Add plugin functionality for link-time optimization (LTO).

include/:
	* plugin-api.h: New file.

gold/:
	* configure.ac (plugins): Add --enable-plugins option.
	* configure: Regenerate.
	* config.in: Regenerate.
	* Makefile.am (LIBDL): New variable.
	(CCFILES): Add plugin.cc.
	(HFILES): Add plugin.h.
	(ldadd_var): Add LIBDL.
	* Makefile.in: Regenerate.

	* archive.cc: Include "plugin.h".
	(Archive::setup): Don't preread archive symbols when using a plugin.
	(Archive::get_file_and_offset): Add memsize parameter.  Change callers.
	(Archive::get_elf_object_for_member): Call plugin hooks for claiming
	files.
	(Archive::include_member): Add symbols from plugin objects.
	* archive.h (Archive::get_file_and_offset): Add memsize parameter.
	* descriptors.cc (Descriptors::open): Check for file descriptors
	abandoned by plugins.
	(Descriptors::claim_for_plugin): New function.
	* descriptors.h (Descriptors::claim_for_plugin): New function.
	(Open_descriptor::is_claimed): New field.
	(claim_descriptor_for_plugin): New function.
	* fileread.cc (File_read::claim_for_plugin): New function.
	* fileread.h (File_read::claim_for_plugin): New function.
	(File_read::descriptor): New function.
	* gold.cc: Include "plugin.h".
	(queue_initial_tasks): Add task to call plugin hooks for generating
	new object files.
	* main.cc: Include "plugin.h".
	(main): Load plugin libraries.
	* object.h (Pluginobj): Declare.
	(Object::pluginobj): New function.
	(Object::do_pluginobj): New function.
	(Object::set_target): New function.
	* options.cc: Include "plugin.h".
	(General_options::parse_plugin): New function.
	(General_options::General_options): Initialize plugins_ field.
	(General_options::add_plugin): New function.
	* options.h (Plugin_manager): Declare.
	(General_options): Add --plugin option.
	(General_options::has_plugins): New function.
	(General_options::plugins): New function.
	(General_options::add_plugin): New function.
	(General_options::plugins_): New field.
	* plugin.cc: New file.
	* plugin.h: New file.
	* readsyms.cc: Include "plugin.h".
	(Read_symbols::do_read_symbols): Check for archive before checking
	for ELF file.  Call plugin hooks to claim files.
	* resolve.cc (Symbol_table::resolve): Record when symbol is referenced
	from a real object file; force override when processing replacement
	files.
	* symtab.cc (Symbol::init_fields): Initialize in_real_elf_ field.
	(Symbol::init_base_object): Likewise.
	(Symbol::init_base_output_data): Likewise.
	(Symbol::init_base_output_segment): Likewise.
	(Symbol::init_base_constant): Likewise.
	(Symbol::init_base_undefined): Likewise.
	(Symbol::output_section): Assert that object is not a plugin.
	(Symbol_table::add_from_pluginobj): New function.
	(Symbol_table::sized_finalize_symbol): Treat symbols from plugins as
	undefined.
	(Symbol_table::sized_write_globals): Likewise.
	(Symbol_table::add_from_pluginobj): Instantiate template.
	* symtab.h (Sized_pluginobj): Declare.
	(Symbol::in_real_elf): New function.
	(Symbol::set_in_real_elf): New function.
	(Symbol::in_real_elf_): New field.
	(Symbol_table::add_from_pluginobj): New function.

	* testsuite/Makefile.am (AM_CFLAGS): New variable.
	(LIBDL): New variable.
	(LDADD): Add LIBDL.
	(check_PROGRAMS): Add plugin_test_1 and plugin_test_2.
	(check_SCRIPTS): Add plugin_test_1.sh and plugin_test_2.sh.
	(check_DATA): Add plugin_test_1.err and plugin_test_2.err.
	(MOSTLYCLEANFILES): Likewise.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/plugin_test.c: New file.
	* testsuite/plugin_test_1.sh: New file.
	* testsuite/plugin_test_2.sh: New file.

1 files changed, 117 insertions, 0 deletions

diff --git a/gold/symtab.cc b/gold/symtab.cc
index 393d71a..3bb88d8 100644
--- a/gold/symtab.cc
+++ b/gold/symtab.cc
@@ -37,6 +37,7 @@
 #include "target.h"
 #include "workqueue.h"
 #include "symtab.h"
+#include "plugin.h"
 
 namespace gold
 {
@@ -73,6 +74,7 @@ Symbol::init_fields(const char* name, const char* version,
   this->is_copied_from_dynobj_ = false;
   this->is_forced_local_ = false;
   this->is_ordinary_shndx_ = false;
+  this->in_real_elf_ = false;
 }
 
 // Return the demangled version of the symbol's name, but only
@@ -117,6 +119,7 @@ Symbol::init_base_object(const char* name, const char* version, Object* object,
   this->source_ = FROM_OBJECT;
   this->in_reg_ = !object->is_dynamic();
   this->in_dyn_ = object->is_dynamic();
+  this->in_real_elf_ = object->pluginobj() == NULL;
 }
 
 // Initialize the fields in the base class Symbol for a symbol defined
@@ -133,6 +136,7 @@ Symbol::init_base_output_data(const char* name, const char* version,
   this->u_.in_output_data.offset_is_from_end = offset_is_from_end;
   this->source_ = IN_OUTPUT_DATA;
   this->in_reg_ = true;
+  this->in_real_elf_ = true;
 }
 
 // Initialize the fields in the base class Symbol for a symbol defined
@@ -150,6 +154,7 @@ Symbol::init_base_output_segment(const char* name, const char* version,
   this->u_.in_output_segment.offset_base = offset_base;
   this->source_ = IN_OUTPUT_SEGMENT;
   this->in_reg_ = true;
+  this->in_real_elf_ = true;
 }
 
 // Initialize the fields in the base class Symbol for a symbol defined
@@ -163,6 +168,7 @@ Symbol::init_base_constant(const char* name, const char* version,
   this->init_fields(name, version, type, binding, visibility, nonvis);
   this->source_ = IS_CONSTANT;
   this->in_reg_ = true;
+  this->in_real_elf_ = true;
 }
 
 // Initialize the fields in the base class Symbol for an undefined
@@ -177,6 +183,7 @@ Symbol::init_base_undefined(const char* name, const char* version,
   this->dynsym_index_ = -1U;
   this->source_ = IS_UNDEFINED;
   this->in_reg_ = true;
+  this->in_real_elf_ = true;
 }
 
 // Allocate a common symbol in the base.
@@ -357,6 +364,7 @@ Symbol::output_section() const
 	if (shndx != elfcpp::SHN_UNDEF && this->is_ordinary_shndx_)
 	  {
 	    gold_assert(!this->u_.from_object.object->is_dynamic());
+	    gold_assert(this->u_.from_object.object->pluginobj() == NULL);
 	    Relobj* relobj = static_cast<Relobj*>(this->u_.from_object.object);
 	    return relobj->output_section(shndx);
 	  }
@@ -973,6 +981,68 @@ Symbol_table::add_from_relobj(
     }
 }
 
+// Add a symbol from a plugin-claimed file.
+
+template<int size, bool big_endian>
+Symbol*
+Symbol_table::add_from_pluginobj(
+    Sized_pluginobj<size, big_endian>* obj,
+    const char* name,
+    const char* ver,
+    elfcpp::Sym<size, big_endian>* sym)
+{
+  unsigned int st_shndx = sym->get_st_shndx();
+
+  Stringpool::Key ver_key = 0;
+  bool def = false;
+  bool local = false;
+
+  if (ver != NULL)
+    {
+      ver = this->namepool_.add(ver, true, &ver_key);
+    }
+  // We don't want to assign a version to an undefined symbol,
+  // even if it is listed in the version script.  FIXME: What
+  // about a common symbol?
+  else
+    {
+      if (!this->version_script_.empty()
+          && st_shndx != elfcpp::SHN_UNDEF)
+        {
+          // The symbol name did not have a version, but the
+          // version script may assign a version anyway.
+          std::string version;
+          if (this->version_script_.get_symbol_version(name, &version))
+            {
+              // The version can be empty if the version script is
+              // only used to force some symbols to be local.
+              if (!version.empty())
+                {
+                  ver = this->namepool_.add_with_length(version.c_str(),
+                                                        version.length(),
+                                                        true,
+                                                        &ver_key);
+                  def = true;
+                }
+            }
+          else if (this->version_script_.symbol_is_local(name))
+            local = true;
+        }
+    }
+
+  Stringpool::Key name_key;
+  name = this->namepool_.add(name, true, &name_key);
+
+  Sized_symbol<size>* res;
+  res = this->add_from_object(obj, name, name_key, ver, ver_key,
+		              def, *sym, st_shndx, true, st_shndx);
+
+  if (local)
+	this->force_local(res);
+
+  return res;
+}
+
 // Add all the symbols in a dynamic object to the hash table.
 
 template<int size, bool big_endian>
@@ -2043,6 +2113,11 @@ Symbol_table::sized_finalize_symbol(Symbol* unsized_sym)
 	    value = 0;
 	    shndx = elfcpp::SHN_UNDEF;
 	  }
+	else if (symobj->pluginobj() != NULL)
+	  {
+	    value = 0;
+	    shndx = elfcpp::SHN_UNDEF;
+	  }
 	else if (shndx == elfcpp::SHN_UNDEF)
 	  value = 0;
 	else if (!is_ordinary
@@ -2261,6 +2336,8 @@ Symbol_table::sized_write_globals(const Input_objects* input_objects,
 		      dynsym_value = target.dynsym_value(sym);
 		    shndx = elfcpp::SHN_UNDEF;
 		  }
+		else if (symobj->pluginobj() != NULL)
+		  shndx = elfcpp::SHN_UNDEF;
 		else if (in_shndx == elfcpp::SHN_UNDEF
 			 || (!is_ordinary
 			     && (in_shndx == elfcpp::SHN_ABS
@@ -2703,6 +2780,46 @@ Symbol_table::add_from_relobj<64, true>(
 
 #ifdef HAVE_TARGET_32_LITTLE
 template
+Symbol*
+Symbol_table::add_from_pluginobj<32, false>(
+    Sized_pluginobj<32, false>* obj,
+    const char* name,
+    const char* ver,
+    elfcpp::Sym<32, false>* sym);
+#endif
+
+#ifdef HAVE_TARGET_32_BIG
+template
+Symbol*
+Symbol_table::add_from_pluginobj<32, true>(
+    Sized_pluginobj<32, true>* obj,
+    const char* name,
+    const char* ver,
+    elfcpp::Sym<32, true>* sym);
+#endif
+
+#ifdef HAVE_TARGET_64_LITTLE
+template
+Symbol*
+Symbol_table::add_from_pluginobj<64, false>(
+    Sized_pluginobj<64, false>* obj,
+    const char* name,
+    const char* ver,
+    elfcpp::Sym<64, false>* sym);
+#endif
+
+#ifdef HAVE_TARGET_64_BIG
+template
+Symbol*
+Symbol_table::add_from_pluginobj<64, true>(
+    Sized_pluginobj<64, true>* obj,
+    const char* name,
+    const char* ver,
+    elfcpp::Sym<64, true>* sym);
+#endif
+
+#ifdef HAVE_TARGET_32_LITTLE
+template
 void
 Symbol_table::add_from_dynobj<32, false>(
     Sized_dynobj<32, false>* dynobj,