Don't save function_used_regs if it contains all call_used_regs

2014-06-20  Tom de Vries  <tom@codesourcery.com>

	* final.c (collect_fn_hard_reg_usage): Don't save function_used_regs if
	it contains all call_used_regs.

From-SVN: r211840

gcc/ChangeLog

 2014-06-20  Tom de Vries  <tom@codesourcery.com>
 
+	* final.c (collect_fn_hard_reg_usage): Don't save function_used_regs if
+	it contains all call_used_regs.
+
+2014-06-20  Tom de Vries  <tom@codesourcery.com>
+
 	* final.c (collect_fn_hard_reg_usage): Add and use variable
 	function_used_regs.
 

gcc/final.c

@@ -4795,6 +4795,11 @@ collect_fn_hard_reg_usage (void)
     SET_HARD_REG_BIT (function_used_regs, i);
 #endif
 
+  /* The information we have gathered is only interesting if it exposes a
+     register from the call_used_regs that is not used in this function.  */
+  if (hard_reg_set_subset_p (call_used_reg_set, function_used_regs))
+    return;
+
   node = cgraph_rtl_info (current_function_decl);
   gcc_assert (node != NULL);