Bug Summary

File:lib/MC/MCDisassembler/Disassembler.cpp
Warning:line 82, column 12
Potential leak of memory pointed to by 'Ctx'

Annotated Source Code

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#include "llvm/ADT/ArrayRef.h"
13#include "llvm/ADT/SmallVector.h"
14#include "llvm/ADT/Triple.h"
15#include "llvm/MC/MCAsmInfo.h"
16#include "llvm/MC/MCContext.h"
17#include "llvm/MC/MCDisassembler/MCDisassembler.h"
18#include "llvm/MC/MCDisassembler/MCRelocationInfo.h"
19#include "llvm/MC/MCDisassembler/MCSymbolizer.h"
20#include "llvm/MC/MCInst.h"
21#include "llvm/MC/MCInstPrinter.h"
22#include "llvm/MC/MCInstrDesc.h"
23#include "llvm/MC/MCInstrInfo.h"
24#include "llvm/MC/MCInstrItineraries.h"
25#include "llvm/MC/MCRegisterInfo.h"
26#include "llvm/MC/MCSchedule.h"
27#include "llvm/MC/MCSubtargetInfo.h"
28#include "llvm/Support/ErrorHandling.h"
29#include "llvm/Support/FormattedStream.h"
30#include "llvm/Support/raw_ostream.h"
31#include "llvm/Support/TargetRegistry.h"
32#include <cassert>
33#include <cstddef>
34#include <cstring>
35
36using namespace llvm;
37
38// LLVMCreateDisasm() creates a disassembler for the TripleName. Symbolic
39// disassembly is supported by passing a block of information in the DisInfo
40// parameter and specifying the TagType and callback functions as described in
41// the header llvm-c/Disassembler.h . The pointer to the block and the
42// functions can all be passed as NULL. If successful, this returns a
43// disassembler context. If not, it returns NULL.
44//
45LLVMDisasmContextRef
46LLVMCreateDisasmCPUFeatures(const char *TT, const char *CPU,
47 const char *Features, void *DisInfo, int TagType,
48 LLVMOpInfoCallback GetOpInfo,
49 LLVMSymbolLookupCallback SymbolLookUp) {
50 // Get the target.
51 std::string Error;
52 const Target *TheTarget = TargetRegistry::lookupTarget(TT, Error);
53 if (!TheTarget)
2
Assuming 'TheTarget' is non-null
3
Taking false branch
54 return nullptr;
55
56 const MCRegisterInfo *MRI = TheTarget->createMCRegInfo(TT);
57 if (!MRI)
4
Assuming 'MRI' is non-null
5
Taking false branch
58 return nullptr;
59
60 // Get the assembler info needed to setup the MCContext.
61 const MCAsmInfo *MAI = TheTarget->createMCAsmInfo(*MRI, TT);
62 if (!MAI)
6
Assuming 'MAI' is non-null
7
Taking false branch
63 return nullptr;
64
65 const MCInstrInfo *MII = TheTarget->createMCInstrInfo();
66 if (!MII)
8
Assuming 'MII' is non-null
9
Taking false branch
67 return nullptr;
68
69 const MCSubtargetInfo *STI =
70 TheTarget->createMCSubtargetInfo(TT, CPU, Features);
71 if (!STI)
10
Assuming 'STI' is non-null
11
Taking false branch
72 return nullptr;
73
74 // Set up the MCContext for creating symbols and MCExpr's.
75 MCContext *Ctx = new MCContext(MAI, MRI, nullptr);
12
Memory is allocated
76 if (!Ctx)
13
Taking false branch
77 return nullptr;
78
79 // Set up disassembler.
80 MCDisassembler *DisAsm = TheTarget->createMCDisassembler(*STI, *Ctx);
81 if (!DisAsm)
14
Taking true branch
82 return nullptr;
15
Potential leak of memory pointed to by 'Ctx'
83
84 std::unique_ptr<MCRelocationInfo> RelInfo(
85 TheTarget->createMCRelocationInfo(TT, *Ctx));
86 if (!RelInfo)
87 return nullptr;
88
89 std::unique_ptr<MCSymbolizer> Symbolizer(TheTarget->createMCSymbolizer(
90 TT, GetOpInfo, SymbolLookUp, DisInfo, Ctx, std::move(RelInfo)));
91 DisAsm->setSymbolizer(std::move(Symbolizer));
92
93 // Set up the instruction printer.
94 int AsmPrinterVariant = MAI->getAssemblerDialect();
95 MCInstPrinter *IP = TheTarget->createMCInstPrinter(
96 Triple(TT), AsmPrinterVariant, *MAI, *MII, *MRI);
97 if (!IP)
98 return nullptr;
99
100 LLVMDisasmContext *DC =
101 new LLVMDisasmContext(TT, DisInfo, TagType, GetOpInfo, SymbolLookUp,
102 TheTarget, MAI, MRI, STI, MII, Ctx, DisAsm, IP);
103 if (!DC)
104 return nullptr;
105
106 DC->setCPU(CPU);
107 return DC;
108}
109
110LLVMDisasmContextRef
111LLVMCreateDisasmCPU(const char *TT, const char *CPU, void *DisInfo, int TagType,
112 LLVMOpInfoCallback GetOpInfo,
113 LLVMSymbolLookupCallback SymbolLookUp) {
114 return LLVMCreateDisasmCPUFeatures(TT, CPU, "", DisInfo, TagType, GetOpInfo,
115 SymbolLookUp);
116}
117
118LLVMDisasmContextRef LLVMCreateDisasm(const char *TT, void *DisInfo,
119 int TagType, LLVMOpInfoCallback GetOpInfo,
120 LLVMSymbolLookupCallback SymbolLookUp) {
121 return LLVMCreateDisasmCPUFeatures(TT, "", "", DisInfo, TagType, GetOpInfo,
1
Calling 'LLVMCreateDisasmCPUFeatures'
122 SymbolLookUp);
123}
124
125//
126// LLVMDisasmDispose() disposes of the disassembler specified by the context.
127//
128void LLVMDisasmDispose(LLVMDisasmContextRef DCR){
129 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
130 delete DC;
131}
132
133/// \brief Emits the comments that are stored in \p DC comment stream.
134/// Each comment in the comment stream must end with a newline.
135static void emitComments(LLVMDisasmContext *DC,
136 formatted_raw_ostream &FormattedOS) {
137 // Flush the stream before taking its content.
138 StringRef Comments = DC->CommentsToEmit.str();
139 // Get the default information for printing a comment.
140 const MCAsmInfo *MAI = DC->getAsmInfo();
141 StringRef CommentBegin = MAI->getCommentString();
142 unsigned CommentColumn = MAI->getCommentColumn();
143 bool IsFirst = true;
144 while (!Comments.empty()) {
145 if (!IsFirst)
146 FormattedOS << '\n';
147 // Emit a line of comments.
148 FormattedOS.PadToColumn(CommentColumn);
149 size_t Position = Comments.find('\n');
150 FormattedOS << CommentBegin << ' ' << Comments.substr(0, Position);
151 // Move after the newline character.
152 Comments = Comments.substr(Position+1);
153 IsFirst = false;
154 }
155 FormattedOS.flush();
156
157 // Tell the comment stream that the vector changed underneath it.
158 DC->CommentsToEmit.clear();
159}
160
161/// \brief Gets latency information for \p Inst from the itinerary
162/// scheduling model, based on \p DC information.
163/// \return The maximum expected latency over all the operands or -1
164/// if no information is available.
165static int getItineraryLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
166 const int NoInformationAvailable = -1;
167
168 // Check if we have a CPU to get the itinerary information.
169 if (DC->getCPU().empty())
170 return NoInformationAvailable;
171
172 // Get itinerary information.
173 const MCSubtargetInfo *STI = DC->getSubtargetInfo();
174 InstrItineraryData IID = STI->getInstrItineraryForCPU(DC->getCPU());
175 // Get the scheduling class of the requested instruction.
176 const MCInstrDesc& Desc = DC->getInstrInfo()->get(Inst.getOpcode());
177 unsigned SCClass = Desc.getSchedClass();
178
179 int Latency = 0;
180 for (unsigned OpIdx = 0, OpIdxEnd = Inst.getNumOperands(); OpIdx != OpIdxEnd;
181 ++OpIdx)
182 Latency = std::max(Latency, IID.getOperandCycle(SCClass, OpIdx));
183
184 return Latency;
185}
186
187/// \brief Gets latency information for \p Inst, based on \p DC information.
188/// \return The maximum expected latency over all the definitions or -1
189/// if no information is available.
190static int getLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
191 // Try to compute scheduling information.
192 const MCSubtargetInfo *STI = DC->getSubtargetInfo();
193 const MCSchedModel SCModel = STI->getSchedModel();
194 const int NoInformationAvailable = -1;
195
196 // Check if we have a scheduling model for instructions.
197 if (!SCModel.hasInstrSchedModel())
198 // Try to fall back to the itinerary model if the scheduling model doesn't
199 // have a scheduling table. Note the default does not have a table.
200 return getItineraryLatency(DC, Inst);
201
202 // Get the scheduling class of the requested instruction.
203 const MCInstrDesc& Desc = DC->getInstrInfo()->get(Inst.getOpcode());
204 unsigned SCClass = Desc.getSchedClass();
205 const MCSchedClassDesc *SCDesc = SCModel.getSchedClassDesc(SCClass);
206 // Resolving the variant SchedClass requires an MI to pass to
207 // SubTargetInfo::resolveSchedClass.
208 if (!SCDesc || !SCDesc->isValid() || SCDesc->isVariant())
209 return NoInformationAvailable;
210
211 // Compute output latency.
212 int Latency = 0;
213 for (unsigned DefIdx = 0, DefEnd = SCDesc->NumWriteLatencyEntries;
214 DefIdx != DefEnd; ++DefIdx) {
215 // Lookup the definition's write latency in SubtargetInfo.
216 const MCWriteLatencyEntry *WLEntry = STI->getWriteLatencyEntry(SCDesc,
217 DefIdx);
218 Latency = std::max(Latency, WLEntry->Cycles);
219 }
220
221 return Latency;
222}
223
224/// \brief Emits latency information in DC->CommentStream for \p Inst, based
225/// on the information available in \p DC.
226static void emitLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
227 int Latency = getLatency(DC, Inst);
228
229 // Report only interesting latencies.
230 if (Latency < 2)
231 return;
232
233 DC->CommentStream << "Latency: " << Latency << '\n';
234}
235
236//
237// LLVMDisasmInstruction() disassembles a single instruction using the
238// disassembler context specified in the parameter DC. The bytes of the
239// instruction are specified in the parameter Bytes, and contains at least
240// BytesSize number of bytes. The instruction is at the address specified by
241// the PC parameter. If a valid instruction can be disassembled its string is
242// returned indirectly in OutString which whos size is specified in the
243// parameter OutStringSize. This function returns the number of bytes in the
244// instruction or zero if there was no valid instruction. If this function
245// returns zero the caller will have to pick how many bytes they want to step
246// over by printing a .byte, .long etc. to continue.
247//
248size_t LLVMDisasmInstruction(LLVMDisasmContextRef DCR, uint8_t *Bytes,
249 uint64_t BytesSize, uint64_t PC, char *OutString,
250 size_t OutStringSize){
251 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
252 // Wrap the pointer to the Bytes, BytesSize and PC in a MemoryObject.
253 ArrayRef<uint8_t> Data(Bytes, BytesSize);
254
255 uint64_t Size;
256 MCInst Inst;
257 const MCDisassembler *DisAsm = DC->getDisAsm();
258 MCInstPrinter *IP = DC->getIP();
259 MCDisassembler::DecodeStatus S;
260 SmallVector<char, 64> InsnStr;
261 raw_svector_ostream Annotations(InsnStr);
262 S = DisAsm->getInstruction(Inst, Size, Data, PC,
263 /*REMOVE*/ nulls(), Annotations);
264 switch (S) {
265 case MCDisassembler::Fail:
266 case MCDisassembler::SoftFail:
267 // FIXME: Do something different for soft failure modes?
268 return 0;
269
270 case MCDisassembler::Success: {
271 StringRef AnnotationsStr = Annotations.str();
272
273 SmallVector<char, 64> InsnStr;
274 raw_svector_ostream OS(InsnStr);
275 formatted_raw_ostream FormattedOS(OS);
276 IP->printInst(&Inst, FormattedOS, AnnotationsStr, *DC->getSubtargetInfo());
277
278 if (DC->getOptions() & LLVMDisassembler_Option_PrintLatency16)
279 emitLatency(DC, Inst);
280
281 emitComments(DC, FormattedOS);
282
283 assert(OutStringSize != 0 && "Output buffer cannot be zero size")((OutStringSize != 0 && "Output buffer cannot be zero size"
) ? static_cast<void> (0) : __assert_fail ("OutStringSize != 0 && \"Output buffer cannot be zero size\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301235/lib/MC/MCDisassembler/Disassembler.cpp"
, 283, __PRETTY_FUNCTION__))
;
284 size_t OutputSize = std::min(OutStringSize-1, InsnStr.size());
285 std::memcpy(OutString, InsnStr.data(), OutputSize);
286 OutString[OutputSize] = '\0'; // Terminate string.
287
288 return Size;
289 }
290 }
291 llvm_unreachable("Invalid DecodeStatus!")::llvm::llvm_unreachable_internal("Invalid DecodeStatus!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301235/lib/MC/MCDisassembler/Disassembler.cpp"
, 291)
;
292}
293
294//
295// LLVMSetDisasmOptions() sets the disassembler's options. It returns 1 if it
296// can set all the Options and 0 otherwise.
297//
298int LLVMSetDisasmOptions(LLVMDisasmContextRef DCR, uint64_t Options){
299 if (Options & LLVMDisassembler_Option_UseMarkup1){
300 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
301 MCInstPrinter *IP = DC->getIP();
302 IP->setUseMarkup(true);
303 DC->addOptions(LLVMDisassembler_Option_UseMarkup1);
304 Options &= ~LLVMDisassembler_Option_UseMarkup1;
305 }
306 if (Options & LLVMDisassembler_Option_PrintImmHex2){
307 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
308 MCInstPrinter *IP = DC->getIP();
309 IP->setPrintImmHex(true);
310 DC->addOptions(LLVMDisassembler_Option_PrintImmHex2);
311 Options &= ~LLVMDisassembler_Option_PrintImmHex2;
312 }
313 if (Options & LLVMDisassembler_Option_AsmPrinterVariant4){
314 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
315 // Try to set up the new instruction printer.
316 const MCAsmInfo *MAI = DC->getAsmInfo();
317 const MCInstrInfo *MII = DC->getInstrInfo();
318 const MCRegisterInfo *MRI = DC->getRegisterInfo();
319 int AsmPrinterVariant = MAI->getAssemblerDialect();
320 AsmPrinterVariant = AsmPrinterVariant == 0 ? 1 : 0;
321 MCInstPrinter *IP = DC->getTarget()->createMCInstPrinter(
322 Triple(DC->getTripleName()), AsmPrinterVariant, *MAI, *MII, *MRI);
323 if (IP) {
324 DC->setIP(IP);
325 DC->addOptions(LLVMDisassembler_Option_AsmPrinterVariant4);
326 Options &= ~LLVMDisassembler_Option_AsmPrinterVariant4;
327 }
328 }
329 if (Options & LLVMDisassembler_Option_SetInstrComments8) {
330 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
331 MCInstPrinter *IP = DC->getIP();
332 IP->setCommentStream(DC->CommentStream);
333 DC->addOptions(LLVMDisassembler_Option_SetInstrComments8);
334 Options &= ~LLVMDisassembler_Option_SetInstrComments8;
335 }
336 if (Options & LLVMDisassembler_Option_PrintLatency16) {
337 LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
338 DC->addOptions(LLVMDisassembler_Option_PrintLatency16);
339 Options &= ~LLVMDisassembler_Option_PrintLatency16;
340 }
341 return (Options == 0);
342}