On Sun, Dec 16, 2018 at 9:33 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> find_slot_with_hash has
>
> if (insert == INSERT && m_size * 3 <= m_n_elements * 4)
> expand ();
>
> which may expand hash table even if no insert is neeed and change hash
> table traverse order. When output_macinfo_op is called, all index
> strings have been added to hash table by save_macinfo_strings, we
> shouldn't expand index string hash table. Otherwise find_slot_with_hash
> will expand hash table when hash table has the right size.
So the point is that output_macinfo_op is called from code traversing the
hashtable? I didn't really manage to quickly spot that.
> Tested on i686 and x86-64. OK for trunk?
OK if called from htab traverse (please clarify that in the comment you add).
Richard.
>
> Thanks.
>
> H.J.
> ---
> PR debug/79342
> * dwarf2out.c (find_AT_string_in_table): Add insert argument
> and replace INSERT.
> (find_AT_string): Add insert argument defaulting to INSERT
> and replace INSERT.
> (output_macinfo_op): Pass NO_INSERT to find_AT_string.
> ---
> gcc/dwarf2out.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
> index b2381056991..2fc88c0c12d 100644
> --- a/gcc/dwarf2out.c
> +++ b/gcc/dwarf2out.c
> @@ -4618,12 +4618,13 @@ indirect_string_hasher::equal (indirect_string_node
> *x1, const char *x2)
>
> static struct indirect_string_node *
> find_AT_string_in_table (const char *str,
> - hash_table<indirect_string_hasher> *table)
> + hash_table<indirect_string_hasher> *table,
> + enum insert_option insert = INSERT)
> {
> struct indirect_string_node *node;
>
> indirect_string_node **slot
> - = table->find_slot_with_hash (str, htab_hash_string (str), INSERT);
> + = table->find_slot_with_hash (str, htab_hash_string (str), insert);
> if (*slot == NULL)
> {
> node = ggc_cleared_alloc<indirect_string_node> ();
> @@ -4640,12 +4641,12 @@ find_AT_string_in_table (const char *str,
> /* Add STR to the indirect string hash table. */
>
> static struct indirect_string_node *
> -find_AT_string (const char *str)
> +find_AT_string (const char *str, enum insert_option insert = INSERT)
> {
> if (! debug_str_hash)
> debug_str_hash = hash_table<indirect_string_hasher>::create_ggc (10);
>
> - return find_AT_string_in_table (str, debug_str_hash);
> + return find_AT_string_in_table (str, debug_str_hash, insert);
> }
>
> /* Add a string attribute value to a DIE. */
> @@ -28095,7 +28096,12 @@ output_macinfo_op (macinfo_entry *ref)
> break;
> case DW_MACRO_define_strp:
> case DW_MACRO_undef_strp:
> - node = find_AT_string (ref->info);
> + /* NB: output_macinfo_op is called after save_macinfo_strings.
> + All index strings have been added to hash table at this point.
> + We can't pass INSERT to find_slot_with_hash which may expand
> + hash table even if no insert is neeed and change hash table
> + traverse order. */
> + node = find_AT_string (ref->info, NO_INSERT);
> gcc_assert (node
> && (node->form == DW_FORM_strp
> || node->form == dwarf_FORM (DW_FORM_strx)));
> --
> 2.19.2
>
