RFR: 8305959: x86: Improve itable_stub [v2]

[Boris Ulasevich]

On Fri, 2 Jun 2023 18:41:38 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> src/hotspot/cpu/x86/vtableStubs_x86_32.cpp line 203:
>> 
>>> 201: 
>>> 202:   start_pc = __ pc();
>>> 203:   __ push(temp_reg);
>> 
>> Why do we need to save this one? Do we care if this "tmp" is clobbered?
>
> This one is still not addressed, in case you missed it, @bulasevich.

Right. Thanks.
On x86_32 we have register pressure. I have to push-pop rdx to avoid crash. The question must be caused by temp_reg name, which is similar to rscatch. On x86_32 we do not have any scratch register.
Will it be better if I replace push/pop(temp_reg) with explicit push/pop(rdx)?

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PR Review Comment: https://git.openjdk.org/jdk/pull/13460#discussion_r1217785799