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[PATCH] Use the new DWARF4 mandated DW_FORMs for -gdwarf-4
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Jason Merrill <jason at redhat dot com>, Richard Henderson <rth at redhat dot com>, Cary Coutant <ccoutant at google dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Wed, 31 Mar 2010 17:16:54 +0200
- Subject: [PATCH] Use the new DWARF4 mandated DW_FORMs for -gdwarf-4
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
This patch makes -gdwarf-4 use the forms that are required by the
DWARF4 standard instead of the legacy forms. For flags we always
seem to use just flags with value 1, so we can use DW_FORM_flag_present
in all places for -gdwarf-4 and save 1 byte per flag in DIE.
Bootstrapped/regtested on x86_64-linux and i686-linux. Ok?
2010-03-31 Jakub Jelinek <jakub@redhat.com>
* dwarf2out.c (size_of_die): For -gdwarf-4 use
uleb128 size instead of fixed 1 or 2 for dw_val_class_loc
and 0 instead of 1 for dw_val_class_flag.
(value_format): For -gdwarf-4 use DW_FORM_sec_offset for
dw_val_class_range_list, dw_val_class_loc_list,
dw_val_class_lineptr and dw_val_class_macptr, use
DW_FORM_flag_present for dw_val_class_flag and
DW_FORM_exprloc for dw_val_class_loc.
(output_die): For -gdwarf-4 print dw_val_class_loc
size as uleb128 instead of 1 or 2 bytes and don't print
anything for dw_val_class_flag.
--- gcc/dwarf2out.c.jj 2010-03-31 13:41:12.000000000 +0200
+++ gcc/dwarf2out.c 2010-03-31 14:26:48.000000000 +0200
@@ -9920,7 +9920,10 @@ size_of_die (dw_die_ref die)
unsigned long lsize = size_of_locs (AT_loc (a));
/* Block length. */
- size += constant_size (lsize);
+ if (dwarf_version >= 4)
+ size += size_of_uleb128 (lsize);
+ else
+ size += constant_size (lsize);
size += lsize;
}
break;
@@ -9948,7 +9951,16 @@ size_of_die (dw_die_ref die)
* a->dw_attr_val.v.val_vec.elt_size; /* block */
break;
case dw_val_class_flag:
- size += 1;
+ if (dwarf_version >= 4)
+ /* Currently all add_AT_flag calls pass in 1 as last argument,
+ so DW_FORM_flag_present can be used. If that ever changes,
+ we'll need to use DW_FORM_flag and have some optimization
+ in build_abbrev_table that will change those to
+ DW_FORM_flag_present if it is set to 1 in all DIEs using
+ the same abbrev entry. */
+ gcc_assert (a->dw_attr_val.v.val_flag == 1);
+ else
+ size += 1;
break;
case dw_val_class_die_ref:
if (AT_ref_external (a))
@@ -10142,8 +10154,11 @@ value_format (dw_attr_ref a)
gcc_unreachable ();
}
case dw_val_class_range_list:
- case dw_val_class_offset:
case dw_val_class_loc_list:
+ if (dwarf_version >= 4)
+ return DW_FORM_sec_offset;
+ /* FALLTHRU */
+ case dw_val_class_offset:
switch (DWARF_OFFSET_SIZE)
{
case 4:
@@ -10154,6 +10169,8 @@ value_format (dw_attr_ref a)
gcc_unreachable ();
}
case dw_val_class_loc:
+ if (dwarf_version >= 4)
+ return DW_FORM_exprloc;
switch (constant_size (size_of_locs (AT_loc (a))))
{
case 1:
@@ -10206,6 +10223,17 @@ value_format (dw_attr_ref a)
gcc_unreachable ();
}
case dw_val_class_flag:
+ if (dwarf_version >= 4)
+ {
+ /* Currently all add_AT_flag calls pass in 1 as last argument,
+ so DW_FORM_flag_present can be used. If that ever changes,
+ we'll need to use DW_FORM_flag and have some optimization
+ in build_abbrev_table that will change those to
+ DW_FORM_flag_present if it is set to 1 in all DIEs using
+ the same abbrev entry. */
+ gcc_assert (a->dw_attr_val.v.val_flag == 1);
+ return DW_FORM_flag_present;
+ }
return DW_FORM_flag;
case dw_val_class_die_ref:
if (AT_ref_external (a))
@@ -10218,7 +10246,7 @@ value_format (dw_attr_ref a)
return DW_FORM_addr;
case dw_val_class_lineptr:
case dw_val_class_macptr:
- return DW_FORM_data;
+ return dwarf_version >= 4 ? DW_FORM_sec_offset : DW_FORM_data;
case dw_val_class_str:
return AT_string_form (a);
case dw_val_class_file:
@@ -10450,7 +10478,10 @@ output_die (dw_die_ref die)
size = size_of_locs (AT_loc (a));
/* Output the block length for this list of location operations. */
- dw2_asm_output_data (constant_size (size), size, "%s", name);
+ if (dwarf_version >= 4)
+ dw2_asm_output_data_uleb128 (size, "%s", name);
+ else
+ dw2_asm_output_data (constant_size (size), size, "%s", name);
output_loc_sequence (AT_loc (a));
break;
@@ -10518,6 +10549,20 @@ output_die (dw_die_ref die)
}
case dw_val_class_flag:
+ if (dwarf_version >= 4)
+ {
+ /* Currently all add_AT_flag calls pass in 1 as last argument,
+ so DW_FORM_flag_present can be used. If that ever changes,
+ we'll need to use DW_FORM_flag and have some optimization
+ in build_abbrev_table that will change those to
+ DW_FORM_flag_present if it is set to 1 in all DIEs using
+ the same abbrev entry. */
+ gcc_assert (AT_flag (a) == 1);
+ if (flag_debug_asm)
+ fprintf (asm_out_file, "\t\t\t%s %s\n",
+ ASM_COMMENT_START, name);
+ break;
+ }
dw2_asm_output_data (1, AT_flag (a), "%s", name);
break;
Jakub