Date: Tue, 8 Sep 2020 14:15:49 -0700 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Dimitry Andric <dim@freebsd.org> Cc: freebsd-toolchain@freebsd.org, freebsd-current@freebsd.org Subject: Re: clang miscompiles OpenLibm on i686-*-freebsd Message-ID: <20200908211549.GA84481@troutmask.apl.washington.edu> In-Reply-To: <66AE2F5B-F150-4D52-BF43-8F453217FC33@FreeBSD.org> References: <20200908021002.GA76325@troutmask.apl.washington.edu> <20200908025513.GA76566@troutmask.apl.washington.edu> <20200908174721.GA81469@troutmask.apl.washington.edu> <66AE2F5B-F150-4D52-BF43-8F453217FC33@FreeBSD.org>
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On Tue, Sep 08, 2020 at 09:11:50PM +0200, Dimitry Andric wrote:
> On 8 Sep 2020, at 19:47, Steve Kargl <sgk@troutmask.apl.washington.edu> wrote:
> >
> > I think I've found the problem, and it appears to be
> > due to a change byt Openlibm developers to the file
> > math_private.h copied from FreeBSD. Namely, one finds
> >
> > //VBS
> > #define STRICT_ASSIGN(type, lval, rval) ((lval) = (rval))
> >
> > /* VBS
> > #ifdef FLT_EVAL_METHOD
> > // Attempt to get strict C99 semantics for assignment with non-C99 compilers.
> > #if FLT_EVAL_METHOD == 0 || __GNUC__ == 0
> > #define STRICT_ASSIGN(type, lval, rval) ((lval) = (rval))
> > #else
> > #define STRICT_ASSIGN(type, lval, rval) do { \
> > volatile type __lval; \
> > \
> > if (sizeof(type) >= sizeof(double)) \
> > (lval) = (rval); \
> > else { \
> > __lval = (rval); \
> > (lval) = __lval; \
> > } \
> > } while (0)
> > #endif
> > #endif
> > */
> >
> > So, STRICT_ASSIGN is broken in Openlibm. I'll be reporting
> > a bug upstream. Apoogies for the noise.
>
> Hi Steve,
>
> I'm curious what their rationale was, as the commit that changed it is:
>
> https://github.com/JuliaMath/openlibm/commit/f5fb92746715beb0441a60feca202ee16cb19fc9
>
> with a description of just "Build with gcc"... Maybe they've assumed gcc
> never needs the volatile approach?
>
I have no idea why OpenLibm would change math_private.h. I've
reported the issue at https://github.com/JuliaMath/openlibm/issues/215
--
Steve
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