gold patch committed: Add support for -pie

[Ian Lance Taylor <iant at google dot com>]

I committed this patch to gold to add support for -pie.  It was mostly
working already.  I mostly just needed to add the option, and change a
few tests of shared() to test output_is_position_independent()
instead.

Ian


2009-10-13  Ian Lance Taylor  <iant@google.com>

	Add support for -pie.
	* options.h (class General_options): Add -pie and
	--pic-executable.
	(General_options::output_is_position_independent): Test -pie.
	(General_options::output_is_executable): Return true if not shared
	and not relocatable.
	(General_options::output_is_pie): Remove.
	* options.cc (General_options::finalize): Reject incompatible uses
	of -pie.
	* gold.cc (queue_middle_tasks): A -pie link is not static.
	* symtab.h (Symbol::needs_plt_entry): Return false if -pie.
	* symtab.cc (Symbol::final_value_is_known): Return false if
	output_is_position_independent.
	* layout.cc (Layout::set_segment_offsets): Start at address 0 if
	output_is_position_independent.
	* output.cc (Output_file_header::do_sized_write): Use ET_DYN if
	output_is_position_independent.
	* i386.cc (Output_data_plt_i386::do_write): Use the PIC PLT if
	output_is_position_independent.
	* testsuite/Makefile.am (check_PROGRAMS): Add basic_pie_test and
	two_file_pie_test.
	(basic_pie_test.o, basic_pie_test): New targets.
	(two_file_test_1_pie.o, two_file_test_1b_pie.o): New targets.
	(two_file_test_2_pie.o, two_file_test_main_pie.o): New targets.
	(two_file_pie_test): New target.
	* testsuite/Makefile.in: Rebuild.
	* README: Remove note saying that -pie is not supported.


Index: README
===================================================================
RCS file: /cvs/src/src/gold/README,v
retrieving revision 1.3
diff -p -u -r1.3 README
--- README	28 Feb 2009 18:08:30 -0000	1.3
+++ README	14 Oct 2009 05:22:55 -0000
@@ -18,7 +18,6 @@ gold--are:
   * MEMORY regions in linker scripts
   * MRI compatible linker scripts
   * cross-reference reports (--cref)
-  * position independent executables (-pie)
   * various other minor options
 
 
Index: gold.cc
===================================================================
RCS file: /cvs/src/src/gold/gold.cc,v
retrieving revision 1.72
diff -p -u -r1.72 gold.cc
--- gold.cc	13 Oct 2009 21:17:43 -0000	1.72
+++ gold.cc	14 Oct 2009 05:22:55 -0000
@@ -396,8 +396,9 @@ queue_middle_tasks(const General_options
   workqueue->set_thread_count(thread_count);
 
   // Now we have seen all the input files.
-  const bool doing_static_link = (!input_objects->any_dynamic()
-				  && !parameters->options().shared());
+  const bool doing_static_link =
+    (!input_objects->any_dynamic()
+     && !parameters->options().output_is_position_independent());
   set_parameters_doing_static_link(doing_static_link);
   if (!doing_static_link && options.is_static())
     {
Index: i386.cc
===================================================================
RCS file: /cvs/src/src/gold/i386.cc,v
retrieving revision 1.93
diff -p -u -r1.93 i386.cc
--- i386.cc	13 Oct 2009 00:39:31 -0000	1.93
+++ i386.cc	14 Oct 2009 05:22:55 -0000
@@ -692,7 +692,7 @@ Output_data_plt_i386::do_write(Output_fi
   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 
-  if (parameters->options().shared())
+  if (parameters->options().output_is_position_independent())
     memcpy(pov, dyn_first_plt_entry, plt_entry_size);
   else
     {
@@ -724,7 +724,7 @@ Output_data_plt_i386::do_write(Output_fi
     {
       // Set and adjust the PLT entry itself.
 
-      if (parameters->options().shared())
+      if (parameters->options().output_is_position_independent())
 	{
 	  memcpy(pov, dyn_plt_entry, plt_entry_size);
 	  elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
Index: layout.cc
===================================================================
RCS file: /cvs/src/src/gold/layout.cc,v
retrieving revision 1.138
diff -p -u -r1.138 layout.cc
--- layout.cc	13 Oct 2009 21:23:00 -0000	1.138
+++ layout.cc	14 Oct 2009 05:22:56 -0000
@@ -2144,7 +2144,7 @@ Layout::set_segment_offsets(const Target
   uint64_t addr;
   if (parameters->options().user_set_Ttext())
     addr = parameters->options().Ttext();
-  else if (parameters->options().shared())
+  else if (parameters->options().output_is_position_independent())
     addr = 0;
   else
     addr = target->default_text_segment_address();
Index: options.cc
===================================================================
RCS file: /cvs/src/src/gold/options.cc,v
retrieving revision 1.93
diff -p -u -r1.93 options.cc
--- options.cc	13 Oct 2009 21:17:43 -0000	1.93
+++ options.cc	14 Oct 2009 05:22:57 -0000
@@ -1001,17 +1001,24 @@ General_options::finalize()
   // Now that we've normalized the options, check for contradictory ones.
   if (this->shared() && this->is_static())
     gold_fatal(_("-shared and -static are incompatible"));
+  if (this->shared() && this->pie())
+    gold_fatal(_("-shared and -pie are incompatible"));
 
   if (this->shared() && this->relocatable())
     gold_fatal(_("-shared and -r are incompatible"));
+  if (this->pie() && this->relocatable())
+    gold_fatal(_("-pie and -r are incompatible"));
 
   // TODO: implement support for -retain-symbols-file with -r, if needed.
   if (this->relocatable() && this->retain_symbols_file())
     gold_fatal(_("-retain-symbols-file does not yet work with -r"));
 
   if (this->oformat_enum() != General_options::OBJECT_FORMAT_ELF
-      && (this->shared() || this->relocatable()))
-    gold_fatal(_("binary output format not compatible with -shared or -r"));
+      && (this->shared()
+	  || this->pie()
+	  || this->relocatable()))
+    gold_fatal(_("binary output format not compatible "
+		 "with -shared or -pie or -r"));
 
   if (this->user_set_hash_bucket_empty_fraction()
       && (this->hash_bucket_empty_fraction() < 0.0
Index: options.h
===================================================================
RCS file: /cvs/src/src/gold/options.h,v
retrieving revision 1.113
diff -p -u -r1.113 options.h
--- options.h	13 Oct 2009 21:23:00 -0000	1.113
+++ options.h	14 Oct 2009 05:22:57 -0000
@@ -763,6 +763,12 @@ class General_options
   DEFINE_string(oformat, options::EXACTLY_TWO_DASHES, '\0', "elf",
 		N_("Set output format"), N_("[binary]"));
 
+  DEFINE_bool(pie, options::ONE_DASH, '\0', false,
+	      N_("Create a position independent executable"), NULL);
+  DEFINE_bool_alias(pic_executable, pie, options::TWO_DASHES, '\0',
+		    N_("Create a position independent executable"), NULL,
+		    false);
+
 #ifdef ENABLE_PLUGINS
   DEFINE_special(plugin, options::TWO_DASHES, '\0',
                  N_("Load a plugin library"), N_("PLUGIN"));
@@ -1009,7 +1015,7 @@ class General_options
   // the output is position-independent or not.
   bool
   output_is_position_independent() const
-  { return this->shared(); }
+  { return this->shared() || this->pie(); }
 
   // Return true if the output is something that can be exec()ed, such
   // as a static executable, or a position-dependent or
@@ -1017,13 +1023,7 @@ class General_options
   // object file.
   bool
   output_is_executable() const
-  { return !this->shared() || this->output_is_pie(); }
-
-  // Return true if the output is a position-independent executable.
-  // This is currently not supported.
-  bool
-  output_is_pie() const
-  { return false; }
+  { return !this->shared() && !this->relocatable(); }
 
   // This would normally be static(), and defined automatically, but
   // since static is a keyword, we need to come up with our own name.
Index: output.cc
===================================================================
RCS file: /cvs/src/src/gold/output.cc,v
retrieving revision 1.98
diff -p -u -r1.98 output.cc
--- output.cc	9 Oct 2009 23:18:19 -0000	1.98
+++ output.cc	14 Oct 2009 05:22:58 -0000
@@ -442,7 +442,7 @@ Output_file_header::do_sized_write(Outpu
   elfcpp::ET e_type;
   if (parameters->options().relocatable())
     e_type = elfcpp::ET_REL;
-  else if (parameters->options().shared())
+  else if (parameters->options().output_is_position_independent())
     e_type = elfcpp::ET_DYN;
   else
     e_type = elfcpp::ET_EXEC;
Index: symtab.cc
===================================================================
RCS file: /cvs/src/src/gold/symtab.cc,v
retrieving revision 1.125
diff -p -u -r1.125 symtab.cc
--- symtab.cc	13 Oct 2009 21:17:43 -0000	1.125
+++ symtab.cc	14 Oct 2009 05:23:00 -0000
@@ -394,7 +394,8 @@ Symbol::final_value_is_known() const
 {
   // If we are not generating an executable, then no final values are
   // known, since they will change at runtime.
-  if (parameters->options().shared() || parameters->options().relocatable())
+  if (parameters->options().output_is_position_independent()
+      || parameters->options().relocatable())
     return false;
 
   // If the symbol is not from an object file, and is not undefined,
Index: symtab.h
===================================================================
RCS file: /cvs/src/src/gold/symtab.h,v
retrieving revision 1.94
diff -p -u -r1.94 symtab.h
--- symtab.h	13 Oct 2009 00:39:31 -0000	1.94
+++ symtab.h	14 Oct 2009 05:23:00 -0000
@@ -533,7 +533,7 @@ class Symbol
   // Return true if this symbol is a function that needs a PLT entry.
   // If the symbol is defined in a dynamic object or if it is subject
   // to pre-emption, we need to make a PLT entry. If we're doing a
-  // static link, we don't create PLT entries.
+  // static link or a -pie link, we don't create PLT entries.
   bool
   needs_plt_entry() const
   {
@@ -542,6 +542,7 @@ class Symbol
       return false;
 
     return (!parameters->doing_static_link()
+	    && !parameters->options().pie()
             && this->type() == elfcpp::STT_FUNC
             && (this->is_from_dynobj()
                 || this->is_undefined()
Index: testsuite/Makefile.am
===================================================================
RCS file: /cvs/src/src/gold/testsuite/Makefile.am,v
retrieving revision 1.106
diff -p -u -r1.106 Makefile.am
--- testsuite/Makefile.am	13 Oct 2009 21:17:43 -0000	1.106
+++ testsuite/Makefile.am	14 Oct 2009 05:23:01 -0000
@@ -176,6 +176,11 @@ basic_pic_test: basic_pic_test.o gcctest
 basic_static_pic_test: basic_pic_test.o gcctestdir/ld
 	$(CXXLINK) -Bgcctestdir/ -static basic_pic_test.o
 
+check_PROGRAMS += basic_pie_test
+basic_pie_test.o: basic_test.cc
+	$(CXXCOMPILE) -O0 -c -fpie -o $@ $<
+basic_pie_test: basic_pie_test.o gcctestdir/ld
+	$(CXXLINK) -Bgcctestdir/ -pie basic_pie_test.o
 
 check_PROGRAMS += constructor_test
 check_PROGRAMS += constructor_static_test
@@ -281,6 +286,19 @@ two_file_relocatable_test_LDADD = two_fi
 two_file_relocatable.o: gcctestdir/ld two_file_test_1.o two_file_test_1b.o two_file_test_2.o
 	gcctestdir/ld -r -o $@ two_file_test_1.o two_file_test_1b.o two_file_test_2.o
 
+check_PROGRAMS += two_file_pie_test
+two_file_test_1_pie.o: two_file_test_1.cc
+	$(CXXCOMPILE) -c -fpie -o $@ $<
+two_file_test_1b_pie.o: two_file_test_1b.cc
+	$(CXXCOMPILE) -c -fpie -o $@ $<
+two_file_test_2_pie.o: two_file_test_2.cc
+	$(CXXCOMPILE) -c -fpie -o $@ $<
+two_file_test_main_pie.o: two_file_test_main.cc
+	$(CXXCOMPILE) -c -fpie -o $@ $<
+two_file_pie_test: two_file_test_1_pie.o two_file_test_1b_pie.o \
+		two_file_test_2_pie.o two_file_test_main_pie.o gcctestdir/ld
+	$(CXXLINK) -Bgcctestdir/ -pie two_file_test_1_pie.o two_file_test_1b_pie.o two_file_test_2_pie.o two_file_test_main_pie.o
+
 check_SCRIPTS += two_file_shared.sh
 check_DATA += two_file_shared.dbg
 MOSTLYCLEANFILES += two_file_shared.dbg