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Re: Pre_dec and Post_inc insns
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: "Natasha Wilson" <nat_w at operamail dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: 01 Jul 2003 11:38:19 -0300
- Subject: Re: Pre_dec and Post_inc insns
- Organization: GCC Team, Red Hat
- References: <20030630132652.18586.qmail@operamail.com>
On Jun 30, 2003, "Natasha Wilson" <nat_w@operamail.com> wrote:
> What are the potentials areas where they could create problems if
> they are generated before the flow pass?
I just found out, the hard way, that cse is one such area. It simply
doesn't notice changes caused by autoinc modifiers, and it may also
replace pseudos that are marked as equivalent to constants, and then
reload barfs.
Unfortunately, cse may also turn increments that flow could turn into
autoinc addressing modes into computations of a base register plus a
constant, which flow then can't handle.
--
Alexandre Oliva Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer aoliva@{redhat.com, gcc.gnu.org}
CS PhD student at IC-Unicamp oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist Professional serial bug killer