From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 47684 invoked by alias); 27 May 2015 10:55:23 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 47670 invoked by uid 89); 27 May 2015 10:55:22 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-0.3 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,FROM_LOCAL_NOVOWEL,HK_RANDOM_ENVFROM,HK_RANDOM_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=no version=3.3.2 X-HELO: mail-oi0-f42.google.com Received: from mail-oi0-f42.google.com (HELO mail-oi0-f42.google.com) (209.85.218.42) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Wed, 27 May 2015 10:55:21 +0000 Received: by oifu123 with SMTP id u123so4268272oif.1 for ; Wed, 27 May 2015 03:55:19 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.60.132.208 with SMTP id ow16mr25849796oeb.66.1432724119855; Wed, 27 May 2015 03:55:19 -0700 (PDT) Received: by 10.76.26.178 with HTTP; Wed, 27 May 2015 03:55:19 -0700 (PDT) In-Reply-To: <55659984.90103@redhat.com> References: <1431904329-13965-1-git-send-email-jcmvbkbc@gmail.com> <55659984.90103@redhat.com> Date: Wed, 27 May 2015 10:55:00 -0000 Message-ID: Subject: Re: [PATCH] xtensa: fix access to the last pseudo register From: Max Filippov To: Pedro Alves Cc: gdb-patches@sourceware.org, Maxim Grigoriev , Woody LaRue , Marc Gauthier Content-Type: text/plain; charset=UTF-8 X-SW-Source: 2015-05/txt/msg00658.txt.bz2 On Wed, May 27, 2015 at 1:16 PM, Pedro Alves wrote: > On 05/18/2015 12:12 AM, Max Filippov wrote: >> Currently access to the last pseudo register is aliased to a1. This is >> done by little snippets in the beginning of xtensa_pseudo_register_read >> and xtensa_pseudo_register_write that used to do such aliasing for FP >> register since bdb4c075a29dd086f0868b394b488b1c94666be6, but then >> FP_ALIAS was expanded into gdbarch_num_regs (current_gdbarch) + >> gdbarch_num_pseudo_regs (current_gdbarch) (one register past the last >> pseudo register) in 304fe2552d6e0821e8fdb7575f8e7ba6607a076d, which >> then was changed to the last pseudo register in >> 94a0e877111421d300d26b858bd3a0a27078d1e8. > > IIUC, the original intention was for FP to alias a1, and then through > that series of patches (part of old current_gdbarch elimination) > we ended up aliasing the wrong register. Instead of fixing the > aliasing, you're just removing it altogether. Correct? I'm removing that aliasing to expose the last pseudoregister. After that patch fp pseudo register still exists and it is a read only alias for a1. I don't think that's right, because normally frame pointer is a7 or a15, depending on ABI, but that's definitely a separate question. -- Thanks. -- Max