re PR debug/41371 (var-tracking is slow and memory hungry)

PR debug/41371
* var-tracking.c (find_loc_in_1pdv): Remove recursion, only
tail-recurse into canonical node.  Fast-forward over
non-canonical VALUEs.

From-SVN: r160559

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 725a52d6b9ce4cf5bb6bbee99fbdee1dec4c0515..685a346211ad0540c8e94d2eb7b4b85ae6f52314 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2010-06-10  Alexandre Oliva  <aoliva@redhat.com>
+
+       PR debug/41371
+       * var-tracking.c (find_loc_in_1pdv): Remove recursion, only
+       tail-recurse into canonical node.  Fast-forward over
+       non-canonical VALUEs.
+
 2010-06-10  H.J. Lu  <hongjiu.lu@intel.com>
 
        PR boostrap/44470

diff --git a/gcc/var-tracking.c b/gcc/var-tracking.c
index eb6144fa3e5a06ba0b12c0f076e92b9154b3d4c3..57405583e58404616af3476e78a7d8b6fe1bd65d 100644 (file)
--- a/gcc/var-tracking.c
+++ b/gcc/var-tracking.c
@@ -2479,125 +2479,81 @@ dv_changed_p (decl_or_value dv)
 
 /* Return a location list node whose loc is rtx_equal to LOC, in the
    location list of a one-part variable or value VAR, or in that of
-   any values recursively mentioned in the location lists.  */
+   any values recursively mentioned in the location lists.  VARS must
+   be in star-canonical form.  */
 
 static location_chain
 find_loc_in_1pdv (rtx loc, variable var, htab_t vars)
 {
   location_chain node;
   enum rtx_code loc_code;
-  location_chain ret = NULL;
-  int unmark_self = 0;
-#ifdef ENABLE_CHECKING
-  static int mark_count;
-#endif
 
   if (!var)
-    return ret;
+    return NULL;
 
 #ifdef ENABLE_CHECKING
   gcc_assert (dv_onepart_p (var->dv));
 #endif
 
   if (!var->n_var_parts)
-    return ret;
+    return NULL;
 
 #ifdef ENABLE_CHECKING
   gcc_assert (var->var_part[0].offset == 0);
+  gcc_assert (loc != dv_as_opaque (var->dv));
 #endif
 
   loc_code = GET_CODE (loc);
   for (node = var->var_part[0].loc_chain; node; node = node->next)
     {
+      decl_or_value dv;
+      variable rvar;
+
       if (GET_CODE (node->loc) != loc_code)
        {
          if (GET_CODE (node->loc) != VALUE)
            continue;
        }
       else if (loc == node->loc)
-       {
-         ret = node;
-         break;
-       }
+       return node;
       else if (loc_code != VALUE)
        {
          if (rtx_equal_p (loc, node->loc))
-           {
-             ret = node;
-             break;
-           }
+           return node;
          continue;
        }
-      if (!VALUE_RECURSED_INTO (node->loc))
-       {
-         decl_or_value dv = dv_from_value (node->loc);
-         variable rvar = (variable)
-           htab_find_with_hash (vars, dv, dv_htab_hash (dv));
 
-         if (rvar)
+      /* Since we're in star-canonical form, we don't need to visit
+        non-canonical nodes: one-part variables and non-canonical
+        values would only point back to the canonical node.  */
+      if (dv_is_value_p (var->dv)
+         && !canon_value_cmp (node->loc, dv_as_value (var->dv)))
+       {
+         /* Skip all subsequent VALUEs.  */
+         while (node->next && GET_CODE (node->next->loc) == VALUE)
            {
-             location_chain where;
-
-             if (!unmark_self)
-               {
-                 if (dv_is_value_p (var->dv)
-                     && !VALUE_RECURSED_INTO (dv_as_value (var->dv)))
-                   {
-                     unmark_self = 1;
+             node = node->next;
 #ifdef ENABLE_CHECKING
-                     mark_count++;
-#endif
-                     VALUE_RECURSED_INTO (dv_as_value (var->dv)) = true;
-                   }
-                 else
-                   unmark_self = -1;
-               }
-
-#ifdef ENABLE_CHECKING
-             mark_count++;
-             /* The recursion count is bounded because we're
-                searching in a star-canonicalized set, i.e., each
-                equivalence set of values is arranged so that the
-                canonical value has all locations and equivalent
-                values, whereas equivalent values only point back to
-                the canonical.  So, if we start at the canonical
-                value, we'll recurse at most into each sibling, so
-                the recurse limit will be 2.  If we start at a
-                non-canonical value, we'll recurse into the
-                canonical, and from there to other siblings, so
-                recurse limit will be 3.  If we start at a one-part
-                variable, we add one level of recursion, but we don't
-                count it.  */
-             gcc_assert (mark_count <= 3);
-#endif
-             VALUE_RECURSED_INTO (node->loc) = true;
-             if ((where = find_loc_in_1pdv (loc, rvar, vars)))
-               {
-#ifdef ENABLE_CHECKING
-                 mark_count--;
-#endif
-                 VALUE_RECURSED_INTO (node->loc) = false;
-                 ret = where;
-                 break;
-               }
-             VALUE_RECURSED_INTO (node->loc) = false;
-#ifdef ENABLE_CHECKING
-             mark_count--;
+             gcc_assert (!canon_value_cmp (node->loc,
+                                           dv_as_value (var->dv)));
 #endif
+             if (loc == node->loc)
+               return node;
            }
+         continue;
        }
-    }
 
-  if (unmark_self > 0)
-    {
-      VALUE_RECURSED_INTO (dv_as_value (var->dv)) = false;
 #ifdef ENABLE_CHECKING
-      mark_count--;
-      gcc_assert (mark_count == 0);
+      gcc_assert (node == var->var_part[0].loc_chain);
+      gcc_assert (!node->next);
 #endif
+
+      dv = dv_from_value (node->loc);
+      rvar = (variable) htab_find_with_hash (vars, dv, dv_htab_hash (dv));
+      return find_loc_in_1pdv (loc, rvar, vars);
     }
 
-  return ret;
+  return NULL;
 }
 
 /* Hash table iteration argument passed to variable_merge.  */
@@ -4031,6 +3987,12 @@ variable_post_merge_perm_vals (void **pslot, void *info)
   var = shared_hash_find (set->vars, dv);
   if (var)
     {
+      /* Although variable_post_merge_new_vals may have made decls
+        non-star-canonical, values that pre-existed in canonical form
+        remain canonical, and newly-created values reference a single
+        REG, so they are canonical as well.  Since VAR has the
+        location list for a VALUE, using find_loc_in_1pdv for it is
+        fine, since VALUEs don't map back to DECLs.  */
       if (find_loc_in_1pdv (pnode->loc, var, shared_hash_htab (set->vars)))
        return 1;
       val_reset (set, dv);