1//===--------- IncrementalParser.cpp - Incremental Compilation -----------===//
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 implements the class which performs incremental code compilation.
10//
11//===----------------------------------------------------------------------===//
12
13#include "IncrementalParser.h"
14
15#include "clang/AST/DeclContextInternals.h"
16#include "clang/Frontend/CompilerInstance.h"
17#include "clang/Interpreter/PartialTranslationUnit.h"
18#include "clang/Parse/Parser.h"
19#include "clang/Sema/Sema.h"
20#include "llvm/Support/CrashRecoveryContext.h"
21#include "llvm/Support/Error.h"
22
23#include <sstream>
24
25namespace clang {
26
27// IncrementalParser::IncrementalParser() {}
28
29IncrementalParser::IncrementalParser(CompilerInstance &Instance,
30 llvm::Error &Err)
31 : S(Instance.getSema()) {
32 llvm::ErrorAsOutParameter EAO(&Err);
33 Consumer = &S.getASTConsumer();
34 P.reset(p: new Parser(S.getPreprocessor(), S, /*SkipBodies=*/false));
35 P->Initialize();
36}
37
38IncrementalParser::~IncrementalParser() { P.reset(); }
39
40llvm::Expected<TranslationUnitDecl *>
41IncrementalParser::ParseOrWrapTopLevelDecl() {
42 // Recover resources if we crash before exiting this method.
43 llvm::CrashRecoveryContextCleanupRegistrar<Sema> CleanupSema(&S);
44 Sema::GlobalEagerInstantiationScope GlobalInstantiations(S, /*Enabled=*/true,
45 /*AtEndOfTU=*/true);
46 Sema::LocalEagerInstantiationScope LocalInstantiations(S, /*AtEndOfTU=*/true);
47
48 // Add a new PTU.
49 ASTContext &C = S.getASTContext();
50 C.addTranslationUnitDecl();
51
52 // Skip previous eof due to last incremental input.
53 if (P->getCurToken().is(K: tok::annot_repl_input_end)) {
54 P->ConsumeAnyToken();
55 // FIXME: Clang does not call ExitScope on finalizing the regular TU, we
56 // might want to do that around HandleEndOfTranslationUnit.
57 P->ExitScope();
58 S.CurContext = nullptr;
59 // Start a new PTU.
60 P->EnterScope(ScopeFlags: Scope::DeclScope);
61 S.ActOnTranslationUnitScope(S: P->getCurScope());
62 }
63
64 Parser::DeclGroupPtrTy ADecl;
65 Sema::ModuleImportState ImportState;
66 for (bool AtEOF = P->ParseFirstTopLevelDecl(Result&: ADecl, ImportState); !AtEOF;
67 AtEOF = P->ParseTopLevelDecl(Result&: ADecl, ImportState)) {
68 if (ADecl && !Consumer->HandleTopLevelDecl(D: ADecl.get()))
69 return llvm::make_error<llvm::StringError>(Args: "Parsing failed. "
70 "The consumer rejected a decl",
71 Args: std::error_code());
72 }
73
74 DiagnosticsEngine &Diags = S.getDiagnostics();
75 if (Diags.hasErrorOccurred()) {
76 CleanUpPTU(MostRecentTU: C.getTranslationUnitDecl());
77
78 Diags.Reset(/*soft=*/true);
79 Diags.getClient()->clear();
80 return llvm::make_error<llvm::StringError>(Args: "Parsing failed.",
81 Args: std::error_code());
82 }
83
84 // Process any TopLevelDecls generated by #pragma weak.
85 for (Decl *D : S.WeakTopLevelDecls()) {
86 DeclGroupRef DGR(D);
87 Consumer->HandleTopLevelDecl(D: DGR);
88 }
89
90 LocalInstantiations.perform();
91 GlobalInstantiations.perform();
92
93 Consumer->HandleTranslationUnit(Ctx&: C);
94
95 return C.getTranslationUnitDecl();
96}
97
98llvm::Expected<TranslationUnitDecl *>
99IncrementalParser::Parse(llvm::StringRef input) {
100 Preprocessor &PP = S.getPreprocessor();
101 assert(PP.isIncrementalProcessingEnabled() && "Not in incremental mode!?");
102
103 std::ostringstream SourceName;
104 SourceName << "input_line_" << InputCount++;
105
106 // Create an uninitialized memory buffer, copy code in and append "\n"
107 size_t InputSize = input.size(); // don't include trailing 0
108 // MemBuffer size should *not* include terminating zero
109 std::unique_ptr<llvm::MemoryBuffer> MB(
110 llvm::WritableMemoryBuffer::getNewUninitMemBuffer(Size: InputSize + 1,
111 BufferName: SourceName.str()));
112 char *MBStart = const_cast<char *>(MB->getBufferStart());
113 memcpy(dest: MBStart, src: input.data(), n: InputSize);
114 MBStart[InputSize] = '\n';
115
116 SourceManager &SM = S.getSourceManager();
117
118 // FIXME: Create SourceLocation, which will allow clang to order the overload
119 // candidates for example
120 SourceLocation NewLoc = SM.getLocForStartOfFile(FID: SM.getMainFileID());
121
122 // Create FileID for the current buffer.
123 FileID FID = SM.createFileID(Buffer: std::move(MB), FileCharacter: SrcMgr::C_User, /*LoadedID=*/0,
124 /*LoadedOffset=*/0, IncludeLoc: NewLoc);
125
126 // NewLoc only used for diags.
127 if (PP.EnterSourceFile(FID, /*DirLookup=*/Dir: nullptr, Loc: NewLoc))
128 return llvm::make_error<llvm::StringError>(Args: "Parsing failed. "
129 "Cannot enter source file.",
130 Args: std::error_code());
131
132 auto PTU = ParseOrWrapTopLevelDecl();
133 if (!PTU)
134 return PTU.takeError();
135
136 if (PP.getLangOpts().DelayedTemplateParsing) {
137 // Microsoft-specific:
138 // Late parsed templates can leave unswallowed "macro"-like tokens.
139 // They will seriously confuse the Parser when entering the next
140 // source file. So lex until we are EOF.
141 Token Tok;
142 do {
143 PP.Lex(Result&: Tok);
144 } while (Tok.isNot(K: tok::annot_repl_input_end));
145 } else {
146 Token AssertTok;
147 PP.Lex(Result&: AssertTok);
148 assert(AssertTok.is(tok::annot_repl_input_end) &&
149 "Lexer must be EOF when starting incremental parse!");
150 }
151
152 return PTU;
153}
154
155void IncrementalParser::CleanUpPTU(TranslationUnitDecl *MostRecentTU) {
156 if (StoredDeclsMap *Map = MostRecentTU->getPrimaryContext()->getLookupPtr()) {
157 for (auto &&[Key, List] : *Map) {
158 DeclContextLookupResult R = List.getLookupResult();
159 std::vector<NamedDecl *> NamedDeclsToRemove;
160 bool RemoveAll = true;
161 for (NamedDecl *D : R) {
162 if (D->getTranslationUnitDecl() == MostRecentTU)
163 NamedDeclsToRemove.push_back(x: D);
164 else
165 RemoveAll = false;
166 }
167 if (LLVM_LIKELY(RemoveAll)) {
168 Map->erase(Val: Key);
169 } else {
170 for (NamedDecl *D : NamedDeclsToRemove)
171 List.remove(D);
172 }
173 }
174 }
175
176 // FIXME: We should de-allocate MostRecentTU
177 for (Decl *D : MostRecentTU->decls()) {
178 auto *ND = dyn_cast<NamedDecl>(Val: D);
179 if (!ND || ND->getDeclName().isEmpty())
180 continue;
181 // Check if we need to clean up the IdResolver chain.
182 if (ND->getDeclName().getFETokenInfo() && !D->getLangOpts().ObjC &&
183 !D->getLangOpts().CPlusPlus)
184 S.IdResolver.RemoveDecl(D: ND);
185 }
186}
187
188} // end namespace clang
189