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