8319764: C2 compilation asserts during incremental inlining because Phi input is out of bounds #16648

rwestrel · 2023-11-14T08:56:09Z

In the test case:

lateInlined1() and lateInlined2() are inlined incrementally
because they are invoked wih a method handle which is known constant
only after igvn. For the failure to reproduce, lateInlined2() must
be inlined after lateInlined1() which depends on igvn processing
order (that's why the test needs StressIGVN). lateInlined1() has 2
virtual calls that are inlined with bimorphic inlining. At each call
site, exception state is merged from A.m() and B.m(), the 2
methods that are inlined. c is casted to non null in A.m(). At the
first call site, c is live and merging the exception states causes
the creation of a Phi for c that merges c and the cast to non
null of c. At the second call site, c is not live so it's ignored
when merging exception states. When the exception states for the 2
call sites are combined, the region that merges the states at the
first call site is extended to have 4 inputs but the Phi for c at
the first call site is left with 2 inputs. When lateInlined2() is
inlined, it records a replaced node for a cast of c to non null. On
completion of incremental inlining, that replaced nodes is "applied".
In the process, the dead Phi for c created at the previous
incremental inline is found and because it has less inputs that its
region, the crash occurs.

The fix I propose is to simply ignore phi nodes that don't have the
same number of inputs as their region because they can only be a dead
Phi.

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Issue

JDK-8319764: C2 compilation asserts during incremental inlining because Phi input is out of bounds (Bug - P3)

Reviewers

Tobias Hartmann (@TobiHartmann - Reviewer) ⚠️ Review applies to f598fe25
Christian Hagedorn (@chhagedorn - Reviewer) ⚠️ Review applies to f598fe25

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bridgekeeper · 2023-11-14T08:57:43Z

👋 Welcome back roland! 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 · 2023-11-14T08:59:30Z

@rwestrel 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 · 2023-11-14T09:08:46Z

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TobiHartmann · 2023-11-14T10:12:21Z

test/hotspot/jtreg/compiler/inlining/TestLateInlineReplacedNodesExceptionPath.java

+ * @run main/othervm -XX:-TieredCompilation -XX:-BackgroundCompilation -XX:CompileCommand=dontinline,TestLateInlineReplacedNodesExceptionPath::notInlined
+ *                   -XX:+StressIGVN -XX:StressSeed=1246687813 TestLateInlineReplacedNodesExceptionPath
+ * @run main/othervm -XX:-TieredCompilation -XX:-BackgroundCompilation -XX:CompileCommand=dontinline,TestLateInlineReplacedNodesExceptionPath::notInlined
+ *                   -XX:+StressIGVN TestLateInlineReplacedNodesExceptionPath


VM option 'StressIGVN' is diagnostic and must be enabled via -XX:+UnlockDiagnosticVMOptions.

Thanks for looking at this. Fixed in the new commit.

TobiHartmann

Looks reasonable to me. Could you elaborate on why this wasn't an issue before JDK-8312980?

openjdk · 2023-11-15T08:31:52Z

@rwestrel 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:

8319764: C2 compilation asserts during incremental inlining because Phi input is out of bounds

Reviewed-by: thartmann, chagedorn

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 94 new commits pushed to the master branch:

6868b37: 8318826: C2: "Bad graph detected in build_loop_late" with incremental inlining
1d96886: 8319531: FileServerHandler::discardRequestBody could be improved
73e19f6: 8319825: jdk.net/jdk.net.ExtendedSocketOptions::IP_DONTFRAGMENT is missing @SInCE 19
faeea07: 8319747: galoisCounterMode_AESCrypt stack walking broken
b4c2d1c: 8319542: Fix boundaries of region to be tested with os::is_readable_range
c36ec2c: 8316653: Large NMethodSizeLimit triggers assert during C1 code buffer allocation
2db9ea9: 8317723: C2: CountedLoopEndNodes and Zero Trip Guards are wrongly treated as Runtime Predicate
eaa4417: 8319301: Static analysis warnings after JDK-8318016
3452210: 8283140: Remove unused encoding classes/operands from x86_64.ad
f0b7eb5: 8304020: Speed up test/jdk/java/util/zip/ZipFile/TestTooManyEntries.java and clarify its purpose
... and 84 more: https://git.openjdk.org/jdk/compare/7c7f8ea30da7fe552bcd4f2b593fa9aad27dcdb4...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.

TobiHartmann · 2023-11-15T13:46:36Z

src/hotspot/share/opto/replacednodes.cpp

+                if (in != nullptr && !in->is_top()) {
+                  if (is_dominator(ctl, in)) {


Ifs can be merged.

Done in new commit.

chhagedorn

That looks reasonable to me, too!

test/hotspot/jtreg/compiler/inlining/TestLateInlineReplacedNodesExceptionPath.java

chhagedorn · 2023-11-15T14:22:35Z

test/hotspot/jtreg/compiler/inlining/TestLateInlineReplacedNodesExceptionPath.java

+ * bug 8319764
+ * @summary C2 compilation asserts during incremental inlining because Phi input is out of bounds
+ * @run main/othervm -XX:-TieredCompilation -XX:-BackgroundCompilation -XX:CompileCommand=dontinline,TestLateInlineReplacedNodesExceptionPath::notInlined
+ *                   -XX:+UnlockDiagnosticVMOptions -XX:+StressIGVN -XX:StressSeed=1246687813 TestLateInlineReplacedNodesExceptionPath


Since StressIGVN is C2 specific, you should add a @requires vm.compiler2.enabled.

Done in new commit.

chhagedorn · 2023-11-15T14:58:10Z

src/hotspot/share/opto/replacednodes.cpp

-                if (is_dominator(ctl, in)) {
-                  valid_control.set(in->_idx);
-                  collect_nodes_to_clone(stack, to_fix);
+          if (n->req() == region->req()) { // dead phi?


Maybe you can change this comment to "ignore dead phis".

Done in new commit.

rwestrel · 2023-11-15T16:05:21Z

Looks reasonable to me. Could you elaborate on why this wasn't an issue before JDK-8312980?

Logic was quite different: it would go over the phi inputs looking for one that was of interest and then only looked at the region's input for that phi input so a phi with fewer inputs than the region wasn't an issue.

…esExceptionPath.java Co-authored-by: Christian Hagedorn <christian.hagedorn@oracle.com>

rwestrel · 2023-11-15T16:13:09Z

That looks reasonable to me, too!

Thanks for reviewing and making suggestions.

TobiHartmann

Thanks for the explanation. Looks good.

chhagedorn

Still looks good

test/hotspot/jtreg/compiler/inlining/TestLateInlineReplacedNodesExceptionPath.java

…esExceptionPath.java Co-authored-by: Christian Hagedorn <christian.hagedorn@oracle.com>

rwestrel · 2023-11-16T12:42:13Z

@TobiHartmann @chhagedorn thanks for the reviews.

rwestrel · 2023-11-16T12:42:20Z

/integrate

openjdk · 2023-11-16T12:43:55Z

Going to push as commit f33c874.
Since your change was applied there have been 94 commits pushed to the master branch:

6868b37: 8318826: C2: "Bad graph detected in build_loop_late" with incremental inlining
1d96886: 8319531: FileServerHandler::discardRequestBody could be improved
73e19f6: 8319825: jdk.net/jdk.net.ExtendedSocketOptions::IP_DONTFRAGMENT is missing @SInCE 19
faeea07: 8319747: galoisCounterMode_AESCrypt stack walking broken
b4c2d1c: 8319542: Fix boundaries of region to be tested with os::is_readable_range
c36ec2c: 8316653: Large NMethodSizeLimit triggers assert during C1 code buffer allocation
2db9ea9: 8317723: C2: CountedLoopEndNodes and Zero Trip Guards are wrongly treated as Runtime Predicate
eaa4417: 8319301: Static analysis warnings after JDK-8318016
3452210: 8283140: Remove unused encoding classes/operands from x86_64.ad
f0b7eb5: 8304020: Speed up test/jdk/java/util/zip/ZipFile/TestTooManyEntries.java and clarify its purpose
... and 84 more: https://git.openjdk.org/jdk/compare/7c7f8ea30da7fe552bcd4f2b593fa9aad27dcdb4...master

Your commit was automatically rebased without conflicts.

openjdk · 2023-11-16T12:44:04Z

@rwestrel Pushed as commit f33c874.

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

fix & test

7ec097e

rwestrel marked this pull request as draft November 14, 2023 08:58

openjdk bot added the hotspot-compiler hotspot-compiler-dev@openjdk.org label Nov 14, 2023

rwestrel changed the title ~~;; This buffer is for text that is not saved, and for Lisp evaluation.~~ 8319764: C2 compilation asserts during incremental inlining because Phi input is out of bounds Nov 14, 2023

rwestrel marked this pull request as ready for review November 14, 2023 09:04

openjdk bot added the rfr Pull request is ready for review label Nov 14, 2023

TobiHartmann reviewed Nov 14, 2023

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-XX:+UnlockDiagnosticVMOptions

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rwestrel and others added 2 commits November 15, 2023 17:05

Update test/hotspot/jtreg/compiler/inlining/TestLateInlineReplacedNod…

e49aca9

…esExceptionPath.java Co-authored-by: Christian Hagedorn <christian.hagedorn@oracle.com>

reviews

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TobiHartmann approved these changes Nov 16, 2023

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chhagedorn approved these changes Nov 16, 2023

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test/hotspot/jtreg/compiler/inlining/TestLateInlineReplacedNodesExceptionPath.java Outdated Show resolved Hide resolved

Update test/hotspot/jtreg/compiler/inlining/TestLateInlineReplacedNod…

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…esExceptionPath.java Co-authored-by: Christian Hagedorn <christian.hagedorn@oracle.com>

openjdk bot added the integrated Pull request has been integrated label Nov 16, 2023

openjdk bot closed this Nov 16, 2023

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Nov 16, 2023

		if (in != nullptr && !in->is_top()) {
		if (is_dominator(ctl, in)) {

8319764: C2 compilation asserts during incremental inlining because Phi input is out of bounds #16648

8319764: C2 compilation asserts during incremental inlining because Phi input is out of bounds #16648

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