Fix ivopts estimates for internal functions

tree-ssa-loop-ivopts.c:loop_body_includes_call was treating internal
calls such as IFN_SQRT as clobbering all caller-saved registers, which
I don't think is appropriate for any current internal function.

Tested on aarch64-linux-gnu and x86_64-linux-gnu.

gcc/
	* tree-ssa-loop-ivopts.c (loop_body_includes_call): Don't assume
	that internal functions will clobber all caller-saved registers.

From-SVN: r236780

gcc/ChangeLog

+2016-05-26  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* tree-ssa-loop-ivopts.c (loop_body_includes_call): Don't assume
+	that internal functions will clobber all caller-saved registers.
+
 2016-05-26  Wilco Dijkstra  <wdijkstr@arm.com>
 
 	* config/aarch64/aarch64.c (aarch64_case_values_threshold):

gcc/tree-ssa-loop-ivopts.c

@@ -7643,6 +7643,7 @@ loop_body_includes_call (basic_block *body, unsigned num_nodes)
       {
 	gimple *stmt = gsi_stmt (gsi);
 	if (is_gimple_call (stmt)
+	    && !gimple_call_internal_p (stmt)
 	    && !is_inexpensive_builtin (gimple_call_fndecl (stmt)))
 	  return true;
       }