re PR tree-optimization/26135 (store copyprop not effective)

2006-04-07  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/26135
	* tree-ssa-copy.c (stmt_may_generate_copy): Handle memory
	loads for store copy-prop.
	(copy_prop_visit_stmt): Likewise.

	* gcc.dg/tree-ssa/ssa-copyprop-1.c: New testcase.

From-SVN: r112749

gcc/ChangeLog

-2006-03-05  Robert Millan  <robertmh@gnu.org>
+2006-04-07  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/26135
+	* tree-ssa-copy.c (stmt_may_generate_copy): Handle memory
+	loads for store copy-prop.
+	(copy_prop_visit_stmt): Likewise.
+
+2006-04-05  Robert Millan  <robertmh@gnu.org>
 
 	* gcc/config/i386/linux.h:  Add a comment to mark macros that are
 	being overriden in config/k*bsd-gnu.h.

gcc/testsuite/ChangeLog

+2006-04-07  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/26135
+	* gcc.dg/tree-ssa/ssa-copyprop-1.c: New testcase.
+
 2006-04-06  Jan Hubicka  <jh@suse.cz>
 
 	PR profile/26399

gcc/testsuite/gcc.dg/tree-ssa/ssa-copyprop-1.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-tree-dominator-opts -fdump-tree-store_copyprop-details" } */
+
+typedef struct { int i; int j; } A;
+int foo(A *a, int i)
+{
+  a->i = i;
+  return a->i;
+}
+
+/* { dg-final { scan-tree-dump "return i" "store_copyprop" } } */
+/* { dg-final { cleanup-tree-dump "store_copyprop" } } */

gcc/tree-ssa-copy.c

@@ -376,7 +376,10 @@ stmt_may_generate_copy (tree stmt)
   /* Otherwise, the only statements that generate useful copies are
      assignments whose RHS is just an SSA name that doesn't flow
      through abnormal edges.  */
-  return TREE_CODE (rhs) == SSA_NAME && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs);
+  return (do_store_copy_prop
+	  && TREE_CODE (lhs) == SSA_NAME)
+	 || (TREE_CODE (rhs) == SSA_NAME
+	     && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs));
 }
 
 
@@ -681,6 +684,34 @@ copy_prop_visit_stmt (tree stmt, edge *taken_edge_p, tree *result_p)
 	 see if the lattice value of its output has changed.  */
       retval = copy_prop_visit_assignment (stmt, result_p);
     }
+  else if (TREE_CODE (stmt) == MODIFY_EXPR
+	   && TREE_CODE (TREE_OPERAND (stmt, 0)) == SSA_NAME
+	   && do_store_copy_prop
+	   && stmt_makes_single_load (stmt))
+    {
+      /* If the statement is a copy assignment with a memory load
+	 on the RHS, see if we know the value of this load and
+	 update the lattice accordingly.  */
+      prop_value_t *val = get_value_loaded_by (stmt, copy_of);
+      if (val
+	  && val->mem_ref
+	  && is_gimple_reg (val->value)
+	  && operand_equal_p (val->mem_ref, TREE_OPERAND (stmt, 1), 0))
+        {
+	  bool changed;
+	  changed = set_copy_of_val (TREE_OPERAND (stmt, 0),
+				     val->value, val->mem_ref);
+	  if (changed)
+	    {
+	      *result_p = TREE_OPERAND (stmt, 0);
+	      retval = SSA_PROP_INTERESTING;
+	    }
+	  else
+	    retval = SSA_PROP_NOT_INTERESTING;
+	}
+      else
+        retval = SSA_PROP_VARYING;
+    }
   else if (TREE_CODE (stmt) == COND_EXPR)
     {
       /* See if we can determine which edge goes out of a conditional