PR 22843: ld, gold: Add --dependency-file option.

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

ld/
	* NEWS: Note --dependency-file.
	* ld.texi (Options): Document --dependency-file.
	* ldlex.h (enum option_values): Add OPTION_DEPENDENCY_FILE.
	* ld.h (ld_config_type): New member dependency_file.
	* lexsup.c (ld_options, parse_args): Parse --dependency-file.
	* ldmain.c (struct dependency_file): New type.
	(dependency_files, dependency_files_tail): New static variables.
	(track_dependency_files): New function.
	(write_dependency_file): New function.
	(main): Call it when --dependency-file was passed.
	* ldfile.c (ldfile_try_open_bfd): Call track_dependency_files.
	(ldfile_open_command_file_1): Likewise.
	* ldelf.c (ldelf_try_needed): Likewise.
	* pe-dll.c (pe_implied_import_dll): Likewise.

5 files changed, 103 insertions, 38 deletions

diff --git a/gold/ChangeLog b/gold/ChangeLog
index f4679f9..4d524d7 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,16 @@
+2020-06-23  Roland McGrath  <mcgrathr@google.com>
+
+	PR 22843
+	* options.h (class General_options): Add --dependency-file option.
+	* fileread.cc (File_read::files_read): New static variable.
+	(File_read::open): Add the file to the files_read list.
+	(File_read::record_file_read): New static member function.
+	(File_read::write_dependency_file): New static member function.
+	* fileread.h (class File_read): Declare them.
+	* layout.cc (Layout::read_layout_from_file): Call record_file_read.
+	(Close_task_runner::run): Call write_dependency_file if
+	--dependency-file was passed.
+
 2020-06-18  Fangrui Song  <i@maskray.me>
 
 	PR gold/26039
diff --git a/gold/fileread.cc b/gold/fileread.cc
index bebe0ab..f5ca719 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::vector<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);
+      record_file_read(this->name_);
     }
 
   return this->descriptor_ >= 0;
@@ -1138,4 +1141,31 @@ Input_file::open_binary(const Task* task, const std::string& name)
 			  binary_to_elf.converted_size());
 }
 
+void
+File_read::record_file_read(const std::string& name)
+{
+  File_read::files_read.push_back(name);
+}
+
+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::vector<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::vector<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 cf92367..2120135 100644
--- a/gold/fileread.h
+++ b/gold/fileread.h
@@ -207,6 +207,15 @@ 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);
+
+  // Record that a file was read.  File_read::open does this.
+  static void
+  record_file_read(const std::string& name);
+
   // Return the open file descriptor (for plugins).
   int
   descriptor()
@@ -214,7 +223,7 @@ 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 +256,9 @@ class File_read
   // --stats.
   static unsigned long long maximum_mapped_bytes;
 
+  // Set of names of all files read.
+  static std::vector<std::string> files_read;
+
   // A view into the file.
   class View
   {
diff --git a/gold/layout.cc b/gold/layout.cc
index 0c7be85..13e533a 100644
--- a/gold/layout.cc
+++ b/gold/layout.cc
@@ -1183,11 +1183,11 @@ Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
       // All ".text.unlikely.*" sections can be moved to a unique
       // segment with --text-unlikely-segment option.
       bool text_unlikely_segment
-          = (parameters->options().text_unlikely_segment()
-             && is_prefix_of(".text.unlikely",
-                             object->section_name(shndx).c_str()));
+	  = (parameters->options().text_unlikely_segment()
+	     && is_prefix_of(".text.unlikely",
+			     object->section_name(shndx).c_str()));
       if (text_unlikely_segment)
-        {
+	{
 	  elfcpp::Elf_Xword flags
 	    = this->get_output_section_flags(shdr.get_sh_flags());
 
@@ -1196,11 +1196,11 @@ Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
 						    &name_key);
 	  os = this->get_output_section(os_name, name_key, sh_type, flags,
 					ORDER_INVALID, false);
-          // Map this output section to a unique segment.  This is done to
-          // separate "text" that is not likely to be executed from "text"
-          // that is likely executed.
+	  // Map this output section to a unique segment.  This is done to
+	  // separate "text" that is not likely to be executed from "text"
+	  // that is likely executed.
 	  os->set_is_unique_segment();
-        }
+	}
       else
 	{
 	  // Plugins can choose to place one or more subsets of sections in
@@ -1221,7 +1221,7 @@ Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
 	      // We know the name of the output section, directly call
 	      // get_output_section here by-passing choose_output_section.
 	      elfcpp::Elf_Xword flags
-	        = this->get_output_section_flags(shdr.get_sh_flags());
+		= this->get_output_section_flags(shdr.get_sh_flags());
 
 	      const char* os_name = it->second->name;
 	      Stringpool::Key name_key;
@@ -1229,11 +1229,11 @@ Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
 	      os = this->get_output_section(os_name, name_key, sh_type, flags,
 					ORDER_INVALID, false);
 	      if (!os->is_unique_segment())
-	        {
-	          os->set_is_unique_segment();
-	          os->set_extra_segment_flags(it->second->flags);
-	          os->set_segment_alignment(it->second->align);
-	        }
+		{
+		  os->set_is_unique_segment();
+		  os->set_extra_segment_flags(it->second->flags);
+		  os->set_segment_alignment(it->second->align);
+		}
 	    }
 	  }
       if (os == NULL)
@@ -2268,9 +2268,9 @@ Layout::layout_gnu_property(unsigned int note_type,
       const int size = parameters->target().get_size();
       const bool is_big_endian = parameters->target().is_big_endian();
       if (size == 32)
-        {
-          if (is_big_endian)
-            {
+	{
+	  if (is_big_endian)
+	    {
 #ifdef HAVE_TARGET_32_BIG
 	      parameters->sized_target<32, true>()->
 		  record_gnu_property(note_type, pr_type, pr_datasz, pr_data,
@@ -2278,9 +2278,9 @@ Layout::layout_gnu_property(unsigned int note_type,
 #else
 	      gold_unreachable();
 #endif
-            }
-          else
-            {
+	    }
+	  else
+	    {
 #ifdef HAVE_TARGET_32_LITTLE
 	      parameters->sized_target<32, false>()->
 		  record_gnu_property(note_type, pr_type, pr_datasz, pr_data,
@@ -2288,12 +2288,12 @@ Layout::layout_gnu_property(unsigned int note_type,
 #else
 	      gold_unreachable();
 #endif
-            }
-        }
+	    }
+	}
       else if (size == 64)
-        {
-          if (is_big_endian)
-            {
+	{
+	  if (is_big_endian)
+	    {
 #ifdef HAVE_TARGET_64_BIG
 	      parameters->sized_target<64, true>()->
 		  record_gnu_property(note_type, pr_type, pr_datasz, pr_data,
@@ -2301,9 +2301,9 @@ Layout::layout_gnu_property(unsigned int note_type,
 #else
 	      gold_unreachable();
 #endif
-            }
-          else
-            {
+	    }
+	  else
+	    {
 #ifdef HAVE_TARGET_64_LITTLE
 	      parameters->sized_target<64, false>()->
 		  record_gnu_property(note_type, pr_type, pr_datasz, pr_data,
@@ -2311,10 +2311,10 @@ Layout::layout_gnu_property(unsigned int note_type,
 #else
 	      gold_unreachable();
 #endif
-            }
-        }
+	    }
+	}
       else
-        gold_unreachable();
+	gold_unreachable();
       return;
     }
 
@@ -2922,6 +2922,8 @@ Layout::read_layout_from_file()
     gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
 	       filename, strerror(errno));
 
+  File_read::record_file_read(filename);
+
   std::getline(in, line);   // this chops off the trailing \n, if any
   unsigned int position = 1;
   this->set_section_ordering_specified();
@@ -3299,7 +3301,7 @@ Layout::create_gnu_properties_note()
       write_sized_value(datasz, 4, p + 4, is_big_endian);
       memcpy(p + 8, prop->second.pr_data, datasz);
       if (aligned_datasz > datasz)
-        memset(p + 8 + datasz, 0, aligned_datasz - datasz);
+	memset(p + 8 + datasz, 0, aligned_datasz - datasz);
       p += 8 + aligned_datasz;
     }
   Output_section_data* posd = new Output_data_const(desc, descsz, 4);
@@ -6156,6 +6158,10 @@ 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 f0e9fbd..3c8d25a 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"));
@@ -1501,10 +1505,10 @@ class General_options
   DEFINE_uint64(stack_size, options::DASH_Z, '\0', 0,
 		N_("Set PT_GNU_STACK segment p_memsz to SIZE"), N_("SIZE"));
   DEFINE_enum(start_stop_visibility, options::DASH_Z, '\0', "protected",
-              N_("ELF symbol visibility for synthesized "
-                 "__start_* and __stop_* symbols"),
-              ("[default,internal,hidden,protected]"),
-              {"default", "internal", "hidden", "protected"});
+	      N_("ELF symbol visibility for synthesized "
+		 "__start_* and __stop_* symbols"),
+	      ("[default,internal,hidden,protected]"),
+	      {"default", "internal", "hidden", "protected"});
   DEFINE_bool(text, options::DASH_Z, '\0', false,
 	      N_("Do not permit relocations in read-only segments"),
 	      N_("Permit relocations in read-only segments"));