JDK 10 RFR(S): 8173465: Introduce NearLabel for branches known to be short.

Vladimir Kozlov vladimir.kozlov at oracle.com
Mon Feb 13 22:20:47 UTC 2017

I assume you are talking about hand written assembler code snippets (stubs, etc.)

Usually we use appropriate short branch instructions for short forward distance (and there is assert which check that it is correct). For back branches we do it automatically depending on distance.

So why you need special NearLabel for s390? Can you just have general short branch macroassembler method for this?


On 1/30/17 2:57 AM, Lindenmaier, Goetz wrote:
> Hi
> please review this small optimization of Labels.
> This so far targets s390, but could be used on other platforms as well.
> I please need a sponsor.
> http://cr.openjdk.java.net/~goetz/wr17/8173465-NearLbl/webrev.01/index.html
> Some branches issued to assembly code are obviously of short distance. Due to separation into shared and platform code this not always is known when the branch instruction is selected.
> NearLabels indicate that a branch with short reach can be used.
> Best regards,
>   Goetz

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