RFR: 8283327: Add methods to save/restore registers when calling into the VM from C1/interpreter barrier code/improve push pop stuff for x86

[Erik Österlund]

On Fri, 18 Mar 2022 17:38:57 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> If you look below for the SysV ABI, in the '#else' part, the code unconditionally adds all xmm registers that are available:
>> 
>> 
>> XMMRegSet::range(xmm0, as_XMMRegister(FrameMap::get_num_caller_save_xmms() - 1));
>> 
>> If you want we can do the same for Win64 if you think this is better.
>
> Of course, if C1 never uses xmm >= 8, then I can limit the number of register saving.

Pretty sure C1 will use more than that.

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PR: https://git.openjdk.java.net/jdk/pull/7867