RFR: 8283232: x86: Improve vector broadcast operations [v2]

Jatin Bhateja jbhateja at openjdk.java.net
Wed Mar 16 15:59:53 UTC 2022


On Wed, 16 Mar 2022 14:52:07 GMT, Quan Anh Mai <duke at openjdk.java.net> wrote:

> Hi, forwarding results within the same bypass domain does not result in delay, data bypass delay happens when the data crosses different domains, according to "Intel® 64 and IA-32 Architectures Optimization Reference Manual"
> 
> > When a source of a micro-op executed in one stack comes from a micro-op executed in another stack, a delay can occur. The delay occurs also for transitions between Intel SSE integer and Intel SSE floating-point operations. In some of the cases, the data transition is done using a micro-op that is added to the instruction flow.
> 
> The manual mentions the guideline at section 3.5.2.2
> 
> ![image](https://user-images.githubusercontent.com/49088128/158618209-c0674ba7-1c93-4014-a7e1-330f4e5846da.png)
> 
> Thanks.

Thanks meant to refer to above text.  I have removed incorrect reference.

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PR: https://git.openjdk.java.net/jdk/pull/7832


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