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Re: using frame pointer + constant in reg_equiv_constant
- To: law at cygnus dot com
- Subject: Re: using frame pointer + constant in reg_equiv_constant
- From: Joern Rennecke <amylaar at cygnus dot co dot uk>
- Date: Mon, 30 Nov 1998 17:20:07 +0000 (GMT)
- Cc: amylaar at cygnus dot co dot uk, egcs-patches at cygnus dot com, wilson at cygnus dot com
> I disagree strongly because of how reg_equiv_constant entries can be
> substituted into insns without any checks as to the validity of the
> substitution.
But it is really an extension of register elimination: the constants are of
the form frame_pointer + CONST or arg_pointer + CONST, and this gets
transformed into stack_pointer + CONST or hard_frame_pointer + CONST
just like an eliminated frame or arg pointer. The usual reloading
is done on the result, so any invalidity introduced by the substitution
gets fixed up.