From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 29A14C43334 for ; Wed, 29 Jun 2022 13:53:51 +0000 (UTC) Received: from localhost ([::1]:33778 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o6Y8c-0007TU-5T for qemu-devel@archiver.kernel.org; Wed, 29 Jun 2022 09:53:50 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41878) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o6XQb-0005tk-M2 for qemu-devel@nongnu.org; Wed, 29 Jun 2022 09:08:21 -0400 Received: from mail-yw1-x1135.google.com ([2607:f8b0:4864:20::1135]:37672) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1o6XQZ-0002N9-3Q for qemu-devel@nongnu.org; Wed, 29 Jun 2022 09:08:21 -0400 Received: by mail-yw1-x1135.google.com with SMTP id 00721157ae682-31772f8495fso147342327b3.4 for ; Wed, 29 Jun 2022 06:08:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=yfqKmAHpj0JEz6EA4ekbJTLGituDPawbqw3N/hp1Tio=; b=UmaBvc4pVDmY0KHppBssC4zMdYr6D6EXlJHM3hG7y/pf+zIw0tbIfiwUOEpo3s0Omt su8vLdle5F5pvbPhfmHtl79JiC1kpG+GopYilVAJIwKUzrI7W8s9tzV7UrzbLIfvgWgH i/S1rR7Z8UB++mmrW+g7pQ1+xKTAiTEFByduHbR/yww5xACuCgoa84aCJnd5Ob+86qYU amqUfWBuhBDumTshzcY6vbfobxiN/xFRQig8HP8XlCb1q8vyiB3cyeMpBpUyGavDF0cJ iMhkBOLDW4qv1QYDfT4X64K0XkjWaF7UBemut2y1yeIwz8vRUZpiudJGBN8WfEMPhGZU r0DA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=yfqKmAHpj0JEz6EA4ekbJTLGituDPawbqw3N/hp1Tio=; b=BLws6f5i9BGeeGJRpKOPGMciTU5LiRMAqxKqu98CpWWUifVzP3b/SnSny/Mt8vF/x5 yjXgiLkowR1YQga9tp6lshdSLsaGkaOAlcoET7SQWv4Q3Cntv40VOEnwbwLR+u/mn5Bg D2AVXKtBHZsayXmtDPMBjwsSpf9VjfI2zZLEkuBFbDvxcDddJGl6FCpZlXZShh0U/btM 4NjKtv/07CrqoJNdhQ5pB8yk75gmIme7aNLt3w9c3Pww8uFpl9WYYAMvuvlACwOvnDSP UK685QOq/DYpneFhk/BSd9Beua/zbubErKmDFcCXECxAXmiBS5d0z0+T0zTqkpDJvjk1 DSMQ== X-Gm-Message-State: AJIora+OsVV2UhFg7jR9cuwDKxnkO0sj1zb8ra+OW49hRJ2B8rcYUPjQ TUpVeb4ZHu+cA1sG1iaVIxpavnOkRdxyBUQ79802vAS0+88= X-Google-Smtp-Source: AGRyM1vS/73ic+JbXEyyDEfli7xRSeIFTHkZRtBzozQK+kvJZI/Tmp/Yyoq+RVNJ9AhbkaR6e2naeX3uTKc0iHxCm+k= X-Received: by 2002:a81:1cc:0:b0:317:a0fa:7a61 with SMTP id 195-20020a8101cc000000b00317a0fa7a61mr3789726ywb.10.1656508096898; Wed, 29 Jun 2022 06:08:16 -0700 (PDT) MIME-Version: 1.0 References: <20190131210851.9842-1-richard.henderson@linaro.org> <20190131210851.9842-2-richard.henderson@linaro.org> In-Reply-To: <20190131210851.9842-2-richard.henderson@linaro.org> From: Peter Maydell Date: Wed, 29 Jun 2022 14:07:38 +0100 Message-ID: Subject: Re: [Qemu-devel] [PATCH 1/2] decodetree: Initial support for variable-length ISAs To: Richard Henderson Cc: qemu-devel@nongnu.org, ysato@users.sourceforge.jp Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2607:f8b0:4864:20::1135; envelope-from=peter.maydell@linaro.org; helo=mail-yw1-x1135.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 31 Jan 2019 at 21:10, Richard Henderson wrote: > > Assuming that the ISA clearly describes how to determine > the length of the instruction, and the ISA has a reasonable > maximum instruction length, the input to the decoder can be > right-justified in an appropriate insn word. > > This is not 100% convenient, as out-of-line %fields are > numbered relative to the maximum instruction length, but > this appears to still be usable. Prompted by a query on IRC I noticed that this patch from a few years back added variable-insn-width support to decodetree, including a new commandline argument --varinsnwidth, but we don't document how to use it in docs/devel/decodetree.rst. In fact decodetree.rst doesn't document decodetree.py's commandline options at all. Could you maybe write up a docs patch to describe them? thanks -- PMM