Re: [PATCH] sparc: Fix llrint and llround missing exceptions on SPARC32

[Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>]

On 12/01/24 06:26, Daniel Cederman wrote:
> Conversions from a float to a long long on 32-bit SPARC may not
> raise the correct exceptions on overflow. It also may raise spurious
> "inexact" exceptions on non overflow cases. This patch fixes the
> problem in the same way as for RV32.
> 
> Signed-off-by: Daniel Cederman <cederman@gaisler.com>
> ---
>  .../sparc32/fpu/fix-fp-int-convert-overflow.h | 35 +++++++++++++++++++
>  1 file changed, 35 insertions(+)
>  create mode 100644 sysdeps/sparc/sparc32/fpu/fix-fp-int-convert-overflow.h
> 
> diff --git a/sysdeps/sparc/sparc32/fpu/fix-fp-int-convert-overflow.h b/sysdeps/sparc/sparc32/fpu/fix-fp-int-convert-overflow.h
> new file mode 100644
> index 0000000000..ae79a106e7
> --- /dev/null
> +++ b/sysdeps/sparc/sparc32/fpu/fix-fp-int-convert-overflow.h
> @@ -0,0 +1,35 @@
> +/* Fix for conversion of floating point to integer overflow.  SPARC32 version.
> +   Copyright (C) 2015-2020 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef FIX_FP_INT_CONVERT_OVERFLOW_H
> +#define FIX_FP_INT_CONVERT_OVERFLOW_H	1
> +
> +/* Define these macros to 1 to workaround conversions of out-of-range
> +   floating-point numbers to integer types failing to raise the
> +   "invalid" exception, or raising spurious "inexact" or other
> +   exceptions.  */

This is not really true for all sparc32, at least with sparcv9 I have
access I have not seen any issues with missing exception overflows or
spurious inexact.  Are these some leon3 limitation or issue?

I think we need to know exactly how/when this happens and only enable
such workaound when required.

> +#define FIX_FLT_LONG_CONVERT_OVERFLOW 0
> +#define FIX_FLT_LLONG_CONVERT_OVERFLOW 1
> +#define FIX_DBL_LONG_CONVERT_OVERFLOW 0
> +#define FIX_DBL_LLONG_CONVERT_OVERFLOW 1
> +#define FIX_LDBL_LONG_CONVERT_OVERFLOW 0
> +#define FIX_LDBL_LLONG_CONVERT_OVERFLOW 0
> +#define FIX_FLT128_LONG_CONVERT_OVERFLOW 0
> +#define FIX_FLT128_LLONG_CONVERT_OVERFLOW 0
> +
> +#endif /* fix-fp-int-convert-overflow.h */