From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeffrey A Law To: "Michael P. Hayes" Cc: Joern Rennecke , gcc2@cygnus.com, egcs@cygnus.com Subject: Re: Autoincrement addressing modes Date: Wed, 11 Feb 1998 18:20:00 -0000 Message-id: <20650.887245518@hurl.cygnus.com> References: <199802120014.NAA29645@ongaonga.chch.cri.nz> X-SW-Source: 1998-02/msg00515.html In message < 199802120014.NAA29645@ongaonga.chch.cri.nz >you write: > > The PA has similar constraints. > > Does this asymmetry only apply to these update forms of addressing > modes? Well, there's some weird asymmetry problems with nearly all of the addressing modes, except for (reg) on the PA. Many we are able to ignore, others we deal with by not considering such addresses valid according to GO_IF_LEGITIMATE_ADDRESS -- we do allow them in some predicates when we can check for the weird problems. > Any ideas how to describe this to GCC? I suppose if there was a flag > to differentiate memory reads from writes, then > GO_IF_LEGITIMATE_ADDRESS could reject the invalid forms. So far we haven't tried. Being able to distinguish between loads & stores in GO_IF_LEG... would be a big step forward, but a lot of work. My recommendation would be to not try and handle *all* the cases in the first submission. Just get something that can be extended, particularly if we do fix GO_IF_LEG... later. jeff