From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-out.m-online.net (mail-out.m-online.net [212.18.0.9]) by sourceware.org (Postfix) with ESMTPS id 60B78383CD18 for ; Sat, 17 Dec 2022 10:21:53 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 60B78383CD18 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=linux-m68k.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=nefkom.net Received: from frontend03.mail.m-online.net (unknown [192.168.6.182]) by mail-out.m-online.net (Postfix) with ESMTP id 4NZ2803cnbz1r0mT; Sat, 17 Dec 2022 11:21:52 +0100 (CET) Received: from localhost (dynscan3.mnet-online.de [192.168.6.84]) by mail.m-online.net (Postfix) with ESMTP id 4NZ28032sDz1qqlR; Sat, 17 Dec 2022 11:21:52 +0100 (CET) X-Virus-Scanned: amavisd-new at mnet-online.de Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan3.mail.m-online.net [192.168.6.84]) (amavisd-new, port 10024) with ESMTP id eVAdg9Q1keGT; Sat, 17 Dec 2022 11:21:51 +0100 (CET) X-Auth-Info: SMh2JNOncu5xiXM6a+wf43UO8AFGkSLMix7c+5/M8r/Q0sBxN5qYv0OjiTwwpnLo Received: from tiger.home (aftr-62-216-205-197.dynamic.mnet-online.de [62.216.205.197]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Sat, 17 Dec 2022 11:21:51 +0100 (CET) Received: by tiger.home (Postfix, from userid 1000) id 4C490148F94; Sat, 17 Dec 2022 11:21:51 +0100 (CET) From: Andreas Schwab To: Andrew Waterman Cc: Palmer Dabbelt , Kito Cheng , gcc-patches@gcc.gnu.org, Greg Favor Subject: Re: [PATCH] RISC-V: Note that __builtin_riscv_pause() implies Xgnuzihintpausestate References: <87r0wypcgw.fsf@linux-m68k.org> X-Yow: In order to make PLANS for the WEEKEND...so that we can read RESTAURANT REVIEWS and decide to GO to that restaurant & then NEVER GO...so we can meet a FRIEND after work in a BAR and COMPLAIN about Interior Sect'y JAMES WATT until the SUBJECT is changed to NUCLEAR BLACKMAIL...and so our RELATIVES can FORCE us to listen to HOCKEY STATISTICS while we wait for them to LEAVE on the 7:48.... Date: Sat, 17 Dec 2022 11:21:51 +0100 In-Reply-To: (Andrew Waterman's message of "Sat, 17 Dec 2022 02:16:08 -0800") Message-ID: <87mt7mpby8.fsf@linux-m68k.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-0.7 required=5.0 tests=BAYES_00,HEADER_FROM_DIFFERENT_DOMAINS,KAM_DMARC_STATUS,RCVD_IN_BARRACUDACENTRAL,RCVD_IN_DNSWL_LOW,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Dez 17 2022, Andrew Waterman wrote: > On Sat, Dec 17, 2022 at 2:10 AM Andreas Schwab wrote: >> >> On Dez 17 2022, Andrew Waterman wrote: >> >> > It took me a few minutes to understand the purpose of this chicanery, but >> > there's indeed a contradiction in the ISA spec. HINT instructions _do_ >> > affect architectural state in a limited fashion--namely, updating the PC. >> >> How can an insn _not_ affect the PC? (Other than the trivial infinite >> loop.) > > Heh, yeah, that's roughly what I meant by "common-sense reading" (and > that's my rationale for simply clarifying the spec and nuking this > Xgnuzihintpausestate extension). My point is that the implicit update of the PC cannot be part of the architectural state in the first place. Even the trivial infinite loop has this, before the actual state change (setting PC back) is performed. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 "And now for something completely different."