Date: Sat, 13 May 2017 10:12:08 -0700 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Dimitry Andric <dimitry@andric.com> Cc: freebsd-hackers@freebsd.org, numerics@freebsd.org, Bruce Evans <brde@optusnet.com.au> Subject: Re: catrig[fl].c and inexact Message-ID: <20170513171208.GA89162@troutmask.apl.washington.edu> In-Reply-To: <FB138623-DF5B-4DBD-94FE-29E21FF7FDC6@andric.com> References: <20170512215654.GA82545@troutmask.apl.washington.edu> <20170513103208.M845@besplex.bde.org> <20170513060803.GA84399@troutmask.apl.washington.edu> <F5F8736B-D7E1-48AD-BC6C-8C74AF0A3272@andric.com> <20170513162153.GB88653@troutmask.apl.washington.edu> <FB138623-DF5B-4DBD-94FE-29E21FF7FDC6@andric.com>
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On Sat, May 13, 2017 at 06:55:27PM +0200, Dimitry Andric wrote:
> On 13 May 2017, at 18:21, Steve Kargl <sgk@troutmask.apl.washington.edu> wrote:
> >
> > On Sat, May 13, 2017 at 03:08:26PM +0200, Dimitry Andric wrote:
> ...
> >
> >> Using the full catrig.c and -O3, I tried gcc 4.2.1, 4.7.4, 4.8.5, 4.9.4,
> >> 5.4.0, 6.3.0 and 7.0.1, in addition to clang 3.4.1, 3.8.0, 3.9.1, 4.0.0
> >> and 5.0.0.
> >
> > Thanks for checking. I reduced catrig.c to a small self-contained
> > program and indeed I was getting the desired addition of 1 + tiny
> > to raise FE_INEXACT. I suppose that I'll need to add an appropriate
> > -Wno-foo to my CFLAGS line to suppress the spurious warning, which
> > might be tricky because -Wunused is one option I'ld like to have.
>
> The following also gets rid of the warnings:
>
> Index: lib/msun/src/catrig.c
> ===================================================================
> --- lib/msun/src/catrig.c (revision 318032)
> +++ lib/msun/src/catrig.c (working copy)
> @@ -37,7 +37,7 @@
> #define isinf(x) (fabs(x) == INFINITY)
> #undef isnan
> #define isnan(x) ((x) != (x))
> -#define raise_inexact() do { volatile float junk = 1 + tiny; } while(0)
> +#define raise_inexact() do { volatile float junk __unused = 1 + tiny; } while(0)
> #undef signbit
> #define signbit(x) (__builtin_signbit(x))
>
> Index: lib/msun/src/catrigf.c
> ===================================================================
> --- lib/msun/src/catrigf.c (revision 318032)
> +++ lib/msun/src/catrigf.c (working copy)
> @@ -51,7 +51,7 @@
> #define isinf(x) (fabsf(x) == INFINITY)
> #undef isnan
> #define isnan(x) ((x) != (x))
> -#define raise_inexact() do { volatile float junk = 1 + tiny; } while(0)
> +#define raise_inexact() do { volatile float junk __unused = 1 + tiny; } while(0)
> #undef signbit
> #define signbit(x) (__builtin_signbitf(x))
>
> Index: lib/msun/src/catrigl.c
> ===================================================================
> --- lib/msun/src/catrigl.c (revision 318032)
> +++ lib/msun/src/catrigl.c (working copy)
> @@ -53,7 +53,7 @@
> #define isinf(x) (fabsl(x) == INFINITY)
> #undef isnan
> #define isnan(x) ((x) != (x))
> -#define raise_inexact() do { volatile float junk = 1 + tiny; } while(0)
> +#define raise_inexact() do { volatile float junk __unused = 1 + tiny; } while(0)
> #undef signbit
> #define signbit(x) (__builtin_signbitl(x))
>
> If you are OK with that, I will commit it later today.
>
I'm OK with this change, but I typically defer to Bruce
as he knows much more about C and floating point.
--
Steve
20170425 https://www.youtube.com/watch?v=VWUpyCsUKR4
20161221 https://www.youtube.com/watch?v=IbCHE-hONow
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