From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id kOR8Dufjkl87YgAAWB0awg (envelope-from ) for ; Fri, 23 Oct 2020 10:08:39 -0400 Received: by simark.ca (Postfix, from userid 112) id 38FCD1EE09; Fri, 23 Oct 2020 10:08:39 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 0B3A61E58D for ; Fri, 23 Oct 2020 10:08:38 -0400 (EDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 999993987C09; Fri, 23 Oct 2020 14:08:37 +0000 (GMT) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by sourceware.org (Postfix) with ESMTPS id B4EFF3858036 for ; Fri, 23 Oct 2020 14:08:34 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org B4EFF3858036 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=tdevries@suse.de X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C4564AEC1; Fri, 23 Oct 2020 14:08:33 +0000 (UTC) Subject: Re: [committed][gdb/symtab] Make find_block_in_blockvector more robust To: Simon Marchi , Tom Tromey References: <20201022152431.GA13910@delia> <87ft66144u.fsf@tromey.com> <8d84b50e-530a-a33c-b523-c72305438c19@suse.de> <4052e022-30fd-b24e-2ad6-53eb4d790d85@simark.ca> From: Tom de Vries Autocrypt: addr=tdevries@suse.de; keydata= xsBNBF0ltCcBCADDhsUnMMdEXiHFfqJdXeRvgqSEUxLCy/pHek88ALuFnPTICTwkf4g7uSR7 HvOFUoUyu8oP5mNb4VZHy3Xy8KRZGaQuaOHNhZAT1xaVo6kxjswUi3vYgGJhFMiLuIHdApoc u5f7UbV+egYVxmkvVLSqsVD4pUgHeSoAcIlm3blZ1sDKviJCwaHxDQkVmSsGXImaAU+ViJ5l CwkvyiiIifWD2SoOuFexZyZ7RUddLosgsO0npVUYbl6dEMq2a5ijGF6/rBs1m3nAoIgpXk6P TCKlSWVW6OCneTaKM5C387972qREtiArTakRQIpvDJuiR2soGfdeJ6igGA1FZjU+IsM5ABEB AAHNH1RvbSBkZSBWcmllcyA8dGRldnJpZXNAc3VzZS5kZT7CwKsEEwEIAD4WIQSsnSe5hKbL MK1mGmjuhV2rbOJEoAUCXSW0JwIbAwUJA8JnAAULCQgHAgYVCgkICwIEFgIDAQIeAQIXgAAh CRDuhV2rbOJEoBYhBKydJ7mEpsswrWYaaO6FXats4kSgc48H/Ra2lq5p3dHsrlQLqM7N68Fo eRDf3PMevXyMlrCYDGLVncQwMw3O/AkousktXKQ42DPJh65zoXB22yUt8m0g12xkLax98KFJ 5NyUloa6HflLl+wQL/uZjIdNUQaHQLw3HKwRMVi4l0/Jh/TygYG1Dtm8I4o708JS4y8GQxoQ UL0z1OM9hyM3gI2WVTTyprsBHy2EjMOu/2Xpod95pF8f90zBLajy6qXEnxlcsqreMaqmkzKn 3KTZpWRxNAS/IH3FbGQ+3RpWkNGSJpwfEMVCeyK5a1n7yt1podd1ajY5mA1jcaUmGppqx827 8TqyteNe1B/pbiUt2L/WhnTgW1NC1QDOwE0EXSW0JwEIAM99H34Bu4MKM7HDJVt864MXbx7B 1M93wVlpJ7Uq+XDFD0A0hIal028j+h6jA6bhzWto4RUfDl/9mn1StngNVFovvwtfzbamp6+W pKHZm9X5YvlIwCx131kTxCNDcF+/adRW4n8CU3pZWYmNVqhMUiPLxElA6QhXTtVBh1RkjCZQ Kmbd1szvcOfaD8s+tJABJzNZsmO2hVuFwkDrRN8Jgrh92a+yHQPd9+RybW2l7sJv26nkUH5Z 5s84P6894ebgimcprJdAkjJTgprl1nhgvptU5M9Uv85Pferoh2groQEAtRPlCGrZ2/2qVNe9 XJfSYbiyedvApWcJs5DOByTaKkcAEQEAAcLAkwQYAQgAJhYhBKydJ7mEpsswrWYaaO6FXats 4kSgBQJdJbQnAhsMBQkDwmcAACEJEO6FXats4kSgFiEErJ0nuYSmyzCtZhpo7oVdq2ziRKD3 twf7BAQBZ8TqR812zKAD7biOnWIJ0McV72PFBxmLIHp24UVe0ZogtYMxSWKLg3csh0yLVwc7 H3vldzJ9AoK3Qxp0Q6K/rDOeUy3HMqewQGcqrsRRh0NXDIQk5CgSrZslPe47qIbe3O7ik/MC q31FNIAQJPmKXX25B115MMzkSKlv4udfx7KdyxHrTSkwWZArLQiEZj5KG4cCKhIoMygPTA3U yGaIvI/BGOtHZ7bEBVUCFDFfOWJ26IOCoPnSVUvKPEOH9dv+sNy7jyBsP5QxeTqwxC/1ZtNS DUCSFQjqA6bEGwM22dP8OUY6SC94x1G81A9/xbtm9LQxKm0EiDH8KBMLfQ== Message-ID: <8204bf8a-40f7-de0f-96a4-714f4db06d64@suse.de> Date: Fri, 23 Oct 2020 16:08:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <4052e022-30fd-b24e-2ad6-53eb4d790d85@simark.ca> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: gdb-patches@sourceware.org Errors-To: gdb-patches-bounces@sourceware.org Sender: "Gdb-patches" On 10/22/20 11:42 PM, Simon Marchi wrote: > On 2020-10-22 5:21 p.m., Tom de Vries wrote: >> On 10/22/20 8:56 PM, Tom Tromey wrote: >>>>>>>> "Tom" == Tom de Vries writes: >>> >>> Tom> + if (!(BLOCK_START (b) <= pc)) >>> Tom> + return NULL; >>> >>> This seems a bit weird to me, in that if BLOCK_START(b) == pc, then I >>> would be inclined to say that the pc is in fact in that block. >>> >> >> So if BLOCK_START(b) == pc, indeed the pc is in the block, and we have: >> ... >> if (!(true)) >> return NULL; >> ... >> which I'd say correctly handles that case. >> >> Thanks, >> - Tom >> > > I think that turning: > > if (!(BLOCK_START (b) <= pc)) > > into > > if (BLOCK_START (b) > pc) > > or > > if (pc < BLOCK_START (b)) > > would make it easier to read. Thanks for the feedback. I agree it would make it easier to read, but I'm afraid it would make it harder to understand. In general I prefer range tests to conform to this layout: ... min cmp-op-1 val && val cmp-op-2 max ... which IMO is the best approximation of the non-C: ... min cmp-op-1 val cmp-op-2 max ... and then use the range expression as a whole, either negated or not. But indeed, the negated case is a bit harder to read, something I sometimes fix by using a variable with a somewhat helpful name. This follows my preferred layout for the range expression (albeit split up into two variables), while not negating non-trivial expressions: ... while (bot >= STATIC_BLOCK) { b = BLOCKVECTOR_BLOCK (bl, bot); bool start_ok = BLOCK_START (b) <= pc; bool end_ok = pc < BLOCK_END (b); if (!start_ok) return NULL; if (end_ok) return b; bot--; } ... but perhaps this is making things less clear? WDYT? Thanks, - Tom