Date: Sun, 22 Mar 2015 14:37:28 -0700 From: Garrett Cooper <yaneurabeya@gmail.com> To: Dimitry Andric <dim@FreeBSD.org> Cc: "freebsd-testing@freebsd.org" <freebsd-testing@freebsd.org>, freebsd-current Current <freebsd-current@freebsd.org>, "jenkins-admin@freebsd.org" <jenkins-admin@freebsd.org>, freebsd-toolchain@freebsd.org Subject: Re: Jenkins build is still unstable: FreeBSD_HEAD-tests2 #867 Message-ID: <3E288A39-D7DB-458A-B425-8B449DD57E35@gmail.com> In-Reply-To: <864EB4DB-2DF7-4294-9498-95E54E6B49CC@FreeBSD.org> References: <1669399171.13.1427029129760.JavaMail.jenkins@jenkins-9.freebsd.org> <799490341.14.1427048792932.JavaMail.jenkins@jenkins-9.freebsd.org> <CAG=rPVeyamLPnC5i05_=Ub0D%2BV256U_8t8R5tfDitC=NkjBOFQ@mail.gmail.com> <BE5A3694-E1D1-4A47-8707-D6214E997363@FreeBSD.org> <494AEF4B-0AF8-449A-9B41-9AC4F4552AF0@FreeBSD.org> <CAG=rPVchdm_VaTshq%2BRN%2BkHX0YC0_Tsx22oJVNNnoOamdm00mQ@mail.gmail.com> <864EB4DB-2DF7-4294-9498-95E54E6B49CC@FreeBSD.org>
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[-- Attachment #1 --]
On Mar 22, 2015, at 14:36, Dimitry Andric <dim@FreeBSD.org> wrote:
> On 22 Mar 2015, at 22:32, Craig Rodrigues <rodrigc@FreeBSD.org> wrote:
>>
>> On Sun, Mar 22, 2015 at 2:29 PM, Dimitry Andric <dim@freebsd.org> wrote:
>>
>> Ah right, that was on i386, on amd64 it does result in -2^63. It is indeed caused by reliance on signed integer wrapping.
>>
>> This diff should fix it, without rewriting the utility:
>>
>> Index: bin/expr/Makefile
>> ===================================================================
>> --- bin/expr/Makefile (revision 280156)
>> +++ bin/expr/Makefile (working copy)
>> @@ -6,6 +6,9 @@ PROG= expr
>> SRCS= expr.y
>> YFLAGS=
>>
>> +# expr relies on signed integer wrapping
>> +CFLAGS+= -fwrapv
>> +
>> NO_WMISSING_VARIABLE_DECLARATIONS=
>>
>> .if ${MK_TESTS} != "no"
>>
>>
>> Well, another alternative is to patch expr.y:
>>
>> Index: expr.y
>> ===================================================================
>> --- expr.y (revision 280353)
>> +++ expr.y (working copy)
>> @@ -393,7 +393,7 @@
>> }
>>
>> void
>> -assert_plus(intmax_t a, intmax_t b, intmax_t r)
>> +assert_plus(intmax_t a, intmax_t b, volatile intmax_t r)
>> {
>> /*
>> * sum of two positive numbers must be positive,
>> @@ -420,7 +420,7 @@
>> }
>>
>> void
>> -assert_minus(intmax_t a, intmax_t b, intmax_t r)
>> +assert_minus(intmax_t a, intmax_t b, volatile intmax_t r)
>> {
>> /* special case subtraction of INTMAX_MIN */
>> if (b == INTMAX_MIN && a < 0)
>>
>>
>> There were already some patches previously done to this
>> file to add "volatile", so maybe this would be OK to do.
>>
>> What do you think?
>
> Volatile is not the solution, it is completely orthogonal. The correct
> way would be to use unsigned integers, for which wrapping is defined,
> then convert those back and forth when presenting the results to the
> user.
Before doing that — what changed in the past week that changed the behavior of expr?
Thanks!
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