[PATCH] DWARF: Don't expand hash table when no insert is needed

[H.J. Lu]

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.

Tested on i686 and x86-64.  OK for trunk?

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