In FFM, native function would be called via `nep_invoker_blob`. If the function
has two arguments, it would be following:
Decoding RuntimeStub - nep_invoker_blob 0x00007fcae394cd10
--------------------------------------------------------------------------------
0x00007fcae394cd80: pushq %rbp
0x00007fcae394cd81: movq %rsp, %rbp
0x00007fcae394cd84: subq $0, %rsp
;; { argument shuffle
0x00007fcae394cd88: movq %r8, %rax
0x00007fcae394cd8b: movq %rsi, %r10
0x00007fcae394cd8e: movq %rcx, %rsi
0x00007fcae394cd91: movq %rdx, %rdi
;; } argument shuffle
0x00007fcae394cd94: callq *%r10
0x00007fcae394cd97: leave
0x00007fcae394cd98: retq
`subq $0, %rsp` is for shadow space on stack, and `movq %r8, %rax` is number of
args for variadic function. So they are not necessary in some case. They should
be remove following if they are not needed:
Decoding RuntimeStub - nep_invoker_blob 0x00007fd8778e2810
--------------------------------------------------------------------------------
0x00007fd8778e2880: pushq %rbp
0x00007fd8778e2881: movq %rsp, %rbp
;; { argument shuffle
0x00007fd8778e2884: movq %rsi, %r10
0x00007fd8778e2887: movq %rcx, %rsi
0x00007fd8778e288a: movq %rdx, %rdi
;; } argument shuffle
0x00007fd8778e288d: callq *%r10
0x00007fd8778e2890: leave
0x00007fd8778e2891: retq
All java/foreign jtreg tests are passed.
We can see these stub code on [ffmasm
testcase](https://github.com/YaSuenag/ffmasm/tree/ef7a466ca9607164dbe7be7e68ea509d4bdac998/examples/cpumodel)
with `-XX:+UnlockDiagnosticVMOptions -XX:+PrintStubCode` and hsdis library.
This testcase linked the code with `Linker.Option.isTrivial()`.
After this change, FFM performance on [another ffmasm
testcase](https://github.com/YaSuenag/ffmasm/tree/ef7a466ca9607164dbe7be7e68ea509d4bdac998/benchmarks/funccall)
was improved:
before:
Benchmark Mode Cnt Score Error
Units
FuncCallComparison.invokeFFMRDTSC thrpt 3 106664071.816 ± 14396524.718
ops/s
FuncCallComparison.rdtsc thrpt 3 108024079.738 ± 13223921.011
ops/s
after:
Benchmark Mode Cnt Score Error
Units
FuncCallComparison.invokeFFMRDTSC thrpt 3 107622971.525 ± 12249767.134
ops/s
FuncCallComparison.rdtsc thrpt 3 107695741.608 ± 23983281.346
ops/s
Environment:
* CPU: AMD Ryzen 3 3300X
* OS: Fedora 38 x86_64 (Kernel 6.3.8-200.fc38.x86_64)
* Hyper-V 4vCPU, 8GB mem
-------------
Commit messages:
- 8313406: nep_invoker_blob can be simplified more
Changes: https://git.openjdk.org/jdk/pull/15089/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15089&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8313406
Stats: 41 lines in 3 files changed: 4 ins; 11 del; 26 mod
Patch: https://git.openjdk.org/jdk/pull/15089.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/15089/head:pull/15089
PR: https://git.openjdk.org/jdk/pull/15089
