From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS17314 8.43.84.0/22 X-Spam-Status: No, score=-4.2 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham 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 (4096 bits) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id ECA6F1F8C6 for ; Sat, 4 Sep 2021 09:17:52 +0000 (UTC) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 241EF3870C07 for ; Sat, 4 Sep 2021 09:17:52 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 241EF3870C07 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1630747072; bh=3Lw1gxv4G4w6KoAB/FLhxMoPiyPghTEZEQgvDIerIro=; h=Date:To:Subject:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=F6WtVeDC2fP/JVJ0nJ+qvxztzghFNEoMZN0zzGYLZU2e1+OoRacrK6Aa5k9zqavhD jekqikQ5qzLvzUqwcD5Y05MoM2x/Odb2iw+7q3V73GUvRZitm+vJEOnNAVSFBzDX+J nrSQ76+B57BweFCAO1imS2RyX7429w9KDtdj7+JM= Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by sourceware.org (Postfix) with ESMTPS id 7B1CD3857C40 for ; Sat, 4 Sep 2021 09:17:33 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 7B1CD3857C40 Received: from [10.10.3.121] (unknown [10.10.3.121]) by mail.ispras.ru (Postfix) with ESMTPS id 6B01E40D403D; Sat, 4 Sep 2021 09:17:32 +0000 (UTC) Date: Sat, 4 Sep 2021 09:17:32 +0000 (-00) To: Adhemerval Zanella Subject: Re: [PATCH v3 6/7] stdlib: Implement introsort with qsort In-Reply-To: <20210903171144.952737-7-adhemerval.zanella@linaro.org> Message-ID: References: <20210903171144.952737-1-adhemerval.zanella@linaro.org> <20210903171144.952737-7-adhemerval.zanella@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Alexander Monakov via Libc-alpha Reply-To: Alexander Monakov Cc: libc-alpha@sourceware.org Errors-To: libc-alpha-bounces+e=80x24.org@sourceware.org Sender: "Libc-alpha" On Fri, 3 Sep 2021, Adhemerval Zanella via Libc-alpha wrote: > @@ -235,6 +305,9 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, > else > swap_func = SWAP_BYTES; > > + /* Maximum depth before quicksort switches to heapsort. */ > + size_t depth = 2 * (CHAR_BIT - 1 - __builtin_clzl (total_elems)); > + This doesn't look right, the expression in parenthesis is usually negative, conversion to size_t wraps around and you make 'depth' a huge positive value. The first term probably should have been 'CHAR_BIT * sizeof(size_t)'. Does this mean that heapsort fallback was not exercised in testing? Also, is it certain at that point that total_elems is nonzero? __builtin_clzl is undefined for a zero argument. Alexander