From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from resqmta-a1p-077724.sys.comcast.net (resqmta-a1p-077724.sys.comcast.net [IPv6:2001:558:fd01:2bb4::5]) by sourceware.org (Postfix) with ESMTPS id 8E5D2385829E for ; Fri, 16 Feb 2024 14:50:31 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 8E5D2385829E Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=comcast.net Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=comcast.net ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 8E5D2385829E Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=2001:558:fd01:2bb4::5 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1708095033; cv=none; b=hv93PcmxHc57K9OHY/ZijPWFwv94D50Lk2LiUToydyUMQDM737HT/rGMGHup6qzVlmJjNAQ7XE9JGFdYMwHx/ufuvdsh1hxESd+YZxvjRvOwd/MoSkKmQarq3wO6xIuZ5OpEZhuGKSKw9QymUvq4hrfvF049EU6FDhpiOGbhtN8= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1708095033; c=relaxed/simple; bh=/7mV91i+GW9rXvvjvr56S9NQfMVtfrKMj2NzF3Av0RI=; h=DKIM-Signature:Mime-Version:Subject:From:Date:Message-Id:To; b=CMb6Y1UJOWfBeBczwFyHX2SwKYkNvYG9cQ0Ou7nqsbndLJ2HurXks4g3C4vaXX7cGSQNAkvNNcm859F6lR1Y1IAtRWa/6Y7hnuLEnjPcE48t5NQZPm8FpZO2Ha53N3rIF/VfMz75aPXQcCPbIu53nrknw/14aeh/IK5lTRaGmEk= ARC-Authentication-Results: i=1; server2.sourceware.org Received: from resomta-a1p-077058.sys.comcast.net ([96.103.145.239]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 256/256 bits) (Client did not present a certificate) by resqmta-a1p-077724.sys.comcast.net with ESMTP id azGzrCEFQfUcmazXqr1MGf; Fri, 16 Feb 2024 14:50:30 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=20190202a; t=1708095030; bh=2w6crQIi6+fhneaUNW5m9FXO4EkSg34OE7MK+fiu+HE=; h=Received:Received:Content-Type:Mime-Version:Subject:From:Date: Message-Id:To:Xfinity-Spam-Result; b=lVgvV/RzNcxQOpEWimFifx+eRt+RZtgowWG/tU0VWawgKhuVyjSlM3L4/oYUOhdAW xlYUvTIZF2qAYhwqlwGqbqeHPnCuhQ//KXVyfvt3fk9CyvauBgovs4JqeONHrkIepa p+2CEnyZyw8H8GAIpUt5xeHKxyd7206gLD3ErVKSQR+vHt7sITecV0Pxo0gBqfzM2F 3B9cWwXMmNYW41fAukEb+d62FQcngQBISYtt69Bnsvmij5zikEt0DdPFFkpiA1S6l0 TKgSGB5/MIRl4+Gp+0Ba8aUROP1rGN72xc1J5X5r0D5QldXNlTYVeBsh1QJPX+TTOu XCLo8pkC5mF+g== Received: from smtpclient.apple ([73.60.223.101]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 256/256 bits) (Client did not present a certificate) by resomta-a1p-077058.sys.comcast.net with ESMTPSA id azXmrZw9KceAeazXorg4nX; Fri, 16 Feb 2024 14:50:30 +0000 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.8\)) Subject: Re: [PATCH] Turn on LRA on all targets From: Paul Koning In-Reply-To: Date: Fri, 16 Feb 2024 09:50:26 -0500 Cc: Segher Boessenkool , gcc-patches@gcc.gnu.org Content-Transfer-Encoding: quoted-printable Message-Id: <35C2AE25-1227-4AA2-8094-1DC0E4E989A6@comcast.net> References: <283c45ca085ced958cbce6e64331252c83a5899f.1682268126.git.segher@kernel.crashing.org> <20230423203328.GL19790@gate.crashing.org> <2A759520-2D62-472E-A97F-35E09B6E50F5@comcast.net> To: "Maciej W. Rozycki" X-Mailer: Apple Mail (2.3696.120.41.1.8) X-CMAE-Envelope: MS4xfOECcCqibVlT96AiOOWbbi1+5vdBIP/JoDcEEGL1SyGi2443uhjG00cha3uxphbABJU6ELUy3PbpzdpxebuP8lvz+mRge/Max0metYLM3Gje/2ZujaYy ZU9JWW9lE4X7fy0RWj0ie/k7yMe2PkoY4SBiSiHTeqxHb2f1Xkhi4npDD0MOfL9kYhQSjfpS4Y0r5Jbq06RdLBnhqSz4znPWz/mwNCy7w+voUQ5Uh+okLOgQ 6v9ssb+UAu4rvc8eH7HVVPjdms347e+7Tp56fkaq9OU= X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,SPF_HELO_PASS,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham 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 Feb 16, 2024, at 6:34 AM, Maciej W. Rozycki = wrote: >=20 > On Thu, 15 Feb 2024, Paul Koning wrote: >=20 >>> On May 15, 2023, at 5:09 PM, Maciej W. Rozycki = wrote: >>>=20 >>> ... >>>=20 >>> I may choose to implement a non-DWARF unwinder instead, as the VAX = stack=20 >>> frame is always fully described by the hardware and there is never = ever a=20 >>> need for debug information to be able to decode any VAX stack frame = (the=20 >>> RET machine instruction uses the stack frame information to restore = the=20 >>> previous PC, FP, SP, AP and any static registers saved by CALLS). >>=20 >> That would make sense; it's like the heuristic unwinder found in some=20= >> other targets (I remember the MIPS one, which worked fairly well and=20= >> allowed debugging without useable debug data). >=20 > Not really, in particular because EH unwinding has to be reliable and=20= > heuristics inherently is not. Fair enough, but what I meant is only that it's conceptually similar: = unwind based on the code and machine state, rather than auxiliary = information like debug data. And I think your point was that on VAX = this is indeed a reliable technique by virtue of the iSA. In fact, the = standard way to do exeception handling unwinding is part of the = originail VAX architecture (via the otherwise unused first word (I = think) of the call frame). paul