Can Ahead of Time code benefit regular Java applications too?

[Ioi Lam]

On 6/1/2022 2:32 AM, Andrew Haley wrote:
> On 6/1/22 06:07, Julian Waters wrote:
>> Likewise, perhaps working in a similar fashion to
>> intrinsics, you could have certain sections of regularly compiled 
>> Java code
>> within jars replaced by native code compiled by C1 (or C2?) if the 
>> JVM it
>> was compiled by and the target OS/CPU match the current running JVM and
>> OS/CPU
>
> The problem there would be that of jaotc: it worked, but because the pre-
> compiled code was not patchable, it had to use indirection for all 
> accesses.
> So, every field offset, method reference, etc. went through a writable
> section. All of these had to be fixed up, and of course it bulked out
> the runtime. The whole process, in the end, wasn't much quicker than
> C1 compilation.
>
I think part of this can be fixed with my "prelinking" proposal - if the 
app cannot alter the classes that are in the AOT code, then many of the 
redirections can be eliminated.

Also, some of the indirection in the original jaot had to deal with 
object references (e.g., String constants), because it didn't have the 
notion of a cached heap. Hopefully Leyden can have better integration 
between the AOT code and cached heap to make this problem go away.

Thanks
- Ioi