[16] RFR(M) 8251459: Compute caller save exclusion RegMasks once

[Vladimir Ivanov]

Looks good.

Best regards,
Vladimir Ivanov

On 18.08.2020 18:12, Vladimir Kozlov wrote:
> https://cr.openjdk.java.net/~kvn/8251459/webrev.00/
> https://bugs.openjdk.java.net/browse/JDK-8251459
> 
> Claes once again found optimization for C2 code!
> 
> Instead of per bit exclusion SOC and AS registers from debuginfo 
> regmasks he suggested to calculate exclusion masks once in 
> Matcher::init_spill_mask() during first compilation and use these masks 
> to do per word exclusion.
> We can save 27k instructions per compilation on x64 with this!
> 
> I modified Claes's original patch by removing refactoring code to see 
> changes more clear.
> 
> Tested: hs-tier1-3, xcomp
> 
> Thanks,
> Vladimir