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Correct the handling of hidden class field comparisions #18374

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Nov 8, 2023
Merged

Correct the handling of hidden class field comparisions #18374

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9d68a73
Correct the handling of hidden class field comparisions
nbhuiyan Oct 30, 2023
a6584f8
Correct handling of hidden class field comparisions in J9ServerVM
nbhuiyan Nov 3, 2023
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11 changes: 11 additions & 0 deletions runtime/compiler/env/VMJ9.cpp
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Expand Up @@ -6988,6 +6988,17 @@ TR_J9VMBase::jitFieldsAreSame(TR_ResolvedMethod * method1, I_32 cpIndex1, TR_Res
TR::VMAccessCriticalSection jitFieldsAreSame(this);
bool result = false;

// Hidden classes generated within the same host class do not have distinct class names,
// but share the same field names with different field data types and offsets. Therefore,
// name-based check for whether fields are same can result in false positives when it comes
// to hidden classes unless the fields are from the same j9class objects.
if (method1->classOfMethod()
&& method2->classOfMethod()
&& (isHiddenClass(method1->classOfMethod())
|| isHiddenClass(method2->classOfMethod()))
&& method1->classOfMethod() != method2->classOfMethod())
return false;
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bool sigSame = true;
if (method1->fieldsAreSame(cpIndex1, method2, cpIndex2, sigSame))
result = true;
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9 changes: 9 additions & 0 deletions runtime/compiler/env/VMJ9.h
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Expand Up @@ -1295,6 +1295,15 @@ class TR_J9VMBase : public TR_FrontEnd

virtual bool isAnonymousClass(TR_OpaqueClassBlock *j9clazz) { return (J9_ARE_ALL_BITS_SET(((J9Class*)j9clazz)->romClass->extraModifiers, J9AccClassAnonClass)); }
virtual bool isAnonymousClass(J9ROMClass *romClass) { return (J9_ARE_ALL_BITS_SET(romClass->extraModifiers, J9AccClassAnonClass)); }

/**
* \brief Check whether or not the class object is a hidden class
*
* \param j9clazz the class location
* \return true if class is hidden class, false otherwise
*/
virtual bool isHiddenClass(TR_OpaqueClassBlock *j9clazz) { return (J9_ARE_ALL_BITS_SET(((J9Class*)j9clazz)->romClass->extraModifiers, J9AccClassHidden)); }

virtual int64_t getCpuTimeSpentInCompThread(TR::Compilation * comp); // resolution is 0.5 sec or worse. Returns -1 if unavailable

virtual void * getClassLoader(TR_OpaqueClassBlock * classPointer);
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26 changes: 25 additions & 1 deletion runtime/compiler/env/VMJ9Server.cpp
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Expand Up @@ -468,7 +468,21 @@ TR_J9ServerVM::jitFieldsAreSame(TR_ResolvedMethod * method1, I_32 cpIndex1, TR_R
{
bool result = false;
bool sigSame = true;
if (method1->fieldsAreSame(cpIndex1, method2, cpIndex2, sigSame))
TR_OpaqueClassBlock * classOfMethod1 = static_cast<TR_ResolvedJ9JITServerMethod *>(method1)->classOfMethod();
TR_OpaqueClassBlock * classOfMethod2 = static_cast<TR_ResolvedJ9JITServerMethod *>(method2)->classOfMethod();
// Hidden classes generated within the same host class do not have distinct class names,
// but share the same field names with different field data types and offsets. Therefore,
// name-based check for whether fields are same can result in false positives when it comes
// to hidden classes unless the fields are from the same j9class objects.
if (classOfMethod1
&& classOfMethod2
&& (isHiddenClass(classOfMethod1)
|| isHiddenClass(classOfMethod2))
&& classOfMethod1 != classOfMethod2)
{
result = false;
}
else if (method1->fieldsAreSame(cpIndex1, method2, cpIndex2, sigSame))
{
result = true;
}
Expand Down Expand Up @@ -1943,6 +1957,16 @@ TR_J9ServerVM::isAnonymousClass(TR_OpaqueClassBlock *j9clazz)
return (J9_ARE_ALL_BITS_SET(extraModifiers, J9AccClassAnonClass));
}

bool
TR_J9ServerVM::isHiddenClass(TR_OpaqueClassBlock *j9clazz)
{
uintptr_t extraModifiers = 0;
JITServer::ServerStream *stream = _compInfoPT->getMethodBeingCompiled()->_stream;
JITServerHelpers::getAndCacheRAMClassInfo((J9Class *)j9clazz, _compInfoPT->getClientData(), stream, JITServerHelpers::CLASSINFO_ROMCLASS_EXTRAMODIFIERS, (void *)&extraModifiers);

return (J9_ARE_ALL_BITS_SET(extraModifiers, J9AccClassHidden));
}

TR_IProfiler *
TR_J9ServerVM::getIProfiler()
{
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1 change: 1 addition & 0 deletions runtime/compiler/env/VMJ9Server.hpp
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Expand Up @@ -203,6 +203,7 @@ class TR_J9ServerVM: public TR_J9VM
virtual bool transformJlrMethodInvoke(J9Method *callerMethod, J9Class *callerClass) override;
using TR_J9VM :: isAnonymousClass;
virtual bool isAnonymousClass(TR_OpaqueClassBlock *j9clazz) override;
virtual bool isHiddenClass(TR_OpaqueClassBlock *j9clazz) override;
virtual TR_IProfiler *getIProfiler() override;
virtual TR_StaticFinalData dereferenceStaticFinalAddress(void *staticAddress, TR::DataType addressType) override;
virtual void reserveTrampolineIfNecessary( TR::Compilation *, TR::SymbolReference *symRef, bool inBinaryEncoding) override;
Expand Down