RFR: 8144028: Use AArch64 bit-test instructions in C2

Vladimir Kozlov vladimir.kozlov at oracle.com
Wed Nov 25 17:11:57 UTC 2015

Why -XX:TieredStopAtLevel=3 and not =1? =3 is C1 generated code with additional full profiling code. If you want to test 
without profiling code use =1.

Note, since the test will have to run on all platforms we have to sponsor it and push through JPRT.


On 11/25/15 7:49 AM, Andrew Haley wrote:
> For some reason (oversight, I guess) we never got around to using the
> bit-testing AArch64 instructions in C2.  TBZ/TBNZ are quite nice in
> that they allow bit tests and branches (and tests for +ve/-ve) without
> hitting the condition codes.  TST sets the condition codes based on a
> set of bits in a register: it's an AND which throws the result away.
> http://cr.openjdk.java.net/~aph/8144028/
> Andrew.

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