Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1rtdpp-00GPoU-O8 for pgsql-hackers@arkaria.postgresql.org; Mon, 08 Apr 2024 01:30:10 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.94.2) (envelope-from ) id 1rtdpo-00FOXv-Nj for pgsql-hackers@arkaria.postgresql.org; Mon, 08 Apr 2024 01:30:08 +0000 Received: from makus.postgresql.org ([2001:4800:3e1:1::229]) by malur.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1rtdpo-00FOXn-EV for pgsql-hackers@lists.postgresql.org; Mon, 08 Apr 2024 01:30:08 +0000 Received: from mail-io1-xd2c.google.com ([2607:f8b0:4864:20::d2c]) by makus.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1rtdpm-001k4F-2A for pgsql-hackers@lists.postgresql.org; Mon, 08 Apr 2024 01:30:07 +0000 Received: by mail-io1-xd2c.google.com with SMTP id ca18e2360f4ac-7c8b777ff8bso138318039f.0 for ; Sun, 07 Apr 2024 18:30:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1712539805; x=1713144605; darn=lists.postgresql.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=+heiXD7JIFd01lmAqYQmogazQfpwa0fBOlTzMLbryYg=; b=Ose7Yibk1Tt2AnlhaqRpnqi85+BP9ZP3UOzysOl7eXpIo53bO1O/8mBMsqUGQNoGQL X5Y93zXJMd1RmBGThnDOqEvNDjnDiS4J3DvylYi9iGApJktlCbef9g6HpQxXxB8ndvEf mRW0kgSQhqYYO4wnBGFeRONXruMIQ8svuMzHPoCQOt4/MFrlHiVJNl00vndGvt8FaLDs ZEgyB3MiED3AUWR8jwgC0KTX+dM80knC7J1BPE6I45iCP0iDGrS3s7oXz2fHHhTUkdem nYrBf/ek27ZZS3j9QGvc88qsfzPSvNOYgKEKIx+XQlfMnpvwhM6740fIoT7+18QtIvJ7 6/Yg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712539805; x=1713144605; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=+heiXD7JIFd01lmAqYQmogazQfpwa0fBOlTzMLbryYg=; b=OetGJPBRoR2gZtZqHGYgJ3mc73p0Xva65j7aNx7lx+wn35k631Wu6U57o2METjAz4o 5cN4YHJcXWSLne242BDcr99r3bMQuGzUBl9yfaOtSPxUgsjDEjWBwLYxxl1Dk+AP/VlL rzEGhNWiGRlp8aJe+croo1tkdZ+Er3+DFKoTpZct4g7EKmjBLlQK7DbhoWgVLuRrRxRL gaUATmTbYWcKsr8ucK0QnBj3e7RUSK4GVkV56HVl0CW1EuzYmiZ11tsxc2AcLupTYQZC 5hTnPyl4Kn0ReaSb6lh5Sn6bDtCT/AMTugVnNMJDw/x5uEQxXYdKN0UsO+uaBSRSSz16 6wNA== X-Forwarded-Encrypted: i=1; AJvYcCVxRwdPsFYQzam7wPSbQL7hkrYDo1j9EvkwKlwSNE+MCJxUqGF++lS3M3qszonL4eBl/HPJ0FWna8ytybLbX+Uz/QhHvtq6TsGXSY98mezIA6zu X-Gm-Message-State: AOJu0YzA+2qX+Bm8FFzxKVtzE3OhyCa3e9dT75aUmZmFaIfYVYIoObP6 Mepv6ZvshQcakkE//2thjVK8bE+9JsQeNYhaKwVgbqMZmikdr8L/ X-Google-Smtp-Source: AGHT+IHK/V4nOz3rp9fhzL8NpYrTyEyTdiBGscuwtfKMsmXV3E5/27RA3GMxLol15R7ZVF+6OvH2ZA== X-Received: by 2002:a6b:e516:0:b0:7d3:4d48:a0cb with SMTP id y22-20020a6be516000000b007d34d48a0cbmr8066154ioc.18.1712539805232; Sun, 07 Apr 2024 18:30:05 -0700 (PDT) Received: from nathanxps13 (162-195-168-172.lightspeed.stlsmo.sbcglobal.net. [162.195.168.172]) by smtp.gmail.com with ESMTPSA id b1-20020a056638150100b0048296f794besm140137jat.65.2024.04.07.18.30.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 07 Apr 2024 18:30:04 -0700 (PDT) Date: Sun, 7 Apr 2024 20:30:02 -0500 From: Nathan Bossart To: Tom Lane Cc: David Rowley , Ants Aasma , Alvaro Herrera , "Amonson, Paul D" , Andres Freund , "Shankaran, Akash" , Noah Misch , Matthias van de Meent , "pgsql-hackers@lists.postgresql.org" Subject: Re: Popcount optimization using AVX512 Message-ID: <20240408013002.GA1352058@nathanxps13> References: <20240405041543.GA4100924@nathanxps13> <20240405125844.GB4102502@nathanxps13> <20240405153811.GA9352@nathanxps13> <20240406011704.GB167028@nathanxps13> <20240406194101.GA533391@nathanxps13> <2999492.1712536932@sss.pgh.pa.us> <20240408012332.GA1351547@nathanxps13> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240408012332.GA1351547@nathanxps13> List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk On Sun, Apr 07, 2024 at 08:23:32PM -0500, Nathan Bossart wrote: > The Intel documentation for _mm256_undefined_si256() [0] > indicates that it is intended to return "undefined elements," so it seems > like the use of an uninitialized variable might be intentional. See also https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=72af61b122. -- Nathan Bossart Amazon Web Services: https://aws.amazon.com