Add .gdb_index version 7 support.

This patch adds support for .gdb_index version 7, which adds several
flag bits to the symbol index.  It also fixes a problem where it did
not handle compressed debug sections correctly.

Tested with a google/gcc-4_8 branch compiler, which supports
the -ggnu-pubnames option to generate .debug_gnu_pubnames/pubtypes
tables. (We will submit that patch to GCC when stage 1 reopens.)

2014-01-28  Cary Coutant  <ccoutant@google.com>

	* gold/dwarf_reader.cc: include <utility> (for make_pair).
	(Dwarf_abbrev_table::do_read_abbrevs): Check for compressed
	debug sections.
	(Dwarf_ranges_table::read_ranges_table): Likewise.
	(Dwarf_pubnames_table::read_section): Check for GNU-style
	sections, and for compressed debug sections.
	(Dwarf_pubnames_table::read_header): Compute end address of table.
	(Dwarf_pubnames_table::next_name): Return flag_byte.  Check
	for end of list by offset, not by offset == 0.
	(Dwarf_info_reader::do_read_string_table): Check for compressed
	debug sections.
	* gold/dwarf_reader.h (Dwarf_pubnames_table::Dwarf_pubnames_table):
	Initialize new data members.
	(Dwarf_pubnames_table::next_name): return flag_byte.
	(Dwarf_pubnames_table::end_of_table_): New data member.
	(Dwarf_pubnames_table::is_gnu_style_): New data member.
	* gold/gdb-index.cc (gdb_index_version): Update to version 7.
	(Gdb_index_info_reader::read_pubtable): Read flag_byte.
	(Gdb_index_info_reader::read_pubnames_and_pubtypes): Don't
	read skeleton type unit DIEs.
	(Gdb_index::add_symbol): Add flag_byte; adjust all callers.
	(Gdb_index::do_write): Write flag_byte.
	* gold/gdb-index.h (Gdb_index::add_symbol): Add flags parameter.
	(Gdb_index::Cu_vector): Store flags along with cu indexes.
	* gold/testsuite/gdb_index_test_3.sh: Allow versions 4-7.
	* gold/testsuite/gdb_index_test_comm.sh: Likewise.

1 files changed, 41 insertions, 18 deletions

diff --git a/gold/dwarf_reader.cc b/gold/dwarf_reader.cc
index 3aad27f..a628c54 100644
--- a/gold/dwarf_reader.cc
+++ b/gold/dwarf_reader.cc
@@ -23,6 +23,7 @@
 #include "gold.h"
 
 #include <algorithm>
+#include <utility>
 #include <vector>
 
 #include "elfcpp_swap.h"
@@ -180,7 +181,7 @@ Dwarf_abbrev_table::do_read_abbrevs(
       for (unsigned int i = 1; i < object->shnum(); ++i)
 	{
 	  std::string name = object->section_name(i);
-	  if (name == ".debug_abbrev")
+	  if (name == ".debug_abbrev" || name == ".zdebug_abbrev")
 	    {
 	      abbrev_shndx = i;
 	      // Correct the offset.  For incremental update links, we have a
@@ -317,7 +318,7 @@ Dwarf_ranges_table::read_ranges_table(
       for (unsigned int i = 1; i < object->shnum(); ++i)
 	{
 	  std::string name = object->section_name(i);
-	  if (name == ".debug_ranges")
+	  if (name == ".debug_ranges" || name == ".zdebug_ranges")
 	    {
 	      ranges_shndx = i;
 	      this->output_section_offset_ = object->output_section_offset(i);
@@ -486,24 +487,38 @@ Dwarf_pubnames_table::read_section(Relobj* object, const unsigned char* symtab,
 {
   section_size_type buffer_size;
   unsigned int shndx = 0;
+  const char* name = this->is_pubtypes_ ? "pubtypes" : "pubnames";
+  const char* gnu_name = (this->is_pubtypes_
+			  ? "gnu_pubtypes"
+			  : "gnu_pubnames");
 
-  // Find the .debug_pubnames/pubtypes section.
-  const char* name = (this->is_pubtypes_
-                      ? ".debug_pubtypes"
-                      : ".debug_pubnames");
   for (unsigned int i = 1; i < object->shnum(); ++i)
     {
-      if (object->section_name(i) == name)
+      std::string section_name = object->section_name(i);
+      const char* section_name_suffix = section_name.c_str();
+      if (is_prefix_of(".debug_", section_name_suffix))
+	section_name_suffix += 7;
+      else if (is_prefix_of(".zdebug_", section_name_suffix))
+	section_name_suffix += 8;
+      else
+	continue;
+      if (strcmp(section_name_suffix, name) == 0)
+        {
+          shndx = i;
+          this->output_section_offset_ = object->output_section_offset(i);
+          break;
+        }
+      else if (strcmp(section_name_suffix, gnu_name) == 0)
         {
           shndx = i;
           this->output_section_offset_ = object->output_section_offset(i);
+          this->is_gnu_style_ = true;
           break;
         }
     }
   if (shndx == 0)
     return false;
 
-
   this->buffer_ = object->decompressed_section_contents(shndx,
 							&buffer_size,
 							&this->owns_buffer_);
@@ -570,6 +585,7 @@ Dwarf_pubnames_table::read_header(off_t offset)
       this->unit_length_ = unit_length + 4;
       this->offset_size_ = 4;
     }
+  this->end_of_table_ = pinfo + unit_length;
 
   // Check the version.
   unsigned int version = this->dwinfo_->read_from_pointer<16>(pinfo);
@@ -593,20 +609,27 @@ Dwarf_pubnames_table::read_header(off_t offset)
 // Read the next name from the set.
 
 const char*
-Dwarf_pubnames_table::next_name()
+Dwarf_pubnames_table::next_name(uint8_t* flag_byte)
 {
   const unsigned char* pinfo = this->pinfo_;
 
-  // Read the offset within the CU.  If this is zero, we have reached
-  // the end of the list.
-  uint32_t offset;
-  if (this->offset_size_ == 4)
-    offset = this->dwinfo_->read_from_pointer<32>(&pinfo);
-  else
-    offset = this->dwinfo_->read_from_pointer<64>(&pinfo);
-  if (offset == 0)
+  // Check for end of list.  The table should be terminated by an
+  // entry containing nothing but a DIE offset of 0.
+  if (pinfo + this->offset_size_ >= this->end_of_table_)
     return NULL;
 
+  // Skip the offset within the CU.  If this is zero, but we're not
+  // at the end of the table, then we have a real pubnames entry
+  // whose DIE offset is 0 (likely to be a GCC bug).  Since we
+  // don't actually use the DIE offset in building .gdb_index,
+  // it's harmless.
+  pinfo += this->offset_size_;
+
+  if (this->is_gnu_style_)
+    *flag_byte = *pinfo++;
+  else
+    *flag_byte = 0;
+
   // Return a pointer to the string at the current location,
   // and advance the pointer to the next entry.
   const char* ret = reinterpret_cast<const char*>(pinfo);
@@ -1366,7 +1389,7 @@ Dwarf_info_reader::do_read_string_table(unsigned int string_shndx)
       for (unsigned int i = 1; i < this->object_->shnum(); ++i)
 	{
 	  std::string name = object->section_name(i);
-	  if (name == ".debug_str")
+	  if (name == ".debug_str" || name == ".zdebug_str")
 	    {
 	      string_shndx = i;
 	      this->string_output_section_offset_ =