From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 13092 invoked by alias); 10 Mar 2002 19:30:29 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 13040 invoked from network); 10 Mar 2002 19:30:27 -0000 Received: from unknown (HELO nevyn.them.org) (128.2.145.6) by sources.redhat.com with SMTP; 10 Mar 2002 19:30:27 -0000 Received: from drow by nevyn.them.org with local (Exim 3.35 #1 (Debian)) id 16k91X-00017X-00; Sun, 10 Mar 2002 14:30:27 -0500 Date: Sun, 10 Mar 2002 11:30:00 -0000 From: Daniel Jacobowitz To: Andrew Cagney Cc: Don Howard , gdb-patches@sources.redhat.com Subject: Re: [RFA] mips: Fix "info registers" output Message-ID: <20020310143027.A3933@nevyn.them.org> Mail-Followup-To: Andrew Cagney , Don Howard , gdb-patches@sources.redhat.com References: <20010619225007.A10141@nevyn.them.org> <20020307165956.A22042@nevyn.them.org> <3C8ABF59.7080908@cygnus.com> <20020310015637.A13373@nevyn.them.org> <3C8B8A11.8070609@cygnus.com> <20020310120037.A29124@nevyn.them.org> <3C8B9C06.9020506@cygnus.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3C8B9C06.9020506@cygnus.com> User-Agent: Mutt/1.3.23i X-SW-Source: 2002-03/txt/msg00141.txt.bz2 On Sun, Mar 10, 2002 at 12:46:46PM -0500, Andrew Cagney wrote: > >On Sun, Mar 10, 2002 at 11:30:09AM -0500, Andrew Cagney wrote: > > >>Suggest a FIXME and bug report here. It isn't safe to assume things > >>like builtin_type_double is 64 bit. The code should use the ABI > >>independant builtin_type_ieee_BLAH. But this is a separate bug and not > >>your problem :-) > > > > > >builtin_type_double = > > init_type (TYPE_CODE_FLT, TARGET_DOUBLE_BIT / TARGET_CHAR_BIT, > > 0, > > "double", (struct objfile *) NULL); > > > > > > set_gdbarch_double_bit (gdbarch, 64); > > > > > >Why isn't it safe to assume that a double is 64-bit when we explicitly > >set it that way? I assume that the builtin types get swapped out when > >we change gdbarch... yes, they do. Besides, is MIPS FP actually IEEE? > >Oh, I suppose the values probably are and only some of the math isn't. > > Have a look at GCC's -fshort-double option. I'm not sure how MIPS would > respond to it but I suspect it would make everyones head hurt. :-) I suspect the stabs reader would go insane :) You'd have two floating point types with different names but the same size... all sorts of assumptions would probably get confused. That wouldn't affect builtin_type_double, though, which we define in terms of the 64 bits. Are you saying that should be updated based on the type of 'double' in the objfile? I don't really think so, since 'the type associated with the word "double"' isn't necessarily tied to "what this architecture would normally call a double" and builtin_type_double is the latter. MIPS would normally call a 64-bit FP quantity a double, whatever GCC is up to. > The ``info registers'' code is both ISA and ABI dependant. ISA since > that determines the raw format of registers (ieee_double_{big,little} > not double) - the ABI shouldn't change a MIPS DOUBLE. ABI since that > determins where bits of registers end up being saved on the stack. Right; the way registers are acquired is both ISA and ABI dependent. I don't know that the way they are interpreted afterwards is ABI dependent... > >Committed without that last FIXME; I'll add it if it's really > >necessary > Er, where's the fire? With all respect, it is always better to give the > other party the chance to respond. Sorry, no fire. Perhaps I'm just unconscionably impatient, but the more almost-entirely-approved patches I have lying around from nine months ago, the more confused I become. I'll try to curb myself. -- Daniel Jacobowitz Carnegie Mellon University MontaVista Software Debian GNU/Linux Developer