[v2,4/5] x86 long double: Consider pseudo numbers as signaling
Commit Message
Add support to treat pseudo-numbers specially and implement x86
version to consider all of them as signaling.
---
sysdeps/generic/nan-pseudo-number.h | 27 ++++++++++++++++++++
sysdeps/ieee754/ldbl-96/s_issignalingl.c | 7 +++++-
sysdeps/x86/fpu/nan-pseudo-number.h | 32 ++++++++++++++++++++++++
3 files changed, 65 insertions(+), 1 deletion(-)
create mode 100644 sysdeps/generic/nan-pseudo-number.h
create mode 100644 sysdeps/x86/fpu/nan-pseudo-number.h
Comments
On 23/12/2020 08:56, Siddhesh Poyarekar wrote:
> Add support to treat pseudo-numbers specially and implement x86
> version to consider all of them as signaling.
> ---
> sysdeps/generic/nan-pseudo-number.h | 27 ++++++++++++++++++++
> sysdeps/ieee754/ldbl-96/s_issignalingl.c | 7 +++++-
> sysdeps/x86/fpu/nan-pseudo-number.h | 32 ++++++++++++++++++++++++
> 3 files changed, 65 insertions(+), 1 deletion(-)
> create mode 100644 sysdeps/generic/nan-pseudo-number.h
> create mode 100644 sysdeps/x86/fpu/nan-pseudo-number.h
>
> diff --git a/sysdeps/generic/nan-pseudo-number.h b/sysdeps/generic/nan-pseudo-number.h
> new file mode 100644
> index 0000000000..ce1176a208
> --- /dev/null
> +++ b/sysdeps/generic/nan-pseudo-number.h
> @@ -0,0 +1,27 @@
> +/* Pseudo-normal number handling. Generic version.
> + Copyright (C) 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 NAN_PSEUDO_NUMBER_H
> +#define NAN_PSEUDO_NUMBER_H 1
> +
> +/* Define this macro to 1 and provide an definition for IS_PSEUDO_SIGNALING if
> + pseudo-normal numbers need special handling. */
> +#define HANDLE_PSEUDO_NUMBERS 0
> +#define IS_PSEUDO_SIGNALING(x) 0
> +
> +#endif /* nan-pseudo-number.h */
> diff --git a/sysdeps/ieee754/ldbl-96/s_issignalingl.c b/sysdeps/ieee754/ldbl-96/s_issignalingl.c
> index ec542ad468..fff6a85932 100644
> --- a/sysdeps/ieee754/ldbl-96/s_issignalingl.c
> +++ b/sysdeps/ieee754/ldbl-96/s_issignalingl.c
> @@ -19,12 +19,14 @@
> #include <math.h>
> #include <math_private.h>
> #include <nan-high-order-bit.h>
> +#include <nan-pseudo-number.h>
>
> int
> __issignalingl (long double x)
> {
> uint32_t exi, hxi, lxi;
> GET_LDOUBLE_WORDS (exi, hxi, lxi, x);
> + int ret = 0;
> #if HIGH_ORDER_BIT_IS_SET_FOR_SNAN
> # error not implemented
> #else
> @@ -36,9 +38,12 @@ __issignalingl (long double x)
> hxi |= (lxi | -lxi) >> 31;
> /* We do not recognize a pseudo NaN as sNaN; they're invalid on 80387 and
> later. */
> +#if HANDLE_PSEUDO_NUMBERS
> + ret = IS_PSEUDO_SIGNALING(x);
> +#endif
> /* We have to compare for greater (instead of greater or equal), because x's
> significand being all-zero designates infinity not NaN. */
> - return ((exi & 0x7fff) == 0x7fff) && (hxi > 0xc0000000);
> + return ret || (((exi & 0x7fff) == 0x7fff) && (hxi > 0xc0000000));
> #endif
> }
> libm_hidden_def (__issignalingl)
> diff --git a/sysdeps/x86/fpu/nan-pseudo-number.h b/sysdeps/x86/fpu/nan-pseudo-number.h
> new file mode 100644
> index 0000000000..9cc37a3eee
> --- /dev/null
> +++ b/sysdeps/x86/fpu/nan-pseudo-number.h
> @@ -0,0 +1,32 @@
> +/* Pseudo-normal number handling. x86 version.
> + Copyright (C) 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 NAN_PSEUDO_NUMBER_H
> +#define NAN_PSEUDO_NUMBER_H 1
> +
> +#define HANDLE_PSEUDO_NUMBERS 1
> +/* A pseudo-normal number (that is not pseudo-denormal) has a non-zero exponent
> + and the MSB of significand is clear. All pseudo-normal numbers are deemed
> + signaling. */
> +#define IS_PSEUDO_SIGNALING(x) ({ \
> + uint32_t exi, hxi, lxi __attribute__ ((unused)); \
> + GET_LDOUBLE_WORDS (exi, hxi, lxi, x); \
> + ((exi & 0x7fff) && ((hxi & 0x80000000) == 0)); \
> +})
> +
> +#endif /* nan-pseudo-number.h */
>
Maybe a static inline function would be better? Something like:
static inline int pseudo_signaling (uint32_t exi, uint32_t hxi)
{
return (exi & 0x7fff) && (hxi & 0x80000000) == 0;
}
new file mode 100644
@@ -0,0 +1,27 @@
+/* Pseudo-normal number handling. Generic version.
+ Copyright (C) 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 NAN_PSEUDO_NUMBER_H
+#define NAN_PSEUDO_NUMBER_H 1
+
+/* Define this macro to 1 and provide an definition for IS_PSEUDO_SIGNALING if
+ pseudo-normal numbers need special handling. */
+#define HANDLE_PSEUDO_NUMBERS 0
+#define IS_PSEUDO_SIGNALING(x) 0
+
+#endif /* nan-pseudo-number.h */
@@ -19,12 +19,14 @@
#include <math.h>
#include <math_private.h>
#include <nan-high-order-bit.h>
+#include <nan-pseudo-number.h>
int
__issignalingl (long double x)
{
uint32_t exi, hxi, lxi;
GET_LDOUBLE_WORDS (exi, hxi, lxi, x);
+ int ret = 0;
#if HIGH_ORDER_BIT_IS_SET_FOR_SNAN
# error not implemented
#else
@@ -36,9 +38,12 @@ __issignalingl (long double x)
hxi |= (lxi | -lxi) >> 31;
/* We do not recognize a pseudo NaN as sNaN; they're invalid on 80387 and
later. */
+#if HANDLE_PSEUDO_NUMBERS
+ ret = IS_PSEUDO_SIGNALING(x);
+#endif
/* We have to compare for greater (instead of greater or equal), because x's
significand being all-zero designates infinity not NaN. */
- return ((exi & 0x7fff) == 0x7fff) && (hxi > 0xc0000000);
+ return ret || (((exi & 0x7fff) == 0x7fff) && (hxi > 0xc0000000));
#endif
}
libm_hidden_def (__issignalingl)
new file mode 100644
@@ -0,0 +1,32 @@
+/* Pseudo-normal number handling. x86 version.
+ Copyright (C) 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 NAN_PSEUDO_NUMBER_H
+#define NAN_PSEUDO_NUMBER_H 1
+
+#define HANDLE_PSEUDO_NUMBERS 1
+/* A pseudo-normal number (that is not pseudo-denormal) has a non-zero exponent
+ and the MSB of significand is clear. All pseudo-normal numbers are deemed
+ signaling. */
+#define IS_PSEUDO_SIGNALING(x) ({ \
+ uint32_t exi, hxi, lxi __attribute__ ((unused)); \
+ GET_LDOUBLE_WORDS (exi, hxi, lxi, x); \
+ ((exi & 0x7fff) && ((hxi & 0x80000000) == 0)); \
+})
+
+#endif /* nan-pseudo-number.h */