Java 8 Integer and Long unsigned methods - are there plans to add intrinsics for them?

[Andrew Haley]

On 04/11/2014 12:54 AM, Roman Leventov wrote:
>  > 11.04.2014, 02:51, "Christian Thalinger" <christian.thalinger at oracle.com>:
>  > Do you see a performance problem with these methods?
> Currently divideUnsigned and remainderUnsigned take a dozen of instructions with 
> widening to long, while there is a signle div assembly instruction for this.

It seems this is an x86 thing rather than a HotSpot thing.  On AArch64
I get

01c     ubfm  R10, R2, 0, 31    # ui2l
020     ubfm  R11, R1, 0, 31    # ui2l
024     cbeq   R10, B4  P=0.000001 C=-1.000000
028     sdiv   R10, R11, R10

This isn't exactly ideal, given that long division is slower than int
division, but it's not terrible.

I can't match on

(Set dst (DivL (AndL (ConvI2L src1) mask) (AndL (ConvI2L src2) mask1)))

and generate a simple udiv because of the pesky (If ...) that checks for
division by zero.  I suppose we could persuade HotSpot to rearrange things.

Andrew.