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

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

[Mark Wielaard]

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.
---

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);
     }
 }
-- 
1.8.3.1

Re: [PATCH] gas: Emit name, comp_dir and producer strings in .debug_str.

[Alan Modra]

On Fri, Mar 03, 2017 at 10:59:27AM +0100, Mark Wielaard wrote:
> 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.

OK, but please adjust gas/testsuite/gas/aarch64/dwarf.d for this
change.

-- 
Alan Modra
Australia Development Lab, IBM

Re: [PATCH] gas: Emit name, comp_dir and producer strings in .debug_str.

[Mark Wielaard]

[-- Attachment #1: Type: text/plain, Size: 678 bytes --]

On Sun, Mar 05, 2017 at 10:46:23PM +1030, Alan Modra wrote:
> OK, but please adjust gas/testsuite/gas/aarch64/dwarf.d for this
> change.

Thanks, I added the extra section symbol to that testcase as attached.

But this shows I failed to properly run all testcases for gas.
I had assumed running configure --enable-targets=all from the top-level
binutils-gdb would enable all targets/checks for gas. But I see now that
all non-native targets/checks were build/run. I could check this change
with configure --target=aarch64-pc-linux-gnu. But what is the correct
way to configure/build/check binutils-gdb for such a change to gas to
get all gas target tests to run?

Thanks,

Mark

[-- Attachment #2: gas-gdwarf-aarch64-extra-section-sym.patch --]
[-- Type: text/plain, Size: 1061 bytes --]

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)

Re: [PATCH] gas: Emit name, comp_dir and producer strings in .debug_str.

[Alan Modra]

[-- Attachment #1: Type: text/plain, Size: 1002 bytes --]

On Sun, Mar 05, 2017 at 10:57:41PM +0100, Mark Wielaard wrote:
> On Sun, Mar 05, 2017 at 10:46:23PM +1030, Alan Modra wrote:
> > OK, but please adjust gas/testsuite/gas/aarch64/dwarf.d for this
> > change.
> 
> Thanks, I added the extra section symbol to that testcase as attached.
> 
> But this shows I failed to properly run all testcases for gas.
> I had assumed running configure --enable-targets=all from the top-level
> binutils-gdb would enable all targets/checks for gas. But I see now that
> all non-native targets/checks were build/run. I could check this change
> with configure --target=aarch64-pc-linux-gnu. But what is the correct
> way to configure/build/check binutils-gdb for such a change to gas to
> get all gas target tests to run?

Unfortunately, we don't have a canned official test procedure.  I
still use a bash script I hacked together a long time ago.

There's also this:
https://sourceware.org/ml/binutils/2017-02/msg00135.html

-- 
Alan Modra
Australia Development Lab, IBM

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let i=0
test -e gastest_pass && mv -f gastest_pass gastest_lastpass
for z in `cat targets`
do
  ( test -d $z || mkdir $z
  cd $z;
  echo "~/src/binutils-gdb/configure --build=x86_64-linux --disable-nls --enable-plugins --disable-gdb --disable-sim --disable-readline --disable-libdecnumber --enable-obsolete --target=$z" > zzz.$$
  chmod 755 zzz.$$
  xx=29
  for x in 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
  do
    test -f make.log$x && mv -f make.log$x make.log$xx
    test -f check.log$x && mv -f check.log$x check.log$xx
    xx=$x
  done
  if test x$1 = xfull || ! test -f zzz || ! cmp -s zzz zzz.$$; then
    rm -rf bfd binutils etc gas gprof intl ld libiberty opcodes Makefile config.log config.status serdep.tmp gdb sim readline libdecnumber cgen zlib
    mv -f zzz.$$ zzz
    ./zzz &> make.log0
  else
    rm zzz.$$
    ./zzz &> make.log0
  fi
  if make &>> make.log0; then
    ( eval cd `sed -n -e '/\/configure/{s,/configure .*,,p;q}' <zzz` && git show -s --oneline FETCH_HEAD ) &> check.log0
    if make -k check &>> check.log0; then
      echo "$z OK"
      echo "$z OK" >> ../gastest_pass
    else
      echo "$z check"
    fi
  else
    echo "$z ********make"
  fi
  cd ..
  ) &
  let i++
#Don't let m68hc11-elf and m68hc12-elf write to the source at the same time.
  if test $i = 16 -o $z = m68hc11-elf; then
     let i=0
     wait
  fi
done
if test $i != 0; then
  wait
fi
egrep -a '(XPASS|FAIL|ERROR|UNRESOLVED):' */check.log0 | sed -e s,/check.log0:,\ \ , > gastest_results
sort < gastest_pass > gastest_$$ && mv -f gastest_$$ gastest_pass
diff -u gastest_lastpass gastest_pass &> gastest_changes
for z in */check.log1; do diff -u $z ${z%[0-9]}0 | sed -e s,^,${z%/*}\ \ ,; done | egrep -a '  [\+\-](XPASS|FAIL|ERROR|UNRESOLVED)' >> gastest_changes

[-- Attachment #3: targets --]
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aarch64-linux alpha-dec-vms alpha-linux alpha-linuxecoff alpha-netbsd alpha-unknown-freebsd4.7 am33_2.0-linux arc-linux-uclibc arm-aout arm-coff arm-epoc-pe arm-linuxeabi arm-nacl arm-netbsdelf arm-nto arm-pe arm-symbianelf arm-vxworks arm-wince-pe avr-elf bfin-elf cr16-elf cris-elf crisv32-linux crx-elf d10v-elf d30v-elf dlx-elf epiphany-elf fr30-elf frv-elf frv-linux ft32-elf h8300-elf hppa-linux hppa-hp-hpux10 hppa64-hp-hpux11.23 hppa64-linux i370-linux i386-darwin i386-lynxos i386-netware i386-linuxaout i586-aout i586-coff i586-linux i686-nacl i686-pc-beos i686-pc-elf i686-pe i686-vxworks i860-stardent-elf i960-elf ia64-elf ia64-freebsd5 ia64-hpux ia64-linux ia64-netbsd ia64-vms ip2k-elf iq2000-elf lm32-elf m32c-elf m32r-elf m68hc11-elf m68hc12-elf m68k-elf m68k-linux m68k-netbsd mcore-elf mcore-pe mep-elf metag-linux microblaze-elf mips-ecoff mips-linux mips-vxworks mips64-linux mipsel-linux-gnu mipsisa32el-linux mipstx39-elf mmix mn10200-elf mn10300-elf moxie-elf ms1-elf msp430-elf mt-elf nds32le-elf nios2-linux ns32k-netbsd or1k-elf pdp11-dec-aout pj-elf powerpc-eabisim powerpc-eabivle powerpc-linux powerpc-nto powerpc-wrs-vxworks powerpc64-linux powerpcle-cygwin powerpcle-elf powerpc64le-linux ppc-lynxos pru-elf riscv32-elf riscv64-elf rl78-elf rs6000-aix4.3.3 rs6000-aix5.1 rx-elf s390-linux s390x-linux score-elf sh-linux sh-nto sh-pe sh-rtems sh-vxworks shl-unknown-netbsdelf sparc-aout sparc-coff sparc-linux sparc-vxworks sparc64-linux spu-elf tic30-unknown-aout tic30-unknown-coff tic4x-coff tic54x-coff tic6x-elf tilegx-linux tilepro-linux v850-elf vax-netbsdelf visium-elf x86_64-linux x86_64-mingw32 x86_64-nacl xgate-elf xstormy16-elf xtensa-elf z8k-coff z80-coff