1//===-- lib/MC/Disassembler.cpp - Disassembler Public C Interface ---------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "Disassembler.h"
10#include "llvm-c/Disassembler.h"
11#include "llvm/ADT/ArrayRef.h"
12#include "llvm/ADT/SmallVector.h"
13#include "llvm/MC/MCAsmInfo.h"
14#include "llvm/MC/MCContext.h"
15#include "llvm/MC/MCDisassembler/MCDisassembler.h"
16#include "llvm/MC/MCDisassembler/MCRelocationInfo.h"
17#include "llvm/MC/MCDisassembler/MCSymbolizer.h"
18#include "llvm/MC/MCInst.h"
19#include "llvm/MC/MCInstPrinter.h"
20#include "llvm/MC/MCInstrDesc.h"
21#include "llvm/MC/MCInstrInfo.h"
22#include "llvm/MC/MCInstrItineraries.h"
23#include "llvm/MC/MCRegisterInfo.h"
24#include "llvm/MC/MCSchedule.h"
25#include "llvm/MC/MCSubtargetInfo.h"
26#include "llvm/MC/MCTargetOptions.h"
27#include "llvm/MC/TargetRegistry.h"
28#include "llvm/Support/ErrorHandling.h"
29#include "llvm/Support/FormattedStream.h"
30#include "llvm/Support/raw_ostream.h"
31#include "llvm/TargetParser/Triple.h"
32#include <cassert>
33#include <cstring>
34
35using namespace llvm;
36
37// LLVMCreateDisasm() creates a disassembler for the TripleName. Symbolic
38// disassembly is supported by passing a block of information in the DisInfo
39// parameter and specifying the TagType and callback functions as described in
40// the header llvm-c/Disassembler.h . The pointer to the block and the
41// functions can all be passed as NULL. If successful, this returns a
42// disassembler context. If not, it returns NULL.
43//
44LLVMDisasmContextRef
45LLVMCreateDisasmCPUFeatures(const char *TT, const char *CPU,
46 const char *Features, void *DisInfo, int TagType,
47 LLVMOpInfoCallback GetOpInfo,
48 LLVMSymbolLookupCallback SymbolLookUp) {
49 // Get the target.
50 std::string Error;
51 const Target *TheTarget = TargetRegistry::lookupTarget(Triple: TT, Error);
52 if (!TheTarget)
53 return nullptr;
54
55 std::unique_ptr<const MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TT));
56 if (!MRI)
57 return nullptr;
58
59 MCTargetOptions MCOptions;
60 // Get the assembler info needed to setup the MCContext.
61 std::unique_ptr<const MCAsmInfo> MAI(
62 TheTarget->createMCAsmInfo(MRI: *MRI, TheTriple: TT, Options: MCOptions));
63 if (!MAI)
64 return nullptr;
65
66 std::unique_ptr<const MCInstrInfo> MII(TheTarget->createMCInstrInfo());
67 if (!MII)
68 return nullptr;
69
70 std::unique_ptr<const MCSubtargetInfo> STI(
71 TheTarget->createMCSubtargetInfo(TheTriple: TT, CPU, Features));
72 if (!STI)
73 return nullptr;
74
75 // Set up the MCContext for creating symbols and MCExpr's.
76 std::unique_ptr<MCContext> Ctx(
77 new MCContext(Triple(TT), MAI.get(), MRI.get(), STI.get()));
78 if (!Ctx)
79 return nullptr;
80
81 // Set up disassembler.
82 std::unique_ptr<MCDisassembler> DisAsm(
83 TheTarget->createMCDisassembler(STI: *STI, Ctx&: *Ctx));
84 if (!DisAsm)
85 return nullptr;
86
87 std::unique_ptr<MCRelocationInfo> RelInfo(
88 TheTarget->createMCRelocationInfo(TT, Ctx&: *Ctx));
89 if (!RelInfo)
90 return nullptr;
91
92 std::unique_ptr<MCSymbolizer> Symbolizer(TheTarget->createMCSymbolizer(
93 TT, GetOpInfo, SymbolLookUp, DisInfo, Ctx: Ctx.get(), RelInfo: std::move(RelInfo)));
94 DisAsm->setSymbolizer(std::move(Symbolizer));
95
96 // Set up the instruction printer.
97 int AsmPrinterVariant = MAI->getAssemblerDialect();
98 std::unique_ptr<MCInstPrinter> IP(TheTarget->createMCInstPrinter(
99 T: Triple(TT), SyntaxVariant: AsmPrinterVariant, MAI: *MAI, MII: *MII, MRI: *MRI));
100 if (!IP)
101 return nullptr;
102
103 LLVMDisasmContext *DC = new LLVMDisasmContext(
104 TT, DisInfo, TagType, GetOpInfo, SymbolLookUp, TheTarget, std::move(MAI),
105 std::move(MRI), std::move(STI), std::move(MII), std::move(Ctx),
106 std::move(DisAsm), std::move(IP));
107 if (!DC)
108 return nullptr;
109
110 DC->setCPU(CPU);
111 return DC;
112}
113
114LLVMDisasmContextRef
115LLVMCreateDisasmCPU(const char *TT, const char *CPU, void *DisInfo, int TagType,
116 LLVMOpInfoCallback GetOpInfo,
117 LLVMSymbolLookupCallback SymbolLookUp) {
118 return LLVMCreateDisasmCPUFeatures(TT, CPU, Features: "", DisInfo, TagType, GetOpInfo,
119 SymbolLookUp);
120}
121
122LLVMDisasmContextRef LLVMCreateDisasm(const char *TT, void *DisInfo,
123 int TagType, LLVMOpInfoCallback GetOpInfo,
124 LLVMSymbolLookupCallback SymbolLookUp) {
125 return LLVMCreateDisasmCPUFeatures(TT, CPU: "", Features: "", DisInfo, TagType, GetOpInfo,
126 SymbolLookUp);
127}
128
129//
130// LLVMDisasmDispose() disposes of the disassembler specified by the context.
131//
132void LLVMDisasmDispose(LLVMDisasmContextRef DCR){
133 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
134 delete DC;
135}
136
137/// Emits the comments that are stored in \p DC comment stream.
138/// Each comment in the comment stream must end with a newline.
139static void emitComments(LLVMDisasmContext *DC,
140 formatted_raw_ostream &FormattedOS) {
141 // Flush the stream before taking its content.
142 StringRef Comments = DC->CommentsToEmit.str();
143 // Get the default information for printing a comment.
144 const MCAsmInfo *MAI = DC->getAsmInfo();
145 StringRef CommentBegin = MAI->getCommentString();
146 unsigned CommentColumn = MAI->getCommentColumn();
147 bool IsFirst = true;
148 while (!Comments.empty()) {
149 if (!IsFirst)
150 FormattedOS << '\n';
151 // Emit a line of comments.
152 FormattedOS.PadToColumn(NewCol: CommentColumn);
153 size_t Position = Comments.find(C: '\n');
154 FormattedOS << CommentBegin << ' ' << Comments.substr(Start: 0, N: Position);
155 // Move after the newline character.
156 Comments = Comments.substr(Start: Position+1);
157 IsFirst = false;
158 }
159 FormattedOS.flush();
160
161 // Tell the comment stream that the vector changed underneath it.
162 DC->CommentsToEmit.clear();
163}
164
165/// Gets latency information for \p Inst from the itinerary
166/// scheduling model, based on \p DC information.
167/// \return The maximum expected latency over all the operands or -1
168/// if no information is available.
169static int getItineraryLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
170 const int NoInformationAvailable = -1;
171
172 // Check if we have a CPU to get the itinerary information.
173 if (DC->getCPU().empty())
174 return NoInformationAvailable;
175
176 // Get itinerary information.
177 const MCSubtargetInfo *STI = DC->getSubtargetInfo();
178 InstrItineraryData IID = STI->getInstrItineraryForCPU(CPU: DC->getCPU());
179 // Get the scheduling class of the requested instruction.
180 const MCInstrDesc& Desc = DC->getInstrInfo()->get(Opcode: Inst.getOpcode());
181 unsigned SCClass = Desc.getSchedClass();
182
183 unsigned Latency = 0;
184
185 for (unsigned Idx = 0, IdxEnd = Inst.getNumOperands(); Idx != IdxEnd; ++Idx)
186 if (std::optional<unsigned> OperCycle = IID.getOperandCycle(ItinClassIndx: SCClass, OperandIdx: Idx))
187 Latency = std::max(a: Latency, b: *OperCycle);
188
189 return (int)Latency;
190}
191
192/// Gets latency information for \p Inst, based on \p DC information.
193/// \return The maximum expected latency over all the definitions or -1
194/// if no information is available.
195static int getLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
196 // Try to compute scheduling information.
197 const MCSubtargetInfo *STI = DC->getSubtargetInfo();
198 const MCSchedModel SCModel = STI->getSchedModel();
199 const int NoInformationAvailable = -1;
200
201 // Check if we have a scheduling model for instructions.
202 if (!SCModel.hasInstrSchedModel())
203 // Try to fall back to the itinerary model if the scheduling model doesn't
204 // have a scheduling table. Note the default does not have a table.
205 return getItineraryLatency(DC, Inst);
206
207 // Get the scheduling class of the requested instruction.
208 const MCInstrDesc& Desc = DC->getInstrInfo()->get(Opcode: Inst.getOpcode());
209 unsigned SCClass = Desc.getSchedClass();
210 const MCSchedClassDesc *SCDesc = SCModel.getSchedClassDesc(SchedClassIdx: SCClass);
211 // Resolving the variant SchedClass requires an MI to pass to
212 // SubTargetInfo::resolveSchedClass.
213 if (!SCDesc || !SCDesc->isValid() || SCDesc->isVariant())
214 return NoInformationAvailable;
215
216 // Compute output latency.
217 int16_t Latency = 0;
218 for (unsigned DefIdx = 0, DefEnd = SCDesc->NumWriteLatencyEntries;
219 DefIdx != DefEnd; ++DefIdx) {
220 // Lookup the definition's write latency in SubtargetInfo.
221 const MCWriteLatencyEntry *WLEntry = STI->getWriteLatencyEntry(SC: SCDesc,
222 DefIdx);
223 Latency = std::max(a: Latency, b: WLEntry->Cycles);
224 }
225
226 return Latency;
227}
228
229/// Emits latency information in DC->CommentStream for \p Inst, based
230/// on the information available in \p DC.
231static void emitLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
232 int Latency = getLatency(DC, Inst);
233
234 // Report only interesting latencies.
235 if (Latency < 2)
236 return;
237
238 DC->CommentStream << "Latency: " << Latency << '\n';
239}
240
241//
242// LLVMDisasmInstruction() disassembles a single instruction using the
243// disassembler context specified in the parameter DC. The bytes of the
244// instruction are specified in the parameter Bytes, and contains at least
245// BytesSize number of bytes. The instruction is at the address specified by
246// the PC parameter. If a valid instruction can be disassembled its string is
247// returned indirectly in OutString which whos size is specified in the
248// parameter OutStringSize. This function returns the number of bytes in the
249// instruction or zero if there was no valid instruction. If this function
250// returns zero the caller will have to pick how many bytes they want to step
251// over by printing a .byte, .long etc. to continue.
252//
253size_t LLVMDisasmInstruction(LLVMDisasmContextRef DCR, uint8_t *Bytes,
254 uint64_t BytesSize, uint64_t PC, char *OutString,
255 size_t OutStringSize){
256 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
257 // Wrap the pointer to the Bytes, BytesSize and PC in a MemoryObject.
258 ArrayRef<uint8_t> Data(Bytes, BytesSize);
259
260 uint64_t Size;
261 MCInst Inst;
262 const MCDisassembler *DisAsm = DC->getDisAsm();
263 MCInstPrinter *IP = DC->getIP();
264 MCDisassembler::DecodeStatus S;
265 SmallVector<char, 64> InsnStr;
266 raw_svector_ostream Annotations(InsnStr);
267 S = DisAsm->getInstruction(Instr&: Inst, Size, Bytes: Data, Address: PC, CStream&: Annotations);
268 switch (S) {
269 case MCDisassembler::Fail:
270 case MCDisassembler::SoftFail:
271 // FIXME: Do something different for soft failure modes?
272 return 0;
273
274 case MCDisassembler::Success: {
275 StringRef AnnotationsStr = Annotations.str();
276
277 SmallVector<char, 64> InsnStr;
278 raw_svector_ostream OS(InsnStr);
279 formatted_raw_ostream FormattedOS(OS);
280 IP->printInst(MI: &Inst, Address: PC, Annot: AnnotationsStr, STI: *DC->getSubtargetInfo(),
281 OS&: FormattedOS);
282
283 if (DC->getOptions() & LLVMDisassembler_Option_PrintLatency)
284 emitLatency(DC, Inst);
285
286 emitComments(DC, FormattedOS);
287
288 assert(OutStringSize != 0 && "Output buffer cannot be zero size");
289 size_t OutputSize = std::min(a: OutStringSize-1, b: InsnStr.size());
290 std::memcpy(dest: OutString, src: InsnStr.data(), n: OutputSize);
291 OutString[OutputSize] = '\0'; // Terminate string.
292
293 return Size;
294 }
295 }
296 llvm_unreachable("Invalid DecodeStatus!");
297}
298
299//
300// LLVMSetDisasmOptions() sets the disassembler's options. It returns 1 if it
301// can set all the Options and 0 otherwise.
302//
303int LLVMSetDisasmOptions(LLVMDisasmContextRef DCR, uint64_t Options){
304 if (Options & LLVMDisassembler_Option_UseMarkup){
305 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
306 MCInstPrinter *IP = DC->getIP();
307 IP->setUseMarkup(true);
308 DC->addOptions(LLVMDisassembler_Option_UseMarkup);
309 Options &= ~LLVMDisassembler_Option_UseMarkup;
310 }
311 if (Options & LLVMDisassembler_Option_PrintImmHex){
312 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
313 MCInstPrinter *IP = DC->getIP();
314 IP->setPrintImmHex(true);
315 DC->addOptions(LLVMDisassembler_Option_PrintImmHex);
316 Options &= ~LLVMDisassembler_Option_PrintImmHex;
317 }
318 if (Options & LLVMDisassembler_Option_AsmPrinterVariant){
319 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
320 // Try to set up the new instruction printer.
321 const MCAsmInfo *MAI = DC->getAsmInfo();
322 const MCInstrInfo *MII = DC->getInstrInfo();
323 const MCRegisterInfo *MRI = DC->getRegisterInfo();
324 int AsmPrinterVariant = MAI->getAssemblerDialect();
325 AsmPrinterVariant = AsmPrinterVariant == 0 ? 1 : 0;
326 MCInstPrinter *IP = DC->getTarget()->createMCInstPrinter(
327 T: Triple(DC->getTripleName()), SyntaxVariant: AsmPrinterVariant, MAI: *MAI, MII: *MII, MRI: *MRI);
328 if (IP) {
329 DC->setIP(IP);
330 DC->addOptions(LLVMDisassembler_Option_AsmPrinterVariant);
331 Options &= ~LLVMDisassembler_Option_AsmPrinterVariant;
332 }
333 }
334 if (Options & LLVMDisassembler_Option_SetInstrComments) {
335 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
336 MCInstPrinter *IP = DC->getIP();
337 IP->setCommentStream(DC->CommentStream);
338 DC->addOptions(LLVMDisassembler_Option_SetInstrComments);
339 Options &= ~LLVMDisassembler_Option_SetInstrComments;
340 }
341 if (Options & LLVMDisassembler_Option_PrintLatency) {
342 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
343 DC->addOptions(LLVMDisassembler_Option_PrintLatency);
344 Options &= ~LLVMDisassembler_Option_PrintLatency;
345 }
346 return (Options == 0);
347}
348

source code of llvm/lib/MC/MCDisassembler/Disassembler.cpp