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8258459: Decouple gc_globals.hpp from globals.hpp #1797

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iklam
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@iklam iklam commented Dec 16, 2020

Currently, globals.hpp is including gc_globals.hpp. This exposes all the GC command-line flags to almost all cpp files. However, only about 1/3 of the cpp files would require gc_globals.hpp.

This RFE improves modularity and HotSpot build time.

Review notes:

  • Please start with globals.hpp, gc_globals.hpp.
  • Flags related to TLAB are frequently used by other header files. I moved these flags to a new header tlab_globals.hpp.
  • Some tweaking of oop.hpp to avoid including gc_globals.hpp in this popular header file. (Otherwise gc_globals.hpp would be included by everyone).
  • The other changes are just files that use GC flags. They should have included gc_globals.hpp but didn't.

Testing:
Tested with mach5: tier1, builds-tier2, builds-tier3, builds-tier4 and builds-tier5. Also locally: aarch64, arm, ppc64, s390, x86, and zero.


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  • Commit message must refer to an issue
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Issue

  • JDK-8258459: Decouple gc_globals.hpp from globals.hpp

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$ git fetch https://git.openjdk.java.net/jdk pull/1797/head:pull/1797
$ git checkout pull/1797

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@bridgekeeper bridgekeeper bot commented Dec 16, 2020

👋 Welcome back iklam! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

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@openjdk openjdk bot commented Dec 16, 2020

@iklam The following labels will be automatically applied to this pull request:

  • hotspot
  • shenandoah

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

@openjdk openjdk bot added hotspot shenandoah labels Dec 16, 2020
@iklam iklam marked this pull request as ready for review Dec 16, 2020
@openjdk openjdk bot added the rfr label Dec 16, 2020
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@mlbridge mlbridge bot commented Dec 16, 2020

Webrevs

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@lfoltan lfoltan left a comment

LGTM.
Lois

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@openjdk openjdk bot commented Dec 16, 2020

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

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

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

8258459: Decouple gc_globals.hpp from globals.hpp

Reviewed-by: lfoltan, coleenp

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been no new commits pushed to the master branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential automatic rebasing, please check the documentation for the /integrate command for further details.

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@openjdk openjdk bot added the ready label Dec 16, 2020
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@coleenp coleenp left a comment

Looks good! I had a couple of minor change requests.

@@ -185,7 +185,7 @@ int oopDesc::size_given_klass(Klass* klass) {
// disjunct below to fail if the two comparands are computed across such
// a concurrent change.
assert((s == klass->oop_size(this)) ||
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@coleenp coleenp Dec 22, 2020

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It might be nicer to throw the second half of this assert into the .cpp file, like
assert(s == klass->oop_size(this) || gc_has_forwarded(), "wrong array object size");
With the special comment above it in the cpp file. Then someone has the potential to add more information if the assert fails, and that gets Universe::hpp out of the inline file (if that helps with future cleanups).

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@iklam iklam Jan 4, 2021

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I'd like to keep this PR minimal. If I change (Universe::heap()->is_gc_active() && is_objArray() && is_forwarded() && (get_UseParallelGC() || get_UseG1GC()) to gc_has_forwarded(), I would also need to move the comments about UseParallelGC and UseG1GC can change the length field of an "old copy".... I think that should be done in a separate PR.

@@ -58,6 +58,10 @@ ThreadLocalAllocBuffer::ThreadLocalAllocBuffer() :
// do nothing. TLABs must be inited by initialize() calls
}

size_t ThreadLocalAllocBuffer::initial_refill_waste_limit() { return desired_size() / TLABRefillWasteFraction; }
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@coleenp coleenp Dec 22, 2020

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nit: please line this up.

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@iklam iklam Jan 4, 2021

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Fixed

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@iklam iklam commented Jan 5, 2021

Thanks @coleenp and @lfoltan for the review!
/integrate

@openjdk openjdk bot closed this Jan 5, 2021
@openjdk openjdk bot added integrated and removed ready rfr labels Jan 5, 2021
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@openjdk openjdk bot commented Jan 5, 2021

@iklam Pushed as commit 5ea9607.

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

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