re PR tree-optimization/51683 (__builtin_memcpy etc. with constant first…

re PR tree-optimization/51683 (__builtin_memcpy etc. with constant first argument optimized away by ccp)

	PR tree-optimization/51683
	* tree-ssa-propagate.c (substitute_and_fold): Don't optimize away
	calls with side-effects.
	* tree-ssa-ccp.c (ccp_fold_stmt): Likewise.

	* gcc.dg/pr51683.c: New test.

From-SVN: r182761

gcc/ChangeLog

+2012-01-01  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/51683
+	* tree-ssa-propagate.c (substitute_and_fold): Don't optimize away
+	calls with side-effects.
+	* tree-ssa-ccp.c (ccp_fold_stmt): Likewise.
+
 2011-12-31  Alexandre Oliva  <aoliva@redhat.com>
 
 	* cselib.h (cselib_add_permanent_equiv): Declare.

gcc/testsuite/ChangeLog

+2012-01-01  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/51683
+	* gcc.dg/pr51683.c: New test.
+
 2011-12-31  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/51397

gcc/testsuite/gcc.dg/pr51683.c

+/* PR tree-optimization/51683 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+static inline void *
+bar (void *p, void *q, int r)
+{
+  return __builtin_memcpy (p, q, r);
+}
+
+void *
+foo (void *p)
+{
+  return bar ((void *) 0x12345000, p, 256);
+}
+
+/* { dg-final { scan-tree-dump "memcpy" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */

gcc/tree-ssa-ccp.c

 /* Conditional constant propagation pass for the GNU compiler.
    Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
-   2010, 2011 Free Software Foundation, Inc.
+   2010, 2011, 2012 Free Software Foundation, Inc.
    Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org>
    Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.com>
 
@@ -1878,6 +1878,7 @@ ccp_fold_stmt (gimple_stmt_iterator *gsi)
     case GIMPLE_CALL:
       {
 	tree lhs = gimple_call_lhs (stmt);
+	int flags = gimple_call_flags (stmt);
 	tree val;
 	tree argt;
 	bool changed = false;
@@ -1888,7 +1889,10 @@ ccp_fold_stmt (gimple_stmt_iterator *gsi)
 	   type issues.  */
 	if (lhs
 	    && TREE_CODE (lhs) == SSA_NAME
-	    && (val = get_constant_value (lhs)))
+	    && (val = get_constant_value (lhs))
+	    /* Don't optimize away calls that have side-effects.  */
+	    && (flags & (ECF_CONST|ECF_PURE)) != 0
+	    && (flags & ECF_LOOPING_CONST_OR_PURE) == 0)
 	  {
 	    tree new_rhs = unshare_expr (val);
 	    bool res;

gcc/tree-ssa-propagate.c

 /* Generic SSA value propagation engine.
-   Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
+   Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
    Free Software Foundation, Inc.
    Contributed by Diego Novillo <dnovillo@redhat.com>
 
@@ -1056,6 +1056,12 @@ substitute_and_fold (ssa_prop_get_value_fn get_value_fn,
 	  }
 	else if (is_gimple_call (def_stmt))
 	  {
+	    int flags = gimple_call_flags (def_stmt);
+
+	    /* Don't optimize away calls that have side-effects.  */
+	    if ((flags & (ECF_CONST|ECF_PURE)) == 0
+		|| (flags & ECF_LOOPING_CONST_OR_PURE))
+	      continue;
 	    if (update_call_from_tree (&gsi, val)
 		&& maybe_clean_or_replace_eh_stmt (def_stmt, gsi_stmt (gsi)))
 	      gimple_purge_dead_eh_edges (gimple_bb (gsi_stmt (gsi)));