8300247: Harden C1 xchg on AArch64 and PPC #12065

fisk · 2023-01-18T09:00:10Z

In the C1 xchg operation, AArch64 and PPC don't deal well with the input register and output register being the same. In some new code, that can happen. This change aims at solving that issue.

As for AArch64, the xchg implementation in the macro assembler already deals well with the input and output register being the same. So we just need to remove an assert. As for the PPC implementation, @TheRealMDoerr has written a variation that uses a temp operand ensuring that they are not the same register.

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Issue

JDK-8300247: Harden C1 xchg on AArch64 and PPC

Reviewers

Andrew Haley (@theRealAph - Reviewer) ⚠️ Review applies to b361fe26
Roberto Castañeda Lozano (@robcasloz - Reviewer)

Contributors

Martin Doerr <mdoerr@openjdk.org>

Reviewing

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk pull/12065/head:pull/12065
$ git checkout pull/12065

Update a local copy of the PR:
$ git checkout pull/12065
$ git pull https://git.openjdk.org/jdk pull/12065/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 12065

View PR using the GUI difftool:
$ git pr show -t 12065

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Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/12065.diff

fisk · 2023-01-18T09:01:14Z

/contributor add @TheRealMDoerr

fisk · 2023-01-18T09:01:26Z

/contributor @xmas92

bridgekeeper · 2023-01-18T09:02:20Z

👋 Welcome back eosterlund! 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 · 2023-01-18T09:03:41Z

@fisk
Contributor Martin Doerr <mdoerr@openjdk.org> successfully added.

openjdk · 2023-01-18T09:05:08Z

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openjdk · 2023-01-18T09:06:02Z

@fisk The following label will be automatically applied to this pull request:

hotspot-compiler

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

mlbridge · 2023-01-18T09:10:24Z

Webrevs

01: Full - Incremental (a423daf6)
00: Full (b361fe26)

openjdk · 2023-01-18T10:08:34Z

@fisk 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:

8300247: Harden C1 xchg on AArch64 and PPC

Co-authored-by: Martin Doerr <mdoerr@openjdk.org>
Reviewed-by: aph, rcastanedalo

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 204 new commits pushed to the master branch:

3f63381: 8300913: ZGC: assert(to_addr != 0) failed: Should be forwarded
da80e7a: 8300962: Parallel: Remove PSParallelCompact::_total_invocations
7725fe8: 8299953: Merge ContiguousSpaceDCTOC into DirtyCardToOopClosure
a9b8acb: 8300652: Parallel: Refactor oop marking stack in Full GC
15a1488: 8297437: javadoc cannot link to old docs (with old style anchors)
b0376a5: 8301069: Replace NULL with nullptr in share/libadt/
7328182: 8300958: Parallel: Remove unused MutableNUMASpace::capacity_in_words
30cb305: 8292170: Convert CodeRootSetTable to use ResourceHashtable
3589b80: 8300127: Serial: Remove unnecessary from-space iteration in DefNewGeneration::oop_since_save_marks_iterate
48152ef: 8287134: HttpURLConnection chunked streaming mode doesn't enforce specified size
... and 194 more: https://git.openjdk.org/jdk/compare/a734285314a34ed61583132f2fc6be9d9c861af4...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.

TheRealMDoerr · 2023-01-18T14:35:46Z

Thanks for including my PPC64 code!

fisk · 2023-01-18T14:53:00Z

Thanks for the review, @theRealAph!

RealFYang · 2023-01-20T04:57:39Z

Hi, I think we could also relax the same assertion for riscv too.
The ultimate 'amoswap.w/d' instruction emitted in this case does not require that 'dst' and 'obj' must be different registers.
Could you please also add this extra small change while are you at it? Thanks.

diff --git a/src/hotspot/cpu/riscv/c1_LIRAssembler_riscv.cpp b/src/hotspot/cpu/riscv/c1_LIRAssembler_riscv.cpp
index aec62aba489..d960d64522c 100644
--- a/src/hotspot/cpu/riscv/c1_LIRAssembler_riscv.cpp
+++ b/src/hotspot/cpu/riscv/c1_LIRAssembler_riscv.cpp
@@ -1967,7 +1967,8 @@ void LIR_Assembler::atomic_op(LIR_Code code, LIR_Opr src, LIR_Opr data, LIR_Opr
           __ encode_heap_oop(t0, obj);
           obj = t0;
         }
-        assert_different_registers(obj, addr.base(), tmp, dst);
+        assert_different_registers(obj, addr.base(), tmp);
+        assert_different_registers(dst, addr.base(), tmp);
         __ la(tmp, addr);
         (_masm->*xchg)(dst, obj, tmp);
         if (is_oop && UseCompressedOops) {

fisk · 2023-01-23T09:06:57Z

@RealFYang Sure - fixed!

robcasloz

Looks good.

fisk · 2023-01-26T14:32:23Z

Looks good.

Thanks for the review!

fisk · 2023-01-26T14:34:57Z

/integrate

openjdk · 2023-01-26T14:35:32Z

Going to push as commit 28545dc.
Since your change was applied there have been 204 commits pushed to the master branch:

3f63381: 8300913: ZGC: assert(to_addr != 0) failed: Should be forwarded
da80e7a: 8300962: Parallel: Remove PSParallelCompact::_total_invocations
7725fe8: 8299953: Merge ContiguousSpaceDCTOC into DirtyCardToOopClosure
a9b8acb: 8300652: Parallel: Refactor oop marking stack in Full GC
15a1488: 8297437: javadoc cannot link to old docs (with old style anchors)
b0376a5: 8301069: Replace NULL with nullptr in share/libadt/
7328182: 8300958: Parallel: Remove unused MutableNUMASpace::capacity_in_words
30cb305: 8292170: Convert CodeRootSetTable to use ResourceHashtable
3589b80: 8300127: Serial: Remove unnecessary from-space iteration in DefNewGeneration::oop_since_save_marks_iterate
48152ef: 8287134: HttpURLConnection chunked streaming mode doesn't enforce specified size
... and 194 more: https://git.openjdk.org/jdk/compare/a734285314a34ed61583132f2fc6be9d9c861af4...master

Your commit was automatically rebased without conflicts.

openjdk · 2023-01-26T14:35:45Z

@fisk Pushed as commit 28545dc.

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

8300247: Harden C1 xchg on AArch64 and PPC

b361fe2

openjdk bot added the rfr Pull request is ready for review label Jan 18, 2023

openjdk bot added the hotspot-compiler hotspot-compiler-dev@openjdk.org label Jan 18, 2023

theRealAph approved these changes Jan 18, 2023

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openjdk bot added the ready Pull request is ready to be integrated label Jan 18, 2023

RISC-V fix

a423daf

robcasloz approved these changes Jan 26, 2023

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8300247: Harden C1 xchg on AArch64 and PPC #12065

8300247: Harden C1 xchg on AArch64 and PPC #12065

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8300247: Harden C1 xchg on AArch64 and PPC #12065

8300247: Harden C1 xchg on AArch64 and PPC #12065

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