[00/12] Improve rounding to interger function for C23

  As indicated by GCC documentation [1], ISO C23 does not allow that C
bindings ceil, floor, round, and trunc (in all floating point formats)
to raise 
inexact exceptions (different than ISO C99/C11 where this is allowed).

A recent MIPS patch to used some arch-specific instructions raised this
issue [1] and it was not caught because there was no proper testing. By
adding the missing tests, some implementations do indeed raise inexact
exceptions. 

The generic implementation all uses integer operation, so they are not
subject to this issue. The powerpc (for power4 and lower) and the riscv
avoid the inexact exception by disabling/enabling exceptions. The x86
uses some arch-specific implementation for long double and on i386 (due
to the use of x87 instruction).

Instead of adding newer symbols depending on the required standard
version, the patchset adapts the faulty ones to avoid raising the
inexact exception. The x86 version already saves/restore the floating
point status, so I think it is unlikely the patch would yield much
performance difference (I did not do any performance analysis on whether
a generic implementation would yield better performance).

I checked on powerpc, powerpc64, aarch64, armhf, x86, and did some
regression checks on riscv.

[1] https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-fno-fp-int-builtin-inexact
[2] https://sourceware.org/pipermail/libc-alpha/2023-December/153528.html

Adhemerval Zanella (12):
  math: Reformat Makefile.
  powerpc: Add missing arch flags on rounding ifunc variants
  math: Add test to check if ceil raise inexact floating-point exception
  math: Add test to check if floor raise inexact floating-point
    exception
  math: Add test to check if trunc raise inexact floating-point
    exception
  math: Add test to check if round raise inexact floating-point
    exception
  x86: Do not raise inexact exception on ceill
  x86: Do not raise inexact exception on floorl
  x86: Do not raise inexact exception on truncl
  x86: Do not raise inexact exception on floor/floorf
  i386: Do not raise inexact exception on ceil/ceilf
  i386: Do not raise inexact exception on trunc/truncf

 math/Makefile                                 | 861 ++++++++++++++----
 math/test-ceil-except-2.c                     |  67 ++
 math/test-ceil-except.c                       |  85 ++
 math/test-floor-except-2.c                    |  67 ++
 math/test-floor-except.c                      |  85 ++
 math/test-round-except-2.c                    |  67 ++
 math/test-round-except.c                      |  85 ++
 math/test-trunc-except-2.c                    |  67 ++
 math/test-trunc-except.c                      |  85 ++
 sysdeps/i386/fpu/s_ceil.S                     |  34 -
 sysdeps/i386/fpu/s_ceil.c                     |  38 +
 sysdeps/i386/fpu/s_ceilf.S                    |  34 -
 sysdeps/i386/fpu/s_ceilf.c                    |  38 +
 sysdeps/i386/fpu/s_ceill.S                    |  39 -
 sysdeps/i386/fpu/s_floor.S                    |  34 -
 sysdeps/i386/fpu/s_floor.c                    |  38 +
 sysdeps/i386/fpu/s_floorf.S                   |  34 -
 sysdeps/i386/fpu/s_floorf.c                   |  38 +
 sysdeps/i386/fpu/s_floorl.S                   |  39 -
 sysdeps/i386/fpu/{s_trunc.S => s_trunc.c}     |  37 +-
 sysdeps/i386/fpu/{s_truncf.S => s_truncf.c}   |  37 +-
 .../powerpc32/power4/fpu/multiarch/Makefile   |   6 +
 .../fpu/s_truncl.S => x86/fpu/s_ceill.c}      |  38 +-
 sysdeps/x86/fpu/s_floorl.c                    |  38 +
 .../fpu/s_truncl.S => x86/fpu/s_truncl.c}     |  40 +-
 sysdeps/x86_64/fpu/s_ceill.S                  |  34 -
 sysdeps/x86_64/fpu/s_floorl.S                 |  33 -
 27 files changed, 1583 insertions(+), 515 deletions(-)
 create mode 100644 math/test-ceil-except-2.c
 create mode 100644 math/test-ceil-except.c
 create mode 100644 math/test-floor-except-2.c
 create mode 100644 math/test-floor-except.c
 create mode 100644 math/test-round-except-2.c
 create mode 100644 math/test-round-except.c
 create mode 100644 math/test-trunc-except-2.c
 create mode 100644 math/test-trunc-except.c
 delete mode 100644 sysdeps/i386/fpu/s_ceil.S
 create mode 100644 sysdeps/i386/fpu/s_ceil.c
 delete mode 100644 sysdeps/i386/fpu/s_ceilf.S
 create mode 100644 sysdeps/i386/fpu/s_ceilf.c
 delete mode 100644 sysdeps/i386/fpu/s_ceill.S
 delete mode 100644 sysdeps/i386/fpu/s_floor.S
 create mode 100644 sysdeps/i386/fpu/s_floor.c
 delete mode 100644 sysdeps/i386/fpu/s_floorf.S
 create mode 100644 sysdeps/i386/fpu/s_floorf.c
 delete mode 100644 sysdeps/i386/fpu/s_floorl.S
 rename sysdeps/i386/fpu/{s_trunc.S => s_trunc.c} (61%)
 rename sysdeps/i386/fpu/{s_truncf.S => s_truncf.c} (61%)
 rename sysdeps/{x86_64/fpu/s_truncl.S => x86/fpu/s_ceill.c} (57%)
 create mode 100644 sysdeps/x86/fpu/s_floorl.c
 rename sysdeps/{i386/fpu/s_truncl.S => x86/fpu/s_truncl.c} (61%)
 delete mode 100644 sysdeps/x86_64/fpu/s_ceill.S
 delete mode 100644 sysdeps/x86_64/fpu/s_floorl.S
  

Ping.

On 28/12/23 14:20, Adhemerval Zanella wrote:
> As indicated by GCC documentation [1], ISO C23 does not allow that C
> bindings ceil, floor, round, and trunc (in all floating point formats)
> to raise 
> inexact exceptions (different than ISO C99/C11 where this is allowed).
> 
> A recent MIPS patch to used some arch-specific instructions raised this
> issue [1] and it was not caught because there was no proper testing. By
> adding the missing tests, some implementations do indeed raise inexact
> exceptions. 
> 
> The generic implementation all uses integer operation, so they are not
> subject to this issue. The powerpc (for power4 and lower) and the riscv
> avoid the inexact exception by disabling/enabling exceptions. The x86
> uses some arch-specific implementation for long double and on i386 (due
> to the use of x87 instruction).
> 
> Instead of adding newer symbols depending on the required standard
> version, the patchset adapts the faulty ones to avoid raising the
> inexact exception. The x86 version already saves/restore the floating
> point status, so I think it is unlikely the patch would yield much
> performance difference (I did not do any performance analysis on whether
> a generic implementation would yield better performance).
> 
> I checked on powerpc, powerpc64, aarch64, armhf, x86, and did some
> regression checks on riscv.
> 
> [1] https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-fno-fp-int-builtin-inexact
> [2] https://sourceware.org/pipermail/libc-alpha/2023-December/153528.html
> 
> Adhemerval Zanella (12):
>   math: Reformat Makefile.
>   powerpc: Add missing arch flags on rounding ifunc variants
>   math: Add test to check if ceil raise inexact floating-point exception
>   math: Add test to check if floor raise inexact floating-point
>     exception
>   math: Add test to check if trunc raise inexact floating-point
>     exception
>   math: Add test to check if round raise inexact floating-point
>     exception
>   x86: Do not raise inexact exception on ceill
>   x86: Do not raise inexact exception on floorl
>   x86: Do not raise inexact exception on truncl
>   x86: Do not raise inexact exception on floor/floorf
>   i386: Do not raise inexact exception on ceil/ceilf
>   i386: Do not raise inexact exception on trunc/truncf
> 
>  math/Makefile                                 | 861 ++++++++++++++----
>  math/test-ceil-except-2.c                     |  67 ++
>  math/test-ceil-except.c                       |  85 ++
>  math/test-floor-except-2.c                    |  67 ++
>  math/test-floor-except.c                      |  85 ++
>  math/test-round-except-2.c                    |  67 ++
>  math/test-round-except.c                      |  85 ++
>  math/test-trunc-except-2.c                    |  67 ++
>  math/test-trunc-except.c                      |  85 ++
>  sysdeps/i386/fpu/s_ceil.S                     |  34 -
>  sysdeps/i386/fpu/s_ceil.c                     |  38 +
>  sysdeps/i386/fpu/s_ceilf.S                    |  34 -
>  sysdeps/i386/fpu/s_ceilf.c                    |  38 +
>  sysdeps/i386/fpu/s_ceill.S                    |  39 -
>  sysdeps/i386/fpu/s_floor.S                    |  34 -
>  sysdeps/i386/fpu/s_floor.c                    |  38 +
>  sysdeps/i386/fpu/s_floorf.S                   |  34 -
>  sysdeps/i386/fpu/s_floorf.c                   |  38 +
>  sysdeps/i386/fpu/s_floorl.S                   |  39 -
>  sysdeps/i386/fpu/{s_trunc.S => s_trunc.c}     |  37 +-
>  sysdeps/i386/fpu/{s_truncf.S => s_truncf.c}   |  37 +-
>  .../powerpc32/power4/fpu/multiarch/Makefile   |   6 +
>  .../fpu/s_truncl.S => x86/fpu/s_ceill.c}      |  38 +-
>  sysdeps/x86/fpu/s_floorl.c                    |  38 +
>  .../fpu/s_truncl.S => x86/fpu/s_truncl.c}     |  40 +-
>  sysdeps/x86_64/fpu/s_ceill.S                  |  34 -
>  sysdeps/x86_64/fpu/s_floorl.S                 |  33 -
>  27 files changed, 1583 insertions(+), 515 deletions(-)
>  create mode 100644 math/test-ceil-except-2.c
>  create mode 100644 math/test-ceil-except.c
>  create mode 100644 math/test-floor-except-2.c
>  create mode 100644 math/test-floor-except.c
>  create mode 100644 math/test-round-except-2.c
>  create mode 100644 math/test-round-except.c
>  create mode 100644 math/test-trunc-except-2.c
>  create mode 100644 math/test-trunc-except.c
>  delete mode 100644 sysdeps/i386/fpu/s_ceil.S
>  create mode 100644 sysdeps/i386/fpu/s_ceil.c
>  delete mode 100644 sysdeps/i386/fpu/s_ceilf.S
>  create mode 100644 sysdeps/i386/fpu/s_ceilf.c
>  delete mode 100644 sysdeps/i386/fpu/s_ceill.S
>  delete mode 100644 sysdeps/i386/fpu/s_floor.S
>  create mode 100644 sysdeps/i386/fpu/s_floor.c
>  delete mode 100644 sysdeps/i386/fpu/s_floorf.S
>  create mode 100644 sysdeps/i386/fpu/s_floorf.c
>  delete mode 100644 sysdeps/i386/fpu/s_floorl.S
>  rename sysdeps/i386/fpu/{s_trunc.S => s_trunc.c} (61%)
>  rename sysdeps/i386/fpu/{s_truncf.S => s_truncf.c} (61%)
>  rename sysdeps/{x86_64/fpu/s_truncl.S => x86/fpu/s_ceill.c} (57%)
>  create mode 100644 sysdeps/x86/fpu/s_floorl.c
>  rename sysdeps/{i386/fpu/s_truncl.S => x86/fpu/s_truncl.c} (61%)
>  delete mode 100644 sysdeps/x86_64/fpu/s_ceill.S
>  delete mode 100644 sysdeps/x86_64/fpu/s_floorl.S
>