PR debug/52001

[pf3gnuchains/gcc-fork.git] / gcc / cselib.c

diff --git a/gcc/cselib.c b/gcc/cselib.c
index d7cb355..4985357 100644 (file)
--- a/gcc/cselib.c
+++ b/gcc/cselib.c
@@ -383,22 +383,29 @@ cselib_clear_table (void)
   cselib_reset_table (1);
 }
 
-/* Remove from hash table all VALUEs except constants
-   and function invariants.  */
+/* Return TRUE if V is a constant, a function invariant or a VALUE
+   equivalence; FALSE otherwise.  */
 
-static int
-preserve_only_constants (void **x, void *info ATTRIBUTE_UNUSED)
+static bool
+invariant_or_equiv_p (cselib_val *v)
 {
-  cselib_val *v = (cselib_val *)*x;
   struct elt_loc_list *l;
 
+  if (v == cfa_base_preserved_val)
+    return true;
+
+  /* Keep VALUE equivalences around.  */
+  for (l = v->locs; l; l = l->next)
+    if (GET_CODE (l->loc) == VALUE)
+      return true;
+
   if (v->locs != NULL
       && v->locs->next == NULL)
     {
       if (CONSTANT_P (v->locs->loc)
          && (GET_CODE (v->locs->loc) != CONST
              || !references_value_p (v->locs->loc, 0)))
-       return 1;
+       return true;
       /* Although a debug expr may be bound to different expressions,
         we can preserve it as if it was constant, to get unification
         and proper merging within var-tracking.  */
@@ -406,24 +413,29 @@ preserve_only_constants (void **x, void *info ATTRIBUTE_UNUSED)
          || GET_CODE (v->locs->loc) == DEBUG_IMPLICIT_PTR
          || GET_CODE (v->locs->loc) == ENTRY_VALUE
          || GET_CODE (v->locs->loc) == DEBUG_PARAMETER_REF)
-       return 1;
-      if (cfa_base_preserved_val)
-       {
-         if (v == cfa_base_preserved_val)
-           return 1;
-         if (GET_CODE (v->locs->loc) == PLUS
-             && CONST_INT_P (XEXP (v->locs->loc, 1))
-             && XEXP (v->locs->loc, 0) == cfa_base_preserved_val->val_rtx)
-           return 1;
-       }
+       return true;
+
+      /* (plus (value V) (const_int C)) is invariant iff V is invariant.  */
+      if (GET_CODE (v->locs->loc) == PLUS
+         && CONST_INT_P (XEXP (v->locs->loc, 1))
+         && GET_CODE (XEXP (v->locs->loc, 0)) == VALUE
+         && invariant_or_equiv_p (CSELIB_VAL_PTR (XEXP (v->locs->loc, 0))))
+       return true;
     }
 
-  /* Keep VALUE equivalences around.  */
-  for (l = v->locs; l; l = l->next)
-    if (GET_CODE (l->loc) == VALUE)
-      return 1;
+  return false;
+}
+
+/* Remove from hash table all VALUEs except constants, function
+   invariants and VALUE equivalences.  */
+
+static int
+preserve_constants_and_equivs (void **x, void *info ATTRIBUTE_UNUSED)
+{
+  cselib_val *v = (cselib_val *)*x;
 
-  htab_clear_slot (cselib_hash_table, x);
+  if (!invariant_or_equiv_p (v))
+    htab_clear_slot (cselib_hash_table, x);
   return 1;
 }
 
@@ -463,7 +475,7 @@ cselib_reset_table (unsigned int num)
     }
 
   if (cselib_preserve_constants)
-    htab_traverse (cselib_hash_table, preserve_only_constants, NULL);
+    htab_traverse (cselib_hash_table, preserve_constants_and_equivs, NULL);
   else
     htab_empty (cselib_hash_table);