[foreign-memaccess+abi] RFR: 8275646: Implement optimized upcall stubs on AArch64 [v2]

[Nick Gasson]

> This is a fairly direct port of the X86 code.  The changes to
> frame_aarch64 and foreign_globals_aarch64 are identical: perhaps
> ForeignGlobals::parse_call_regs_impl() could be moved to shared code?
> 
> The X86 version has a call to reinit_heapbase() before the return from
> the stub.  I think this is redundant because the heap base register will
> be clobbered immediately by the native code?
> 
> I hit a really weird bug in release builds where the first few
> instructions in the code buffer were overwritten by the fields of
> OptimizedEntryBlob.  I think we need to pass sizeof(OptimizedEntryBlob)
> instead of sizeof(BufferBlob) as the header_size argument to the
> RuntimeBlob constructor (none of the other subclasses of BufferBlob have
> extra fields).  I added a header_size argument to BufferBlob's
> constructor to thread this through.
> 
> I removed the calls to change the W^X state in on_entry/on_exit calls:
> in the on_entry case the stub must already be executable because we
> called into the VM from there, and for on_exit we need the code to be
> executable not writable otherwise we'll get a SIGBUS as soon as we
> return to the stub.  The newly added stack tests in TestUpcall hit
> JDK-8275584 on MacOS/AArch64 so I've problem-listed that for now.
> 
> JMH results from org.openjdk.bench.jdk.incubator.foreign.Upcalls before:
> 
> 
> Benchmark                Mode  Cnt     Score    Error  Units
> Upcalls.jni_args10       avgt   30   450.417 ?  4.755  ns/op
> Upcalls.jni_args5        avgt   30   245.898 ?  3.171  ns/op
> Upcalls.jni_blank        avgt   30   195.606 ?  5.459  ns/op
> Upcalls.jni_identity     avgt   30   369.788 ? 15.165  ns/op
> Upcalls.panama_args10    avgt   30  1253.189 ? 62.261  ns/op
> Upcalls.panama_args5     avgt   30   927.101 ? 35.369  ns/op
> Upcalls.panama_blank     avgt   30   637.708 ? 11.353  ns/op
> Upcalls.panama_identity  avgt   30   697.109 ?  9.971  ns/op
> 
> 
> After:
> 
> 
> Benchmark                Mode  Cnt    Score    Error  Units
> Upcalls.jni_args10       avgt   30  455.304 ? 21.838  ns/op
> Upcalls.jni_args5        avgt   30  247.279 ?  2.513  ns/op
> Upcalls.jni_blank        avgt   30  194.113 ?  4.317  ns/op
> Upcalls.jni_identity     avgt   30  366.145 ?  4.912  ns/op
> Upcalls.panama_args10    avgt   30  236.337 ? 11.072  ns/op
> Upcalls.panama_args5     avgt   30  223.858 ? 12.345  ns/op
> Upcalls.panama_blank     avgt   30  203.631 ?  8.840  ns/op
> Upcalls.panama_identity  avgt   30  208.783 ?  9.914  ns/op
> 
> 
> Tested tier1 and jdk_foreign on Linux/AArch64 and MacOS/AArch64.

Nick Gasson has updated the pull request incrementally with one additional commit since the last revision:

  Review comments

-------------

Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/610/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/610/files/d385e964..e3fa6210

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=610&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=610&range=00-01

  Stats: 10 lines in 2 files changed: 0 ins; 8 del; 2 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/610.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/610/head:pull/610

PR: https://git.openjdk.java.net/panama-foreign/pull/610