[PATCH 2/3] msvcrt: Improve sqrt accuracy and performance on i386.

[Piotr Caban]

Signed-off-by: Piotr Caban 
---
  dlls/msvcrt/math.c | 36 ++++++++++++++++++++++++++++++++++++
  1 file changed, 36 insertions(+)

[Zebediah Figura (she/her)]

IIRC from bug 50429, the asin results were affected by setting the x87 
control word beforehand. Is that not the case for sqrt?

[Piotr Caban]

Hi Zebediah,
> On 2 Feb 2021, at 21:18, Zebediah Figura (she/her)  wrote:
>
> IIRC from bug 50429, the asin results were affected by setting the x87 control word beforehand. Is that not the case for sqrt?

The code only resets rounding mode (and preserves other control word bits). I haven’t tested all the x87 control word values but it seems to be matching with native. AFAIR asin was also ignoring rounding mode.

Thanks,
Piotr

[Zebediah Figura (she/her)]

On 2/2/21 4:38 PM, Piotr Caban wrote:
> Hi Zebediah,
> > On 2 Feb 2021, at 21:18, Zebediah Figura (she/her)  wrote:
> >
> > IIRC from bug 50429, the asin results were affected by setting the x87 control word beforehand. Is that not the case for sqrt?
>
> The code only resets rounding mode (and preserves other control word bits). I haven’t tested all the x87 control word values but it seems to be matching with native. AFAIR asin was also ignoring rounding mode.

Ah, cool, I didn't pay attention to which bits this was actually setting.
> Thanks,
> Piotr