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Guard a call to VMwrtbarWithoutStoreEvaluator #18027

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Sep 8, 2023
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Guard a call to VMwrtbarWithoutStoreEvaluator #18027

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23 changes: 18 additions & 5 deletions runtime/compiler/x/codegen/J9TreeEvaluator.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9703,11 +9703,24 @@ static TR::Register* inlineCompareAndSwapObjectNative(TR::Node* node, TR::CodeGe
generateRegInstruction(TR::InstOpCode::SETE1Reg, node, result, cg);
generateRegRegInstruction(TR::InstOpCode::MOVZXReg4Reg1, node, result, result, cg);

// We could insert a runtime test for whether the write actually succeeded or not.
// However, since in practice it will almost always succeed we do not want to
// penalize general runtime performance especially if it is still correct to do
// a write barrier even if the store never actually happened.
TR::TreeEvaluator::VMwrtbarWithoutStoreEvaluator(node, objectNode, newValueNode, NULL, cg->generateScratchRegisterManager(), cg);
// Non-realtime: Generate a write barrier for this kind of object.
//
if (!comp->getOptions()->realTimeGC())
{
// We could insert a runtime test for whether the write actually succeeded or not.
// However, since in practice it will almost always succeed we do not want to
// penalize general runtime performance especially if it is still correct to do
// a write barrier even if the store never actually happened.
TR_X86ScratchRegisterManager *scratchRegisterManager = cg->generateScratchRegisterManager();

TR::TreeEvaluator::VMwrtbarWithoutStoreEvaluator(
node,
objectNode,
newValueNode,
NULL,
scratchRegisterManager,
cg);
}

cg->stopUsingRegister(tmp);
cg->stopUsingRegister(EAX);
Expand Down