commit 49fced1206db40c71208c201165d65f92c69cebe

Author: Mark Wielaard <mark@klomp.org>

Date:   Sun Mar 5 23:37:54 2017 +0100

    gas: Emit name, comp_dir and producer strings in .debug_str.

    Putting the name, comp_dir and producer strings in the .debug_str section

    makes it possible to share them across CUs. This saves a small amount of

    space (about ~20K on a glibc libc.so.6 build with debuginfo). And makes

    it easier for tools like rpm debugedit to adjust the source paths when

    generating separate debuginfo files.

    gas/

           * dwarf2dbg.c (out_debug_abbrev): Use DW_FORM_strp instead of

           DW_FORM_string for DW_AT_name, DW_AT_comp_dir and DW_AT_producer.

           (out_debug_info): Accept symbols to name, comp_dir and producer

           in the .debug_str section and emit those offsets not full strings.

           (out_debug_str): New function that outputs the strings for name,

           comp_dir and producer in .debug_str and generates symbols to

           those strings.

           (out_debug_line): Create a .debug_str section if necessary and

           call out_debug_str before calling out_debug_info.

           * testsuite/gas/aarch64/dwarf.d: Add extra section symbol to

           expected output.

diff --git a/gas/dwarf2dbg.c b/gas/dwarf2dbg.c

index 4bb658b..e02b6e8 100644

--- a/gas/dwarf2dbg.c

+++ b/gas/dwarf2dbg.c

@@ -1726,9 +1726,9 @@ out_debug_abbrev (segT abbrev_seg,

       else

 	out_abbrev (DW_AT_ranges, DW_FORM_data8);

     }

-  out_abbrev (DW_AT_name, DW_FORM_string);

-  out_abbrev (DW_AT_comp_dir, DW_FORM_string);

-  out_abbrev (DW_AT_producer, DW_FORM_string);

+  out_abbrev (DW_AT_name, DW_FORM_strp);

+  out_abbrev (DW_AT_comp_dir, DW_FORM_strp);

+  out_abbrev (DW_AT_producer, DW_FORM_strp);

   out_abbrev (DW_AT_language, DW_FORM_data2);

   out_abbrev (0, 0);

@@ -1739,15 +1739,11 @@ out_debug_abbrev (segT abbrev_seg,

 /* Emit a description of this compilation unit for .debug_info.  */

 static void

-out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT ranges_seg)

+out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT ranges_seg,

+		symbolS *name_sym, symbolS *comp_dir_sym, symbolS *producer_sym)

 {

-  char producer[128];

-  const char *comp_dir;

-  const char *dirname;

   expressionS exp;

   symbolS *info_end;

-  char *p;

-  int len;

   int sizeof_offset;

   sizeof_offset = out_header (info_seg, &exp);

@@ -1798,10 +1794,38 @@ out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT ranges_seg)

       TC_DWARF2_EMIT_OFFSET (section_symbol (ranges_seg), sizeof_offset);

     }

+  /* DW_AT_name, DW_AT_comp_dir and DW_AT_producer.  Symbols in .debug_str

+     setup in out_debug_str below.  */

+  TC_DWARF2_EMIT_OFFSET (name_sym, sizeof_offset);

+  TC_DWARF2_EMIT_OFFSET (comp_dir_sym, sizeof_offset);

+  TC_DWARF2_EMIT_OFFSET (producer_sym, sizeof_offset);

+

+  /* DW_AT_language.  Yes, this is probably not really MIPS, but the

+     dwarf2 draft has no standard code for assembler.  */

+  out_two (DW_LANG_Mips_Assembler);

+

+  symbol_set_value_now (info_end);

+}

+

+/* Emit the three debug strings needed in .debug_str and setup symbols

+   to them for use in out_debug_info.  */

+static void

+out_debug_str (segT str_seg, symbolS **name_sym, symbolS **comp_dir_sym,

+	       symbolS **producer_sym)

+{

+  char producer[128];

+  const char *comp_dir;

+  const char *dirname;

+  char *p;

+  int len;

+

+  subseg_set (str_seg, 0);

+

   /* DW_AT_name.  We don't have the actual file name that was present

      on the command line, so assume files[1] is the main input file.

      We're not supposed to get called unless at least one line number

      entry was emitted, so this should always be defined.  */

+  *name_sym = symbol_temp_new_now ();

   if (files_in_use == 0)

     abort ();

   if (files[1].dir)

@@ -1823,22 +1847,18 @@ out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT ranges_seg)

   memcpy (p, files[1].filename, len);

   /* DW_AT_comp_dir */

+  *comp_dir_sym = symbol_temp_new_now ();

   comp_dir = remap_debug_filename (getpwd ());

   len = strlen (comp_dir) + 1;

   p = frag_more (len);

   memcpy (p, comp_dir, len);

   /* DW_AT_producer */

+  *producer_sym = symbol_temp_new_now ();

   sprintf (producer, "GNU AS %s", VERSION);

   len = strlen (producer) + 1;

   p = frag_more (len);

   memcpy (p, producer, len);

-

-  /* DW_AT_language.  Yes, this is probably not really MIPS, but the

-     dwarf2 draft has no standard code for assembler.  */

-  out_two (DW_LANG_Mips_Assembler);

-

-  symbol_set_value_now (info_end);

 }

 void

@@ -1907,19 +1927,22 @@ dwarf2_finish (void)

   out_debug_line (line_seg);

   /* If this is assembler generated line info, and there is no

-     debug_info already, we need .debug_info and .debug_abbrev

-     sections as well.  */

+     debug_info already, we need .debug_info, .debug_abbrev and

+     .debug_str sections as well.  */

   if (emit_other_sections)

     {

       segT abbrev_seg;

       segT aranges_seg;

       segT ranges_seg;

+      segT str_seg;

+      symbolS *name_sym, *comp_dir_sym, *producer_sym;

       gas_assert (all_segs);

       info_seg = subseg_new (".debug_info", 0);

       abbrev_seg = subseg_new (".debug_abbrev", 0);

       aranges_seg = subseg_new (".debug_aranges", 0);

+      str_seg = subseg_new (".debug_str", 0);

       bfd_set_section_flags (stdoutput, info_seg,

 			     SEC_READONLY | SEC_DEBUGGING);

@@ -1927,6 +1950,10 @@ dwarf2_finish (void)

 			     SEC_READONLY | SEC_DEBUGGING);

       bfd_set_section_flags (stdoutput, aranges_seg,

 			     SEC_READONLY | SEC_DEBUGGING);

+      bfd_set_section_flags (stdoutput, str_seg,

+			     (SEC_READONLY | SEC_DEBUGGING

+			      | SEC_MERGE | SEC_STRINGS));

+      str_seg->entsize = 1;

       record_alignment (aranges_seg, ffs (2 * sizeof_address) - 1);

@@ -1943,6 +1970,8 @@ dwarf2_finish (void)

       out_debug_aranges (aranges_seg, info_seg);

       out_debug_abbrev (abbrev_seg, info_seg, line_seg);

-      out_debug_info (info_seg, abbrev_seg, line_seg, ranges_seg);

+      out_debug_str (str_seg, &name_sym, &comp_dir_sym, &producer_sym);

+      out_debug_info (info_seg, abbrev_seg, line_seg, ranges_seg,

+		      name_sym, comp_dir_sym, producer_sym);

     }

 }

diff --git a/gas/testsuite/gas/aarch64/dwarf.d b/gas/testsuite/gas/aarch64/dwarf.d

index 005f1d5..2a75e0b 100644

--- a/gas/testsuite/gas/aarch64/dwarf.d

+++ b/gas/testsuite/gas/aarch64/dwarf.d

@@ -1,7 +1,7 @@

 #readelf: -s --debug-dump=aranges

 #as: -g

-Symbol table '.symtab' contains 10 entries:

+Symbol table '.symtab' contains 11 entries:

    Num:[ ]+Value[ ]+Size[ ]+Type[ ]+Bind[ ]+Vis[ ]+Ndx[ ]+Name

      0: 0+     0 NOTYPE  LOCAL  DEFAULT  UND[ ]+

      1: 0+     0 SECTION LOCAL  DEFAULT    1[ ]+

@@ -11,8 +11,9 @@ Symbol table '.symtab' contains 10 entries:

      5: 0+     0 SECTION LOCAL  DEFAULT    6[ ]+

      6: 0+     0 SECTION LOCAL  DEFAULT    8[ ]+

      7: 0+     0 SECTION LOCAL  DEFAULT    4[ ]+

-     8: 0+     0 SECTION LOCAL  DEFAULT    9[ ]+

-     9: 0+     8 FUNC    GLOBAL DEFAULT    1 testfunc

+     8: 0+     0 SECTION LOCAL  DEFAULT   11[ ]+

+     9: 0+     0 SECTION LOCAL  DEFAULT    9[ ]+

+    10: 0+     8 FUNC    GLOBAL DEFAULT    1 testfunc

 Contents of the .debug_aranges section:

   Length:                   (44|28)

--- binutils.orig/gas/config/tc-s390.c	2017-07-19 17:04:18.038524453 +0100

+++ binutils-2.28/gas/config/tc-s390.c	2017-07-19 17:04:46.117211159 +0100

@@ -2135,8 +2135,9 @@ md_pcrel_from_section (fixS *fixp, segT

 int

 tc_s390_fix_adjustable (fixS *fixP)

 {

-  /* Don't adjust references to merge sections.  */

-  if ((S_GET_SEGMENT (fixP->fx_addsy)->flags & SEC_MERGE) != 0)

+  /* Don't adjust pc-relative references to merge sections.  */

+  if (fixP->fx_pcrel

+      && (S_GET_SEGMENT (fixP->fx_addsy)->flags & SEC_MERGE) != 0)

     return 0;

   /* adjust_reloc_syms doesn't know about the GOT.  */

   if (   fixP->fx_r_type == BFD_RELOC_16_GOTOFF