Unhide compressed refs logic from Unsafe CAS codegen #20400
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Disables code on Power and Z that hides compressedrefs logic from the fast path code generation for the following recognized methods: sun_misc_Unsafe_compareAndSwapObject_jlObjectJjlObjectjlObject_Z jdk_internal_misc_Unsafe_compareAndExchangeObject jdk_internal_misc_Unsafe_compareAndExchangeReference Fast path code generation for those recognized methods is updated to handle compressedrefs. Original behavior can be restored by setting the TR_UseOldCompareAndSwapObject environment variable. This behavior matches the X implementation which has already disabled the compressedrefs hiding logic when the envvar is not set. Signed-off-by: jimmyk <[email protected]>
| // Hiding compressedref logic from CodeGen doesn't seem a good practise, the evaluator always need the uncompressedref node for write barrier, | ||
| // therefore, this part is deprecated. It'll be removed once P and Z update their corresponding evaluators. | ||
| // Hiding compressedref logic from CodeGen isn't a good practice, and the evaluator still needs the uncompressedref node for write barriers. | ||
| // Therefore, this part is deprecated. It can only be activated on X, P or Z with the TR_UseOldCompareAndSwapObject envvar. | ||
| static bool UseOldCompareAndSwapObject = (bool)feGetEnv("TR_UseOldCompareAndSwapObject"); |
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Something that already in code, but not related to overall changes, Should we change UseOldCompareAndSwapObject to useOldCompareAndSwapObject ?
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I can change this.
| @@ -11952,7 +11952,7 @@ TR::Register* | |||
| J9::Z::TreeEvaluator::VMinlineCompareAndSwap(TR::Node *node, TR::CodeGenerator *cg, TR::InstOpCode::Mnemonic casOp, bool isObj, bool isExchange) | |||
| { | |||
| TR::Register *scratchReg = NULL; | |||
| TR::Register *objReg, *oldVReg, *newVReg; | |||
| TR::Register *objReg, *oldVReg, *newVReg, *decompressedValueRegister; | |||
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I understand this exists, but we should initialize the registers here with NULL.
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I can change this.
| @@ -11969,9 +11969,10 @@ J9::Z::TreeEvaluator::VMinlineCompareAndSwap(TR::Node *node, TR::CodeGenerator * | |||
| // compression sequence. | |||
| bool isValueCompressedReference = false; | |||
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| TR::Node* decompressedValueNode = newVNode; | |||
| static bool UseOldCompareAndSwapObject = (bool)feGetEnv("TR_UseOldCompareAndSwapObject"); | |||
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I understand the intention was to match the environment set throughout the code base, but we should rename variable name useOldCompareAndSwapObject
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Added more comments to clarify issues. Renamed UseOldCompareAndSwapObject to useOldCompareAndSwapObject.
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My latest commit should address all previous comments. |
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jenkins test sanity all jdk21 |
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Failure in https://openj9-jenkins.osuosl.org/job/Test_openjdk21_j9_sanity.openjdk_aarch64_linux_Personal/84/ is not related with the changes in this PR, they are related to #18463. |
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Given the one failure related to #18463, other tests on all other platform passes. Merging this one. |
Disables code on Power and Z that hides compressedrefs logic from the fast path code generation for the following recognized methods:
sun_misc_Unsafe_compareAndSwapObject_jlObjectJjlObjectjlObject_Zjdk_internal_misc_Unsafe_compareAndExchangeObjectjdk_internal_misc_Unsafe_compareAndExchangeReferenceFast path code generation for those recognized methods is updated to handle compressedrefs.
Original behavior can be restored by setting the
TR_UseOldCompareAndSwapObjectenvironment variable. This behavior matches the X implementation which has already disabled the compressedrefs hiding logic when the envvar is not set.