* elflink.c (_bfd_elf_gc_mark_extra_sections): Remove mark from

fragmented .debug_line sections associated with unmarked code
	sections.

	* dwarf.c (read_debug_line_header): New function.  Reads in a
	header in a .debug_line section.
	(display_debug_lines_raw): Use new function.  Handle fragmentary
	.debug_line sections.
	(display_debug_lines_decoded): Likewise.
	* readelf.c (process_section_headers): Handle fragmenatry
	.debug_line sections.
	(display_debug_section): Likewise.

	* as.c (Options): Add -gdwarf-sections.
	(parse_args): Likewise.
	* as.h (flag_dwarf_sections): Declare.
	* dwarf2dbg.c (emit_fixed_inc_line_addr): Skip section changes.
	(process_entries): When -gdwarf-sections is enabled generate
	fragmentary .debug_line sections.
	(out_debug_line): Set the section for the .debug_line section end
	symbol.
	* doc/as.texinfo: Document -gdwarf-sections.
	* NEWS: Mention -gdwarf-sections.

	* gas/elf/dwarf2-3.d: Fix expected readelf output.

	* scripttempl/DWARF.sc: Add support for .debug_line.* and
	.debug_line_end.

bfd/ChangeLog

@@ -1,3 +1,9 @@
+2013-04-29  Nick Clifton  <nickc@redhat.com>
+
+	* elflink.c (_bfd_elf_gc_mark_extra_sections): Remove mark from
+	fragmented .debug_line sections associated with unmarked code
+	sections.
+
 2013-04-29  Will Newton  <will.newton@linaro.org>
 
 	* elf32-arm.c (elf32_arm_populate_plt_entry): Call

bfd/elflink.c

@@ -11814,23 +11814,30 @@ _bfd_elf_gc_mark_extra_sections (struct bfd_link_info *info,
     {
       asection *isec;
       bfd_boolean some_kept;
+      bfd_boolean debug_frag_seen;
 
       if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour)
 	continue;
 
-      /* Ensure all linker created sections are kept, and see whether
-	 any other section is already marked.  */
-      some_kept = FALSE;
+      /* Ensure all linker created sections are kept,
+	 see if any other section is already marked,
+	 and note if we have any fragmented debug sections.  */
+      debug_frag_seen = some_kept = FALSE;
       for (isec = ibfd->sections; isec != NULL; isec = isec->next)
 	{
 	  if ((isec->flags & SEC_LINKER_CREATED) != 0)
 	    isec->gc_mark = 1;
 	  else if (isec->gc_mark)
 	    some_kept = TRUE;
+
+	  if (debug_frag_seen == FALSE
+	      && (isec->flags & SEC_DEBUGGING)
+	      && CONST_STRNEQ (isec->name, ".debug_line."))
+	    debug_frag_seen = TRUE;
 	}
 
       /* If no section in this file will be kept, then we can
-	 toss out debug sections.  */
+	 toss out the debug and special sections.  */
       if (!some_kept)
 	continue;
 
@@ -11842,6 +11849,45 @@ _bfd_elf_gc_mark_extra_sections (struct bfd_link_info *info,
 	    && ((isec->flags & SEC_DEBUGGING) != 0
 		|| (isec->flags & (SEC_ALLOC | SEC_LOAD | SEC_RELOC)) == 0))
 	  isec->gc_mark = 1;
+
+      if (! debug_frag_seen)
+	continue;
+
+      /* Look for CODE sections which are going to be discarded,
+	 and find and discard any fragmented debug sections which
+	 are associated with that code section.  */
+      for (isec = ibfd->sections; isec != NULL; isec = isec->next)
+	if ((isec->flags & SEC_CODE) != 0
+	    && isec->gc_mark == 0)
+	  {
+	    unsigned int ilen;
+	    asection *dsec;
+
+	    ilen = strlen (isec->name);
+
+	    /* Association is determined by the name of the debug section
+	       containing the name of the code section as a suffix.  For
+	       example .debug_line.text.foo is a debug section associated
+	       with .text.foo.  */
+	    for (dsec = ibfd->sections; dsec != NULL; dsec = dsec->next)
+	      {
+		unsigned int dlen;
+
+		if (dsec->gc_mark == 0
+		    || (dsec->flags & SEC_DEBUGGING) == 0)
+		  continue;
+
+		dlen = strlen (dsec->name);
+
+		if (dlen > ilen
+		    && strncmp (dsec->name + (dlen - ilen),
+				isec->name, ilen) == 0)
+		  {
+		    dsec->gc_mark = 0;
+		    break;
+		  }
+	      }
+	  }
     }
   return TRUE;
 }

binutils/ChangeLog

@@ -1,3 +1,14 @@
+2013-04-29  Nick Clifton  <nickc@redhat.com>
+
+	* dwarf.c (read_debug_line_header): New function.  Reads in a
+	header in a .debug_line section.
+	(display_debug_lines_raw): Use new function.  Handle fragmentary
+	.debug_line sections.
+	(display_debug_lines_decoded): Likewise.
+	* readelf.c (process_section_headers): Handle fragmenatry
+	.debug_line sections.
+	(display_debug_section): Likewise.
+
 2013-04-26  Ian Lance Taylor  <iant@google.com>
 
 	* MAINTAINERS: Add myself and Cary as gold maintainers.

binutils/readelf.c

@@ -4838,7 +4838,8 @@ process_section_headers (FILE * file)
 	      || (do_debug_info     && const_strneq (name, "info"))
 	      || (do_debug_info     && const_strneq (name, "types"))
 	      || (do_debug_abbrevs  && const_strneq (name, "abbrev"))
-	      || (do_debug_lines    && const_strneq (name, "line"))
+	      || (do_debug_lines    && strcmp (name, "line") == 0)
+	      || (do_debug_lines    && const_strneq (name, "line."))
 	      || (do_debug_pubnames && const_strneq (name, "pubnames"))
 	      || (do_debug_pubtypes && const_strneq (name, "pubtypes"))
 	      || (do_debug_aranges  && const_strneq (name, "aranges"))
@@ -10972,6 +10973,7 @@ display_debug_section (int shndx, Elf_Internal_Shdr * section, FILE * file)
   /* See if we know how to display the contents of this section.  */
   for (i = 0; i < max; i++)
     if (streq (debug_displays[i].section.uncompressed_name, name)
+	|| (i == line && const_strneq (name, ".debug_line."))
         || streq (debug_displays[i].section.compressed_name, name))
       {
 	struct dwarf_section * sec = &debug_displays [i].section;
@@ -10980,7 +10982,9 @@ display_debug_section (int shndx, Elf_Internal_Shdr * section, FILE * file)
 	if (secondary)
 	  free_debug_section ((enum dwarf_section_display_enum) i);
 
-	if (streq (sec->uncompressed_name, name))
+	if (i == line && const_strneq (name, ".debug_line."))
+	  sec->name = name;
+	else if (streq (sec->uncompressed_name, name))
 	  sec->name = sec->uncompressed_name;
 	else
 	  sec->name = sec->compressed_name;

gas/ChangeLog

@@ -1,3 +1,16 @@
+2013-04-29  Nick Clifton  <nickc@redhat.com>
+
+	* as.c (Options): Add -gdwarf-sections.
+	(parse_args): Likewise.
+	* as.h (flag_dwarf_sections): Declare.
+	* dwarf2dbg.c (emit_fixed_inc_line_addr): Skip section changes.
+	(process_entries): When -gdwarf-sections is enabled generate
+	fragmentary .debug_line sections.
+	(out_debug_line): Set the section for the .debug_line section end
+	symbol.
+	* doc/as.texinfo: Document -gdwarf-sections.
+	* NEWS: Mention -gdwarf-sections.
+
 2013-04-26  Christian Groessler  <chris@groessler.org>
 
 	* config/tc-z8k.c (md_parse_option): Set z8k_target_from_cmdline

gas/NEWS

@@ -1,5 +1,8 @@
 -*- text -*-
 
+* Add -gdwarf-sections command line option to enable per-code-section
+  generation of DWARF .debug_line sections.
+
 * Add support for Altera Nios II.
 
 * Add support for the Imagination Technologies Meta processor.

gas/as.c

@@ -1,8 +1,5 @@
 /* as.c - GAS main program.
-   Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
-   2010, 2011, 2012, 2013
-   Free Software Foundation, Inc.
+   Copyright 1987-2013 Free Software Foundation, Inc.
 
    This file is part of GAS, the GNU Assembler.
 
@@ -302,6 +299,8 @@ Options:\n\
   fprintf (stream, _("\
   --gdwarf-2              generate DWARF2 debugging information\n"));
   fprintf (stream, _("\
+  --gdwarf-sections       generate per-function section names for DWARF line information\n"));
+  fprintf (stream, _("\
   --hash-size=<value>     set the hash table size close to <value>\n"));
   fprintf (stream, _("\
   --help                  show this message and exit\n"));
@@ -443,6 +442,7 @@ parse_args (int * pargc, char *** pargv)
       OPTION_GSTABS,
       OPTION_GSTABS_PLUS,
       OPTION_GDWARF2,
+      OPTION_GDWARF_SECTIONS,
       OPTION_STRIP_LOCAL_ABSOLUTE,
       OPTION_TRADITIONAL_FORMAT,
       OPTION_WARN,
@@ -490,6 +490,7 @@ parse_args (int * pargc, char *** pargv)
     /* GCC uses --gdwarf-2 but GAS uses to use --gdwarf2,
        so we keep it here for backwards compatibility.  */
     ,{"gdwarf2", no_argument, NULL, OPTION_GDWARF2}
+    ,{"gdwarf-sections", no_argument, NULL, OPTION_GDWARF_SECTIONS}
     ,{"gen-debug", no_argument, NULL, 'g'}
     ,{"gstabs", no_argument, NULL, OPTION_GSTABS}
     ,{"gstabs+", no_argument, NULL, OPTION_GSTABS_PLUS}
@@ -753,6 +754,10 @@ This program has absolutely no warranty.\n"));
 	  debug_type = DEBUG_DWARF2;
 	  break;
 
+	case OPTION_GDWARF_SECTIONS:
+	  flag_dwarf_sections = TRUE;
+	  break;
+
 	case 'J':
 	  flag_signed_overflow_ok = 1;
 	  break;

gas/as.h

@@ -1,7 +1,5 @@
 /* as.h - global header file
-   Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012
-   Free Software Foundation, Inc.
+   Copyright 1987-2013 Free Software Foundation, Inc.
 
    This file is part of GAS, the GNU Assembler.
 
@@ -417,6 +415,7 @@ enum debug_info_type
 
 extern enum debug_info_type debug_type;
 extern int use_gnu_debug_info_extensions;
+COMMON bfd_boolean flag_dwarf_sections;
 
 /* Maximum level of macro nesting.  */
 extern int max_macro_nest;

gas/doc/as.texinfo

@@ -1,7 +1,5 @@
 \input texinfo @c                               -*-Texinfo-*-
-@c  Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
-@c  2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
-@c  Free Software Foundation, Inc.
+@c  Copyright 1991-2013 Free Software Foundation, Inc.
 @c UPDATE!!  On future updates--
 @c   (1)   check for new machine-dep cmdline options in
 @c         md_parse_option definitions in config/tc-*.c
@@ -102,9 +100,7 @@
 This file documents the GNU Assembler "@value{AS}".
 
 @c man begin COPYRIGHT
-Copyright @copyright{} 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-2000, 2001, 2002, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation,
-Inc.
+Copyright @copyright{} 1991-2013 Free Software Foundation, Inc.
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3
@@ -153,9 +149,7 @@ done.
 @end tex
 
 @vskip 0pt plus 1filll
-Copyright @copyright{} 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-2000, 2001, 2002, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation,
-Inc.
+Copyright @copyright{} 1991-2013 Free Software Foundation, Inc.
 
       Permission is granted to copy, distribute and/or modify this document
       under the terms of the GNU Free Documentation License, Version 1.3
@@ -236,7 +230,8 @@ gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
  [@b{--compress-debug-sections}]  [@b{--nocompress-debug-sections}]
  [@b{--debug-prefix-map} @var{old}=@var{new}]
  [@b{--defsym} @var{sym}=@var{val}] [@b{-f}] [@b{-g}] [@b{--gstabs}]
- [@b{--gstabs+}] [@b{--gdwarf-2}] [@b{--help}] [@b{-I} @var{dir}] [@b{-J}]
+ [@b{--gstabs+}] [@b{--gdwarf-2}] [@b{--gdwarf-sections}]
+ [@b{--help}] [@b{-I} @var{dir}] [@b{-J}]
  [@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}]
  [@b{--listing-lhs-width2}=@var{NUM}] [@b{--listing-rhs-width}=@var{NUM}]
  [@b{--listing-cont-lines}=@var{NUM}] [@b{--keep-locals}] [@b{-o}
@@ -648,6 +643,15 @@ Generate DWARF2 debugging information for each assembler line.  This
 may help debugging assembler code, if the debugger can handle it.  Note---this
 option is only supported by some targets, not all of them.
 
+@item --gdwarf-sections
+Instead of creating a .debug_line section, create a series of
+.debug_line.@var{foo} sections where @var{foo} is the name of the
+corresponding code section.  For example a code section called @var{.text.func}
+will have its dwarf line number information placed into a section called
+@var{.debug_line.text.func}.  If the code section is just called @var{.text}
+then debug line section will still be called just @var{.debug_line} without any
+suffix.
+
 @item --size-check=error
 @itemx --size-check=warning
 Issue an error or warning for invalid ELF .size directive.

gas/dwarf2dbg.c

@@ -1,6 +1,5 @@
 /* dwarf2dbg.c - DWARF2 debug support
-   Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
-   Free Software Foundation, Inc.
+   Copyright 1999-2013 Free Software Foundation, Inc.
    Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
 
    This file is part of GAS, the GNU Assembler.
@@ -1109,13 +1108,15 @@ emit_fixed_inc_line_addr (int line_delta, addressT addr_delta, fragS *frag,
 			  char *p, int len)
 {
   expressionS *pexp;
-  segT line_seg;
   char *end = p + len;
 
   /* Line number sequences cannot go backward in addresses.  This means
      we've incorrectly ordered the statements in the sequence.  */
   gas_assert ((offsetT) addr_delta >= 0);
 
+  /* Verify that we have kept in sync with size_fixed_inc_line_addr.  */
+  gas_assert (len == size_fixed_inc_line_addr (line_delta, addr_delta));
+
   /* INT_MAX is a signal that this is actually a DW_LNE_end_sequence.  */
   if (line_delta != INT_MAX)
     {
@@ -1124,7 +1125,6 @@ emit_fixed_inc_line_addr (int line_delta, addressT addr_delta, fragS *frag,
     }
 
   pexp = symbol_get_value_expression (frag->fr_symbol);
-  line_seg = subseg_get (".debug_line", 0);
 
   /* The DW_LNS_fixed_advance_pc opcode has a 2-byte operand so it can
      advance the address by at most 64K.  Linker relaxation (without
@@ -1145,14 +1145,12 @@ emit_fixed_inc_line_addr (int line_delta, addressT addr_delta, fragS *frag,
       exp.X_op = O_symbol;
       exp.X_add_symbol = to_sym;
       exp.X_add_number = 0;
-      subseg_change (line_seg, 0);
       emit_expr_fix (&exp, sizeof_address, frag, p);
       p += sizeof_address;
     }
   else
     {
       *p++ = DW_LNS_fixed_advance_pc;
-      subseg_change (line_seg, 0);
       emit_expr_fix (pexp, 2, frag, p);
       p += 2;
     }
@@ -1294,6 +1292,40 @@ process_entries (segT seg, struct line_entry *e)
   symbolS *last_lab = NULL, *lab;
   struct line_entry *next;
 
+  if (flag_dwarf_sections)
+    {
+      char * name;
+      const char * sec_name;
+
+      /* Switch to the relevent sub-section before we start to emit
+	 the line number table.
+
+	 FIXME: These sub-sections do not have a normal Line Number
+	 Program Header, thus strictly speaking they are not valid
+	 DWARF sections.  Unfortunately the DWARF standard assumes
+	 a one-to-one relationship between compilation units and
+	 line number tables.  Thus we have to have a .debug_line
+	 section, as well as our sub-sections, and we have to ensure
+	 that all of the sub-sections are merged into a proper
+	 .debug_line section before a debugger sees them.  */
+	 
+      sec_name = bfd_get_section_name (stdoutput, seg);
+      if (strcmp (sec_name, ".text") != 0)
+	{
+	  unsigned int len;
+
+	  len = strlen (sec_name);
+	  name = xmalloc (len + 11 + 2);
+	  sprintf (name, ".debug_line%s", sec_name);
+	  subseg_set (subseg_get (name, FALSE), 0);
+	}
+      else
+	/* Don't create a .debug_line.text section -
+	   that is redundant.  Instead just switch back to the
+	   normal .debug_line section.  */
+	subseg_set (subseg_get (".debug_line", FALSE), 0);
+    }
+
   do
     {
       int line_delta;
@@ -1534,6 +1566,16 @@ out_debug_line (segT line_seg)
       as_warn ("dwarf line number information for %s ignored",
 	       segment_name (s->seg));
 
+  if (flag_dwarf_sections)
+    /* We have to switch to the special .debug_line_end section
+       before emitting the end-of-debug_line symbol.  The linker
+       script arranges for this section to be placed after all the
+       (potentially garbage collected) .debug_line.<foo> sections.
+       This section contains the line_end symbol which is used to
+       compute the size of the linked .debug_line section, as seen
+       in the DWARF Line Number header.  */
+    subseg_set (subseg_get (".debug_line_end", FALSE), 0);
+
   symbol_set_value_now (line_end);
 }
 

gas/testsuite/ChangeLog

@@ -1,3 +1,7 @@
+2013-04-29  Nick Clifton  <nickc@redhat.com>
+
+	* gas/elf/dwarf2-3.d: Fix expected readelf output.
+
 2013-04-24  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* gas/i386/rex.d: Skip x86_64-*-elf*.

gas/testsuite/gas/elf/dwarf2-3.d

@@ -34,5 +34,5 @@ Raw dump of debug contents of section \.z?debug_line:
   Entry	Dir	Time	Size	Name
   1	0	0	0	/beginwarn.c
 
- Line Number Statements:
+ No Line Number Statements.
 

ld/ChangeLog

@@ -1,3 +1,8 @@
+2013-04-29  Nick Clifton  <nickc@redhat.com>
+
+	* scripttempl/DWARF.sc: Add support for .debug_line.* and
+	.debug_line_end.
+
 2013-04-29  Yaakov Selkowitz  <yselkowitz@users.sourceforge.net>
 
 	* emultempl/pe.em [cygwin]: Do not merge rdata with v2

ld/scripttempl/DWARF.sc

@@ -18,7 +18,7 @@ cat <<EOF
   /* DWARF 2 */
   .debug_info     0 : { *(.debug_info${RELOCATING+ .gnu.linkonce.wi.*}) }
   .debug_abbrev   0 : { *(.debug_abbrev) }
-  .debug_line     0 : { *(.debug_line) }
+  .debug_line     0 : { *(.debug_line .debug_line.* .debug_line_end ) }
   .debug_frame    0 : { *(.debug_frame) }
   .debug_str      0 : { *(.debug_str) }
   .debug_loc      0 : { *(.debug_loc) }