tree-eh.c (lower_eh_constructs_2): Don't add assignments below statements that can't fall thru.

        * tree-eh.c (lower_eh_constructs_2): Don't add assignments
        below statements that can't fall thru.

testsuite/
        * g++.dg/tree-ssa/pr41905.C: New testcase.

From-SVN: r154674

gcc/ChangeLog

 2009-11-26  Michael Matz  <matz@suse.de>
 
+	PR tree-optimization/41905
+	* tree-eh.c (lower_eh_constructs_2): Don't add assignments
+	below statements that can't fall thru.
+
+2009-11-26  Michael Matz  <matz@suse.de>
+
 	* builtins.c (expand_builtin_printf, expand_builtin_fprintf,
 	expand_builtin_sprintf): Remove.
 	(expand_builtin): Don't call them.

gcc/testsuite/ChangeLog

+2009-11-26  Michael Matz  <matz@suse.de>
+
+	PR tree-optimization/41905
+	* g++.dg/tree-ssa/pr41905.C: New testcase.
+
 2009-11-25  Richard Henderson  <rth@redhat.com>
 
 	* gcc.dg/vect/slp-21.c: Succeed with vect_extract_even_odd too.

gcc/testsuite/g++.dg/tree-ssa/pr41905.C

+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+int foo() __attribute__((noreturn));
+int bar() { return foo(); }

gcc/tree-eh.c

@@ -1868,9 +1868,12 @@ lower_eh_constructs_2 (struct leh_state *state, gimple_stmt_iterator *gsi)
     case GIMPLE_ASSIGN:
       /* If the stmt can throw use a new temporary for the assignment
          to a LHS.  This makes sure the old value of the LHS is
-	 available on the EH edge.  */
+	 available on the EH edge.  Only do so for statements that
+	 potentially fall thru (no noreturn calls e.g.), otherwise
+	 this new assignment might create fake fallthru regions.  */
       if (stmt_could_throw_p (stmt)
 	  && gimple_has_lhs (stmt)
+	  && gimple_stmt_may_fallthru (stmt)
 	  && !tree_could_throw_p (gimple_get_lhs (stmt))
 	  && is_gimple_reg_type (TREE_TYPE (gimple_get_lhs (stmt))))
 	{