(assign_parms): If STACK_REGS is defined...

(assign_parms): If STACK_REGS is defined, generate USE insns before
the function body, thus showing which registers are filled with
parameters.

From-SVN: r9461

gcc/function.c

@@ -3497,6 +3497,17 @@ assign_parms (fndecl, second_time)
 	}
 #endif /* 0 */
 
+#ifdef STACK_REGS
+      /* We need this "use" info, because the gcc-register->stack-register
+	 converter in reg-stack.c needs to know which registers are active
+	 at the start of the function call.  The actual parameter loading
+	 instructions are not always available then anymore, since they might
+	 have been optimised away.  */
+
+      if (GET_CODE (entry_parm) == REG && !(hide_last_arg && last_named))
+	  emit_insn (gen_rtx (USE, GET_MODE (entry_parm), entry_parm));
+#endif
+
       /* ENTRY_PARM is an RTX for the parameter as it arrives,
 	 in the mode in which it arrives.
 	 STACK_PARM is an RTX for a stack slot where the parameter can live