re PR middle-end/52285 (libgcrypt _gcry_burn_stack slowdown)

	PR tree-optimization/52285
	* tree-tailcall.c (find_tail_calls): Ignore gimple_clobber_p stmts
	when deciding if a call is a tail call or tail recursion.

From-SVN: r184317

gcc/ChangeLog

+2012-02-16  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/52285
+	* tree-tailcall.c (find_tail_calls): Ignore gimple_clobber_p stmts
+	when deciding if a call is a tail call or tail recursion.
+
 2012-02-16  Kai Tietz  <ktietz@redhat.com>
 
 	* config/i386/i386.c (legitimate_pic_address_disp_p): Allow

gcc/tree-tailcall.c

 /* Tail call optimization on trees.
-   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
+   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -400,9 +400,10 @@ find_tail_calls (basic_block bb, struct tailcall **ret)
     {
       stmt = gsi_stmt (gsi);
 
-      /* Ignore labels, returns and debug stmts.  */
+      /* Ignore labels, returns, clobbers and debug stmts.  */
       if (gimple_code (stmt) == GIMPLE_LABEL
 	  || gimple_code (stmt) == GIMPLE_RETURN
+	  || gimple_clobber_p (stmt)
 	  || is_gimple_debug (stmt))
 	continue;
 
@@ -523,6 +524,9 @@ find_tail_calls (basic_block bb, struct tailcall **ret)
       if (gimple_code (stmt) == GIMPLE_RETURN)
 	break;
 
+      if (gimple_clobber_p (stmt))
+	continue;
+
       if (is_gimple_debug (stmt))
 	continue;