On Tue, 2019-01-29 at 14:41 +, Roland Scheidegger wrote:
> Am 29.01.19 um 10:10 schrieb Erik Faye-Lund:
> > On Mon, 2019-01-28 at 09:31 -0800, Matt Turner wrote:
> > > Use the trick of adding and then subtracting 2**52 (52 is the
> > > number
> > > of
> > > explicit mantissa bits a
Am 29.01.19 um 10:10 schrieb Erik Faye-Lund:
> On Mon, 2019-01-28 at 09:31 -0800, Matt Turner wrote:
>> Use the trick of adding and then subtracting 2**52 (52 is the number
>> of
>> explicit mantissa bits a double-precision floating-point value has)
>> to
>> implement round-to-even.
>>
>> Cuts the
On Tue, 2019-01-29 at 10:10 +0100, Erik Faye-Lund wrote:
> On Mon, 2019-01-28 at 09:31 -0800, Matt Turner wrote:
> > Use the trick of adding and then subtracting 2**52 (52 is the number
> > of
> > explicit mantissa bits a double-precision floating-point value has)
> > to
> > implement
On Mon, 2019-01-28 at 09:31 -0800, Matt Turner wrote:
> Use the trick of adding and then subtracting 2**52 (52 is the number
> of
> explicit mantissa bits a double-precision floating-point value has)
> to
> implement round-to-even.
>
> Cuts the number of instructions on SKL of the piglit test
>
On Mon, Jan 28, 2019 at 10:25 AM Roland Scheidegger wrote:
>
> I like it :-).
> That said, there's some caveats as discussed on IRC - in particular for
> gpus which don't do round-to-nearest-even for ordinary fp64 math (or
> rounding mode could be set to something else manually) it won't do the
>
I like it :-).
That said, there's some caveats as discussed on IRC - in particular for
gpus which don't do round-to-nearest-even for ordinary fp64 math (or
rounding mode could be set to something else manually) it won't do the
right thing.
And if you can have fast-math enabled, then it probably
Use the trick of adding and then subtracting 2**52 (52 is the number of
explicit mantissa bits a double-precision floating-point value has) to
implement round-to-even.
Cuts the number of instructions on SKL of the piglit test
fs-roundEven-double.shader_test from 109 to 21.
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