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8262739: String inflation C2 intrinsic prevents insertion of anti-dependencies #3025
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👋 Welcome back thartmann! A progress list of the required criteria for merging this PR into |
@TobiHartmann The following label will be automatically applied to this pull request:
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Looks good.
@TobiHartmann 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:
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
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Thanks for the review, Nils! |
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Otherwise, the fix looks good!
src/hotspot/share/adlc/formssel.cpp
Outdated
@@ -778,6 +778,7 @@ bool InstructForm::captures_bottom_type(FormDict &globals) const { | |||
!strcmp(_matrule->_rChild->_opType,"RotateLeft") || | |||
!strcmp(_matrule->_rChild->_opType,"RotateRight") || | |||
#if INCLUDE_SHENANDOAHGC | |||
!strcmp(_matrule->_rChild->_opType,"StrInflatedCopy") || |
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Should not be inside #if INCLUDE_SHENANDOAHGC
.
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Yes, good catch, thank you! (That happens when doing last-minute re-ordering ...). Fixed.
Thanks for the review, Christian! |
/integrate |
@TobiHartmann Since your change was applied there have been 216 commits pushed to the
Your commit was automatically rebased without conflicts. Pushed as commit 3caea47. 💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored. |
The string inflation intrinsic
StrInflatedCopyNode
which converts the String internal byte[] to char[] hasbottom_type
Type::MEMORY
:jdk/src/hotspot/share/opto/intrinsicnode.hpp
Lines 143 to 145 in f71e8a6
Memory users (i.e. loads) should therefore be checked for nearby anti-dependent stores:
jdk/src/hotspot/share/opto/node.cpp
Lines 1482 to 1486 in f71e8a6
However, since
InstructForm::captures_bottom_type
returnsfalse
forStrInflatedCopyNode
, after matching, the correspondingMachNode
version will havebottom_type
Type::BOTTOM
and no anti-dependency analysis will be performed for its users. Scheduling then incorrectly orders loads from the char array with anti-dependent stores to the same array, leading to incorrect results.StrCompressedCopyNode
does not need this because it hasTypeInt::INT
asbottom_type
(the memory output is handled via aSCMemProjNode
):jdk/src/hotspot/share/opto/intrinsicnode.hpp
Lines 131 to 133 in f71e8a6
Thanks,
Tobias
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$ git fetch https://git.openjdk.java.net/jdk pull/3025/head:pull/3025
$ git checkout pull/3025