RFR: 8356949: AArch64: Tighten up template interpreter method entry code

[Andrew Haley]

On Mon, 19 May 2025 22:16:27 GMT, Chad Rakoczy <duke at openjdk.org> wrote:

> [JDK-8356949](https://bugs.openjdk.org/browse/JDK-8356949)
> 
> This change is the aarch64 version of [JDK-8352415](https://bugs.openjdk.org/browse/JDK-8352415). 
> 
> To improve interpreter performance, which is important for faster startup, the method entry code was refactored to reuse some memory accesses and also spread them out to allow more latency-hiding hardware mechanisms to kick in.
> 
> Additional testing:
> 
> - [x] Ad-hoc -Xint benchmarks
> - [x] Linux aarch64 server fastdebug, tier 1/2/3/4

src/hotspot/cpu/aarch64/templateInterpreterGenerator_aarch64.cpp line 870:

> 868:   // Save ConstMethod* in r5 for later use.
> 869:   __ ldr(r5, Address(rmethod, Method::const_offset()));
> 870: 

This all looks basically good. It's better also to give the registers meaningful names such as `r5_ConstMethod`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25312#discussion_r2097291882