1 //===--- DependencyFile.cpp - Generate dependency file --------------------===//
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 // This code generates dependency files.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/Frontend/Utils.h"
15 #include "clang/Basic/FileManager.h"
16 #include "clang/Basic/SourceLocation.h"
17 #include "clang/Basic/SourceManager.h"
18 #include "clang/Frontend/DependencyOutputOptions.h"
19 #include "clang/Frontend/FrontendDiagnostic.h"
20 #include "clang/Lex/DirectoryLookup.h"
21 #include "clang/Lex/PPCallbacks.h"
22 #include "clang/Lex/Preprocessor.h"
23 #include "llvm/ADT/StringSet.h"
24 #include "llvm/Support/raw_ostream.h"
25 #include <string>
26 
27 using namespace clang;
28 
29 namespace {
30 class DependencyFileCallback : public PPCallbacks {
31   std::vector<std::string> Files;
32   llvm::StringSet<> FilesSet;
33   const Preprocessor *PP;
34   std::vector<std::string> Targets;
35   llvm::raw_ostream *OS;
36   bool IncludeSystemHeaders;
37   bool PhonyTarget;
38 private:
39   bool FileMatchesDepCriteria(const char *Filename,
40                               SrcMgr::CharacteristicKind FileType);
41   void OutputDependencyFile();
42 
43 public:
44   DependencyFileCallback(const Preprocessor *_PP,
45                          llvm::raw_ostream *_OS,
46                          const DependencyOutputOptions &Opts)
47     : PP(_PP), Targets(Opts.Targets), OS(_OS),
48       IncludeSystemHeaders(Opts.IncludeSystemHeaders),
49       PhonyTarget(Opts.UsePhonyTargets) {}
50 
51   virtual void FileChanged(SourceLocation Loc, FileChangeReason Reason,
52                            SrcMgr::CharacteristicKind FileType);
53 
54   virtual void EndOfMainFile() {
55     OutputDependencyFile();
56     delete OS;
57     OS = 0;
58   }
59 };
60 }
61 
62 void clang::AttachDependencyFileGen(Preprocessor &PP,
63                                     const DependencyOutputOptions &Opts) {
64   if (Opts.Targets.empty()) {
65     PP.getDiagnostics().Report(diag::err_fe_dependency_file_requires_MT);
66     return;
67   }
68 
69   std::string Err;
70   llvm::raw_ostream *OS(new llvm::raw_fd_ostream(Opts.OutputFile.c_str(), Err));
71   if (!Err.empty()) {
72     PP.getDiagnostics().Report(diag::err_fe_error_opening)
73       << Opts.OutputFile << Err;
74     return;
75   }
76 
77   PP.addPPCallbacks(new DependencyFileCallback(&PP, OS, Opts));
78 }
79 
80 /// FileMatchesDepCriteria - Determine whether the given Filename should be
81 /// considered as a dependency.
82 bool DependencyFileCallback::FileMatchesDepCriteria(const char *Filename,
83                                           SrcMgr::CharacteristicKind FileType) {
84   if (strcmp("<built-in>", Filename) == 0)
85     return false;
86 
87   if (IncludeSystemHeaders)
88     return true;
89 
90   return FileType == SrcMgr::C_User;
91 }
92 
93 void DependencyFileCallback::FileChanged(SourceLocation Loc,
94                                          FileChangeReason Reason,
95                                          SrcMgr::CharacteristicKind FileType) {
96   if (Reason != PPCallbacks::EnterFile)
97     return;
98 
99   // Dependency generation really does want to go all the way to the
100   // file entry for a source location to find out what is depended on.
101   // We do not want #line markers to affect dependency generation!
102   SourceManager &SM = PP->getSourceManager();
103 
104   const FileEntry *FE =
105     SM.getFileEntryForID(SM.getFileID(SM.getInstantiationLoc(Loc)));
106   if (FE == 0) return;
107 
108   const char *Filename = FE->getName();
109   if (!FileMatchesDepCriteria(Filename, FileType))
110     return;
111 
112   // Remove leading "./"
113   if (Filename[0] == '.' && Filename[1] == '/')
114     Filename = &Filename[2];
115 
116   if (FilesSet.insert(Filename))
117     Files.push_back(Filename);
118 }
119 
120 void DependencyFileCallback::OutputDependencyFile() {
121   // Write out the dependency targets, trying to avoid overly long
122   // lines when possible. We try our best to emit exactly the same
123   // dependency file as GCC (4.2), assuming the included files are the
124   // same.
125   const unsigned MaxColumns = 75;
126   unsigned Columns = 0;
127 
128   for (std::vector<std::string>::iterator
129          I = Targets.begin(), E = Targets.end(); I != E; ++I) {
130     unsigned N = I->length();
131     if (Columns == 0) {
132       Columns += N;
133       *OS << *I;
134     } else if (Columns + N + 2 > MaxColumns) {
135       Columns = N + 2;
136       *OS << " \\\n  " << *I;
137     } else {
138       Columns += N + 1;
139       *OS << ' ' << *I;
140     }
141   }
142 
143   *OS << ':';
144   Columns += 1;
145 
146   // Now add each dependency in the order it was seen, but avoiding
147   // duplicates.
148   for (std::vector<std::string>::iterator I = Files.begin(),
149          E = Files.end(); I != E; ++I) {
150     // Start a new line if this would exceed the column limit. Make
151     // sure to leave space for a trailing " \" in case we need to
152     // break the line on the next iteration.
153     unsigned N = I->length();
154     if (Columns + (N + 1) + 2 > MaxColumns) {
155       *OS << " \\\n ";
156       Columns = 2;
157     }
158     *OS << ' ' << *I;
159     Columns += N + 1;
160   }
161   *OS << '\n';
162 
163   // Create phony targets if requested.
164   if (PhonyTarget) {
165     // Skip the first entry, this is always the input file itself.
166     for (std::vector<std::string>::iterator I = Files.begin() + 1,
167            E = Files.end(); I != E; ++I) {
168       *OS << '\n';
169       *OS << *I << ":\n";
170     }
171   }
172 }
173 
174