8318383: Remove duplicated checks in os::get_native_stack() in posix implementation

[zhengyu123]

Trivial cleanup that removes duplicated checkings.

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Issue

• JDK-8318383: Remove duplicated checks in os::get_native_stack() in posix implementation (Enhancement - P4)

Reviewers

• David Holmes (@dholmes-ora - Reviewer)
• Thomas Stuefe (@tstuefe - Reviewer)

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[mlbridge]

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• 00: Full (ac34ea7e)

[dholmes-ora]

Took me a few minutes to convince myself but looks good. :)

Thanks

[openjdk]

@zhengyu123 This change now passes all automated pre-integration checks.

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

8318383: Remove duplicated checks in os::get_native_stack() in posix implementation

Reviewed-by: dholmes, stuefe

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At the time when this comment was updated there had been 168 new commits pushed to the master branch:

• 24bc5bd: 8318104: macOS 10.13 check in TabButtonAccessibility.m can be removed
• e25a49a: 8318471: ProblemList compiler/sharedstubs/SharedTrampolineTest.java
• ce8ebeb: 8317979: Use TZ database style abbreviations in the CLDR locale provider
• ab13568: 8318029: Minor improvement to logging output in container at-requires
• 278de7a: 8318458: Update javac and java manpages with restricted method options
• 6fc3514: 8318363: Foreign benchmarks fail to build on some platforms
• 31ef400: 8318183: C2: VM may crash after hitting node limit
• 4e77b3c: 8315974: Make fields final in 'com.sun.crypto.provider' package
• 8dd8096: 8317886: Add @sealedGraph to ByteBuffer
• 9843c97: 8318365: Test runtime/cds/appcds/sharedStrings/InternSharedString.java fails after JDK-8311538
• ... and 158 more: https://git.openjdk.org/jdk/compare/a8eacb31ab8466f50a939d6748dbdd1560516878...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[dholmes-ora]

Please fix the typo in JBS and PR title: implemenation -> implementation

[zhengyu123]

Please fix the typo in JBS and PR title: implemenation -> implementation

Fixed.

Thanks, @dholmes-ora

[tstuefe]

Hi Zhengyu,

This is not trivial :)

let
A=> fp == null
B=> cb != null
C=> sender-pc == null
D=> is_first_frame

Old:
if (A || B || C || D) break;
if (!C && !D) get_sender_for...;

New:
if (A || B || C || D) break;
get_sender...

Not sure if that is correct, but it is at least not equivalent, so not a simple cleanup.

(note that I support any cleanup, the old code is terrible).

[zhengyu123]

Hi Zhengyu,

This is not trivial :)

let A=> fp == null B=> cb != null C=> sender-pc == null D=> is_first_frame

Old: if (A || B || C || D) break; if (!C && !D) get_sender_for...;

New: if (A || B || C || D) break; get_sender...

Not sure if that is correct, but it is at least not equivalent, so not a simple cleanup.

(note that I support any cleanup, the old code is terrible).

I agree it is confusing, I stared at it for quite a long while. I think I copied it from somewhere.

In the old code, when it arrives to the second check, it must have:

fr.send_pc() != nullptr and os::is_first_C_frame(&fr) == false

so if (fr.sender_pc() && !os::is_first_C_frame(&fr)) check is always true, no?

For if (A || B || C || D) break; not to break out, it must have C == false and D == false, then !C && !D should always be true.

[dholmes-ora]

@tstuefe It took me a while to get it too. If we don't break then the two conditions we were checking must be true - else we would not reach that check.

[tstuefe]

@zhengyu123 @dholmes-ora Okay, I think you are right.

[zhengyu123]

Thanks, @dholmes-ora @tstuefe

[zhengyu123]

/integrate

[openjdk]

Going to push as commit 9cf334f.
Since your change was applied there have been 175 commits pushed to the master branch:

• defc7e0: 8318454: TestLayoutPaths broken on Big Endian platforms after JDK-8317837
• 3c70f2c: 8318418: hsdis build fails with system binutils on Ubuntu
• 15acf4b: 8318324: Drop redundant default methods from FFM API
• 1a09835: 8317358: G1: Make TestMaxNewSize use createTestJvm
• 47bb1a1: 8318415: Adjust describing comment of os_getChildren after 8315026
• 80bd22d: 8316144: Remove unused field jdk.internal.util.xml.impl.XMLStreamWriterImpl.Element._Depth
• c0e154c: 8318089: Class space not marked as such with NMT when CDS is off
• 24bc5bd: 8318104: macOS 10.13 check in TabButtonAccessibility.m can be removed
• e25a49a: 8318471: ProblemList compiler/sharedstubs/SharedTrampolineTest.java
• ce8ebeb: 8317979: Use TZ database style abbreviations in the CLDR locale provider
• ... and 165 more: https://git.openjdk.org/jdk/compare/a8eacb31ab8466f50a939d6748dbdd1560516878...master

Your commit was automatically rebased without conflicts.

[openjdk]

@zhengyu123 Pushed as commit 9cf334f.

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