OK.
On Thu, Nov 3, 2016 at 12:42 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> Hi!
>
> My recent optimize_abbrev_table optimization apparently broke Solaris
> bootstrap.
> The bug is specific I think just to -gdwarf-{2,3} -gno-strict-dwarf, where
> DW_FORM_exprloc can't be used for location expressions and some location
> expression contains DW_OP_GNU_{{const,regval,deref}_type,convert,reinterpret}
> and there are at least 128 die abbreviations used by more than one DIE.
> Because of the lack of DW_FORM_exprloc we need to decide on
> DW_FORM_block{1,2,4} and size the location expression, for that we need to
> know
> the DIE offsets of base offset DIEs that are referenced (earlier code
> ensures such types appear very early in the CU, right after the
> DW_TAG_compile_unit DIE) and for that their size and their abbreviation values
> need to be constant, so the optimize_abbrev_table opts that reorder
> abbreviation
> numbers by decreasing usage count or for -gdwarf-5 attempt to optimize
> implicit
> constants can't be done for the CU and base types.
> For -gdwarf-4 and above, we can emit DW_FORM_exprloc, so value_format doesn't
> need to compute any sizes and thus calc_base_type_die_sizes shouldn't be
> called.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux and Rainer has kindly
> tested it on Solaris, ok for trunk?
>
> 2016-11-03 Jakub Jelinek <ja...@redhat.com>
>
> * dwarf2out.c (size_of_discr_list): Fix typo in function comment.
>
> PR debug/78191
> * dwarf2out.c (abbrev_opt_base_type_end): New variable.
> (die_abbrev_cmp): Sort dies with die_abbrev smaller than
> abbrev_opt_base_type_end only by increasing die_abbrev, before
> any other dies.
> (optimize_abbrev_table): Don't change abbrev numbers of
> base types and CU or optimize implicit consts in them if
> calc_base_type_die_sizes has been called during build_abbrev_table.
> (calc_base_type_die_sizes): If abbrev_opt_start, set
> abbrev_opt_base_type_end to one plus largest base type's
> die_abbrev.
>
> --- gcc/dwarf2out.c.jj 2016-11-03 08:47:59.000000000 +0100
> +++ gcc/dwarf2out.c 2016-11-03 12:26:03.192459170 +0100
> @@ -1909,7 +1909,7 @@ size_of_discr_value (dw_discr_value *dis
> return size_of_sleb128 (discr_value->v.sval);
> }
>
> -/* Return the size of the value in a DW_discr_list attribute. */
> +/* Return the size of the value in a DW_AT_discr_list attribute. */
>
> static int
> size_of_discr_list (dw_discr_list_ref discr_list)
> @@ -8548,6 +8548,11 @@ optimize_external_refs (dw_die_ref die)
> /* First abbrev_id that can be optimized based on usage. */
> static unsigned int abbrev_opt_start;
>
> +/* Maximum abbrev_id of a base type plus one (we can't optimize DIEs with
> + abbrev_id smaller than this, because they must be already sized
> + during build_abbrev_table). */
> +static unsigned int abbrev_opt_base_type_end;
> +
> /* Vector of usage counts during build_abbrev_table. Indexed by
> abbrev_id - abbrev_opt_start. */
> static vec<unsigned int> abbrev_usage_count;
> @@ -8646,12 +8651,16 @@ die_abbrev_cmp (const void *p1, const vo
> gcc_checking_assert (die1->die_abbrev >= abbrev_opt_start);
> gcc_checking_assert (die2->die_abbrev >= abbrev_opt_start);
>
> - if (abbrev_usage_count[die1->die_abbrev - abbrev_opt_start]
> - > abbrev_usage_count[die2->die_abbrev - abbrev_opt_start])
> - return -1;
> - if (abbrev_usage_count[die1->die_abbrev - abbrev_opt_start]
> - < abbrev_usage_count[die2->die_abbrev - abbrev_opt_start])
> - return 1;
> + if (die1->die_abbrev >= abbrev_opt_base_type_end
> + && die2->die_abbrev >= abbrev_opt_base_type_end)
> + {
> + if (abbrev_usage_count[die1->die_abbrev - abbrev_opt_start]
> + > abbrev_usage_count[die2->die_abbrev - abbrev_opt_start])
> + return -1;
> + if (abbrev_usage_count[die1->die_abbrev - abbrev_opt_start]
> + < abbrev_usage_count[die2->die_abbrev - abbrev_opt_start])
> + return 1;
> + }
>
> /* Stabilize the sort. */
> if (die1->die_abbrev < die2->die_abbrev)
> @@ -8729,10 +8738,12 @@ optimize_abbrev_table (void)
> sorted_abbrev_dies.qsort (die_abbrev_cmp);
>
> unsigned int abbrev_id = abbrev_opt_start - 1;
> - unsigned int first_id = 0;
> + unsigned int first_id = ~0U;
> unsigned int last_abbrev_id = 0;
> unsigned int i;
> dw_die_ref die;
> + if (abbrev_opt_base_type_end > abbrev_opt_start)
> + abbrev_id = abbrev_opt_base_type_end - 1;
> /* Reassign abbreviation ids from abbrev_opt_start above, so that
> most commonly used abbreviations come first. */
> FOR_EACH_VEC_ELT (sorted_abbrev_dies, i, die)
> @@ -8740,10 +8751,15 @@ optimize_abbrev_table (void)
> dw_attr_node *a;
> unsigned ix;
>
> + /* If calc_base_type_die_sizes has been called, the CU and
> + base types after it can't be optimized, because we've already
> + calculated their DIE offsets. We've sorted them first. */
> + if (die->die_abbrev < abbrev_opt_base_type_end)
> + continue;
> if (die->die_abbrev != last_abbrev_id)
> {
> last_abbrev_id = die->die_abbrev;
> - if (dwarf_version >= 5 && i)
> + if (dwarf_version >= 5 && first_id != ~0U)
> optimize_implicit_const (first_id, i, implicit_consts);
> abbrev_id++;
> (*abbrev_die_table)[abbrev_id] = die;
> @@ -8783,11 +8799,12 @@ optimize_abbrev_table (void)
> die->die_abbrev = abbrev_id;
> }
> gcc_assert (abbrev_id == vec_safe_length (abbrev_die_table) - 1);
> - if (dwarf_version >= 5)
> + if (dwarf_version >= 5 && first_id != ~0U)
> optimize_implicit_const (first_id, i, implicit_consts);
> }
>
> abbrev_opt_start = 0;
> + abbrev_opt_base_type_end = 0;
> abbrev_usage_count.release ();
> sorted_abbrev_dies.release ();
> }
> @@ -9041,6 +9058,9 @@ calc_base_type_die_sizes (void)
> && base_type->die_abbrev);
> prev = base_type;
> #endif
> + if (abbrev_opt_start
> + && base_type->die_abbrev >= abbrev_opt_base_type_end)
> + abbrev_opt_base_type_end = base_type->die_abbrev + 1;
> base_type->die_offset = die_offset;
> die_offset += size_of_die (base_type);
> }
>
>
> Jakub
