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/MCInstrInfo.h"
19 #include "llvm/MC/MCRegisterInfo.h"
20 #include "llvm/MC/MCSubtargetInfo.h"
21 #include "llvm/Support/MemoryObject.h"
22 #include "llvm/Support/TargetRegistry.h"
23 #include "llvm/Support/TargetSelect.h"
24 #include "llvm/Support/ErrorHandling.h"
25
26 namespace llvm {
27 class Target;
28 } // namespace llvm
29 using namespace llvm;
30
31 // LLVMCreateDisasm() creates a disassembler for the TripleName. Symbolic
32 // disassembly is supported by passing a block of information in the DisInfo
33 // parameter and specifying the TagType and callback functions as described in
34 // the header llvm-c/Disassembler.h . The pointer to the block and the
35 // functions can all be passed as NULL. If successful, this returns a
36 // disassembler context. If not, it returns NULL.
37 //
LLVMCreateDisasm(const char * TripleName,void * DisInfo,int TagType,LLVMOpInfoCallback GetOpInfo,LLVMSymbolLookupCallback SymbolLookUp)38 LLVMDisasmContextRef LLVMCreateDisasm(const char *TripleName, void *DisInfo,
39 int TagType, LLVMOpInfoCallback GetOpInfo,
40 LLVMSymbolLookupCallback SymbolLookUp) {
41 // Initialize targets and assembly printers/parsers.
42 // FIXME: Clients are responsible for initializing the targets. And this
43 // would be done by calling routines in "llvm-c/Target.h" which are static
44 // line functions. But the current use of LLVMCreateDisasm() is to dynamically
45 // load libLTO with dlopen() and then lookup the symbols using dlsym().
46 // And since these initialize routines are static that does not work which
47 // is why the call to them in this 'C' library API was added back.
48 llvm::InitializeAllTargetInfos();
49 llvm::InitializeAllTargetMCs();
50 llvm::InitializeAllAsmParsers();
51 llvm::InitializeAllDisassemblers();
52
53 // Get the target.
54 std::string Error;
55 const Target *TheTarget = TargetRegistry::lookupTarget(TripleName, Error);
56 assert(TheTarget && "Unable to create target!");
57
58 // Get the assembler info needed to setup the MCContext.
59 const MCAsmInfo *MAI = TheTarget->createMCAsmInfo(TripleName);
60 assert(MAI && "Unable to create target asm info!");
61
62 const MCInstrInfo *MII = TheTarget->createMCInstrInfo();
63 assert(MII && "Unable to create target instruction info!");
64
65 const MCRegisterInfo *MRI = TheTarget->createMCRegInfo(TripleName);
66 assert(MRI && "Unable to create target register info!");
67
68 // Package up features to be passed to target/subtarget
69 std::string FeaturesStr;
70 std::string CPU;
71
72 const MCSubtargetInfo *STI = TheTarget->createMCSubtargetInfo(TripleName, CPU,
73 FeaturesStr);
74 assert(STI && "Unable to create subtarget info!");
75
76 // Set up the MCContext for creating symbols and MCExpr's.
77 MCContext *Ctx = new MCContext(*MAI, *MRI, 0);
78 assert(Ctx && "Unable to create MCContext!");
79
80 // Set up disassembler.
81 MCDisassembler *DisAsm = TheTarget->createMCDisassembler(*STI);
82 assert(DisAsm && "Unable to create disassembler!");
83 DisAsm->setupForSymbolicDisassembly(GetOpInfo, SymbolLookUp, DisInfo, Ctx);
84
85 // Set up the instruction printer.
86 int AsmPrinterVariant = MAI->getAssemblerDialect();
87 MCInstPrinter *IP = TheTarget->createMCInstPrinter(AsmPrinterVariant,
88 *MAI, *MII, *MRI, *STI);
89 assert(IP && "Unable to create instruction printer!");
90
91 LLVMDisasmContext *DC = new LLVMDisasmContext(TripleName, DisInfo, TagType,
92 GetOpInfo, SymbolLookUp,
93 TheTarget, MAI, MRI,
94 STI, MII, Ctx, DisAsm, IP);
95 assert(DC && "Allocation failure!");
96
97 return DC;
98 }
99
100 //
101 // LLVMDisasmDispose() disposes of the disassembler specified by the context.
102 //
LLVMDisasmDispose(LLVMDisasmContextRef DCR)103 void LLVMDisasmDispose(LLVMDisasmContextRef DCR){
104 LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
105 delete DC;
106 }
107
108 namespace {
109 //
110 // The memory object created by LLVMDisasmInstruction().
111 //
112 class DisasmMemoryObject : public MemoryObject {
113 uint8_t *Bytes;
114 uint64_t Size;
115 uint64_t BasePC;
116 public:
DisasmMemoryObject(uint8_t * bytes,uint64_t size,uint64_t basePC)117 DisasmMemoryObject(uint8_t *bytes, uint64_t size, uint64_t basePC) :
118 Bytes(bytes), Size(size), BasePC(basePC) {}
119
getBase() const120 uint64_t getBase() const { return BasePC; }
getExtent() const121 uint64_t getExtent() const { return Size; }
122
readByte(uint64_t Addr,uint8_t * Byte) const123 int readByte(uint64_t Addr, uint8_t *Byte) const {
124 if (Addr - BasePC >= Size)
125 return -1;
126 *Byte = Bytes[Addr - BasePC];
127 return 0;
128 }
129 };
130 } // end anonymous namespace
131
132 //
133 // LLVMDisasmInstruction() disassembles a single instruction using the
134 // disassembler context specified in the parameter DC. The bytes of the
135 // instruction are specified in the parameter Bytes, and contains at least
136 // BytesSize number of bytes. The instruction is at the address specified by
137 // the PC parameter. If a valid instruction can be disassembled its string is
138 // returned indirectly in OutString which whos size is specified in the
139 // parameter OutStringSize. This function returns the number of bytes in the
140 // instruction or zero if there was no valid instruction. If this function
141 // returns zero the caller will have to pick how many bytes they want to step
142 // over by printing a .byte, .long etc. to continue.
143 //
LLVMDisasmInstruction(LLVMDisasmContextRef DCR,uint8_t * Bytes,uint64_t BytesSize,uint64_t PC,char * OutString,size_t OutStringSize)144 size_t LLVMDisasmInstruction(LLVMDisasmContextRef DCR, uint8_t *Bytes,
145 uint64_t BytesSize, uint64_t PC, char *OutString,
146 size_t OutStringSize){
147 LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
148 // Wrap the pointer to the Bytes, BytesSize and PC in a MemoryObject.
149 DisasmMemoryObject MemoryObject(Bytes, BytesSize, PC);
150
151 uint64_t Size;
152 MCInst Inst;
153 const MCDisassembler *DisAsm = DC->getDisAsm();
154 MCInstPrinter *IP = DC->getIP();
155 MCDisassembler::DecodeStatus S;
156 S = DisAsm->getInstruction(Inst, Size, MemoryObject, PC,
157 /*REMOVE*/ nulls(), DC->CommentStream);
158 switch (S) {
159 case MCDisassembler::Fail:
160 case MCDisassembler::SoftFail:
161 // FIXME: Do something different for soft failure modes?
162 return 0;
163
164 case MCDisassembler::Success: {
165 DC->CommentStream.flush();
166 StringRef Comments = DC->CommentsToEmit.str();
167
168 SmallVector<char, 64> InsnStr;
169 raw_svector_ostream OS(InsnStr);
170 IP->printInst(&Inst, OS, Comments);
171 OS.flush();
172
173 // Tell the comment stream that the vector changed underneath it.
174 DC->CommentsToEmit.clear();
175 DC->CommentStream.resync();
176
177 assert(OutStringSize != 0 && "Output buffer cannot be zero size");
178 size_t OutputSize = std::min(OutStringSize-1, InsnStr.size());
179 std::memcpy(OutString, InsnStr.data(), OutputSize);
180 OutString[OutputSize] = '\0'; // Terminate string.
181
182 return Size;
183 }
184 }
185 llvm_unreachable("Invalid DecodeStatus!");
186 }
187