail:
148  case MCDisassembler::SoftFail:
149    // FIXME: Do something different for soft failure modes?
150    return 0;
151
152  case MCDisassembler::Success: {
153    DC->CommentStream.flush();
154    StringRef Comments = DC->CommentsToEmit.str();
155
156    SmallVector<char, 64> InsnStr;
157    raw_svector_ostream OS(InsnStr);
158    IP->printInst(&Inst, OS, Comments);
159    OS.flush();
160
161    // Tell the comment stream that the vector changed underneath it.
162    DC->CommentsToEmit.clear();
163    DC->CommentStream.resync();
164
165    assert(OutStringSize != 0 && "Output buffer cannot be zero size");
166    size_t OutputSize = std::min(OutStringSize-1, InsnStr.size());
167    std::memcpy(OutString, InsnStr.data(), OutputSize);
168    OutString[OutputSize] = '\0'; // Terminate string.
169
170    return Size;
171  }
172  }
173  return 0;
174}
175