RFR: 8363620: AArch64: reimplement emit_static_call_stub()

[Fei Gao]

In the existing implementation, the static call stub typically emits a sequence like:
`isb; movk; movz; movz; movk; movz; movz; br`.

This patch reimplements it using a more compact and patch-friendly sequence:

ldr x12, Label_data
ldr x8, Label_entry
br x8
Label_data:
  0x00000000
  0x00000000
Label_entry:
  0x00000000
  0x00000000

The new approach places the target addresses adjacent to the code and loads them dynamically. This allows us to update the call target by modifying only the data in memory, without changing any instructions. This avoids the need for I-cache flushes or issuing an `isb`[1], which are both relatively expensive operations.

While emitting direct branches in static stubs for small code caches can save 2 instructions compared to the new implementation, modifying those branches still requires I-cache flushes or an `isb`. This patch unifies the code generation by emitting the same static stubs for both small and large code caches.

A microbenchmark (StaticCallStub.java) demonstrates a performance uplift of approximately 43%.


Benchmark                       (length)   Mode   Cnt Master     Patch      Units
StaticCallStubFar.callCompiled    1000     avgt   5   39.346     22.474     us/op
StaticCallStubFar.callCompiled    10000    avgt   5   390.05     218.478    us/op
StaticCallStubFar.callCompiled    100000   avgt   5   3869.264   2174.001   us/op
StaticCallStubNear.callCompiled   1000     avgt   5   39.093     22.582     us/op
StaticCallStubNear.callCompiled   10000    avgt   5   387.319    217.398    us/op
StaticCallStubNear.callCompiled   100000   avgt   5   3855.825   2206.923   us/op


All tests in Tier1 to Tier3, under both release and debug builds, have passed.

[1] https://community.arm.com/arm-community-blogs/b/architectures-and-processors-blog/posts/caches-self-modifying-code-working-with-threads

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Commit messages:
 - 8363620: AArch64: reimplement emit_static_call_stub()

Changes: https://git.openjdk.org/jdk/pull/26638/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26638&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8363620
  Stats: 322 lines in 8 files changed: 135 ins; 167 del; 20 mod
  Patch: https://git.openjdk.org/jdk/pull/26638.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26638/head:pull/26638

PR: https://git.openjdk.org/jdk/pull/26638