RFR: 8265491: Math Signum optimization for x86 [v2]

Marcus G K Williams github.com+168222+mgkwill at openjdk.java.net
Wed Apr 21 16:50:35 UTC 2021


On Wed, 21 Apr 2021 03:48:57 GMT, Jie Fu <jiefu at openjdk.org> wrote:

>> Marcus G K Williams has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add os.arch=="i386" to signum jtreg
>>   
>>   Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>
> src/hotspot/cpu/x86/x86.ad line 5780:
> 
>> 5778: // --------------------------------- Signum ---------------------------
>> 5779: 
>> 5780: instruct signumF_reg(regF dst, regF zero, regF one, rFlagsReg cr) %{
> 
> Do we need `predicate(UseSSE>=2);` here?

It seems ucomiss is SSE, but ucomisd is SSE2. I will add a SSE predicate to `instruct signumF_reg` and an SSE2 predicate to `instruct signumD_reg`. Thanks for the suggestion.

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PR: https://git.openjdk.java.net/jdk/pull/3581


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