RFR: JDK-8302040: Port fdlibm sqrt to Java [v3]

[Andrey Turbanov]

On Fri, 24 Feb 2023 18:40:38 GMT, Joe Darcy <darcy at openjdk.org> wrote:

>> The wheel of FDLIBM porting turns a notch and sqrt comes into play.
>> 
>> While the sqrt operation usually has a hardware implementation that is intrinsified, for completeness a software implementation should be available as well.
>
> Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add one one unsigned shift comment.

src/java.base/share/classes/java/lang/FdLibm.java line 600:

> 598: 
> 599:             // take care of Inf and NaN
> 600:             if((ix0 & 0x7ff0_0000) == 0x7ff0_0000) {

Suggestion:

            if ((ix0 & 0x7ff0_0000) == 0x7ff0_0000) {

src/java.base/share/classes/java/lang/FdLibm.java line 639:

> 637:             r = 0x0020_0000;        // r = moving bit from right to left
> 638: 
> 639:             while(r != 0) {

Suggestion:

            while (r != 0) {

src/java.base/share/classes/java/lang/FdLibm.java line 641:

> 639:             while(r != 0) {
> 640:                 t = s0 + r;
> 641:                 if(t <= ix0) {

Suggestion:

                if (t <= ix0) {

src/java.base/share/classes/java/lang/FdLibm.java line 655:

> 653:                 t1 = s1 + r;
> 654:                 t  = s0;
> 655:                 if((t < ix0) ||

Suggestion:

                if ((t < ix0) ||

src/java.base/share/classes/java/lang/FdLibm.java line 657:

> 655:                 if((t < ix0) ||
> 656:                    ((t == ix0) && (Integer.compareUnsigned(t1, ix1) <= 0 ))) { // t1 <= ix1
> 657:                     s1  = t1 + r;

Suggestion:

                    s1 = t1 + r;

-------------

PR: https://git.openjdk.org/jdk/pull/12736