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Re: [PATCH] Improves __ieee754_exp() performance by greater than 5x on sparc/x86.
On 19/10/17 23:31, Patrick McGehearty wrote:
> Table of hex float constants. I can readily adjust the formating. What
> you see is the formating used in the original source.
> I've been uncomfortable with hex floats approach
> as it only works for ieee754 representations
> that use base 2. I admit that is most current machines.
your entire algorithm depends on ieee754 binary representation,
that's not a good reason for avoiding hexfloats.
decimal floats are not even required to be correctly rounded by
the compiler in iso c, they are only faithfully rounded, so
this is a portability bug in the original source too, you can
silently get completely wrong code generation because of it.
> And the prior ieee754 exp table uses hex format.
> My second reason for resisting the change is my philosophy
> when porting code is that every change without a good reason
> is an opportunity to introduce errors without corresponding benefit.
>
> If you feel strongly about suing hex constants, I will make an effort
> to convert these values to hex format. This conversion seems likely
> to require the most effort on my part.
>