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Re: PR37363: PR36090 and PR36182 all over again (was: Re: Call for testers, ppc64-linux)
- From: Paolo Bonzini <bonzini at gnu dot org>
- To: Hans-Peter Nilsson <hans-peter dot nilsson at axis dot com>, GCC Development <gcc at gcc dot gnu dot org>
- Date: Fri, 05 Sep 2008 12:55:17 +0200
- Subject: Re: PR37363: PR36090 and PR36182 all over again (was: Re: Call for testers, ppc64-linux)
- References: <200809051041.m85AfPEi032534@ignucius.se.axis.com>
> I got negative feedback on that patch (no, not regression
> results :) on IRC from David Edelsohn and understandably you
> held off your testing because of this, as for one the patch
> affects the rs6000 backend.
What kind of negative feedback?
> For CRIS (as well as other targets IIUC) the cause of PR37363 is
> that there's code that wraps a MINUS of two symbol_ref's in a
> CONST without checking that the two symbol_ref's make up a valid
> address. After that, the CONST effectively acts as a barrier
> for target hooks ("no need to look, we know that thing there is
> a valid constant expression").
The three possibilities I see are:
1) removing the wrapping CONST?
2) using the patch in
http://gcc.gnu.org/bugzilla/attachment.cgi?id=15620&action=view which
however just papers around this problem.
3) adding a check that the MINUS is a legitimate address, and only wrap
it in CONST if it is.
Paolo