gold: Add --dependency-file option.users/roland/gold-depfile

gold/
	* options.h (class General_options): Add --dependency-file option.
	* fileread.cc (File_read::files_read): New static variable.
	(File_read::write_dependency_file): New static member function.
	* fileread.h (class File_read): Declare them.
	* layout.cc (Close_task_runner::run): Call write_dependency_file
	if --dependency-file was passed.

5 files changed, 52 insertions, 2 deletions

diff --git a/gold/ChangeLog b/gold/ChangeLog
index f3d37159362..357ea22d0e8 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,12 @@
+2020-06-12  Roland McGrath  <mcgrathr@google.com>
+
+	* options.h (class General_options): Add --dependency-file option.
+	* fileread.cc (File_read::files_read): New static variable.
+	(File_read::write_dependency_file): New static member function.
+	* fileread.h (class File_read): Declare them.
+	* layout.cc (Close_task_runner::run): Call write_dependency_file
+	if --dependency-file was passed.
+
 2020-06-06  Alan Modra  <amodra@gmail.com>
 
 	* powerpc.cc: Update throughout for reloc renaming.
diff --git a/gold/fileread.cc b/gold/fileread.cc
index bebe0aba8d0..e0306e7fabb 100644
--- a/gold/fileread.cc
+++ b/gold/fileread.cc
@@ -124,6 +124,7 @@ static Initialize_lock file_counts_initialize_lock(&file_counts_lock);
 unsigned long long File_read::total_mapped_bytes;
 unsigned long long File_read::current_mapped_bytes;
 unsigned long long File_read::maximum_mapped_bytes;
+std::set<std::string> File_read::files_read;
 
 // Class File_read::View.
 
@@ -211,6 +212,8 @@ File_read::open(const Task* task, const std::string& name)
       gold_debug(DEBUG_FILES, "Attempt to open %s succeeded",
 		 this->name_.c_str());
       this->token_.add_writer(task);
+      Hold_optional_lock hl(file_counts_lock);
+      File_read::files_read.insert(this->name_);
     }
 
   return this->descriptor_ >= 0;
@@ -1138,4 +1141,25 @@ Input_file::open_binary(const Task* task, const std::string& name)
 			  binary_to_elf.converted_size());
 }
 
+void
+File_read::write_dependency_file(const char* dependency_file_name,
+                                 const char* output_file_name)
+{
+  FILE *depfile = fopen(dependency_file_name, "w");
+
+  fprintf(depfile, "%s: ", output_file_name);
+  for (std::set<std::string>::const_iterator it = files_read.begin();
+       it != files_read.end();
+       ++it)
+    fprintf(depfile, "\\\n  %s", it->c_str());
+  fprintf(depfile, "\n");
+
+  for (std::set<std::string>::const_iterator it = files_read.begin();
+       it != files_read.end();
+       ++it)
+    fprintf(depfile, "\n%s:\n", it->c_str());
+
+  fclose(depfile);
+}
+
 } // End namespace gold.
diff --git a/gold/fileread.h b/gold/fileread.h
index cf92367c2ca..005d2e28c84 100644
--- a/gold/fileread.h
+++ b/gold/fileread.h
@@ -27,6 +27,7 @@
 
 #include <list>
 #include <map>
+#include <set>
 #include <string>
 #include <vector>
 
@@ -207,6 +208,11 @@ class File_read
   static void
   print_stats();
 
+  // Write the dependency file listing all files read.
+  static void
+  write_dependency_file(const char* dependency_file_name,
+                        const char* output_file_name);
+
   // Return the open file descriptor (for plugins).
   int
   descriptor()
@@ -214,7 +220,7 @@ class File_read
     this->reopen_descriptor();
     return this->descriptor_;
   }
-  
+
   // Return the file last modification time.  Calls gold_fatal if the stat
   // system call failed.
   Timespec
@@ -247,6 +253,9 @@ class File_read
   // --stats.
   static unsigned long long maximum_mapped_bytes;
 
+  // Set of names of all files read.
+  static std::set<std::string> files_read;
+
   // A view into the file.
   class View
   {
diff --git a/gold/layout.cc b/gold/layout.cc
index be437f3900e..85102108682 100644
--- a/gold/layout.cc
+++ b/gold/layout.cc
@@ -6153,6 +6153,10 @@ Close_task_runner::run(Workqueue*, const Task*)
   if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
     this->layout_->write_binary(this->of_);
 
+  if (this->options_->dependency_file())
+    File_read::write_dependency_file(this->options_->dependency_file(),
+                                     this->options_->output_file_name());
+
   this->of_->close();
 }
 
diff --git a/gold/options.h b/gold/options.h
index b2059d984cd..eaf8727ba3c 100644
--- a/gold/options.h
+++ b/gold/options.h
@@ -472,7 +472,7 @@ struct Struct_special : public Struct_var
   options::String_set::const_iterator					  \
   varname__##_end() const						  \
   { return this->varname__##_.value.end(); }                              \
-                                                                          \
+									  \
   options::String_set::size_type                                          \
   varname__##_size() const                                                \
   { return this->varname__##_.value.size(); }                             \
@@ -800,6 +800,10 @@ class General_options
 	      N_("Do not demangle C++ symbols in log messages"),
 	      NULL);
 
+  DEFINE_string(dependency_file, options::TWO_DASHES, '\0', NULL,
+		N_("Write a dependency file listing all files read"),
+		N_("FILE"));
+
   DEFINE_bool(detect_odr_violations, options::TWO_DASHES, '\0', false,
 	      N_("Look for violations of the C++ One Definition Rule"),
 	      N_("Do not look for violations of the C++ One Definition Rule"));