RFR: 8283494: Factor out calculation of actual number of XMM registers [v2]

[Vladimir Kozlov]

On Wed, 30 Mar 2022 08:51:24 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Hi all,
>> 
>>   can I have reviews for this change that factors out calculation of the actually available number of XMM registers on a given processor/given command line options into a method and reuse that as much as possible?
>> 
>> This relates to this code snippet:
>> 
>>       int xmm_bypass_limit = FrameMap::nof_xmm_regs;
>> #ifdef _LP64
>>       if (UseAVX < 3) {
>>         xmm_bypass_limit = xmm_bypass_limit / 2;
>>       }
>> #endif
>> 
>> 
>> Also, there is already the method `FrameMap::get_num_caller_save_xmms()` that has been updated to use that new method `XMMRegisterImpl::available_xmm_registers()`; further I tried to appropriately use `FrameMap::get_num_caller_save_xmms` in the places where either would work. Please have a look in particular about that.
>> 
>> I did not change strange to me variable names like `xmm_bypass_limit` above as they probably make some sense to somebody as it's used quite often.
>> 
>> This also fixes a compilation error without configuring C1 introduced with [JDK-8283327](https://bugs.openjdk.java.net/browse/JDK-8283327).
>> 
>> Testing: tier1-5 (all but linux-aarch64 done), gha, local compilation with `configure --with-features=-compiler1`.
>> 
>> Thanks,
>>   Thomas
>
> Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Put method implementation in hpp file

Good.

In 32-bit VM it would just one instruction when inlined.

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Marked as reviewed by kvn (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/7917