https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86462
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
The differences are of the form
<3><11d>: Abbrev Number: 9 (DW_TAG_lexical_block)
<4><11e>: Abbrev Number: 10 (DW_TAG_GNU_call_site)
to
<3><11d>: Abbrev Number: 9 (DW_TAG_lexical_block)
<11e> DW_AT_ranges : 0x560
<4><122>: Abbrev Number: 10 (DW_TAG_GNU_call_site)
and similar
<4><6ef>: Abbrev Number: 26 (DW_TAG_lexical_block)
<4><6f0>: Abbrev Number: 26 (DW_TAG_lexical_block)
<4><6f1>: Abbrev Number: 27 (DW_TAG_GNU_call_site)
to
<4><6f3>: Abbrev Number: 26 (DW_TAG_lexical_block)
<6f4> DW_AT_ranges : 0x5a0
<4><6f8>: Abbrev Number: 26 (DW_TAG_lexical_block)
<6f9> DW_AT_ranges : 0x5d0
<4><6fd>: Abbrev Number: 27 (DW_TAG_GNU_call_site)
and I believe the fix involves emitting less lexical blocks in the first
place, not not annotating already generated lexical block DIEs with
ranges.
For computer_time above the frontend generates
computer_time (real(kind=8) & restrict tnow)
{
integer(kind=4) count_max;
integer(kind=4) count_rate;
integer(kind=4) counted;
static logical(kind=4) first = 1;
static logical(kind=4) first_flip;
static real(kind=8) tfirst;
real(kind=8) tmax;
real(kind=8) trate;
{
integer(kind=4) count.0;
integer(kind=4) count_rate.1;
integer(kind=4) count_max.2;
_gfortran_system_clock_4 (&count.0, &count_rate.1, &count_max.2);
...
}
and we output the lexical block because of the vars even though they
are all DECL_IGNORED. This is because of the simplified logic in
gen_block_die:
/* Determine if this block directly contains any "significant"
local declarations which we will need to output DIEs for. */
if (debug_info_level > DINFO_LEVEL_TERSE)
/* We are not in terse mode so *any* local declaration counts
as being a "significant" one. */
must_output_die = ((BLOCK_VARS (stmt) != NULL
|| BLOCK_NUM_NONLOCALIZED_VARS (stmt))
&& (TREE_USED (stmt)
|| TREE_ASM_WRITTEN (stmt)
|| BLOCK_ABSTRACT (stmt)));
else if ((TREE_USED (stmt)
|| TREE_ASM_WRITTEN (stmt)
|| BLOCK_ABSTRACT (stmt))
&& !dwarf2out_ignore_block (stmt))
must_output_die = 1;
Of course the question is why DECL_INGORED vars are retained in BLOCK_VARS
at all. For code-generation local_decls is authorative, BLOCK_VARS is only
for debug information generation. But BLOCK_VARS and gimple_bind_vars
are too interwound to remove those easily which means the above code
would need to walk BLOCK_VARS (and BLOCK_NONLOCALIZED_VARS).
So with that fixed I get an overall saving (comparing trunk and gcc8 though):
> bloaty induct2.o -- ../../gcc8-g/gcc/induct2.o
VM SIZE FILE SIZE
++++++++++++++ GROWING ++++++++++++++
[ = ] 0 .rela.debug_loc +1.45Ki +1.3%
[ = ] 0 .debug_loc +695 +0.9%
[ = ] 0 .debug_line +167 +1.1%
[ = ] 0 .rela.debug_ranges +48 +1.2%
[ = ] 0 .rela.debug_info +24 +0.0%
[ = ] 0 .debug_ranges +16 +0.9%
[ = ] 0 .debug_abbrev +11 +0.8%
[ = ] 0 [Unmapped] +3 +7.5%
-------------- SHRINKING --------------
[ = ] 0 .debug_info -2.44Ki -3.3%
-0.7% -740 .text -740 -0.7%
[ = ] 0 .rela.text -288 -0.3%
[ = ] 0 .symtab -96 -2.0%
-6.6% -32 .rodata.cst8 -32 -6.6%
[ = ] 0 .strtab -24 -0.8%
[ = ] 0 .comment -21 -33.3%
[ = ] 0 .debug_str -16 -0.3%
-0.7% -772 TOTAL -1.23Ki -0.2%
I will test
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 1127713cbaf..995a463bddc 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -25632,13 +25632,30 @@ gen_block_die (tree stmt, dw_die_ref context_die)
/* Determine if this block directly contains any "significant"
local declarations which we will need to output DIEs for. */
if (debug_info_level > DINFO_LEVEL_TERSE)
- /* We are not in terse mode so *any* local declaration counts
- as being a "significant" one. */
- must_output_die = ((BLOCK_VARS (stmt) != NULL
- || BLOCK_NUM_NONLOCALIZED_VARS (stmt))
- && (TREE_USED (stmt)
- || TREE_ASM_WRITTEN (stmt)
- || BLOCK_ABSTRACT (stmt)));
+ {
+ /* We are not in terse mode so any local declaration that
+ is not ignored for debug purposes counts as being a
+ "significant" one. */
+ if (TREE_USED (stmt)
+ || TREE_ASM_WRITTEN (stmt)
+ || BLOCK_ABSTRACT (stmt))
+ {
+ for (tree var = BLOCK_VARS (stmt); var; var = DECL_CHAIN (var))
+ if (!DECL_IGNORED_P (var))
+ {
+ must_output_die = 1;
+ break;
+ }
+ if (!must_output_die)
+ for (unsigned i = 0; i < BLOCK_NUM_NONLOCALIZED_VARS (stmt);
+ ++i)
+ if (!DECL_IGNORED_P (BLOCK_NONLOCALIZED_VAR (stmt, i)))
+ {
+ must_output_die = 1;
+ break;
+ }
+ }
+ }
else if ((TREE_USED (stmt)
|| TREE_ASM_WRITTEN (stmt)
|| BLOCK_ABSTRACT (stmt))
