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, 23 insertions, 9 deletions

diff --git a/gold/gdb-index.cc b/gold/gdb-index.cc
index d42fbbd5b3b..1504abe6db6 100644
--- a/gold/gdb-index.cc
+++ b/gold/gdb-index.cc
@@ -32,7 +32,7 @@
 namespace gold
 {
 
-const int gdb_index_version = 5;
+const int gdb_index_version = 7;
 
 // Sizes of various records in the .gdb_index section.
 const int gdb_index_offset_size = 4;
@@ -436,7 +436,8 @@ Gdb_index_info_reader::visit_die(Dwarf_die* die, Dwarf_die* context)
 	    // If the DIE is not a declaration, add it to the index.
 	    std::string full_name = this->get_qualified_name(die, context);
 	    if (!full_name.empty())
-	      this->gdb_index_->add_symbol(this->cu_index_, full_name.c_str());
+	      this->gdb_index_->add_symbol(this->cu_index_,
+                                           full_name.c_str(), 0);
 	  }
 	break;
       case elfcpp::DW_TAG_typedef:
@@ -476,7 +477,7 @@ Gdb_index_info_reader::visit_die(Dwarf_die* die, Dwarf_die* context)
 		full_name = this->get_qualified_name(die, context);
 	      if (!full_name.empty())
 		this->gdb_index_->add_symbol(this->cu_index_,
-					     full_name.c_str());
+					     full_name.c_str(), 0);
 	    }
 
 	  // We're interested in the children only for namespaces and
@@ -870,11 +871,12 @@ Gdb_index_info_reader::read_pubtable(Dwarf_pubnames_table* table, off_t offset)
     return false;
   while (true)
     {
-      const char* name = table->next_name();
+      uint8_t flag_byte;
+      const char* name = table->next_name(&flag_byte);
       if (name == NULL)
         break;
 
-      this->gdb_index_->add_symbol(this->cu_index_, name);
+      this->gdb_index_->add_symbol(this->cu_index_, name, flag_byte);
     }
   return true;
 }
@@ -885,6 +887,14 @@ Gdb_index_info_reader::read_pubtable(Dwarf_pubnames_table* table, off_t offset)
 bool
 Gdb_index_info_reader::read_pubnames_and_pubtypes(Dwarf_die* die)
 {
+  // If this is a skeleton debug-type die (generated via
+  // -gsplit-dwarf), then the associated pubnames should have been
+  // read along with the corresponding CU.  In any case, there isn't
+  // enough info inside to build a gdb index entry.
+  if (die->tag() == elfcpp::DW_TAG_type_unit
+      && die->string_attribute(elfcpp::DW_AT_GNU_dwo_name))
+    return true;
+
   // We use stmt_list_off as a unique identifier for the
   // compilation unit and its associated type units.
   unsigned int shndx;
@@ -1112,7 +1122,7 @@ Gdb_index::scan_debug_info(bool is_type_unit,
 // Add a symbol.
 
 void
-Gdb_index::add_symbol(int cu_index, const char* sym_name)
+Gdb_index::add_symbol(int cu_index, const char* sym_name, uint8_t flags)
 {
   unsigned int hash = mapped_index_string_hash(
       reinterpret_cast<const unsigned char*>(sym_name));
@@ -1139,8 +1149,10 @@ Gdb_index::add_symbol(int cu_index, const char* sym_name)
   // if it's not already on the list.  We only need to
   // check the last added entry.
   Cu_vector* cu_vec = this->cu_vector_list_[found->cu_vector_index];
-  if (cu_vec->size() == 0 || cu_vec->back() != cu_index)
-    cu_vec->push_back(cu_index);
+  if (cu_vec->size() == 0
+      || cu_vec->back().first != cu_index
+      || cu_vec->back().second != flags)
+    cu_vec->push_back(std::make_pair(cu_index, flags));
 }
 
 // Return TRUE if we have already processed the pubnames associated
@@ -1317,9 +1329,11 @@ Gdb_index::do_write(Output_file* of)
       pov += 4;
       for (unsigned int j = 0; j < cu_vec->size(); ++j)
 	{
-	  int cu_index = (*cu_vec)[j];
+	  int cu_index = (*cu_vec)[j].first;
+          uint8_t flags = (*cu_vec)[j].second;
 	  if (cu_index < 0)
 	    cu_index = comp_units_count + (-1 - cu_index);
+          cu_index |= flags << 24;
 	  elfcpp::Swap<32, false>::writeval(pov, cu_index);
 	  pov += 4;
 	}