1//===--- Preamble.cpp - Reusing expensive parts of the AST ----------------===//
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 "Preamble.h"
10#include "CollectMacros.h"
11#include "Compiler.h"
12#include "Config.h"
13#include "Diagnostics.h"
14#include "FS.h"
15#include "FeatureModule.h"
16#include "Headers.h"
17#include "Protocol.h"
18#include "SourceCode.h"
19#include "clang-include-cleaner/Record.h"
20#include "support/Logger.h"
21#include "support/Path.h"
22#include "support/ThreadsafeFS.h"
23#include "support/Trace.h"
24#include "clang/AST/DeclTemplate.h"
25#include "clang/AST/Type.h"
26#include "clang/Basic/Diagnostic.h"
27#include "clang/Basic/DiagnosticLex.h"
28#include "clang/Basic/DiagnosticOptions.h"
29#include "clang/Basic/LangOptions.h"
30#include "clang/Basic/SourceLocation.h"
31#include "clang/Basic/SourceManager.h"
32#include "clang/Basic/TargetInfo.h"
33#include "clang/Basic/TokenKinds.h"
34#include "clang/Frontend/CompilerInstance.h"
35#include "clang/Frontend/CompilerInvocation.h"
36#include "clang/Frontend/FrontendActions.h"
37#include "clang/Frontend/PrecompiledPreamble.h"
38#include "clang/Lex/HeaderSearch.h"
39#include "clang/Lex/Lexer.h"
40#include "clang/Lex/PPCallbacks.h"
41#include "clang/Lex/Preprocessor.h"
42#include "clang/Lex/PreprocessorOptions.h"
43#include "clang/Serialization/ASTReader.h"
44#include "clang/Tooling/CompilationDatabase.h"
45#include "llvm/ADT/ArrayRef.h"
46#include "llvm/ADT/DenseMap.h"
47#include "llvm/ADT/IntrusiveRefCntPtr.h"
48#include "llvm/ADT/STLExtras.h"
49#include "llvm/ADT/SmallString.h"
50#include "llvm/ADT/SmallVector.h"
51#include "llvm/ADT/StringExtras.h"
52#include "llvm/ADT/StringMap.h"
53#include "llvm/ADT/StringRef.h"
54#include "llvm/Support/Casting.h"
55#include "llvm/Support/Error.h"
56#include "llvm/Support/ErrorHandling.h"
57#include "llvm/Support/ErrorOr.h"
58#include "llvm/Support/FormatVariadic.h"
59#include "llvm/Support/MemoryBuffer.h"
60#include "llvm/Support/Path.h"
61#include "llvm/Support/VirtualFileSystem.h"
62#include "llvm/Support/raw_ostream.h"
63#include <cassert>
64#include <chrono>
65#include <cstddef>
66#include <cstdint>
67#include <cstdlib>
68#include <functional>
69#include <memory>
70#include <optional>
71#include <string>
72#include <system_error>
73#include <tuple>
74#include <utility>
75#include <vector>
76
77namespace clang {
78namespace clangd {
79namespace {
80
81bool compileCommandsAreEqual(const tooling::CompileCommand &LHS,
82 const tooling::CompileCommand &RHS) {
83 // We don't check for Output, it should not matter to clangd.
84 return LHS.Directory == RHS.Directory && LHS.Filename == RHS.Filename &&
85 llvm::ArrayRef(LHS.CommandLine).equals(RHS: RHS.CommandLine);
86}
87
88class CppFilePreambleCallbacks : public PreambleCallbacks {
89public:
90 CppFilePreambleCallbacks(
91 PathRef File, PreambleBuildStats *Stats, bool ParseForwardingFunctions,
92 std::function<void(CompilerInstance &)> BeforeExecuteCallback)
93 : File(File), Stats(Stats),
94 ParseForwardingFunctions(ParseForwardingFunctions),
95 BeforeExecuteCallback(std::move(BeforeExecuteCallback)) {}
96
97 IncludeStructure takeIncludes() { return std::move(Includes); }
98
99 MainFileMacros takeMacros() { return std::move(Macros); }
100
101 std::vector<PragmaMark> takeMarks() { return std::move(Marks); }
102
103 include_cleaner::PragmaIncludes takePragmaIncludes() {
104 return std::move(Pragmas);
105 }
106
107 std::optional<CapturedASTCtx> takeLife() { return std::move(CapturedCtx); }
108
109 bool isMainFileIncludeGuarded() const { return IsMainFileIncludeGuarded; }
110
111 void AfterExecute(CompilerInstance &CI) override {
112 // As part of the Preamble compilation, ASTConsumer
113 // PrecompilePreambleConsumer/PCHGenerator is setup. This would be called
114 // when Preamble consists of modules. Therefore while capturing AST context,
115 // we have to reset ast consumer and ASTMutationListener.
116 if (CI.getASTReader()) {
117 CI.getASTReader()->setDeserializationListener(Listener: nullptr);
118 // This just sets consumer to null when DeserializationListener is null.
119 CI.getASTReader()->StartTranslationUnit(Consumer: nullptr);
120 }
121 CI.getASTContext().setASTMutationListener(nullptr);
122 CapturedCtx.emplace(args&: CI);
123
124 const SourceManager &SM = CI.getSourceManager();
125 OptionalFileEntryRef MainFE = SM.getFileEntryRefForID(FID: SM.getMainFileID());
126 IsMainFileIncludeGuarded =
127 CI.getPreprocessor().getHeaderSearchInfo().isFileMultipleIncludeGuarded(
128 File: *MainFE);
129
130 if (Stats) {
131 const ASTContext &AST = CI.getASTContext();
132 Stats->BuildSize = AST.getASTAllocatedMemory();
133 Stats->BuildSize += AST.getSideTableAllocatedMemory();
134 Stats->BuildSize += AST.Idents.getAllocator().getTotalMemory();
135 Stats->BuildSize += AST.Selectors.getTotalMemory();
136
137 Stats->BuildSize += AST.getSourceManager().getContentCacheSize();
138 Stats->BuildSize += AST.getSourceManager().getDataStructureSizes();
139 Stats->BuildSize +=
140 AST.getSourceManager().getMemoryBufferSizes().malloc_bytes;
141
142 const Preprocessor &PP = CI.getPreprocessor();
143 Stats->BuildSize += PP.getTotalMemory();
144 if (PreprocessingRecord *PRec = PP.getPreprocessingRecord())
145 Stats->BuildSize += PRec->getTotalMemory();
146 Stats->BuildSize += PP.getHeaderSearchInfo().getTotalMemory();
147 }
148 }
149
150 void BeforeExecute(CompilerInstance &CI) override {
151 LangOpts = &CI.getLangOpts();
152 SourceMgr = &CI.getSourceManager();
153 PP = &CI.getPreprocessor();
154 Includes.collect(CI);
155 Pragmas.record(CI);
156 if (BeforeExecuteCallback)
157 BeforeExecuteCallback(CI);
158 }
159
160 std::unique_ptr<PPCallbacks> createPPCallbacks() override {
161 assert(SourceMgr && LangOpts && PP &&
162 "SourceMgr, LangOpts and PP must be set at this point");
163
164 return std::make_unique<PPChainedCallbacks>(
165 args: std::make_unique<CollectMainFileMacros>(args: *PP, args&: Macros),
166 args: collectPragmaMarksCallback(*SourceMgr, Out&: Marks));
167 }
168
169 static bool isLikelyForwardingFunction(FunctionTemplateDecl *FT) {
170 const auto *FD = FT->getTemplatedDecl();
171 const auto NumParams = FD->getNumParams();
172 // Check whether its last parameter is a parameter pack...
173 if (NumParams > 0) {
174 const auto *LastParam = FD->getParamDecl(i: NumParams - 1);
175 if (const auto *PET = dyn_cast<PackExpansionType>(LastParam->getType())) {
176 // ... of the type T&&... or T...
177 const auto BaseType = PET->getPattern().getNonReferenceType();
178 if (const auto *TTPT =
179 dyn_cast<TemplateTypeParmType>(BaseType.getTypePtr())) {
180 // ... whose template parameter comes from the function directly
181 if (FT->getTemplateParameters()->getDepth() == TTPT->getDepth()) {
182 return true;
183 }
184 }
185 }
186 }
187 return false;
188 }
189
190 bool shouldSkipFunctionBody(Decl *D) override {
191 // Usually we don't need to look inside the bodies of header functions
192 // to understand the program. However when forwarding function like
193 // emplace() forward their arguments to some other function, the
194 // interesting overload resolution happens inside the forwarding
195 // function's body. To provide more meaningful diagnostics,
196 // code completion, and parameter hints we should parse (and later
197 // instantiate) the bodies.
198 if (auto *FT = llvm::dyn_cast<clang::FunctionTemplateDecl>(Val: D)) {
199 if (ParseForwardingFunctions) {
200 // Don't skip parsing the body if it looks like a forwarding function
201 if (isLikelyForwardingFunction(FT))
202 return false;
203 } else {
204 // By default, only take care of make_unique
205 // std::make_unique is trivial, and we diagnose bad constructor calls.
206 if (const auto *II = FT->getDeclName().getAsIdentifierInfo()) {
207 if (II->isStr("make_unique") && FT->isInStdNamespace())
208 return false;
209 }
210 }
211 }
212 return true;
213 }
214
215private:
216 PathRef File;
217 IncludeStructure Includes;
218 include_cleaner::PragmaIncludes Pragmas;
219 MainFileMacros Macros;
220 std::vector<PragmaMark> Marks;
221 bool IsMainFileIncludeGuarded = false;
222 const clang::LangOptions *LangOpts = nullptr;
223 const SourceManager *SourceMgr = nullptr;
224 const Preprocessor *PP = nullptr;
225 PreambleBuildStats *Stats;
226 bool ParseForwardingFunctions;
227 std::function<void(CompilerInstance &)> BeforeExecuteCallback;
228 std::optional<CapturedASTCtx> CapturedCtx;
229};
230
231// Represents directives other than includes, where basic textual information is
232// enough.
233struct TextualPPDirective {
234 unsigned DirectiveLine;
235 // Full text that's representing the directive, including the `#`.
236 std::string Text;
237 unsigned Offset;
238 tok::PPKeywordKind Directive = tok::PPKeywordKind::pp_not_keyword;
239 // Name of the macro being defined in the case of a #define directive.
240 std::string MacroName;
241
242 bool operator==(const TextualPPDirective &RHS) const {
243 return std::tie(args: DirectiveLine, args: Offset, args: Text) ==
244 std::tie(args: RHS.DirectiveLine, args: RHS.Offset, args: RHS.Text);
245 }
246};
247
248// Formats a PP directive consisting of Prefix (e.g. "#define ") and Body ("X
249// 10"). The formatting is copied so that the tokens in Body have PresumedLocs
250// with correct columns and lines.
251std::string spellDirective(llvm::StringRef Prefix,
252 CharSourceRange DirectiveRange,
253 const LangOptions &LangOpts, const SourceManager &SM,
254 unsigned &DirectiveLine, unsigned &Offset) {
255 std::string SpelledDirective;
256 llvm::raw_string_ostream OS(SpelledDirective);
257 OS << Prefix;
258
259 // Make sure DirectiveRange is a char range and doesn't contain macro ids.
260 DirectiveRange = SM.getExpansionRange(Range: DirectiveRange);
261 if (DirectiveRange.isTokenRange()) {
262 DirectiveRange.setEnd(
263 Lexer::getLocForEndOfToken(Loc: DirectiveRange.getEnd(), Offset: 0, SM, LangOpts));
264 }
265
266 auto DecompLoc = SM.getDecomposedLoc(Loc: DirectiveRange.getBegin());
267 DirectiveLine = SM.getLineNumber(FID: DecompLoc.first, FilePos: DecompLoc.second);
268 Offset = DecompLoc.second;
269 auto TargetColumn = SM.getColumnNumber(FID: DecompLoc.first, FilePos: DecompLoc.second) - 1;
270
271 // Pad with spaces before DirectiveRange to make sure it will be on right
272 // column when patched.
273 if (Prefix.size() <= TargetColumn) {
274 // There is enough space for Prefix and space before directive, use it.
275 // We try to squeeze the Prefix into the same line whenever we can, as
276 // putting onto a separate line won't work at the beginning of the file.
277 OS << std::string(TargetColumn - Prefix.size(), ' ');
278 } else {
279 // Prefix was longer than the space we had. We produce e.g.:
280 // #line N-1
281 // #define \
282 // X 10
283 OS << "\\\n" << std::string(TargetColumn, ' ');
284 // Decrement because we put an additional line break before
285 // DirectiveRange.begin().
286 --DirectiveLine;
287 }
288 OS << toSourceCode(SM, R: DirectiveRange.getAsRange());
289 return OS.str();
290}
291
292// Collects #define directives inside the main file.
293struct DirectiveCollector : public PPCallbacks {
294 DirectiveCollector(const Preprocessor &PP,
295 std::vector<TextualPPDirective> &TextualDirectives)
296 : LangOpts(PP.getLangOpts()), SM(PP.getSourceManager()),
297 TextualDirectives(TextualDirectives) {}
298
299 void FileChanged(SourceLocation Loc, FileChangeReason Reason,
300 SrcMgr::CharacteristicKind FileType,
301 FileID PrevFID) override {
302 InMainFile = SM.isWrittenInMainFile(Loc);
303 }
304
305 void MacroDefined(const Token &MacroNameTok,
306 const MacroDirective *MD) override {
307 if (!InMainFile)
308 return;
309 TextualDirectives.emplace_back();
310 TextualPPDirective &TD = TextualDirectives.back();
311 TD.Directive = tok::pp_define;
312 TD.MacroName = MacroNameTok.getIdentifierInfo()->getName().str();
313
314 const auto *MI = MD->getMacroInfo();
315 TD.Text =
316 spellDirective(Prefix: "#define ",
317 DirectiveRange: CharSourceRange::getTokenRange(
318 B: MI->getDefinitionLoc(), E: MI->getDefinitionEndLoc()),
319 LangOpts, SM, DirectiveLine&: TD.DirectiveLine, Offset&: TD.Offset);
320 }
321
322private:
323 bool InMainFile = true;
324 const LangOptions &LangOpts;
325 const SourceManager &SM;
326 std::vector<TextualPPDirective> &TextualDirectives;
327};
328
329struct ScannedPreamble {
330 std::vector<Inclusion> Includes;
331 std::vector<TextualPPDirective> TextualDirectives;
332 // Literal lines of the preamble contents.
333 std::vector<llvm::StringRef> Lines;
334 PreambleBounds Bounds = {0, false};
335 std::vector<PragmaMark> Marks;
336 MainFileMacros Macros;
337};
338
339/// Scans the preprocessor directives in the preamble section of the file by
340/// running preprocessor over \p Contents. Returned includes do not contain
341/// resolved paths. \p Cmd is used to build the compiler invocation, which might
342/// stat/read files.
343llvm::Expected<ScannedPreamble>
344scanPreamble(llvm::StringRef Contents, const tooling::CompileCommand &Cmd) {
345 class EmptyFS : public ThreadsafeFS {
346 private:
347 llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> viewImpl() const override {
348 return new llvm::vfs::InMemoryFileSystem;
349 }
350 };
351 EmptyFS FS;
352 // Build and run Preprocessor over the preamble.
353 ParseInputs PI;
354 // Memory buffers below expect null-terminated && non-null strings. So make
355 // sure to always use PI.Contents!
356 PI.Contents = Contents.str();
357 PI.TFS = &FS;
358 PI.CompileCommand = Cmd;
359 IgnoringDiagConsumer IgnoreDiags;
360 auto CI = buildCompilerInvocation(Inputs: PI, D&: IgnoreDiags);
361 if (!CI)
362 return error(Fmt: "failed to create compiler invocation");
363 CI->getDiagnosticOpts().IgnoreWarnings = true;
364 auto ContentsBuffer = llvm::MemoryBuffer::getMemBuffer(InputData: PI.Contents);
365 // This means we're scanning (though not preprocessing) the preamble section
366 // twice. However, it's important to precisely follow the preamble bounds used
367 // elsewhere.
368 auto Bounds = ComputePreambleBounds(LangOpts: CI->getLangOpts(), Buffer: *ContentsBuffer, MaxLines: 0);
369 auto PreambleContents = llvm::MemoryBuffer::getMemBufferCopy(
370 InputData: llvm::StringRef(PI.Contents).take_front(N: Bounds.Size));
371 auto Clang = prepareCompilerInstance(
372 std::move(CI), nullptr, MainFile: std::move(PreambleContents),
373 // Provide an empty FS to prevent preprocessor from performing IO. This
374 // also implies missing resolved paths for includes.
375 FS.view(CWD: std::nullopt), IgnoreDiags);
376 if (Clang->getFrontendOpts().Inputs.empty())
377 return error(Fmt: "compiler instance had no inputs");
378 // We are only interested in main file includes.
379 Clang->getPreprocessorOpts().SingleFileParseMode = true;
380 Clang->getPreprocessorOpts().UsePredefines = false;
381 PreprocessOnlyAction Action;
382 if (!Action.BeginSourceFile(CI&: *Clang, Input: Clang->getFrontendOpts().Inputs[0]))
383 return error(Fmt: "failed BeginSourceFile");
384 Preprocessor &PP = Clang->getPreprocessor();
385 const auto &SM = PP.getSourceManager();
386 IncludeStructure Includes;
387 Includes.collect(CI: *Clang);
388 ScannedPreamble SP;
389 SP.Bounds = Bounds;
390 PP.addPPCallbacks(
391 C: std::make_unique<DirectiveCollector>(args&: PP, args&: SP.TextualDirectives));
392 PP.addPPCallbacks(C: collectPragmaMarksCallback(SM, Out&: SP.Marks));
393 PP.addPPCallbacks(C: std::make_unique<CollectMainFileMacros>(args&: PP, args&: SP.Macros));
394 if (llvm::Error Err = Action.Execute())
395 return std::move(Err);
396 Action.EndSourceFile();
397 SP.Includes = std::move(Includes.MainFileIncludes);
398 llvm::append_range(C&: SP.Lines, R: llvm::split(Str: Contents, Separator: "\n"));
399 return SP;
400}
401
402const char *spellingForIncDirective(tok::PPKeywordKind IncludeDirective) {
403 switch (IncludeDirective) {
404 case tok::pp_include:
405 return "include";
406 case tok::pp_import:
407 return "import";
408 case tok::pp_include_next:
409 return "include_next";
410 default:
411 break;
412 }
413 llvm_unreachable("not an include directive");
414}
415
416// Accumulating wall time timer. Similar to llvm::Timer, but much cheaper,
417// it only tracks wall time.
418// Since this is a generic timer, We may want to move this to support/ if we
419// find a use case outside of FS time tracking.
420class WallTimer {
421public:
422 WallTimer() : TotalTime(std::chrono::steady_clock::duration::zero()) {}
423 // [Re-]Start the timer.
424 void startTimer() { StartTime = std::chrono::steady_clock::now(); }
425 // Stop the timer and update total time.
426 void stopTimer() {
427 TotalTime += std::chrono::steady_clock::now() - StartTime;
428 }
429 // Return total time, in seconds.
430 double getTime() { return std::chrono::duration<double>(TotalTime).count(); }
431
432private:
433 std::chrono::steady_clock::duration TotalTime;
434 std::chrono::steady_clock::time_point StartTime;
435};
436
437class WallTimerRegion {
438public:
439 WallTimerRegion(WallTimer &T) : T(T) { T.startTimer(); }
440 ~WallTimerRegion() { T.stopTimer(); }
441
442private:
443 WallTimer &T;
444};
445
446// Used by TimerFS, tracks time spent in status() and getBuffer() calls while
447// proxying to underlying File implementation.
448class TimerFile : public llvm::vfs::File {
449public:
450 TimerFile(WallTimer &Timer, std::unique_ptr<File> InnerFile)
451 : Timer(Timer), InnerFile(std::move(InnerFile)) {}
452
453 llvm::ErrorOr<llvm::vfs::Status> status() override {
454 WallTimerRegion T(Timer);
455 return InnerFile->status();
456 }
457 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
458 getBuffer(const Twine &Name, int64_t FileSize, bool RequiresNullTerminator,
459 bool IsVolatile) override {
460 WallTimerRegion T(Timer);
461 return InnerFile->getBuffer(Name, FileSize, RequiresNullTerminator,
462 IsVolatile);
463 }
464 std::error_code close() override {
465 WallTimerRegion T(Timer);
466 return InnerFile->close();
467 }
468
469private:
470 WallTimer &Timer;
471 std::unique_ptr<llvm::vfs::File> InnerFile;
472};
473
474// A wrapper for FileSystems that tracks the amount of time spent in status()
475// and openFileForRead() calls.
476class TimerFS : public llvm::vfs::ProxyFileSystem {
477public:
478 TimerFS(llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS)
479 : ProxyFileSystem(std::move(FS)) {}
480
481 llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
482 openFileForRead(const llvm::Twine &Path) override {
483 WallTimerRegion T(Timer);
484 auto FileOr = getUnderlyingFS().openFileForRead(Path);
485 if (!FileOr)
486 return FileOr;
487 return std::make_unique<TimerFile>(args&: Timer, args: std::move(FileOr.get()));
488 }
489
490 llvm::ErrorOr<llvm::vfs::Status> status(const llvm::Twine &Path) override {
491 WallTimerRegion T(Timer);
492 return getUnderlyingFS().status(Path);
493 }
494
495 double getTime() { return Timer.getTime(); }
496
497private:
498 WallTimer Timer;
499};
500
501// Helpers for patching diagnostics between two versions of file contents.
502class DiagPatcher {
503 llvm::ArrayRef<llvm::StringRef> OldLines;
504 llvm::ArrayRef<llvm::StringRef> CurrentLines;
505 llvm::StringMap<llvm::SmallVector<int>> CurrentContentsToLine;
506
507 // Translates a range from old lines to current lines.
508 // Finds the consecutive set of lines that corresponds to the same contents in
509 // old and current, and applies the same translation to the range.
510 // Returns true if translation succeeded.
511 bool translateRange(Range &R) {
512 int OldStart = R.start.line;
513 int OldEnd = R.end.line;
514 assert(OldStart <= OldEnd);
515
516 size_t RangeLen = OldEnd - OldStart + 1;
517 auto RangeContents = OldLines.slice(N: OldStart).take_front(N: RangeLen);
518 // Make sure the whole range is covered in old contents.
519 if (RangeContents.size() < RangeLen)
520 return false;
521
522 std::optional<int> Closest;
523 for (int AlternateLine : CurrentContentsToLine.lookup(Key: RangeContents[0])) {
524 // Check if AlternateLine matches all lines in the range.
525 if (RangeContents !=
526 CurrentLines.slice(N: AlternateLine).take_front(N: RangeLen))
527 continue;
528 int Delta = AlternateLine - OldStart;
529 if (!Closest.has_value() || abs(x: Delta) < abs(x: *Closest))
530 Closest = Delta;
531 }
532 // Couldn't find any viable matches in the current contents.
533 if (!Closest.has_value())
534 return false;
535 R.start.line += *Closest;
536 R.end.line += *Closest;
537 return true;
538 }
539
540 // Translates a Note by patching its range when inside main file. Returns true
541 // on success.
542 bool translateNote(Note &N) {
543 if (!N.InsideMainFile)
544 return true;
545 if (translateRange(R&: N.Range))
546 return true;
547 return false;
548 }
549
550 // Tries to translate all the edit ranges inside the fix. Returns true on
551 // success. On failure fixes might be in an invalid state.
552 bool translateFix(Fix &F) {
553 return llvm::all_of(
554 Range&: F.Edits, P: [this](TextEdit &E) { return translateRange(R&: E.range); });
555 }
556
557public:
558 DiagPatcher(llvm::ArrayRef<llvm::StringRef> OldLines,
559 llvm::ArrayRef<llvm::StringRef> CurrentLines) {
560 this->OldLines = OldLines;
561 this->CurrentLines = CurrentLines;
562 for (int Line = 0, E = CurrentLines.size(); Line != E; ++Line) {
563 llvm::StringRef Contents = CurrentLines[Line];
564 CurrentContentsToLine[Contents].push_back(Elt: Line);
565 }
566 }
567 // Translate diagnostic by moving its main range to new location (if inside
568 // the main file). Preserve all the notes and fixes that can be translated to
569 // new contents.
570 // Drops the whole diagnostic if main range can't be patched.
571 std::optional<Diag> translateDiag(const Diag &D) {
572 Range NewRange = D.Range;
573 // Patch range if it's inside main file.
574 if (D.InsideMainFile && !translateRange(R&: NewRange)) {
575 // Drop the diagnostic if we couldn't patch the range.
576 return std::nullopt;
577 }
578
579 Diag NewD = D;
580 NewD.Range = NewRange;
581 // Translate ranges inside notes and fixes too, dropping the ones that are
582 // no longer relevant.
583 llvm::erase_if(C&: NewD.Notes, P: [this](Note &N) { return !translateNote(N); });
584 llvm::erase_if(C&: NewD.Fixes, P: [this](Fix &F) { return !translateFix(F); });
585 return NewD;
586 }
587};
588} // namespace
589
590std::shared_ptr<const PreambleData>
591buildPreamble(PathRef FileName, CompilerInvocation CI,
592 const ParseInputs &Inputs, bool StoreInMemory,
593 PreambleParsedCallback PreambleCallback,
594 PreambleBuildStats *Stats) {
595 // Note that we don't need to copy the input contents, preamble can live
596 // without those.
597 auto ContentsBuffer =
598 llvm::MemoryBuffer::getMemBuffer(InputData: Inputs.Contents, BufferName: FileName);
599 auto Bounds = ComputePreambleBounds(LangOpts: CI.getLangOpts(), Buffer: *ContentsBuffer, MaxLines: 0);
600
601 trace::Span Tracer("BuildPreamble");
602 SPAN_ATTACH(Tracer, "File", FileName);
603 std::vector<std::unique_ptr<FeatureModule::ASTListener>> ASTListeners;
604 if (Inputs.FeatureModules) {
605 for (auto &M : *Inputs.FeatureModules) {
606 if (auto Listener = M.astListeners())
607 ASTListeners.emplace_back(args: std::move(Listener));
608 }
609 }
610 StoreDiags PreambleDiagnostics;
611 PreambleDiagnostics.setDiagCallback(
612 [&ASTListeners](const clang::Diagnostic &D, clangd::Diag &Diag) {
613 for (const auto &L : ASTListeners)
614 L->sawDiagnostic(D, Diag);
615 });
616 llvm::IntrusiveRefCntPtr<DiagnosticsEngine> PreambleDiagsEngine =
617 CompilerInstance::createDiagnostics(Opts: &CI.getDiagnosticOpts(),
618 Client: &PreambleDiagnostics,
619 /*ShouldOwnClient=*/false);
620 const Config &Cfg = Config::current();
621 PreambleDiagnostics.setLevelAdjuster([&](DiagnosticsEngine::Level DiagLevel,
622 const clang::Diagnostic &Info) {
623 if (Cfg.Diagnostics.SuppressAll ||
624 isBuiltinDiagnosticSuppressed(ID: Info.getID(), Suppressed: Cfg.Diagnostics.Suppress,
625 CI.getLangOpts()))
626 return DiagnosticsEngine::Ignored;
627 switch (Info.getID()) {
628 case diag::warn_no_newline_eof:
629 case diag::warn_cxx98_compat_no_newline_eof:
630 case diag::ext_no_newline_eof:
631 // If the preamble doesn't span the whole file, drop the no newline at
632 // eof warnings.
633 return Bounds.Size != ContentsBuffer->getBufferSize()
634 ? DiagnosticsEngine::Level::Ignored
635 : DiagLevel;
636 }
637 return DiagLevel;
638 });
639
640 // Skip function bodies when building the preamble to speed up building
641 // the preamble and make it smaller.
642 assert(!CI.getFrontendOpts().SkipFunctionBodies);
643 CI.getFrontendOpts().SkipFunctionBodies = true;
644 // We don't want to write comment locations into PCH. They are racy and slow
645 // to read back. We rely on dynamic index for the comments instead.
646 CI.getPreprocessorOpts().WriteCommentListToPCH = false;
647
648 CppFilePreambleCallbacks CapturedInfo(
649 FileName, Stats, Inputs.Opts.PreambleParseForwardingFunctions,
650 [&ASTListeners](CompilerInstance &CI) {
651 for (const auto &L : ASTListeners)
652 L->beforeExecute(CI);
653 });
654 auto VFS = Inputs.TFS->view(CWD: Inputs.CompileCommand.Directory);
655 llvm::SmallString<32> AbsFileName(FileName);
656 VFS->makeAbsolute(Path&: AbsFileName);
657 auto StatCache = std::make_shared<PreambleFileStatusCache>(args&: AbsFileName);
658 auto StatCacheFS = StatCache->getProducingFS(FS: VFS);
659 llvm::IntrusiveRefCntPtr<TimerFS> TimedFS(new TimerFS(StatCacheFS));
660
661 WallTimer PreambleTimer;
662 PreambleTimer.startTimer();
663 auto BuiltPreamble = PrecompiledPreamble::Build(
664 Invocation: CI, MainFileBuffer: ContentsBuffer.get(), Bounds, Diagnostics&: *PreambleDiagsEngine,
665 VFS: Stats ? TimedFS : StatCacheFS, PCHContainerOps: std::make_shared<PCHContainerOperations>(),
666 StoreInMemory, /*StoragePath=*/"", Callbacks&: CapturedInfo);
667 PreambleTimer.stopTimer();
668
669 // We have to setup DiagnosticConsumer that will be alife
670 // while preamble callback is executed
671 PreambleDiagsEngine->setClient(client: new IgnoringDiagConsumer, ShouldOwnClient: true);
672 // Reset references to ref-counted-ptrs before executing the callbacks, to
673 // prevent resetting them concurrently.
674 PreambleDiagsEngine.reset();
675 CI.DiagnosticOpts.reset();
676
677 // When building the AST for the main file, we do want the function
678 // bodies.
679 CI.getFrontendOpts().SkipFunctionBodies = false;
680
681 if (Stats != nullptr) {
682 Stats->TotalBuildTime = PreambleTimer.getTime();
683 Stats->FileSystemTime = TimedFS->getTime();
684 Stats->SerializedSize = BuiltPreamble ? BuiltPreamble->getSize() : 0;
685 }
686
687 if (BuiltPreamble) {
688 log(Fmt: "Built preamble of size {0} for file {1} version {2} in {3} seconds",
689 Vals: BuiltPreamble->getSize(), Vals&: FileName, Vals: Inputs.Version,
690 Vals: PreambleTimer.getTime());
691 std::vector<Diag> Diags = PreambleDiagnostics.take();
692 auto Result = std::make_shared<PreambleData>(args: std::move(*BuiltPreamble));
693 Result->Version = Inputs.Version;
694 Result->CompileCommand = Inputs.CompileCommand;
695 Result->Diags = std::move(Diags);
696 Result->Includes = CapturedInfo.takeIncludes();
697 Result->Pragmas = std::make_shared<const include_cleaner::PragmaIncludes>(
698 args: CapturedInfo.takePragmaIncludes());
699 Result->Macros = CapturedInfo.takeMacros();
700 Result->Marks = CapturedInfo.takeMarks();
701 Result->StatCache = StatCache;
702 Result->MainIsIncludeGuarded = CapturedInfo.isMainFileIncludeGuarded();
703 Result->TargetOpts = CI.TargetOpts;
704 if (PreambleCallback) {
705 trace::Span Tracer("Running PreambleCallback");
706 auto Ctx = CapturedInfo.takeLife();
707 // Stat cache is thread safe only when there are no producers. Hence
708 // change the VFS underneath to a consuming fs.
709 Ctx->getFileManager().setVirtualFileSystem(
710 Result->StatCache->getConsumingFS(FS: VFS));
711 // While extending the life of FileMgr and VFS, StatCache should also be
712 // extended.
713 Ctx->setStatCache(Result->StatCache);
714
715 PreambleCallback(std::move(*Ctx), Result->Pragmas);
716 }
717 return Result;
718 }
719
720 elog(Fmt: "Could not build a preamble for file {0} version {1}: {2}", Vals&: FileName,
721 Vals: Inputs.Version, Vals: BuiltPreamble.getError().message());
722 for (const Diag &D : PreambleDiagnostics.take()) {
723 if (D.Severity < DiagnosticsEngine::Error)
724 continue;
725 // Not an ideal way to show errors, but better than nothing!
726 elog(Fmt: " error: {0}", Vals: D.Message);
727 }
728 return nullptr;
729}
730
731bool isPreambleCompatible(const PreambleData &Preamble,
732 const ParseInputs &Inputs, PathRef FileName,
733 const CompilerInvocation &CI) {
734 auto ContentsBuffer =
735 llvm::MemoryBuffer::getMemBuffer(InputData: Inputs.Contents, BufferName: FileName);
736 auto Bounds = ComputePreambleBounds(LangOpts: CI.getLangOpts(), Buffer: *ContentsBuffer, MaxLines: 0);
737 auto VFS = Inputs.TFS->view(CWD: Inputs.CompileCommand.Directory);
738 return compileCommandsAreEqual(LHS: Inputs.CompileCommand,
739 RHS: Preamble.CompileCommand) &&
740 Preamble.Preamble.CanReuse(Invocation: CI, MainFileBuffer: *ContentsBuffer, Bounds, VFS&: *VFS);
741}
742
743void escapeBackslashAndQuotes(llvm::StringRef Text, llvm::raw_ostream &OS) {
744 for (char C : Text) {
745 switch (C) {
746 case '\\':
747 case '"':
748 OS << '\\';
749 break;
750 default:
751 break;
752 }
753 OS << C;
754 }
755}
756
757// Translate diagnostics from baseline into modified for the lines that have the
758// same spelling.
759static std::vector<Diag> patchDiags(llvm::ArrayRef<Diag> BaselineDiags,
760 const ScannedPreamble &BaselineScan,
761 const ScannedPreamble &ModifiedScan) {
762 std::vector<Diag> PatchedDiags;
763 if (BaselineDiags.empty())
764 return PatchedDiags;
765 DiagPatcher Patcher(BaselineScan.Lines, ModifiedScan.Lines);
766 for (auto &D : BaselineDiags) {
767 if (auto NewD = Patcher.translateDiag(D))
768 PatchedDiags.emplace_back(args: std::move(*NewD));
769 }
770 return PatchedDiags;
771}
772
773static std::string getPatchName(llvm::StringRef FileName) {
774 // This shouldn't coincide with any real file name.
775 llvm::SmallString<128> PatchName;
776 llvm::sys::path::append(path&: PatchName, a: llvm::sys::path::parent_path(path: FileName),
777 b: PreamblePatch::HeaderName);
778 return PatchName.str().str();
779}
780
781PreamblePatch PreamblePatch::create(llvm::StringRef FileName,
782 const ParseInputs &Modified,
783 const PreambleData &Baseline,
784 PatchType PatchType) {
785 trace::Span Tracer("CreatePreamblePatch");
786 SPAN_ATTACH(Tracer, "File", FileName);
787 assert(llvm::sys::path::is_absolute(FileName) && "relative FileName!");
788 // First scan preprocessor directives in Baseline and Modified. These will be
789 // used to figure out newly added directives in Modified. Scanning can fail,
790 // the code just bails out and creates an empty patch in such cases, as:
791 // - If scanning for Baseline fails, no knowledge of existing includes hence
792 // patch will contain all the includes in Modified. Leading to rebuild of
793 // whole preamble, which is terribly slow.
794 // - If scanning for Modified fails, cannot figure out newly added ones so
795 // there's nothing to do but generate an empty patch.
796 auto BaselineScan =
797 scanPreamble(Contents: Baseline.Preamble.getContents(), Cmd: Modified.CompileCommand);
798 if (!BaselineScan) {
799 elog(Fmt: "Failed to scan baseline of {0}: {1}", Vals&: FileName,
800 Vals: BaselineScan.takeError());
801 return PreamblePatch::unmodified(Preamble: Baseline);
802 }
803 auto ModifiedScan = scanPreamble(Contents: Modified.Contents, Cmd: Modified.CompileCommand);
804 if (!ModifiedScan) {
805 elog(Fmt: "Failed to scan modified contents of {0}: {1}", Vals&: FileName,
806 Vals: ModifiedScan.takeError());
807 return PreamblePatch::unmodified(Preamble: Baseline);
808 }
809
810 bool IncludesChanged = BaselineScan->Includes != ModifiedScan->Includes;
811 bool DirectivesChanged =
812 BaselineScan->TextualDirectives != ModifiedScan->TextualDirectives;
813 if ((PatchType == PatchType::MacroDirectives || !IncludesChanged) &&
814 !DirectivesChanged)
815 return PreamblePatch::unmodified(Preamble: Baseline);
816
817 PreamblePatch PP;
818 PP.Baseline = &Baseline;
819 PP.PatchFileName = getPatchName(FileName);
820 PP.ModifiedBounds = ModifiedScan->Bounds;
821
822 llvm::raw_string_ostream Patch(PP.PatchContents);
823 // Set default filename for subsequent #line directives
824 Patch << "#line 0 \"";
825 // FileName part of a line directive is subject to backslash escaping, which
826 // might lead to problems on windows especially.
827 escapeBackslashAndQuotes(Text: FileName, OS&: Patch);
828 Patch << "\"\n";
829
830 if (IncludesChanged && PatchType == PatchType::All) {
831 // We are only interested in newly added includes, record the ones in
832 // Baseline for exclusion.
833 llvm::DenseMap<std::pair<tok::PPKeywordKind, llvm::StringRef>,
834 const Inclusion *>
835 ExistingIncludes;
836 for (const auto &Inc : Baseline.Includes.MainFileIncludes)
837 ExistingIncludes[{Inc.Directive, Inc.Written}] = &Inc;
838 // There might be includes coming from disabled regions, record these for
839 // exclusion too. note that we don't have resolved paths for those.
840 for (const auto &Inc : BaselineScan->Includes)
841 ExistingIncludes.try_emplace(Key: {Inc.Directive, Inc.Written});
842 // Calculate extra includes that needs to be inserted.
843 for (auto &Inc : ModifiedScan->Includes) {
844 auto It = ExistingIncludes.find(Val: {Inc.Directive, Inc.Written});
845 // Include already present in the baseline preamble. Set resolved path and
846 // put into preamble includes.
847 if (It != ExistingIncludes.end()) {
848 if (It->second) {
849 // If this header is included in an active region of the baseline
850 // preamble, preserve it.
851 auto &PatchedInc = PP.PreambleIncludes.emplace_back();
852 // Copy everything from existing include, apart from the location,
853 // when it's coming from baseline preamble.
854 PatchedInc = *It->second;
855 PatchedInc.HashLine = Inc.HashLine;
856 PatchedInc.HashOffset = Inc.HashOffset;
857 }
858 continue;
859 }
860 // Include is new in the modified preamble. Inject it into the patch and
861 // use #line to set the presumed location to where it is spelled.
862 auto LineCol = offsetToClangLineColumn(Code: Modified.Contents, Offset: Inc.HashOffset);
863 Patch << llvm::formatv(Fmt: "#line {0}\n", Vals&: LineCol.first);
864 Patch << llvm::formatv(
865 Fmt: "#{0} {1}\n", Vals: spellingForIncDirective(IncludeDirective: Inc.Directive), Vals&: Inc.Written);
866 }
867 } else {
868 // Make sure we have the full set of includes available even when we're not
869 // patching. As these are used by features we provide afterwards like hover,
870 // go-to-def or include-cleaner when preamble is stale.
871 PP.PreambleIncludes = Baseline.Includes.MainFileIncludes;
872 }
873
874 if (DirectivesChanged) {
875 // We need to patch all the directives, since they are order dependent. e.g:
876 // #define BAR(X) NEW(X) // Newly introduced in Modified
877 // #define BAR(X) OLD(X) // Exists in the Baseline
878 //
879 // If we've patched only the first directive, the macro definition would've
880 // been wrong for the rest of the file, since patch is applied after the
881 // baseline preamble.
882 //
883 // Note that we deliberately ignore conditional directives and undefs to
884 // reduce complexity. The former might cause problems because scanning is
885 // imprecise and might pick directives from disabled regions.
886 for (const auto &TD : ModifiedScan->TextualDirectives) {
887 // Introduce an #undef directive before #defines to suppress any
888 // re-definition warnings.
889 if (TD.Directive == tok::pp_define)
890 Patch << "#undef " << TD.MacroName << '\n';
891 Patch << "#line " << TD.DirectiveLine << '\n';
892 Patch << TD.Text << '\n';
893 }
894 }
895
896 PP.PatchedDiags = patchDiags(BaselineDiags: Baseline.Diags, BaselineScan: *BaselineScan, ModifiedScan: *ModifiedScan);
897 PP.PatchedMarks = std::move(ModifiedScan->Marks);
898 PP.PatchedMacros = std::move(ModifiedScan->Macros);
899 dlog("Created preamble patch: {0}", Patch.str());
900 Patch.flush();
901 return PP;
902}
903
904PreamblePatch PreamblePatch::createFullPatch(llvm::StringRef FileName,
905 const ParseInputs &Modified,
906 const PreambleData &Baseline) {
907 return create(FileName, Modified, Baseline, PatchType: PatchType::All);
908}
909
910PreamblePatch PreamblePatch::createMacroPatch(llvm::StringRef FileName,
911 const ParseInputs &Modified,
912 const PreambleData &Baseline) {
913 return create(FileName, Modified, Baseline, PatchType: PatchType::MacroDirectives);
914}
915
916void PreamblePatch::apply(CompilerInvocation &CI) const {
917 // Make sure the compilation uses same target opts as the preamble. Clang has
918 // no guarantees around using arbitrary options when reusing PCHs, and
919 // different target opts can result in crashes, see
920 // ParsedASTTest.PreambleWithDifferentTarget.
921 CI.TargetOpts = Baseline->TargetOpts;
922
923 // No need to map an empty file.
924 if (PatchContents.empty())
925 return;
926 auto &PPOpts = CI.getPreprocessorOpts();
927 auto PatchBuffer =
928 // we copy here to ensure contents are still valid if CI outlives the
929 // PreamblePatch.
930 llvm::MemoryBuffer::getMemBufferCopy(InputData: PatchContents, BufferName: PatchFileName);
931 // CI will take care of the lifetime of the buffer.
932 PPOpts.addRemappedFile(From: PatchFileName, To: PatchBuffer.release());
933 // The patch will be parsed after loading the preamble ast and before parsing
934 // the main file.
935 PPOpts.Includes.push_back(x: PatchFileName);
936}
937
938std::vector<Inclusion> PreamblePatch::preambleIncludes() const {
939 return PreambleIncludes;
940}
941
942PreamblePatch PreamblePatch::unmodified(const PreambleData &Preamble) {
943 PreamblePatch PP;
944 PP.Baseline = &Preamble;
945 PP.PreambleIncludes = Preamble.Includes.MainFileIncludes;
946 PP.ModifiedBounds = Preamble.Preamble.getBounds();
947 PP.PatchedDiags = Preamble.Diags;
948 return PP;
949}
950
951llvm::ArrayRef<PragmaMark> PreamblePatch::marks() const {
952 if (PatchContents.empty())
953 return Baseline->Marks;
954 return PatchedMarks;
955}
956
957const MainFileMacros &PreamblePatch::mainFileMacros() const {
958 if (PatchContents.empty())
959 return Baseline->Macros;
960 return PatchedMacros;
961}
962
963OptionalFileEntryRef PreamblePatch::getPatchEntry(llvm::StringRef MainFilePath,
964 const SourceManager &SM) {
965 auto PatchFilePath = getPatchName(FileName: MainFilePath);
966 return SM.getFileManager().getOptionalFileRef(Filename: PatchFilePath);
967}
968} // namespace clangd
969} // namespace clang
970

source code of clang-tools-extra/clangd/Preamble.cpp