question about replace_in_call_usage in regmove.c

[Amker.Cheng]

Hi :
  In regmove.c there is function "replace_in_call_usage" called in
fixup_match_1,
It replaces dst register by src in call_insn, I suspect whether it is necessary
Since comment of CALL_INSN_FUNCTION_USAGE says that no pseudo register
can appear in it and seems src is pseudo register.

further more, no replace(dst->src) is done when building bootstrap
gcc-4.2.4, which
confirmed my understanding.

Is it right or I've missed something important? Please help.

Thanks in advance.

-- 
Best Regards.