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Re: [PATCH] v11 Improves __ieee754_exp() performance by greater than 5x on sparc/x86.
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Szabolcs Nagy <szabolcs dot nagy at arm dot com>
- Cc: Patrick McGehearty <patrick dot mcgehearty at oracle dot com>, <libc-alpha at sourceware dot org>, <nd at arm dot com>
- Date: Fri, 2 Feb 2018 15:33:25 +0000
- Subject: Re: [PATCH] v11 Improves __ieee754_exp() performance by greater than 5x on sparc/x86.
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On Fri, 2 Feb 2018, Szabolcs Nagy wrote:
> (i also removed the rounding mode settings in both cases
> as that can be avoided at least on aarch64)
There is or was certainly code in the existing exp that gives completely
wrong results in non-default rounding modes (that was bug 3976) - e.g.
using precision-extension techniques that require round-to-nearest -
though I don't know if that applies to the fast case code or if it's only
in code for slow cases (or code for slow cases but using other rounding
modes results in the slow cases getting used much more).
Joseph S. Myers