RFR: 8283494: Factor out calculation of actual number of XMM registers

[Thomas Schatzl]

On Wed, 23 Mar 2022 08:52:41 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

Ping?

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