regression in tgamma?
Paul Zimmermann
Paul.Zimmermann@inria.fr
Wed Dec 16 06:36:48 GMT 2020
Hi Jeff,
thank you for your answer. Here are the steps I followed to compile Newlib
(thanks Alexei Sibidanov):
# from newlib-3.3.0 or newlib-4.0.0
mkdir build
cd build
../configure --prefix=`pwd` --target=x86_64
# perform the following in $HOME/bin
ln -sf `which ar` x86_64-ar
ln -sf `which as` x86_64-as
ln -sf `which cc` x86_64-cc
ln -sf `which gcc` x86_64-gcc
ln -sf `which c++` x86_64-c++
ln -sf `which ld` x86_64-ld
ln -sf `which nm` x86_64-nm
ln -sf `which objdump` x86_64-objdump
ln -sf `which objcopy` x86_64-objcopy
ln -sf `which ranlib` x86_64-ranlib
ln -sf `which readelf` x86_64-readelf
ln -sf `which strip` x86_64-strip
make # it will fail but it is ok
cd x86_64/newlib/libm
make # fails too
cd tmp
ar cr libm.a *.o
If you have access to the GCC Compile Farm [1], you can reproduce on gcc67:
$ cd /home/zimmerma
$ gcc -DNEWLIB -no-pie test3.c newlib-3.3.0/build/x86_64/newlib/libm/tmp/libm.a
$ ./a.out
x=-0x1.53f198fe3b278p+7 y=0x1.fd6d312572d9cp-1015
$ gcc -DNEWLIB -no-pie test3.c newlib-4.0.0/build/x86_64/newlib/libm/tmp/libm.a
$ ./a.out
x=-0x1.53f198fe3b278p+7 y=0x1p+0
If you have a simpler way to compile Newlib, please tell me.
Best regards,
Paul
[1] https://gcc.gnu.org/wiki/CompileFarm#List_of_machines
> From: Jeff Johnston <jjohnstn@redhat.com>
> Date: Tue, 15 Dec 2020 12:11:25 -0500
>
> Hi Paul,
>
> I copied the newlib/libm/common directory and header files from master to a
> separate directory and called __ieee754_tgamma directly in your test (adding
> a declaration of __ieee754_tgamma as well). I then built as follows:
>
> gcc -g -O0 -I. -DNEWLIB testtgamma.c e_tgamma.c e_exp.c k_sin.c math_err.c
> er_lgamma.c k_cos.c s_floor.c e_log.c w_log.c
>
> I get the same result as you get for 3.3.0.
>
> Can you possibly recheck to see if your 4.0.0 library has been built
> correctly? Perhaps I have somehow by-passed the cause of the problem by
> compiling directly.
>
> -- Jeff J.
>
> On Tue, Dec 15, 2020 at 8:36 AM Paul Zimmermann <Paul.Zimmermann@inria.fr>
> wrote:
>
> Hi,
>
> while updating my comparison from Newlib 3.3.0 to Newlib 4.0.0, I found
> a
> regression in tgamma on x86_64/Linux:
>
> $ cat test3.c
> #include <stdio.h>
> #include <math.h>
>
> #ifdef NEWLIB
> int errno;
> int* __errno () { return &errno; }
> #endif
>
> int main()
> {
> double x = -0x1.53f198fe3b278p+7, y;
> y = tgamma (x);
> printf ("x=%a y=%a\n", x, y);
> }
>
> Newlib 3.3.0:
> $ gcc -DNEWLIB -no-pie test3.c /localdisk/zimmerma/newlib-3.3.0/libm.a;
> ./a.out
> x=-0x1.53f198fe3b278p+7 y=0x1.fd6d312572d9cp-1015
>
> Newlib 4.0.0:
> $ gcc -DNEWLIB -no-pie test3.c /localdisk/zimmerma/newlib-4.0.0/libm.a;
> ./a.out
> x=-0x1.53f198fe3b278p+7 y=0x1p+0
>
> Please can someone confirm?
>
> Best regards,
> Paul
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