DependencyFile.cpp revision ca11f61233b2acc266f371816e48290af4e10528 
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/Compiler.h"
25#include "llvm/Support/raw_ostream.h"
26#include <string>
27
28using namespace clang;
29
30namespace {
31class VISIBILITY_HIDDEN DependencyFileCallback : public PPCallbacks {
32  std::vector<std::string> Files;
33  llvm::StringSet<> FilesSet;
34  const Preprocessor *PP;
35  std::vector<std::string> Targets;
36  llvm::raw_ostream *OS;
37  bool IncludeSystemHeaders;
38  bool PhonyTarget;
39private:
40  bool FileMatchesDepCriteria(const char *Filename,
41                              SrcMgr::CharacteristicKind FileType);
42  void OutputDependencyFile();
43
44public:
45  DependencyFileCallback(const Preprocessor *_PP,
46                         llvm::raw_ostream *_OS,
47                         const DependencyOutputOptions &Opts)
48    : PP(_PP), Targets(Opts.Targets), OS(_OS),
49      IncludeSystemHeaders(Opts.IncludeSystemHeaders),
50      PhonyTarget(Opts.UsePhonyTargets) {}
51
52  ~DependencyFileCallback() {
53    OutputDependencyFile();
54    OS->flush();
55    delete OS;
56  }
57
58  virtual void FileChanged(SourceLocation Loc, FileChangeReason Reason,
59                           SrcMgr::CharacteristicKind FileType);
60};
61}
62
63void clang::AttachDependencyFileGen(Preprocessor &PP,
64                                    const DependencyOutputOptions &Opts) {
65  if (Opts.Targets.empty()) {
66    PP.getDiagnostics().Report(diag::err_fe_dependency_file_requires_MT);
67    return;
68  }
69
70  std::string Err;
71  llvm::raw_ostream *OS(new llvm::raw_fd_ostream(Opts.OutputFile.c_str(), Err));
72  if (!Err.empty()) {
73    PP.getDiagnostics().Report(diag::err_fe_error_opening)
74      << Opts.OutputFile << Err;
75    return;
76  }
77
78  assert(!PP.getPPCallbacks() && "Preprocessor callbacks already registered!");
79  PP.setPPCallbacks(new DependencyFileCallback(&PP, OS, Opts));
80}
81
82/// FileMatchesDepCriteria - Determine whether the given Filename should be
83/// considered as a dependency.
84bool DependencyFileCallback::FileMatchesDepCriteria(const char *Filename,
85                                          SrcMgr::CharacteristicKind FileType) {
86  if (strcmp("<built-in>", Filename) == 0)
87    return false;
88
89  if (IncludeSystemHeaders)
90    return true;
91
92  return FileType == SrcMgr::C_User;
93}
94
95void DependencyFileCallback::FileChanged(SourceLocation Loc,
96                                         FileChangeReason Reason,
97                                         SrcMgr::CharacteristicKind FileType) {
98  if (Reason != PPCallbacks::EnterFile)
99    return;
100
101  // Dependency generation really does want to go all the way to the
102  // file entry for a source location to find out what is depended on.
103  // We do not want #line markers to affect dependency generation!
104  SourceManager &SM = PP->getSourceManager();
105
106  const FileEntry *FE =
107    SM.getFileEntryForID(SM.getFileID(SM.getInstantiationLoc(Loc)));
108  if (FE == 0) return;
109
110  const char *Filename = FE->getName();
111  if (!FileMatchesDepCriteria(Filename, FileType))
112    return;
113
114  // Remove leading "./"
115  if (Filename[0] == '.' && Filename[1] == '/')
116    Filename = &Filename[2];
117
118  if (FilesSet.insert(Filename))
119    Files.push_back(Filename);
120}
121
122void DependencyFileCallback::OutputDependencyFile() {
123  // Write out the dependency targets, trying to avoid overly long
124  // lines when possible. We try our best to emit exactly the same
125  // dependency file as GCC (4.2), assuming the included files are the
126  // same.
127  const unsigned MaxColumns = 75;
128  unsigned Columns = 0;
129
130  for (std::vector<std::string>::iterator
131         I = Targets.begin(), E = Targets.end(); I != E; ++I) {
132    unsigned N = I->length();
133    if (Columns == 0) {
134      Columns += N;
135      *OS << *I;
136    } else if (Columns + N + 2 > MaxColumns) {
137      Columns = N + 2;
138      *OS << " \\\n  " << *I;
139    } else {
140      Columns += N + 1;
141      *OS << ' ' << *I;
142    }
143  }
144
145  *OS << ':';
146  Columns += 1;
147
148  // Now add each dependency in the order it was seen, but avoiding
149  // duplicates.
150  for (std::vector<std::string>::iterator I = Files.begin(),
151         E = Files.end(); I != E; ++I) {
152    // Start a new line if this would exceed the column limit. Make
153    // sure to leave space for a trailing " \" in case we need to
154    // break the line on the next iteration.
155    unsigned N = I->length();
156    if (Columns + (N + 1) + 2 > MaxColumns) {
157      *OS << " \\\n ";
158      Columns = 2;
159    }
160    *OS << ' ' << *I;
161    Columns += N + 1;
162  }
163  *OS << '\n';
164
165  // Create phony targets if requested.
166  if (PhonyTarget) {
167    // Skip the first entry, this is always the input file itself.
168    for (std::vector<std::string>::iterator I = Files.begin() + 1,
169           E = Files.end(); I != E; ++I) {
170      *OS << '\n';
171      *OS << *I << ":\n";
172    }
173  }
174}
175
176