RFR: 8329331: Intrinsify Unsafe::setMemory [v23]

[Scott Gibbons]

On Fri, 19 Apr 2024 20:58:43 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> src/hotspot/cpu/x86/stubGenerator_x86_64_arraycopy.cpp line 2638:
>> 
>>> 2636:                                L_exit, _masm);
>>> 2637:     }
>>> 2638:     __ jmp(L_exit);
>> 
>> Here is long jump to `L_exit` after `do_setmemory_atomic_loop()` call. Should this be also short jump?
>
> Do we have additional code in debug VM wihch increase distance and requires long jump? I don't see it. Usually it something which call `__ STOP()`.

The old code required a long jump due to the size of `do_setmemory_atomic_loop` but has since been refactored.  The `jmp(Label)` code will generate a short jump provided the label has been defined and is in range.  Otherwise a long jump is generated.

Changed to `jmpb`

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PR Review Comment: https://git.openjdk.org/jdk/pull/18555#discussion_r1573012933