8379706: Cleanup and clarify BarrierSetAssembler::try_resolve_weak_handle_in_c2

[xmas92]

This patch is a simple refactor which does a few things:

• Rename try_resolve_weak_handle_in_c2/try_resolve_weak_handle on all platforms to try_peek_weak_handle_in_nmethod to better encapsulate its contract
• Remove its existence depending on C2's existence. It is now a shared API across all platforms
• Create two distinct registers parameters for the weak_handle input and the obj maybe output. These may alias, and do in all current uses.

I did not add reg != noreg preconditions, but did augment the assert_different_registers with it.

I was wondering if try_peek_weak_handle_in_nmethod would be better named try_peek_weak_handle_from_nmethod, as the weak handle is not in the nmethod, but the peek is. Not sure what preposition is less ambiguous. Not that I think the name in the patch will cause problems for developers. But I'd like some input here.

Testing:

• Tier1-3 on Oracle Supported platforms
• GHA
• gc/shenandoah on Linux x64
• Compiled linux x64 without C2
• Cross compiled aarch64, ppc64le and s390x with and without C2

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Issue

• JDK-8379706: Cleanup and clarify BarrierSetAssembler::try_resolve_weak_handle_in_c2 (Enhancement - P4)

Reviewers

• Martin Doerr (@TheRealMDoerr - Reviewer)
• Fei Yang (@RealFYang - Reviewer)
• Amit Kumar (@offamitkumar - Committer)

Reviewing

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8379706: Cleanup and clarify BarrierSetAssembler::try_resolve_weak_handle_in_c2

Reviewed-by: mdoerr, fyang, amitkumar

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At the time when this comment was updated there had been 182 new commits pushed to the master branch:

• c8bb46b: 8381650: Vector rotate operations on AArch64 with NEON
• ca405d0: 8376400: C2: folding ifs may cause incorrect execution when trap is taken
• 0c07aaa: 8383420: SIGSEGV in PhaseChaitin::gather_lrg_masks
• ... and 179 more: https://git.openjdk.org/jdk/compare/0dd0108c1a7b3658df536adbc2bd68fa5167539d...master

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[TheRealMDoerr]

Thanks for improving this! I think an additional comment would be helpful to make sure potential users clearly understand what "peek" means. The peeked object is only valid until we hit the next safepoint.
We'll run tests.

[TheRealMDoerr]

I think the following lines above should also be removed:

#define __ masm->

#undef __

[TheRealMDoerr]

Test results look good on our side. Thanks!

[TheRealMDoerr]

Excellent! Thanks!

[fbredber]

@RealFYang, @offamitkumar
You might want to look at this, and take it for a spin, since it changes code in your platforms.

[RealFYang]

The RISC-V part seems fine to me. My local hs:tier1 - hs:tier3 test on linux-riscv64 using fastdebug build is good.

[offamitkumar]

s390 looks good, hotspot:tier1 test passed on s390x with fastdebug-vm.

[xmas92]

Thanks for the reviews.
/integrate

[openjdk]

Going to push as commit 0588209.
Since your change was applied there have been 205 commits pushed to the master branch:

• 5ccf99b: 8383414: Exhaustiveness rejects a type pattern that covers all permitted subtypes
• f74a447: 8374524: Investigate and cleanup test/jdk/sun/security/provider/SecureRandom/StrongSecureRandom.java and convert to junit
• 0e86b9c: 8376610: Test javax/net/ssl/TLS/TestJSSEClientDefaultProtocol.java times out then completed
• ... and 202 more: https://git.openjdk.org/jdk/compare/0dd0108c1a7b3658df536adbc2bd68fa5167539d...master

Your commit was automatically rebased without conflicts.

[openjdk]

@xmas92 Pushed as commit 0588209.

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