8351156: C1: Remove FPU stack support after 32-bit x86 removal

[shipilev]

C1 has the 32-bit x86 specific code that supports x87 FPU stack allocations. With 32-bit x86 port removed, we can clean up those parts. 64-bit x86 does not need x87 FPU, since it is baselined on SSE2 and using XMM registers instead.

There are lots of deeper cleanups possible, this PR focuses on removing the x87 FPU allocation/uses in C1. Note current C1 nomenclature is confusing. On all arches, "FPU" means floating-point registers. That is except on x86, where "FPU" means x87 FPU stack, and "XMM" means floating-point registers. This is why we only touch "FPU" code on other architectures only in a light manner. After all 32-bit x86 cleanups land, we might consider renaming "XMM" -> "FPU" in x86 C1 to match the common nomenclature.

Brief tour of changes:

• FPU stack simulator is not needed anymore, so I removed it and the related infrastructure
• Lots of 32-bit specific paths that touch x87 FPU registers are pruned
• Related LIR nodes like lir_fxch, lir_fld, lir_fpop_raw are pruned
• Simplified the API that is no longer needed, e.g. dropping pop_fpu_stack

This PR would likely conflict with some in-flight cleanups, so it would require merges later. Take a look meanwhile.

Additional testing:

• Linux x86_64 server fastdebug, tier1
• Linux x86_64 server fastdebug, tier1 + -XX:TieredStopAtLevel=1
• Linux x86_64 server fastdebug, all
• Linux x86_64 server fastdebug, all + -XX:TieredStopAtLevel=1

---

Progress

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Issue

• JDK-8351156: C1: Remove FPU stack support after 32-bit x86 removal (Sub-task - P4)

Reviewers

• Vladimir Ivanov (@iwanowww - Reviewer)
• Vladimir Kozlov (@vnkozlov - Reviewer)

Reviewing

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[openjdk]

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

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

8351156: C1: Remove FPU stack support after 32-bit x86 removal

Reviewed-by: vlivanov, kvn

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At the time when this comment was updated there had been 16 new commits pushed to the master branch:

• c70ad6a: 8352906: stdout/err.encoding on Windows set by incorrect Win32 call
• da3bb06: 8352685: Opensource JInternalFrame tests - series2
• d809033: 8341775: Duplicate manifest files are removed by jarsigner after signing
• a269bef: 8350459: MontgomeryIntegerPolynomialP256 multiply intrinsic with AVX2 on x86_64
• c029220: 8352896: LambdaExpr02.java runs wrong test class
• c0b61d3: 8352680: Opensource few misc swing tests
• 3e9a7a4: 8353063: make/ide/vscode: Invalid Configuration Values
• 8ef7832: 8350471: Unhandled compilation bailout in GraphKit::builtin_throw
• ddf326b: 8346888: [ubsan] block.cpp:1617:30: runtime error: 9.97582e+36 is outside the range of representable values of type 'int'
• bac2aa4: 8352946: SEGV_BND signal code of SIGSEGV missing from our signal-code table
• ... and 6 more: https://git.openjdk.org/jdk/compare/b73663a2b4fe7049fc0990c1a1e51221640b4e29...master

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[mlbridge]

Webrevs

• 01: Full (fcdb6345)
• 00: Full (593501fa)

[vnkozlov]

On all arches, "FPU" means floating-point registers.

Which is wrong I think. It should be "FPR". May be file RFE to rename LIR_Opr::is_*_fpu() methods to LIR_Opr::is_*_fpr()

[shipilev]

Which is wrong I think. It should be "FPR". May be file RFE to rename LIR_Opr::is_*_fpu() methods to LIR_Opr::is_*_fpr()

Yes, that would be more accurate. Remains to be seen how intrusive is this rename.

[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-8351156-x86-c1-fpustack
git fetch https://git.openjdk.org/jdk.git master
git merge FETCH_HEAD
# resolve conflicts and follow the instructions given by git merge
git commit -m "Merge master"
git push

[iwanowww]

Looks good.

[shipilev]

Are you still good with this, @vnkozlov? I would like to integrate it sooner to unblock some dependent cleanup work.

[vnkozlov]

Good.

[shipilev]

Thank you! Here we go.

/integrate

[openjdk]

Going to push as commit 23e3b3f.
Since your change was applied there have been 22 commits pushed to the master branch:

• 2592513: 8350577: Fix missing Assertion Predicates when splitting loops
• 59629f8: 8351040: [REDO] Protection zone for easier detection of accidental zero-nKlass use
• 8cbadf7: 8317976: Optimize SIMD sort for AMD Zen 4
• b9d7a75: 8352879: TestPeriod.java and TestGetContentType.java run wrong test class
• 895aabc: 8351233: [ASAN] avx2-emu-funcs.hpp:151:20: error: ‘D.82188’ is used uninitialized
• 3d2c3cd: 8352970: Remove unnecessary Windows version check in Win32ShellFolderManager2
• c70ad6a: 8352906: stdout/err.encoding on Windows set by incorrect Win32 call
• da3bb06: 8352685: Opensource JInternalFrame tests - series2
• d809033: 8341775: Duplicate manifest files are removed by jarsigner after signing
• a269bef: 8350459: MontgomeryIntegerPolynomialP256 multiply intrinsic with AVX2 on x86_64
• ... and 12 more: https://git.openjdk.org/jdk/compare/b73663a2b4fe7049fc0990c1a1e51221640b4e29...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit 23e3b3f.

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