Patchwork symbol cache: hash STRUCT_DOMAIN symbols as VAR_DOMAIN

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Submitter Doug Evans
Date Feb. 5, 2015, 3:28 a.m.
Message ID <m3zj8t3ulo.fsf@seba.sebabeach.org>
Download mbox | patch
Permalink /patch/4923/
State New
Headers show

Comments

Doug Evans - Feb. 5, 2015, 3:28 a.m.
Hi.

While looking at the contents of the symbol cache after adding support
for trying multiple slots I noticed structs occupying more than one slot.
This is due to symbol_matches_domain support.
This patch fixes it by treating STRUCT_DOMAIN as VAR_DOMAIN
when computing the hash.

I also added symbol domain names to debugging output as it was useful.

2015-02-04  Doug Evans  <xdje42@gmail.com>

	* symtab.c (hash_symbol_entry): Hash STRUCT_DOMAIN symbols as
	VAR_DOMAIN.
	(symbol_cache_lookup): Clarify use of bsc_ptr, slot_ptr parameters.
	Include symbol domain in debugging output.
Doug Evans - April 6, 2015, 3:34 p.m.
On Wed, Feb 4, 2015 at 7:28 PM, Doug Evans <xdje42@gmail.com> wrote:
> Hi.
>
> While looking at the contents of the symbol cache after adding support
> for trying multiple slots I noticed structs occupying more than one slot.
> This is due to symbol_matches_domain support.
> This patch fixes it by treating STRUCT_DOMAIN as VAR_DOMAIN
> when computing the hash.
>
> I also added symbol domain names to debugging output as it was useful.
>
> 2015-02-04  Doug Evans  <xdje42@gmail.com>
>
>         * symtab.c (hash_symbol_entry): Hash STRUCT_DOMAIN symbols as
>         VAR_DOMAIN.
>         (symbol_cache_lookup): Clarify use of bsc_ptr, slot_ptr parameters.
>         Include symbol domain in debugging output.

Committed.

Patch

diff --git a/gdb/symtab.c b/gdb/symtab.c
index 84e2680..efa4f81 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -1173,7 +1173,12 @@  hash_symbol_entry (const struct objfile *objfile_context,
   if (name != NULL)
     hash += htab_hash_string (name);
 
-  hash += domain;
+  /* Because of symbol_matches_domain we need VAR_DOMAIN and STRUCT_DOMAIN
+     to map to the same slot.  */
+  if (domain == STRUCT_DOMAIN)
+    hash += VAR_DOMAIN * 7;
+  else
+    hash += domain * 7;
 
   return hash;
 }
@@ -1387,8 +1392,9 @@  set_symbol_cache_size_handler (char *args, int from_tty,
    The result is the symbol if found, SYMBOL_LOOKUP_FAILED if a previous lookup
    failed (and thus this one will too), or NULL if the symbol is not present
    in the cache.
-   *BSC_PTR, *SLOT_PTR are set to the cache and slot of the symbol, whether
-   found or not found.  */
+   If the symbol is not present in the cache, then *BSC_PTR and *SLOT_PTR are
+   set to the cache and slot of the symbol to save the result of a full lookup
+   attempt.  */
 
 static struct symbol *
 symbol_cache_lookup (struct symbol_cache *cache,
@@ -1414,8 +1420,6 @@  symbol_cache_lookup (struct symbol_cache *cache,
 
   hash = hash_symbol_entry (objfile_context, name, domain);
   slot = bsc->symbols + hash % bsc->size;
-  *bsc_ptr = bsc;
-  *slot_ptr = slot;
 
   if (eq_symbol_entry (slot, objfile_context, name, domain))
     {
@@ -1432,6 +1436,11 @@  symbol_cache_lookup (struct symbol_cache *cache,
       return slot->value.found;
     }
 
+  /* Symbol is not present in the cache.  */
+
+  *bsc_ptr = bsc;
+  *slot_ptr = slot;
+
   if (symbol_lookup_debug)
     {
       fprintf_unfiltered (gdb_stdlog,
@@ -1580,14 +1589,16 @@  symbol_cache_dump (const struct symbol_cache *cache)
 	    case SYMBOL_SLOT_UNUSED:
 	      break;
 	    case SYMBOL_SLOT_NOT_FOUND:
-	      printf_filtered ("  [%-4u] = %s, %s (not found)\n", i,
+	      printf_filtered ("  [%4u] = %s, %s %s (not found)\n", i,
 			       host_address_to_string (slot->objfile_context),
-			       slot->value.not_found.name);
+			       slot->value.not_found.name,
+			       domain_name (slot->value.not_found.domain));
 	      break;
 	    case SYMBOL_SLOT_FOUND:
-	      printf_filtered ("  [%-4u] = %s, %s\n", i,
+	      printf_filtered ("  [%4u] = %s, %s %s\n", i,
 			       host_address_to_string (slot->objfile_context),
-			       SYMBOL_PRINT_NAME (slot->value.found));
+			       SYMBOL_PRINT_NAME (slot->value.found),
+			       domain_name (SYMBOL_DOMAIN (slot->value.found)));
 	      break;
 	    }
 	}