[2.22.90] Backport of two patches from mainline that enable

	  sorting of text sections

Author: Sriraman Tallam <tmsriram@google.com>
Date:   Thu Jan 10 00:18:14 2013 +0000

    Make linker scripts and section ordering via --section-ordering-file or
    linker plugins work. This patch lets linker scripts take precedence.

    2013-01-09  Sriraman Tallam  <tmsriram@google.com>

        * output.h (sort_attached_input_sections): Change to be public.
        * script-sections.cc
        (Output_section_definition::set_section_addresses): Sort
        attached input sections according to section order before linker
        script assigns section addresses.
        (Orphan_output_section::set_section_addresses): Sort
        attached input sections according to section order before linker
        script assigns section addresses.
        * Makefile.am (final_layout.sh): Use a simple linker script to
        check if section ordering still works.
        * Makefile.in: Regenerate.

Author: Ian Lance Taylor <ian@airs.com>
Date:   Fri Dec 21 06:24:31 2012 +0000

        * layout.cc (Layout::special_ordering_of_input_section): New
        function.
        (Layout::layout): If input section requires special ordering, must
        sort input sections.
        (Layout::make_output_section): May sort .text input sections.
        (Layout::is_section_name_prefix_grouped): Remove.
        * layout.h (class Layout): Declare
        special_ordering_of_input_section.  Don't declare
        is_section_name_prefix_grouped.
        * output.cc (Output_section::add_input_section): Revert last
        change.
        (Output_section::Input_section_sort::match_file_name): Don't crash
        if called on output section data.
        (Output_section::Input_section_sort_compare): Sort based on
        special ordering.
        (Output_section::Input_section_sort_section_order_index_compare):
        Revert last patch.
        (Output_section::sort_attached_input_sections): Likewise.

Change-Id: I385c609300f697abcdeb82324c9af903259fe2b6

3 files changed, 69 insertions, 1 deletions

diff --git a/binutils-2.22/gold/layout.cc b/binutils-2.22/gold/layout.cc
index ad667ab..cc800cd 100644
--- a/binutils-2.22/gold/layout.cc
+++ b/binutils-2.22/gold/layout.cc
@@ -993,6 +993,33 @@ Layout::init_fixed_output_section(const char* name,
   return os;
 }
 
+// Return the index by which an input section should be ordered.  This
+// is used to sort some .text sections, for compatibility with GNU ld.
+
+int
+Layout::special_ordering_of_input_section(const char* name)
+{
+  // The GNU linker has some special handling for some sections that
+  // wind up in the .text section.  Sections that start with these
+  // prefixes must appear first, and must appear in the order listed
+  // here.
+  static const char* const text_section_sort[] =
+  {
+    ".text.unlikely",
+    ".text.exit",
+    ".text.startup",
+    ".text.hot"
+  };
+
+  for (size_t i = 0;
+       i < sizeof(text_section_sort) / sizeof(text_section_sort[0]);
+       i++)
+    if (is_prefix_of(text_section_sort[i], name))
+      return i;
+
+  return -1;
+}
+
 // Return the output section to use for input section SHNDX, with name
 // NAME, with header HEADER, from object OBJECT.  RELOC_SHNDX is the
 // index of a relocation section which applies to this section, or 0
@@ -1052,6 +1079,13 @@ Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
 		  || strcmp(name, ".dtors") == 0))))
     os->set_must_sort_attached_input_sections();
 
+  // By default the GNU linker sorts some special text sections ahead
+  // of others.  We are compatible.
+  if (!this->script_options_->saw_sections_clause()
+      && !parameters->options().relocatable()
+      && Layout::special_ordering_of_input_section(name) >= 0)
+    os->set_must_sort_attached_input_sections();
+
   // If this is a .ctors or .ctors.* section being mapped to a
   // .init_array section, or a .dtors or .dtors.* section being mapped
   // to a .fini_array section, we will need to reverse the words if
@@ -1530,6 +1564,15 @@ Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
 		  || strcmp(name, ".dtors") == 0))))
     os->set_may_sort_attached_input_sections();
 
+  // The GNU linker by default sorts .text.{unlikely,exit,startup,hot}
+  // sections before other .text sections.  We are compatible.  We
+  // need to know that this might happen before we attach any input
+  // sections.
+  if (!this->script_options_->saw_sections_clause()
+      && !parameters->options().relocatable()
+      && strcmp(name, ".text") == 0)
+    os->set_may_sort_attached_input_sections();
+
   // Check for .stab*str sections, as .stab* sections need to link to
   // them.
   if (type == elfcpp::SHT_STRTAB
diff --git a/binutils-2.22/gold/layout.h b/binutils-2.22/gold/layout.h
index 4643e32..fc8675f 100644
--- a/binutils-2.22/gold/layout.h
+++ b/binutils-2.22/gold/layout.h
@@ -528,6 +528,14 @@ class Layout
   get_section_order_map()
   { return &this->section_order_map_; }
 
+  // Some input sections require special ordering, for compatibility
+  // with GNU ld.  Given the name of an input section, return -1 if it
+  // does not require special ordering.  Otherwise, return the index
+  // by which it should be ordered compared to other input sections
+  // that require special ordering.
+  static int
+  special_ordering_of_input_section(const char* name);
+
   bool
   is_section_ordering_specified()
   { return this->section_ordering_specified_; }
diff --git a/binutils-2.22/gold/output.cc b/binutils-2.22/gold/output.cc
index aceee1b..82e2ea7 100644
--- a/binutils-2.22/gold/output.cc
+++ b/binutils-2.22/gold/output.cc
@@ -3259,7 +3259,11 @@ class Output_section::Input_section_sort_entry
   // in order to better support gcc, and we need to be compatible.
   bool
   match_file_name(const char* file_name) const
-  { return Layout::match_file_name(this->input_section_.relobj(), file_name); }
+  {
+    if (this->input_section_.is_output_section_data())
+      return false;
+    return Layout::match_file_name(this->input_section_.relobj(), file_name);
+  }
 
   // Returns 1 if THIS should appear before S in section order, -1 if S
   // appears before THIS and 0 if they are not comparable.
@@ -3331,6 +3335,19 @@ Output_section::Input_section_sort_compare::operator()(
       return s1.index() < s2.index();
     }
 
+  // Some input section names have special ordering requirements.
+  int o1 = Layout::special_ordering_of_input_section(s1.section_name().c_str());
+  int o2 = Layout::special_ordering_of_input_section(s2.section_name().c_str());
+  if (o1 != o2)
+    {
+      if (o1 < 0)
+	return false;
+      else if (o2 < 0)
+	return true;
+      else
+	return o1 < o2;
+    }
+
   // A section with a priority follows a section without a priority.
   bool s1_has_priority = s1.has_priority();
   bool s2_has_priority = s2.has_priority();