8253167: ARM32 builds fail after JDK-8247910

[kimbarrett]

Please review this fix for a build failure for arm32.

nconstexpr functions cannot contain asm statements (until C++20), even if
not executed by a constexpr invocation. This means assert (for example)
can't be used in a constexpr function on arm32, because of the
implementation of the BREAKPOINT macro as an asm statement for linux-arm.

The current arm32 implementation is from JDK-8077648: "ARM: BREAKPOINT is
wrong for thumb", which is a Confidential bug about Oracle's old closed
source arm32 port. That port was open sourced by JDK-8168503: "JEP 297:
Unified arm32/arm64 Port". The discussion of JDK-8077648 suggested making
the arm32 port be like nearly all others. That is, have BREAKPOINT expand to
a call to ::breakpoint(), with any empty body for that function and a
comment that one should use a debugger to set a breakpoint there.

This change takes that alternative approach.

The same problem likely exists for win32, which also implements BREAKPOINT
as an asm statement. However, I don't have the infrastructure to do a win32
build to demonstrate that. But I'm making a similar change there on spec.

Note that the Windows implementation of ::breakpoint() ultimately calls the
DebugBreak Win32 library function. That should work for the windows-x86 port
too.

I don't know why we have that difference of some platforms having an
affirmative platform-specific breakpoint operation in place while others
require a debugger to set one, but that difference already exists. This
change does move arm32 from the former to the latter camp though. I'm
guessing that won't matter; if it does then we'll need to conditionalize the
body of ::breakpoint().

There may be some further cleanup that could be done after this change.
We don't really need the BREAKPOINT macro anymore, and could just
use ::breakpoint() directly. But I think that's out of scope for dealing
with the build failure(s).

Testing:
build linux-arm.
tier1 for Oracle supported platforms.

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Issues

• JDK-8253167: ARM32 builds fail after JDK-8247910
• JDK-8213483: ARM32: runtime/ErrorHandling/ShowRegistersOnAssertTest.java jtreg test fail

Reviewers

• Coleen Phillimore (@coleenp - Reviewer)
• Mikael Vidstedt (@vidmik - Reviewer)
• bulasevich - Committer ⚠️ Added manually

Download

$ git fetch https://git.openjdk.java.net/jdk pull/259/head:pull/259
$ git checkout pull/259

[bridgekeeper]

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (b51abfc)

[coleenp]

Looks good!

[openjdk]

@kimbarrett This change now passes all automated pre-integration checks. In addition to the automated checks, the change must also fulfill all project specific requirements

After integration, the commit message will be:

8253167: ARM32 builds fail after JDK-8247910
8213483: ARM32: runtime/ErrorHandling/ShowRegistersOnAssertTest.java jtreg test fail

Removed platform-dependent definitions of BREAKPOINT as asm(breakpoint instruction).

Reviewed-by: coleenp, mikael, bulasevich

• If you would like to add a summary, use the /summary command.
• To credit additional contributors, use the /contributor command.
• To add additional solved issues, use the /issue command.

Since the source branch of this PR was last updated there have been 8 commits pushed to the master branch:

• cc7521c: 8252199: Reimplement support of Type 1 fonts without MappedByteBuffer
• 3d88d38: 8252070: Some platform-specific BLIT optimizations are not effective
• 83b0537: 8253291: bug7072653.java still failed "Popup window height ... is wrong"
• d27835b: 8249142: java/awt/FontClass/CreateFont/DeleteFont.sh is unstable
• 1438ce0: 8252188: Crash in OrINode::Ideal(PhaseGVN*, bool)+0x8b9
• 224a30f: 8252311: AArch64: save two words in itable lookup stub
• 22f7af7: 8253317: The "com/apple/eawt" is missed in the "othervm.dirs" config option
• f55dd9d: 8251548: Remove unnecessary explicit initialization of volatile variables in security-libs code

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid automatic rebasing, please merge master into your branch, and then specify the current head hash when integrating, like this: /integrate cc7521c452ad47a9a0bfca23168ac1ff0aff3343.

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

[mlbridge]

Mailing list message from Boris Ulasevich on hotspot-dev:

Hi,

Yes, the change is Ok.
It will fix JDK-8213483 by the way.
Thanks for doing this!

regards,
Boris

On Sat, Sep 19, 2020 at 12:07 AM Kim Barrett <kbarrett at openjdk.java.net> wrote:

[kimbarrett]

/reviewer credit bulasevich
/issue add 8213483

[openjdk]

@kimbarrett
Reviewer bulasevich successfully credited.

[openjdk]

@kimbarrett
Adding additional issue to issue list: 8213483: ARM32: runtime/ErrorHandling/ShowRegistersOnAssertTest.java jtreg test fail.

[mlbridge]

Mailing list message from Kim Barrett on hotspot-dev:

On Sep 20, 2020, at 10:17 AM, Boris Ulasevich <boris.ulasevich at bell-sw.com> wrote:

Hi,

Yes, the change is Ok.
It will fix JDK-8213483 by the way.
Thanks for doing this!

regards,
Boris

Thanks.

[kimbarrett]

/summary Removed platform-dependent definitions of BREAKPOINT as asm(breakpoint instruction).

[openjdk]

@kimbarrett Setting summary to Removed platform-dependent definitions of BREAKPOINT as asm(breakpoint instruction).

[kimbarrett]

/integrate

[openjdk]

@kimbarrett Since your change was applied there have been 8 commits pushed to the master branch:

• cc7521c: 8252199: Reimplement support of Type 1 fonts without MappedByteBuffer
• 3d88d38: 8252070: Some platform-specific BLIT optimizations are not effective
• 83b0537: 8253291: bug7072653.java still failed "Popup window height ... is wrong"
• d27835b: 8249142: java/awt/FontClass/CreateFont/DeleteFont.sh is unstable
• 1438ce0: 8252188: Crash in OrINode::Ideal(PhaseGVN*, bool)+0x8b9
• 224a30f: 8252311: AArch64: save two words in itable lookup stub
• 22f7af7: 8253317: The "com/apple/eawt" is missed in the "othervm.dirs" config option
• f55dd9d: 8251548: Remove unnecessary explicit initialization of volatile variables in security-libs code

Your commit was automatically rebased without conflicts.

Pushed as commit bca9e55.

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