xref: /freebsd/contrib/llvm-project/llvm/lib/Remarks/BitstreamRemarkParser.cpp (revision 9dba64be9536c28e4800e06512b7f29b43ade345) 
1 //===- BitstreamRemarkParser.cpp ------------------------------------------===//
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 // This file provides utility methods used by clients that want to use the
10 // parser for remark diagnostics in LLVM.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Remarks/BitstreamRemarkParser.h"
15 #include "BitstreamRemarkParser.h"
16 #include "llvm/Remarks/BitstreamRemarkContainer.h"
17 #include "llvm/Support/MemoryBuffer.h"
18 #include "llvm/Support/Path.h"
19 
20 using namespace llvm;
21 using namespace llvm::remarks;
22 
23 static Error unknownRecord(const char *BlockName, unsigned RecordID) {
24   return createStringError(
25       std::make_error_code(std::errc::illegal_byte_sequence),
26       "Error while parsing %s: unknown record entry (%lu).", BlockName,
27       RecordID);
28 }
29 
30 static Error malformedRecord(const char *BlockName, const char *RecordName) {
31   return createStringError(
32       std::make_error_code(std::errc::illegal_byte_sequence),
33       "Error while parsing %s: malformed record entry (%s).", BlockName,
34       RecordName);
35 }
36 
37 BitstreamMetaParserHelper::BitstreamMetaParserHelper(
38     BitstreamCursor &Stream, BitstreamBlockInfo &BlockInfo)
39     : Stream(Stream), BlockInfo(BlockInfo) {}
40 
41 /// Parse a record and fill in the fields in the parser.
42 static Error parseRecord(BitstreamMetaParserHelper &Parser, unsigned Code) {
43   BitstreamCursor &Stream = Parser.Stream;
44   // Note: 2 is used here because it's the max number of fields we have per
45   // record.
46   SmallVector<uint64_t, 2> Record;
47   StringRef Blob;
48   Expected<unsigned> RecordID = Stream.readRecord(Code, Record, &Blob);
49   if (!RecordID)
50     return RecordID.takeError();
51 
52   switch (*RecordID) {
53   case RECORD_META_CONTAINER_INFO: {
54     if (Record.size() != 2)
55       return malformedRecord("BLOCK_META", "RECORD_META_CONTAINER_INFO");
56     Parser.ContainerVersion = Record[0];
57     Parser.ContainerType = Record[1];
58     break;
59   }
60   case RECORD_META_REMARK_VERSION: {
61     if (Record.size() != 1)
62       return malformedRecord("BLOCK_META", "RECORD_META_REMARK_VERSION");
63     Parser.RemarkVersion = Record[0];
64     break;
65   }
66   case RECORD_META_STRTAB: {
67     if (Record.size() != 0)
68       return malformedRecord("BLOCK_META", "RECORD_META_STRTAB");
69     Parser.StrTabBuf = Blob;
70     break;
71   }
72   case RECORD_META_EXTERNAL_FILE: {
73     if (Record.size() != 0)
74       return malformedRecord("BLOCK_META", "RECORD_META_EXTERNAL_FILE");
75     Parser.ExternalFilePath = Blob;
76     break;
77   }
78   default:
79     return unknownRecord("BLOCK_META", *RecordID);
80   }
81   return Error::success();
82 }
83 
84 BitstreamRemarkParserHelper::BitstreamRemarkParserHelper(
85     BitstreamCursor &Stream)
86     : Stream(Stream) {}
87 
88 /// Parse a record and fill in the fields in the parser.
89 static Error parseRecord(BitstreamRemarkParserHelper &Parser, unsigned Code) {
90   BitstreamCursor &Stream = Parser.Stream;
91   // Note: 5 is used here because it's the max number of fields we have per
92   // record.
93   SmallVector<uint64_t, 5> Record;
94   StringRef Blob;
95   Expected<unsigned> RecordID = Stream.readRecord(Code, Record, &Blob);
96   if (!RecordID)
97     return RecordID.takeError();
98 
99   switch (*RecordID) {
100   case RECORD_REMARK_HEADER: {
101     if (Record.size() != 4)
102       return malformedRecord("BLOCK_REMARK", "RECORD_REMARK_HEADER");
103     Parser.Type = Record[0];
104     Parser.RemarkNameIdx = Record[1];
105     Parser.PassNameIdx = Record[2];
106     Parser.FunctionNameIdx = Record[3];
107     break;
108   }
109   case RECORD_REMARK_DEBUG_LOC: {
110     if (Record.size() != 3)
111       return malformedRecord("BLOCK_REMARK", "RECORD_REMARK_DEBUG_LOC");
112     Parser.SourceFileNameIdx = Record[0];
113     Parser.SourceLine = Record[1];
114     Parser.SourceColumn = Record[2];
115     break;
116   }
117   case RECORD_REMARK_HOTNESS: {
118     if (Record.size() != 1)
119       return malformedRecord("BLOCK_REMARK", "RECORD_REMARK_HOTNESS");
120     Parser.Hotness = Record[0];
121     break;
122   }
123   case RECORD_REMARK_ARG_WITH_DEBUGLOC: {
124     if (Record.size() != 5)
125       return malformedRecord("BLOCK_REMARK", "RECORD_REMARK_ARG_WITH_DEBUGLOC");
126     // Create a temporary argument. Use that as a valid memory location for this
127     // argument entry.
128     Parser.TmpArgs.emplace_back();
129     Parser.TmpArgs.back().KeyIdx = Record[0];
130     Parser.TmpArgs.back().ValueIdx = Record[1];
131     Parser.TmpArgs.back().SourceFileNameIdx = Record[2];
132     Parser.TmpArgs.back().SourceLine = Record[3];
133     Parser.TmpArgs.back().SourceColumn = Record[4];
134     Parser.Args =
135         ArrayRef<BitstreamRemarkParserHelper::Argument>(Parser.TmpArgs);
136     break;
137   }
138   case RECORD_REMARK_ARG_WITHOUT_DEBUGLOC: {
139     if (Record.size() != 2)
140       return malformedRecord("BLOCK_REMARK",
141                              "RECORD_REMARK_ARG_WITHOUT_DEBUGLOC");
142     // Create a temporary argument. Use that as a valid memory location for this
143     // argument entry.
144     Parser.TmpArgs.emplace_back();
145     Parser.TmpArgs.back().KeyIdx = Record[0];
146     Parser.TmpArgs.back().ValueIdx = Record[1];
147     Parser.Args =
148         ArrayRef<BitstreamRemarkParserHelper::Argument>(Parser.TmpArgs);
149     break;
150   }
151   default:
152     return unknownRecord("BLOCK_REMARK", *RecordID);
153   }
154   return Error::success();
155 }
156 
157 template <typename T>
158 static Error parseBlock(T &ParserHelper, unsigned BlockID,
159                         const char *BlockName) {
160   BitstreamCursor &Stream = ParserHelper.Stream;
161   Expected<BitstreamEntry> Next = Stream.advance();
162   if (!Next)
163     return Next.takeError();
164   if (Next->Kind != BitstreamEntry::SubBlock || Next->ID != BlockID)
165     return createStringError(
166         std::make_error_code(std::errc::illegal_byte_sequence),
167         "Error while parsing %s: expecting [ENTER_SUBBLOCK, %s, ...].",
168         BlockName, BlockName);
169   if (Stream.EnterSubBlock(BlockID))
170     return createStringError(
171         std::make_error_code(std::errc::illegal_byte_sequence),
172         "Error while entering %s.", BlockName);
173 
174   // Stop when there is nothing to read anymore or when we encounter an
175   // END_BLOCK.
176   while (!Stream.AtEndOfStream()) {
177     Expected<BitstreamEntry> Next = Stream.advance();
178     if (!Next)
179       return Next.takeError();
180     switch (Next->Kind) {
181     case BitstreamEntry::EndBlock:
182       return Error::success();
183     case BitstreamEntry::Error:
184     case BitstreamEntry::SubBlock:
185       return createStringError(
186           std::make_error_code(std::errc::illegal_byte_sequence),
187           "Error while parsing %s: expecting records.", BlockName);
188     case BitstreamEntry::Record:
189       if (Error E = parseRecord(ParserHelper, Next->ID))
190         return E;
191       continue;
192     }
193   }
194   // If we're here, it means we didn't get an END_BLOCK yet, but we're at the
195   // end of the stream. In this case, error.
196   return createStringError(
197       std::make_error_code(std::errc::illegal_byte_sequence),
198       "Error while parsing %s: unterminated block.", BlockName);
199 }
200 
201 Error BitstreamMetaParserHelper::parse() {
202   return parseBlock(*this, META_BLOCK_ID, "META_BLOCK");
203 }
204 
205 Error BitstreamRemarkParserHelper::parse() {
206   return parseBlock(*this, REMARK_BLOCK_ID, "REMARK_BLOCK");
207 }
208 
209 BitstreamParserHelper::BitstreamParserHelper(StringRef Buffer)
210     : Stream(Buffer) {}
211 
212 Expected<std::array<char, 4>> BitstreamParserHelper::parseMagic() {
213   std::array<char, 4> Result;
214   for (unsigned i = 0; i < 4; ++i)
215     if (Expected<unsigned> R = Stream.Read(8))
216       Result[i] = *R;
217     else
218       return R.takeError();
219   return Result;
220 }
221 
222 Error BitstreamParserHelper::parseBlockInfoBlock() {
223   Expected<BitstreamEntry> Next = Stream.advance();
224   if (!Next)
225     return Next.takeError();
226   if (Next->Kind != BitstreamEntry::SubBlock ||
227       Next->ID != llvm::bitc::BLOCKINFO_BLOCK_ID)
228     return createStringError(
229         std::make_error_code(std::errc::illegal_byte_sequence),
230         "Error while parsing BLOCKINFO_BLOCK: expecting [ENTER_SUBBLOCK, "
231         "BLOCKINFO_BLOCK, ...].");
232 
233   Expected<Optional<BitstreamBlockInfo>> MaybeBlockInfo =
234       Stream.ReadBlockInfoBlock();
235   if (!MaybeBlockInfo)
236     return MaybeBlockInfo.takeError();
237 
238   if (!*MaybeBlockInfo)
239     return createStringError(
240         std::make_error_code(std::errc::illegal_byte_sequence),
241         "Error while parsing BLOCKINFO_BLOCK.");
242 
243   BlockInfo = **MaybeBlockInfo;
244 
245   Stream.setBlockInfo(&BlockInfo);
246   return Error::success();
247 }
248 
249 static Expected<bool> isBlock(BitstreamCursor &Stream, unsigned BlockID) {
250   bool Result = false;
251   uint64_t PreviousBitNo = Stream.GetCurrentBitNo();
252   Expected<BitstreamEntry> Next = Stream.advance();
253   if (!Next)
254     return Next.takeError();
255   switch (Next->Kind) {
256   case BitstreamEntry::SubBlock:
257     // Check for the block id.
258     Result = Next->ID == BlockID;
259     break;
260   case BitstreamEntry::Error:
261     return createStringError(
262         std::make_error_code(std::errc::illegal_byte_sequence),
263         "Unexpected error while parsing bitstream.");
264   default:
265     Result = false;
266     break;
267   }
268   if (Error E = Stream.JumpToBit(PreviousBitNo))
269     return std::move(E);
270   return Result;
271 }
272 
273 Expected<bool> BitstreamParserHelper::isMetaBlock() {
274   return isBlock(Stream, META_BLOCK_ID);
275 }
276 
277 Expected<bool> BitstreamParserHelper::isRemarkBlock() {
278   return isBlock(Stream, META_BLOCK_ID);
279 }
280 
281 static Error validateMagicNumber(StringRef Magic) {
282   if (Magic != remarks::ContainerMagic)
283     return createStringError(std::make_error_code(std::errc::invalid_argument),
284                              "Unknown magic number: expecting %s, got %.4s.",
285                              remarks::ContainerMagic.data(), Magic.data());
286   return Error::success();
287 }
288 
289 static Error advanceToMetaBlock(BitstreamParserHelper &Helper) {
290   Expected<std::array<char, 4>> Magic = Helper.parseMagic();
291   if (!Magic)
292     return Magic.takeError();
293   if (Error E = validateMagicNumber(StringRef(Magic->data(), Magic->size())))
294     return E;
295   if (Error E = Helper.parseBlockInfoBlock())
296     return E;
297   Expected<bool> isMetaBlock = Helper.isMetaBlock();
298   if (!isMetaBlock)
299     return isMetaBlock.takeError();
300   if (!*isMetaBlock)
301     return createStringError(
302         std::make_error_code(std::errc::illegal_byte_sequence),
303         "Expecting META_BLOCK after the BLOCKINFO_BLOCK.");
304   return Error::success();
305 }
306 
307 Expected<std::unique_ptr<BitstreamRemarkParser>>
308 remarks::createBitstreamParserFromMeta(
309     StringRef Buf, Optional<ParsedStringTable> StrTab,
310     Optional<StringRef> ExternalFilePrependPath) {
311   BitstreamParserHelper Helper(Buf);
312   Expected<std::array<char, 4>> Magic = Helper.parseMagic();
313   if (!Magic)
314     return Magic.takeError();
315 
316   if (Error E = validateMagicNumber(StringRef(Magic->data(), Magic->size())))
317     return std::move(E);
318 
319   auto Parser =
320       StrTab ? std::make_unique<BitstreamRemarkParser>(Buf, std::move(*StrTab))
321              : std::make_unique<BitstreamRemarkParser>(Buf);
322 
323   if (ExternalFilePrependPath)
324     Parser->ExternalFilePrependPath = *ExternalFilePrependPath;
325 
326   return std::move(Parser);
327 }
328 
329 Expected<std::unique_ptr<Remark>> BitstreamRemarkParser::next() {
330   if (ParserHelper.atEndOfStream())
331     return make_error<EndOfFileError>();
332 
333   if (!ReadyToParseRemarks) {
334     if (Error E = parseMeta())
335       return std::move(E);
336     ReadyToParseRemarks = true;
337   }
338 
339   return parseRemark();
340 }
341 
342 Error BitstreamRemarkParser::parseMeta() {
343   // Advance and to the meta block.
344   if (Error E = advanceToMetaBlock(ParserHelper))
345     return E;
346 
347   BitstreamMetaParserHelper MetaHelper(ParserHelper.Stream,
348                                        ParserHelper.BlockInfo);
349   if (Error E = MetaHelper.parse())
350     return E;
351 
352   if (Error E = processCommonMeta(MetaHelper))
353     return E;
354 
355   switch (ContainerType) {
356   case BitstreamRemarkContainerType::Standalone:
357     return processStandaloneMeta(MetaHelper);
358   case BitstreamRemarkContainerType::SeparateRemarksFile:
359     return processSeparateRemarksFileMeta(MetaHelper);
360   case BitstreamRemarkContainerType::SeparateRemarksMeta:
361     return processSeparateRemarksMetaMeta(MetaHelper);
362   }
363   llvm_unreachable("Unknown BitstreamRemarkContainerType enum");
364 }
365 
366 Error BitstreamRemarkParser::processCommonMeta(
367     BitstreamMetaParserHelper &MetaHelper) {
368   if (Optional<uint64_t> Version = MetaHelper.ContainerVersion)
369     ContainerVersion = *Version;
370   else
371     return createStringError(
372         std::make_error_code(std::errc::illegal_byte_sequence),
373         "Error while parsing BLOCK_META: missing container version.");
374 
375   if (Optional<uint8_t> Type = MetaHelper.ContainerType) {
376     // Always >= BitstreamRemarkContainerType::First since it's unsigned.
377     if (*Type > static_cast<uint8_t>(BitstreamRemarkContainerType::Last))
378       return createStringError(
379           std::make_error_code(std::errc::illegal_byte_sequence),
380           "Error while parsing BLOCK_META: invalid container type.");
381 
382     ContainerType = static_cast<BitstreamRemarkContainerType>(*Type);
383   } else
384     return createStringError(
385         std::make_error_code(std::errc::illegal_byte_sequence),
386         "Error while parsing BLOCK_META: missing container type.");
387 
388   return Error::success();
389 }
390 
391 static Error processStrTab(BitstreamRemarkParser &P,
392                            Optional<StringRef> StrTabBuf) {
393   if (!StrTabBuf)
394     return createStringError(
395         std::make_error_code(std::errc::illegal_byte_sequence),
396         "Error while parsing BLOCK_META: missing string table.");
397   // Parse and assign the string table.
398   P.StrTab.emplace(*StrTabBuf);
399   return Error::success();
400 }
401 
402 static Error processRemarkVersion(BitstreamRemarkParser &P,
403                                   Optional<uint64_t> RemarkVersion) {
404   if (!RemarkVersion)
405     return createStringError(
406         std::make_error_code(std::errc::illegal_byte_sequence),
407         "Error while parsing BLOCK_META: missing remark version.");
408   P.RemarkVersion = *RemarkVersion;
409   return Error::success();
410 }
411 
412 Error BitstreamRemarkParser::processExternalFilePath(
413     Optional<StringRef> ExternalFilePath) {
414   if (!ExternalFilePath)
415     return createStringError(
416         std::make_error_code(std::errc::illegal_byte_sequence),
417         "Error while parsing BLOCK_META: missing external file path.");
418 
419   SmallString<80> FullPath(ExternalFilePrependPath);
420   sys::path::append(FullPath, *ExternalFilePath);
421 
422   // External file: open the external file, parse it, check if its metadata
423   // matches the one from the separate metadata, then replace the current parser
424   // with the one parsing the remarks.
425   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
426       MemoryBuffer::getFile(FullPath);
427   if (std::error_code EC = BufferOrErr.getError())
428     return createFileError(FullPath, EC);
429   TmpRemarkBuffer = std::move(*BufferOrErr);
430 
431   // Create a separate parser used for parsing the separate file.
432   ParserHelper = BitstreamParserHelper(TmpRemarkBuffer->getBuffer());
433   // Advance and check until we can parse the meta block.
434   if (Error E = advanceToMetaBlock(ParserHelper))
435     return E;
436   // Parse the meta from the separate file.
437   // Note: here we overwrite the BlockInfo with the one from the file. This will
438   // be used to parse the rest of the file.
439   BitstreamMetaParserHelper SeparateMetaHelper(ParserHelper.Stream,
440                                                ParserHelper.BlockInfo);
441   if (Error E = SeparateMetaHelper.parse())
442     return E;
443 
444   uint64_t PreviousContainerVersion = ContainerVersion;
445   if (Error E = processCommonMeta(SeparateMetaHelper))
446     return E;
447 
448   if (ContainerType != BitstreamRemarkContainerType::SeparateRemarksFile)
449     return createStringError(
450         std::make_error_code(std::errc::illegal_byte_sequence),
451         "Error while parsing external file's BLOCK_META: wrong container "
452         "type.");
453 
454   if (PreviousContainerVersion != ContainerVersion)
455     return createStringError(
456         std::make_error_code(std::errc::illegal_byte_sequence),
457         "Error while parsing external file's BLOCK_META: mismatching versions: "
458         "original meta: %lu, external file meta: %lu.",
459         PreviousContainerVersion, ContainerVersion);
460 
461   // Process the meta from the separate file.
462   return processSeparateRemarksFileMeta(SeparateMetaHelper);
463 }
464 
465 Error BitstreamRemarkParser::processStandaloneMeta(
466     BitstreamMetaParserHelper &Helper) {
467   if (Error E = processStrTab(*this, Helper.StrTabBuf))
468     return E;
469   return processRemarkVersion(*this, Helper.RemarkVersion);
470 }
471 
472 Error BitstreamRemarkParser::processSeparateRemarksFileMeta(
473     BitstreamMetaParserHelper &Helper) {
474   return processRemarkVersion(*this, Helper.RemarkVersion);
475 }
476 
477 Error BitstreamRemarkParser::processSeparateRemarksMetaMeta(
478     BitstreamMetaParserHelper &Helper) {
479   if (Error E = processStrTab(*this, Helper.StrTabBuf))
480     return E;
481   return processExternalFilePath(Helper.ExternalFilePath);
482 }
483 
484 Expected<std::unique_ptr<Remark>> BitstreamRemarkParser::parseRemark() {
485   BitstreamRemarkParserHelper RemarkHelper(ParserHelper.Stream);
486   if (Error E = RemarkHelper.parse())
487     return std::move(E);
488 
489   return processRemark(RemarkHelper);
490 }
491 
492 Expected<std::unique_ptr<Remark>>
493 BitstreamRemarkParser::processRemark(BitstreamRemarkParserHelper &Helper) {
494   std::unique_ptr<Remark> Result = std::make_unique<Remark>();
495   Remark &R = *Result;
496 
497   if (StrTab == None)
498     return createStringError(
499         std::make_error_code(std::errc::invalid_argument),
500         "Error while parsing BLOCK_REMARK: missing string table.");
501 
502   if (!Helper.Type)
503     return createStringError(
504         std::make_error_code(std::errc::illegal_byte_sequence),
505         "Error while parsing BLOCK_REMARK: missing remark type.");
506 
507   // Always >= Type::First since it's unsigned.
508   if (*Helper.Type > static_cast<uint8_t>(Type::Last))
509     return createStringError(
510         std::make_error_code(std::errc::illegal_byte_sequence),
511         "Error while parsing BLOCK_REMARK: unknown remark type.");
512 
513   R.RemarkType = static_cast<Type>(*Helper.Type);
514 
515   if (!Helper.RemarkNameIdx)
516     return createStringError(
517         std::make_error_code(std::errc::illegal_byte_sequence),
518         "Error while parsing BLOCK_REMARK: missing remark name.");
519 
520   if (Expected<StringRef> RemarkName = (*StrTab)[*Helper.RemarkNameIdx])
521     R.RemarkName = *RemarkName;
522   else
523     return RemarkName.takeError();
524 
525   if (!Helper.PassNameIdx)
526     return createStringError(
527         std::make_error_code(std::errc::illegal_byte_sequence),
528         "Error while parsing BLOCK_REMARK: missing remark pass.");
529 
530   if (Expected<StringRef> PassName = (*StrTab)[*Helper.PassNameIdx])
531     R.PassName = *PassName;
532   else
533     return PassName.takeError();
534 
535   if (!Helper.FunctionNameIdx)
536     return createStringError(
537         std::make_error_code(std::errc::illegal_byte_sequence),
538         "Error while parsing BLOCK_REMARK: missing remark function name.");
539   if (Expected<StringRef> FunctionName = (*StrTab)[*Helper.FunctionNameIdx])
540     R.FunctionName = *FunctionName;
541   else
542     return FunctionName.takeError();
543 
544   if (Helper.SourceFileNameIdx && Helper.SourceLine && Helper.SourceColumn) {
545     Expected<StringRef> SourceFileName = (*StrTab)[*Helper.SourceFileNameIdx];
546     if (!SourceFileName)
547       return SourceFileName.takeError();
548     R.Loc.emplace();
549     R.Loc->SourceFilePath = *SourceFileName;
550     R.Loc->SourceLine = *Helper.SourceLine;
551     R.Loc->SourceColumn = *Helper.SourceColumn;
552   }
553 
554   if (Helper.Hotness)
555     R.Hotness = *Helper.Hotness;
556 
557   if (!Helper.Args)
558     return std::move(Result);
559 
560   for (const BitstreamRemarkParserHelper::Argument &Arg : *Helper.Args) {
561     if (!Arg.KeyIdx)
562       return createStringError(
563           std::make_error_code(std::errc::illegal_byte_sequence),
564           "Error while parsing BLOCK_REMARK: missing key in remark argument.");
565     if (!Arg.ValueIdx)
566       return createStringError(
567           std::make_error_code(std::errc::illegal_byte_sequence),
568           "Error while parsing BLOCK_REMARK: missing value in remark "
569           "argument.");
570 
571     // We have at least a key and a value, create an entry.
572     R.Args.emplace_back();
573 
574     if (Expected<StringRef> Key = (*StrTab)[*Arg.KeyIdx])
575       R.Args.back().Key = *Key;
576     else
577       return Key.takeError();
578 
579     if (Expected<StringRef> Value = (*StrTab)[*Arg.ValueIdx])
580       R.Args.back().Val = *Value;
581     else
582       return Value.takeError();
583 
584     if (Arg.SourceFileNameIdx && Arg.SourceLine && Arg.SourceColumn) {
585       if (Expected<StringRef> SourceFileName =
586               (*StrTab)[*Arg.SourceFileNameIdx]) {
587         R.Args.back().Loc.emplace();
588         R.Args.back().Loc->SourceFilePath = *SourceFileName;
589         R.Args.back().Loc->SourceLine = *Arg.SourceLine;
590         R.Args.back().Loc->SourceColumn = *Arg.SourceColumn;
591       } else
592         return SourceFileName.takeError();
593     }
594   }
595 
596   return std::move(Result);
597 }
598