From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/1378 Path: news.gmane.org!not-for-mail From: John Spencer Newsgroups: gmane.linux.lib.musl.general Subject: Re: clang/musl progress and a small bug. Date: Thu, 26 Jul 2012 20:24:39 +0200 Message-ID: <50118B67.8010208@barfooze.de> References: <4797553.4BPKurOpfG@main.pennware.com> <20120525231727.GA163@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: dough.gmane.org 1343327071 993 80.91.229.3 (26 Jul 2012 18:24:31 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Thu, 26 Jul 2012 18:24:31 +0000 (UTC) To: musl@lists.openwall.com, Richard Pennington Original-X-From: musl-return-1379-gllmg-musl=m.gmane.org@lists.openwall.com Thu Jul 26 20:24:31 2012 Return-path: Envelope-to: gllmg-musl@plane.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1SuSjd-0006on-ES for gllmg-musl@plane.gmane.org; Thu, 26 Jul 2012 20:24:29 +0200 Original-Received: (qmail 3404 invoked by uid 550); 26 Jul 2012 18:24:28 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 3391 invoked from network); 26 Jul 2012 18:24:28 -0000 User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.14) Gecko/20110221 SUSE/3.1.8 Mail/1.0 In-Reply-To: <20120525231727.GA163@brightrain.aerifal.cx> Xref: news.gmane.org gmane.linux.lib.musl.general:1378 Archived-At: On 05/26/2012 01:17 AM, Rich Felker wrote: > On Fri, May 25, 2012 at 04:40:51PM -0500, Richard Pennington wrote: > >> I think I found a bug while running my library regression test. The zero test >> failed in the following code: >> >> TEST_TRACE(C99 7.20.3.1) >> p = calloc(100, sizeof(char)); >> TEST(p != NULL, "calloc() returned a pointer"); >> int flag = 1; >> for (i = 0; i< 100; ++i) { >> if (p[i] != 0) { >> flag = 0; >> } >> } >> TEST(flag, "calloc() returned zeroed memory"); >> >> The TEST() macro is kind of like assert but it prints out the message and >> counts failures and successes: >> >> PASS: 001stdlib.c:74: Stdlib(Stdlib): calloc() returned a pointer >> FAIL: 001stdlib.c:81: Stdlib(Stdlib): calloc() returned zeroed memory >> Stdlib unit tests completed >> 32 tests run >> 1 test failed >> >> Am I missing something? > I'm guessing clang miscompiled calloc.c due to not respecting > -ffreestanding. There was a related issue reported a while back by > someone experimenting with clang and musl but I don't know what came > of it. Basically I think the issue is that clang is treating the > malloc call calloc makes as a call to the standard malloc, and > optimizing out inspections calloc makes on the returned memory because > it's "indeterminate" and thus undefined behavior. This contradicts the > meaning of -ffreestanding which is to behave as a freestanding C > environment where malloc and other library functions are not special. > > I'm not sure how to work around the issue without making the code > behave a lot worse. If you can determine this is the issue, I think it > really calls for a bug report to clang... > > Rich > has this issue been reported on the LLVM list finally ? imo this is a major blocker