8256215: Shenandoah: re-organize saving/restoring machine state in assembler code

[shipilev]

$ CONF=linux-x86-server-fastdebug make images run-test TEST=compiler/c1/Test6855215.java TEST_VM_OPTS="-XX:+UseShenandoahGC"

# Internal Error (/home/shade/trunks/jdk/src/hotspot/cpu/x86/assembler_x86.cpp:3047), pid=1427307, tid=1427311
# Error: assert(VM_Version::supports_sse2()) failed

V [libjvm.so+0x53f9e8] Assembler::movsd(Address, XMMRegisterImpl*)+0x168
V [libjvm.so+0x14647bd] save_xmm_registers(MacroAssembler*)+0x9d
V [libjvm.so+0x1465d8f] ShenandoahBarrierSetAssembler::load_reference_barrier(MacroAssembler*, RegisterImpl*, Address, ShenandoahBarrierSet::AccessKind)+0x91f

This only affects x86_32, as x86_64 uses at least UseSSE >= 2 at all times.

Additional testing:

• tier1, Linux x86_64 -XX:+UseShenandoahGC
• tier1, Linux x86_32 -XX:+UseShenandoahGC
• tier1, Linux x86_32 -XX:+UseShenandoahGC -XX:UseSSE=0
• tier1, Linux x86_32 -XX:+UseShenandoahGC -XX:UseSSE=1

---

Progress

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

Issue

• JDK-8256215: Shenandoah: re-organize saving/restoring machine state in assembler code

Reviewers

• Roman Kennke (@rkennke - Reviewer) ⚠️ Review applies to b4db69e
• Zhengyu Gu (@zhengyu123 - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1172/head:pull/1172
$ git checkout pull/1172

[bridgekeeper]

👋 Welcome back shade! 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.

[openjdk]

@shipilev 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]

@shipilev this pull request can not be integrated into master due to one or more merge conflicts. To resolve these merge conflicts and update this pull request you can run the following commands in the local repository for your personal fork:

git checkout JDK-8256215-shenandoah-no-sse2-fail
git fetch https://git.openjdk.java.net/jdk master
git merge FETCH_HEAD
# resolve conflicts and follow the instructions given by git merge
git commit -m "Merge master"
git push

[rkennke]

Nice change! See comment. Do we need to handle no-SSE case too?

[bridgekeeper]

@shipilev This pull request has been inactive for more than 4 weeks and will be automatically closed if another 4 weeks passes without any activity. To avoid this, simply add a new comment to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

[mlbridge]

Webrevs

• 01: Full - Incremental (489c0db)
• 00: Full (b4db69e)

[zhengyu123]

Probably, no processor that does not support sse2, but should we always use VM_version::supports_sse(x)? instead of UseSSE(x)

[shipilev]

Probably, no processor that does not support sse2, but should we always use VM_version::supports_sse(x)? instead of UseSSE(x)

"Hotspot way" seems to be "check for VM_version::supports_sse* in assemblers" + "check for appropriate UseSSE level in machine-specific code before asking assemblers". This is what the patch does. ...or I misunderstand the question.

[rkennke]

Looks good, but I have questions.

[rkennke]

Looks good to me! Thanks!

[openjdk]

@shipilev 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:

8256215: Shenandoah: re-organize saving/restoring machine state in assembler code

Reviewed-by: rkennke, zgu

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 4 new commits pushed to the master branch:

• 311a0a9: 8259808: Add JFR event to detect GC locker stall
• f353fcf: 8258894: C2: Forbid GCM to move stores into loops
• ac276bb: 8257074: Update the ByteBuffers micro benchmark
• 7ed591c: 8260314: Replace border="1" on tables with CSS

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

[zhengyu123]

Probably, no processor that does not support sse2, but should we always use VM_version::supports_sse(x)? instead of UseSSE(x)

"Hotspot way" seems to be "check for VM_version::supports_sse* in assemblers" + "check for appropriate UseSSE level in machine-specific code before asking assemblers". This is what the patch does. ...or I misunderstand the question.

Okay, then.

[shipilev]

/integrate

[openjdk]

@shipilev Since your change was applied there have been 18 commits pushed to the master branch:

• 316d52c: 8260497: Shenandoah: Improve SATB flushing
• 11a70d1: 8260426: awt debug_mem.c DMem_AllocateBlock might leak memory
• 396a496: 8260467: Move well-known classes from systemDictionary.hpp to vmClasses.hpp
• 62ffe75: Merge
• e28e111: 8260370: C2: LoopLimit node is not eliminated
• 7030d2e: 8260200: G1: Remove unnecessary update in FreeRegionList::remove_starting_at
• c7661ae: 8260561: [doc] HexFormat has incorrect @SInCE tag
• c52212b: Merge
• 408772c: 8259025: Record compact constructor using Objects.requireNonNull
• 81e730e: 8259276: C2: Empty expression stack when reexecuting tableswitch/lookupswitch instructions after deoptimization
• ... and 8 more: https://git.openjdk.java.net/jdk/compare/e696baabfbe71948cec623dcdd50ae84ca99d4c5...master

Your commit was automatically rebased without conflicts.

Pushed as commit a97aedf.

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