8352415: x86: Tighten up template interpreter method entry code

[shipilev]

Interpreter performance is the still important for faster startup, since it would carry application until compilers kick in. After looking at Leyden scenarios in Xint mode, I believe incremental improvements are possible in template interpreter to make it faster.

One of those improvements is tightening up method entry code. Profiling shows the hottest path in the whole ordeal for non-native methods is resolving the Java mirror to store the GC root for currently executing Method*. It involves 4-5 chained memory accesses, which incurs significant latency.

We can massage the code to reuse some memory accesses and also spread them out to allow more latency-hiding hardware mechanisms to kick in.

Additional testing:

• Ad-hoc -Xint benchmarks
• Linux x86_64 server fastdebug, all

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Issue

• JDK-8352415: x86: Tighten up template interpreter method entry code (Enhancement - P4)

Reviewers

• Andrew Dinn (@adinn - Reviewer)
• Johan Sjölen (@jdksjolen - Reviewer)

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[shipilev]

Motivational improvements on 5950X, about 1.8% faster interpreted code.

Benchmark 1: build/linux-x86_64-server-release/images/jdk/bin/java -Xms1g -Xmx1g -XX:+UseSerialGC \
   -Xint -cp JavacBenchApp.jar JavacBenchApp 1

# Before
  Time (mean ± σ):      1.533 s ±  0.013 s    [User: 1.479 s, System: 0.051 s]
  Range (min … max):    1.517 s …  1.551 s    10 runs

# After
  Time (mean ± σ):      1.506 s ±  0.012 s    [User: 1.451 s, System: 0.051 s]
  Range (min … max):    1.493 s …  1.528 s    10 runs

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[openjdk]

@shipilev This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8352415: x86: Tighten up template interpreter method entry code

Reviewed-by: adinn, jsjolen

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At the time when this comment was updated there had been 96 new commits pushed to the master branch:

• 993eae4: 8346948: Update CLDR to Version 47.0
• e98838f: 8352065: [PPC64] C2: Implement PopCountVL, CountLeadingZerosV and CountTrailingZerosV nodes
• 03105fc: 8351601: [JMH] test UnixSocketChannelReadWrite failed for 2 threads config
• fe03e2e: 8351897: Extra closing curly brace typos in Javadoc
• fa0b18b: 8352509: Update jdk.test.lib.SecurityTools jar method to accept List parameter
• 3ac9678: 8351224: Deprecate com.sun.tools.attach.AttachPermission for removal
• 997aa17: 8351310: Deprecate com.sun.jdi.JDIPermission for removal
• c953e0e: 8350579: Remove Template Assertion Predicates belonging to a loop once it is folded away
• 67c4405: 8352866: TestLogJIT.java runs wrong test class
• bab9372: 8352618: Remove old deprecated functionality in the build system
• ... and 86 more: https://git.openjdk.org/jdk/compare/20f1bca0770b6b4d935b068e7f6a742cef4f5449...master

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[mlbridge]

Webrevs

• 00: Full (f67c5151)

[adinn]

Looks good to me.

Have you looked at aarch64 to see if this also a bottleneck there? It could use a similar trick to avoid calling load_mirror (which repeats the first two of three loads that intitialize rcpool).

[shipilev]

Have you looked at aarch64 to see if this also a bottleneck there? It could use a similar trick to avoid calling load_mirror (which repeats the first two of three loads that intitialize rcpool).

Only briefly. AArch64 is clunkier, since it does things in pairs, but I think improvements there are possible as well. As usual, we do arch-specific optimizations in separate PRs, with one architecture being a pilot :)

[jdksjolen]

LGTM

[shipilev]

Thanks for reviews!

@coleenp, you are likely interested in this area :)

[shipilev]

If there are no other comments, I am going to integrate this soon. Thanks!

[shipilev]

There we go!

/integrate

[openjdk]

Going to push as commit 22f630c.
Since your change was applied there have been 170 commits pushed to the master branch:

• 6fbaa06: 8353176: C1: x86 patching stub always calls Thread::current()
• 79d0c94: 8352114: New test runtime/interpreter/CountBytecodesTest.java is failing
• 23e3b3f: 8351156: C1: Remove FPU stack support after 32-bit x86 removal
• 2592513: 8350577: Fix missing Assertion Predicates when splitting loops
• 59629f8: 8351040: [REDO] Protection zone for easier detection of accidental zero-nKlass use
• 8cbadf7: 8317976: Optimize SIMD sort for AMD Zen 4
• b9d7a75: 8352879: TestPeriod.java and TestGetContentType.java run wrong test class
• 895aabc: 8351233: [ASAN] avx2-emu-funcs.hpp:151:20: error: ‘D.82188’ is used uninitialized
• 3d2c3cd: 8352970: Remove unnecessary Windows version check in Win32ShellFolderManager2
• c70ad6a: 8352906: stdout/err.encoding on Windows set by incorrect Win32 call
• ... and 160 more: https://git.openjdk.org/jdk/compare/20f1bca0770b6b4d935b068e7f6a742cef4f5449...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit 22f630c.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

[coleenp]

Sorry I was away and didn't see this. For the record, it looks good. I liked the load_mirror macro assembler function but it did redundant work.