RFR: 8334060: Implementation of Late Barrier Expansion for G1 [v5]

[Roberto Castañeda Lozano]

On Mon, 12 Aug 2024 05:23:06 GMT, Amit Kumar <amitkumar at openjdk.org> wrote:

> is there issue if we replace this code:
> 
> ```
>     if (in_bytes(SATBMarkQueue::byte_width_of_active()) == 4) {
>       __ ldrw(rscratch1, in_progress);
>     } else {
>       assert(in_bytes(SATBMarkQueue::byte_width_of_active()) == 1, "Assumption");
>       __ ldrb(rscratch1, in_progress);
>     }
> ```
> 
> in method `G1BarrierSetAssembler::gen_write_ref_array_pre_barrier` with `generate_queue_test_and_insertion(masm, rthread, rscratch1)` ?
> 
> Though you have to move the `gen_write_ref_array_pre_barrier` on top otherwise compiler wouldn't be able to find it.

Thanks for the suggestion Amit!  this refactoring would work (assuming you mean `generate_pre_barrier_fast_path` instead of `generate_queue_test_and_insertion`), however I am hesitant to apply it because 1) it would further increase the size of the changelog and hence the burden of reviewing it and 2) it is not a clear maintainability win: some engineers prefer a little bit of code duplication to preserve the assembly code flow (see discussion [here](https://github.com/openjdk/jdk/pull/19746#discussion_r1645713269)).

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PR Comment: https://git.openjdk.org/jdk/pull/19746#issuecomment-2283395013