On Wed, 25 Oct 2023 06:31:05 GMT, Emanuel Peter <epe...@openjdk.org> wrote:
>> I imagine it would be beneficial if we could merge stores to fields and
>> stores from loads, which are common in object constructions.
>>
>> Thanks.
>
> @merykitty do you have examples for both? Maybe stores to fields already
> works. Merging loads and stores may be out of scope. That sounds a little
> much like SLP. We can still try to do that in a future RFE. We could even try
> to use (masked) vector instructions.
@eme64 I have tried your patch, it seems that there are some limitations:
- The stores are not merged if the order is not right (e.g `a[2] = 2; a[1] =
1;`)
- The stores are not merged if they are floating point constants.
- The stores are not merged if they are consecutive fields in an object. E.g:
class Point {
int x; int y;
}
p.x = 1;
p.y = 2; // Cannot merge into mov [p.x], 0x200000001
Regarding the final point, fields may be of different types with different
sizes and there may be padding between them. This means that for load-store
sequence merges, I think SLP cannot handle these cases.
Thanks.
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PR Comment: https://git.openjdk.org/jdk/pull/16245#issuecomment-1779472249
