From: Richard Henderson <richard.henderson@linaro.org>
To: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
Laurent Vivier <laurent@vivier.eu>,
qemu-devel@nongnu.org
Subject: Re: [PATCH 2/4] target/m68k: pass sign directly into make_quotient()
Date: Mon, 2 Jan 2023 09:35:36 -0800 [thread overview]
Message-ID: <06c9ed84-22f3-a423-52be-4e006f20cffc@linaro.org> (raw)
In-Reply-To: <004c686f-b5ed-be4f-087d-2736bedd57b9@ilande.co.uk>
On 1/2/23 02:10, Mark Cave-Ayland wrote:
>>> I think you need an "abs(floatx80_to_int32())" in both cases as you do in PATCH 4
>>
>> Or in fact
>>
>> sign = extractFloatx80Sign(res);
>> quot = floatx80_to_int32(floatx80_abs(res->d), status);
>> make_quotient(env, sign, quot);
>
> Thanks for the suggestion. Just out of curiosity, how does moving the abs to before the
> integer conversion make a difference here? Is it because floatx80_to_int32() can fail in
> some circumstances because of the sign of the result?
It's a simple and operation on floats, instead of cmp+cmov on integers.
I think it's a touch clearer as well, having just saved the fp sign, you discard it before
moving on to the next thing.
r~
next prev parent reply other threads:[~2023-01-02 17:36 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-01 14:43 [PATCH 0/4] target/m68k: fix FPSR quotient byte for fmod and frem Mark Cave-Ayland
2023-01-01 14:43 ` [PATCH 1/4] target/m68k: pass quotient directly into make_quotient() Mark Cave-Ayland
2023-01-01 17:20 ` Laurent Vivier
2023-01-01 14:43 ` [PATCH 2/4] target/m68k: pass sign " Mark Cave-Ayland
2023-01-01 17:20 ` Laurent Vivier
2023-01-01 17:26 ` Laurent Vivier
2023-01-01 18:53 ` Richard Henderson
2023-01-02 10:10 ` Mark Cave-Ayland
2023-01-02 17:35 ` Richard Henderson [this message]
2023-01-02 10:04 ` Mark Cave-Ayland
2023-01-01 14:43 ` [PATCH 3/4] target/m68k: fix FPSR quotient byte for fmod instruction Mark Cave-Ayland
2023-01-01 17:21 ` Laurent Vivier
2023-01-01 14:43 ` [PATCH 4/4] target/m68k: fix FPSR quotient byte for frem instruction Mark Cave-Ayland
2023-01-01 17:26 ` Laurent Vivier
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