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Re: [PATCH 1/8] softfloat: Use mulu64 for mul64To128
From: |
David Hildenbrand |
Subject: |
Re: [PATCH 1/8] softfloat: Use mulu64 for mul64To128 |
Date: |
Thu, 24 Sep 2020 09:32:25 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 |
On 24.09.20 03:24, Richard Henderson wrote:
> Via host-utils.h, we use a host widening multiply for
> 64-bit hosts, and a common subroutine for 32-bit hosts.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> include/fpu/softfloat-macros.h | 24 ++++--------------------
> 1 file changed, 4 insertions(+), 20 deletions(-)
>
> diff --git a/include/fpu/softfloat-macros.h b/include/fpu/softfloat-macros.h
> index a35ec2893a..57845f8af0 100644
> --- a/include/fpu/softfloat-macros.h
> +++ b/include/fpu/softfloat-macros.h
> @@ -83,6 +83,7 @@ this code that are retained.
> #define FPU_SOFTFLOAT_MACROS_H
>
> #include "fpu/softfloat-types.h"
> +#include "qemu/host-utils.h"
>
>
> /*----------------------------------------------------------------------------
> | Shifts `a' right by the number of bits given in `count'. If any nonzero
> @@ -515,27 +516,10 @@ static inline void
> | `z0Ptr' and `z1Ptr'.
>
> *----------------------------------------------------------------------------*/
>
> -static inline void mul64To128( uint64_t a, uint64_t b, uint64_t *z0Ptr,
> uint64_t *z1Ptr )
> +static inline void
> +mul64To128(uint64_t a, uint64_t b, uint64_t *z0Ptr, uint64_t *z1Ptr)
> {
> - uint32_t aHigh, aLow, bHigh, bLow;
> - uint64_t z0, zMiddleA, zMiddleB, z1;
> -
> - aLow = a;
> - aHigh = a>>32;
> - bLow = b;
> - bHigh = b>>32;
> - z1 = ( (uint64_t) aLow ) * bLow;
> - zMiddleA = ( (uint64_t) aLow ) * bHigh;
> - zMiddleB = ( (uint64_t) aHigh ) * bLow;
> - z0 = ( (uint64_t) aHigh ) * bHigh;
> - zMiddleA += zMiddleB;
> - z0 += ( ( (uint64_t) ( zMiddleA < zMiddleB ) )<<32 ) + ( zMiddleA>>32 );
> - zMiddleA <<= 32;
> - z1 += zMiddleA;
> - z0 += ( z1 < zMiddleA );
> - *z1Ptr = z1;
> - *z0Ptr = z0;
> -
> + mulu64(z1Ptr, z0Ptr, a, b);
> }
>
>
> /*----------------------------------------------------------------------------
>
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
- [PATCH 0/8] softfloat: Implement float128_muladd, Richard Henderson, 2020/09/23
- [PATCH 1/8] softfloat: Use mulu64 for mul64To128, Richard Henderson, 2020/09/23
- Re: [PATCH 1/8] softfloat: Use mulu64 for mul64To128,
David Hildenbrand <=
- [PATCH 2/8] softfloat: Use int128.h for some operations, Richard Henderson, 2020/09/23
- [PATCH 3/8] softfloat: Tidy a * b + inf return, Richard Henderson, 2020/09/23
- [PATCH 4/8] softfloat: Add float_cmask and constants, Richard Henderson, 2020/09/23
- [PATCH 5/8] softfloat: Inline pick_nan_muladd into its caller, Richard Henderson, 2020/09/23
- [PATCH 6/8] softfloat: Implement float128_muladd, Richard Henderson, 2020/09/23