Date: Mon, 7 Sep 2020 19:55:13 -0700 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: freebsd-toolchain@freebsd.org, freebsd-current@freebsd.org Subject: Re: clang miscompiles OpenLibm on i686-*-freebsd Message-ID: <20200908025513.GA76566@troutmask.apl.washington.edu> In-Reply-To: <20200908021002.GA76325@troutmask.apl.washington.edu> References: <20200908021002.GA76325@troutmask.apl.washington.edu>
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On Mon, Sep 07, 2020 at 07:10:02PM -0700, Steve Kargl wrote:
>
> Interval tested for exp2f: [1,8]
> ulp <= 0.5: 0.056% 14072 | 0.056% 14072
> 0.5 < ulp < 0.6: 0.000% 8 | 0.056% 14080
> 3.0 < ulp < 0.0: 99.944% 25151744 | 100.000% 25165824
> Max ulp: 22729.386719 at 1.00195301e+00
>
Note, compiling s_exp2f.c with gcc9 gives the above
result with -O3 -march=i686 -m32. So, gcc9 is not
nearly as bad as clang, but both give bad results.
Comparing OpenLibm's s_exp2f.c and FreeBSD's s_exp2f.c,
one sees that the files are almost identical.
Note, FreeBSD's libm gives
% ./tlibm_libm -DEfP exp2
Interval tested for exp2f: [1,8]
ulp <= 0.5: 99.959% 25155610 | 99.959% 25155610
0.5 < ulp < 0.6: 0.041% 10214 | 100.000% 25165824
Max ulp: 0.500980 at 1.97115958e+00
which is good, but this is compiled with CPUTYPE ?= core2
in /etc/make.conf.
--
Steve
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