mainline dwarf2 line number tweeks

[Richard Henderson <rth at redhat dot com>]

(1) If the assembler is supposed to respect the file numbers
    we give it, then testing .file 0 is bogus.
(2) Oops, actually emit the .file.
(3) Tweek the order of files so that we elide a change-file directive.


r~


        * dwarf2out.c (lookup_filename): Emit .file if the assembler
        is generating .debug_line.
        (dwarf2out_init): Add main_input_filename to the file table first.
        * configure.in (as_dwarf2_debug_line): Test with file number 1
        instead of file number 0.

Index: configure.in
===================================================================
RCS file: /cvs/gcc/gcc/gcc/configure.in,v
retrieving revision 1.501
diff -c -p -d -r1.501 configure.in
*** configure.in	2001/03/16 20:09:34	1.501
--- configure.in	2001/03/17 18:14:38
*************** then
*** 1491,1498 ****
      gcc_cv_as_dwarf2_debug_line="yes"
    fi
  elif test x$gcc_cv_as != x -a x"$insn" != x ; then
! 	echo '	.file 0 "conftest.s"' > conftest.s
! 	echo '	.loc 0 3 0' >> conftest.s
  	echo "	$insn" >> conftest.s
  	# ??? This fails with non-gnu grep.
  	if $gcc_cv_as -o conftest.o conftest.s > /dev/null 2>&1 \
--- 1491,1498 ----
      gcc_cv_as_dwarf2_debug_line="yes"
    fi
  elif test x$gcc_cv_as != x -a x"$insn" != x ; then
! 	echo '	.file 1 "conftest.s"' > conftest.s
! 	echo '	.loc 1 3 0' >> conftest.s
  	echo "	$insn" >> conftest.s
  	# ??? This fails with non-gnu grep.
  	if $gcc_cv_as -o conftest.o conftest.s > /dev/null 2>&1 \
Index: dwarf2out.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/dwarf2out.c,v
retrieving revision 1.253
diff -c -p -d -r1.253 dwarf2out.c
*** dwarf2out.c	2001/03/16 19:31:19	1.253
--- dwarf2out.c	2001/03/17 18:14:55
*************** lookup_filename (file_name)
*** 10723,10728 ****
--- 10723,10731 ----
    file_table.in_use = i + 1;
    file_table.last_lookup_index = i;
  
+   if (DWARF2_ASM_LINE_DEBUG_INFO)
+     fprintf (asm_out_file, "\t.file %u \"%s\"\n", i, file_name);
+ 
    return i;
  }
  
*************** dwarf2out_init (asm_out_file, main_input
*** 10885,10894 ****
       register FILE *asm_out_file;
       register const char *main_input_filename;
  {
    /* Remember the name of the primary input file.  */
    primary_filename = main_input_filename;
  
!   init_file_table ();
  
    /* Allocate the initial hunk of the decl_die_table.  */
    decl_die_table
--- 10888,10902 ----
       register FILE *asm_out_file;
       register const char *main_input_filename;
  {
+   init_file_table ();
+ 
    /* Remember the name of the primary input file.  */
    primary_filename = main_input_filename;
  
!   /* Add it to the file table first, under the assumption that we'll
!      be emitting line number data for it first, which avoids having
!      to add an initial DW_LNS_set_file.  */
!   lookup_filename (main_input_filename);
  
    /* Allocate the initial hunk of the decl_die_table.  */
    decl_die_table