Date: Thu, 29 Apr 2021 23:11:37 +0200 From: Hans Petter Selasky <hps@selasky.org> To: FreeBSD Current <freebsd-current@freebsd.org>, Konstantin Belousov <kib@FreeBSD.org> Subject: Re: Undefined compiler behaviour or a compiler bug? Message-ID: <16b60c22-be04-cbbf-8fc4-a90c4031c529@selasky.org> In-Reply-To: <59f81323-74c5-e6a8-a62d-6abdf78902e8@selasky.org> References: <59f81323-74c5-e6a8-a62d-6abdf78902e8@selasky.org>
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On 4/29/21 11:06 PM, Hans Petter Selasky wrote: > Hi, > > Can someone please explain what C-compiler flag I'm missing, to make > this simple C-program terminate? > > I have a function _abs() which at some point is equal to one, but the > compiler thinks it is not required to emit the test for the while() at > all, looking at the assembly code! A printf() clearly verifies that the > _abs() function has returned one. > > clang11 -O2 test.c && ./a.out Looks like -fwrapv fixes the issue. Sorry for the noise. --HPS
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