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Add Constant Dynamic in GC Implementation
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Implemented condy iterator in constant pool and added it to the GC
Implementation
(/runtime/gc_glue_java/CollectorLanguageInterfaceImpl.cpp).

This is the first part of two changes, the next change will check if the
class contains any Condy cp entries

Signed-off-by: Charles_Zheng <[email protected]>
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Charles_Zheng authored and Charles_Zheng committed Aug 23, 2018
1 parent 63c305a commit c28567a
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Showing 5 changed files with 119 additions and 29 deletions.
24 changes: 23 additions & 1 deletion runtime/gc_glue_java/CollectorLanguageInterfaceImpl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -394,6 +394,10 @@ MM_CollectorLanguageInterfaceImpl::scavenger_scavengeIndirectObjectSlots(MM_Envi
while((slotPtr = classStaticsIterator.nextSlot()) != NULL) {
shouldBeRemembered = _extensions->scavenger->copyObjectSlot(env, slotPtr) || shouldBeRemembered;
}
GC_ConstantPoolObjectSlotIterator constantPoolObjectSlotIterator((J9JavaVM*)_omrVM->_language_vm, classToScan, true);
while ((slotPtr = constantPoolObjectSlotIterator.nextSlot()) != NULL) {
shouldBeRemembered = _extensions->scavenger->copyObjectSlot(env, slotPtr) || shouldBeRemembered;
}
shouldBeRemembered = _extensions->scavenger->copyObjectSlot(env, (omrobjectptr_t *)&(classToScan->classObject)) || shouldBeRemembered;

classToScan = classToScan->replacedClass;
Expand All @@ -415,7 +419,7 @@ MM_CollectorLanguageInterfaceImpl::scavenger_hasIndirectReferentsInNewSpace(MM_E
return true;
}

/* Iterate though Class Statics */
/* Iterate though Class Statics and Constant Dynamics*/
do {
omrobjectptr_t *slotPtr = NULL;
GC_ClassStaticsIterator classStaticsIterator(env, classToScan);
Expand All @@ -428,6 +432,16 @@ MM_CollectorLanguageInterfaceImpl::scavenger_hasIndirectReferentsInNewSpace(MM_E
}
}
}
GC_ConstantPoolObjectSlotIterator constantPoolObjectSlotIterator((J9JavaVM*)_omrVM->_language_vm, classToScan, true);
while (NULL != (slotPtr = (omrobjectptr_t*)constantPoolObjectSlotIterator.nextSlot())) {
omrobjectptr_t objectPtr = *slotPtr;
if (NULL != objectPtr) {
if (_extensions->scavenger->isObjectInNewSpace(objectPtr)){
Assert_MM_false(_extensions->scavenger->isObjectInEvacuateMemory(objectPtr));
return true;
}
}
}
classToScan = classToScan->replacedClass;
} while (NULL != classToScan);

Expand All @@ -447,6 +461,10 @@ MM_CollectorLanguageInterfaceImpl::scavenger_fixupIndirectObjectSlots(MM_Environ
while((slotPtr = classStaticsIterator.nextSlot()) != NULL) {
_extensions->scavenger->fixupSlotWithoutCompression(slotPtr);
}
GC_ConstantPoolObjectSlotIterator constantPoolObjectSlotIterator((J9JavaVM*)_omrVM->_language_vm, classToScan, true);
while ((slotPtr = constantPoolObjectSlotIterator.nextSlot()) != NULL) {
_extensions->scavenger->fixupSlotWithoutCompression(slotPtr);
}
_extensions->scavenger->fixupSlotWithoutCompression((omrobjectptr_t *)&(classToScan->classObject));
classToScan = classToScan->replacedClass;
} while (NULL != classToScan);
Expand All @@ -465,6 +483,10 @@ MM_CollectorLanguageInterfaceImpl::scavenger_backOutIndirectObjectSlots(MM_Envir
while((slotPtr = classStaticsIterator.nextSlot()) != NULL) {
_extensions->scavenger->backOutFixSlotWithoutCompression(slotPtr);
}
GC_ConstantPoolObjectSlotIterator constantPoolObjectSlotIterator((J9JavaVM*)_omrVM->_language_vm, classToScan, true);
while ((slotPtr = constantPoolObjectSlotIterator.nextSlot()) != NULL) {
_extensions->scavenger->backOutFixSlotWithoutCompression(slotPtr);
}
_extensions->scavenger->backOutFixSlotWithoutCompression((omrobjectptr_t *)&(classToScan->classObject));
classToScan = classToScan->replacedClass;
} while (NULL != classToScan);
Expand Down
4 changes: 2 additions & 2 deletions runtime/gc_structs/ClassIterator.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,7 @@ class GC_ClassIterator {
, _state(classiterator_state_start)
, _scanIndex(0)
, _classStaticsIterator(env, clazz)
, _constantPoolObjectSlotIterator(clazz)
, _constantPoolObjectSlotIterator((J9JavaVM *)env->getLanguageVM(), clazz)
, _callSitesIterator(clazz)
, _methodTypesIterator(clazz->romClass->methodTypeCount, clazz->methodTypes)
, _varHandlesMethodTypesIterator(clazz->romClass->varHandleMethodTypeCount, clazz->varHandleMethodTypes)
Expand All @@ -92,7 +92,7 @@ class GC_ClassIterator {
, _state(classiterator_state_start)
, _scanIndex(0)
, _classStaticsIterator(extensions, clazz)
, _constantPoolObjectSlotIterator(clazz)
, _constantPoolObjectSlotIterator((J9JavaVM *)extensions->getOmrVM()->_language_vm, clazz)
, _callSitesIterator(clazz)
, _methodTypesIterator(clazz->romClass->methodTypeCount, clazz->methodTypes)
, _varHandlesMethodTypesIterator(clazz->romClass->varHandleMethodTypeCount, clazz->varHandleMethodTypes)
Expand Down
64 changes: 43 additions & 21 deletions runtime/gc_structs/ConstantPoolObjectSlotIterator.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,18 +35,27 @@


/**
* If condyOnly flag is not set:
* @return the next object slot in the constant pool
* @return NULL if there are no more object references
*
* If condyOnly flag is set and Java version is SE11 and above:
* @return the next Condy reference from the constant pool
* @return NULL if there are no more references
*/
j9object_t *
GC_ConstantPoolObjectSlotIterator::nextSlot()
{
GC_ConstantPoolObjectSlotIterator::nextSlot() {
/* Return NULL if _condyOnly is true but system is not condy-enabled */
if (_condyOnly && !_condyEnabled) {
return NULL;
}
U_32 slotType;
j9object_t *slotPtr;
j9object_t *result = NULL;
bool nextSlot = true;

while(_cpEntryCount) {
if(0 == _cpDescriptionIndex) {
while (_cpEntryCount) {
if (0 == _cpDescriptionIndex) {
_cpDescription = *_cpDescriptionSlots;
_cpDescriptionSlots += 1;
_cpDescriptionIndex = J9_CP_DESCRIPTIONS_PER_U32;
Expand All @@ -55,15 +64,17 @@ GC_ConstantPoolObjectSlotIterator::nextSlot()
slotType = _cpDescription & J9_CP_DESCRIPTION_MASK;
slotPtr = _cpEntry;

/* Adjust the CP slot and description information */
_cpEntry = (j9object_t *)( ((U_8 *)_cpEntry) + sizeof(J9RAMConstantPoolItem) );
_cpEntryCount -= 1;

_cpDescription >>= J9_CP_BITS_PER_DESCRIPTION;
_cpDescriptionIndex -= 1;

/* Determine if the slot should be processed */
switch (slotType) {
/* If _condyOnly is TRUE, return the next constant dynamic slot in constant pool
* Otherwise return the next object */
if (_condyOnly) {
/* Determine if the slot is constant dynamic */
if (slotType == J9CPTYPE_CONSTANT_DYNAMIC) {
result = scanCondySlot(slotPtr, &nextSlot);
break;
}
} else {
/* Determine if the slot should be processed */
switch (slotType) {
case J9CPTYPE_STRING: /* fall through */
case J9CPTYPE_ANNOTATION_UTF8:
result = &(((J9RAMStringRef *) slotPtr)->stringObject);
Expand All @@ -75,19 +86,30 @@ GC_ConstantPoolObjectSlotIterator::nextSlot()
result = &(((J9RAMMethodHandleRef *) slotPtr)->methodHandle);
break;
case J9CPTYPE_CONSTANT_DYNAMIC:
if (NULL != ((J9RAMConstantDynamicRef *) slotPtr)->value) {
result = &(((J9RAMConstantDynamicRef *) slotPtr)->value);
} else {
result = &(((J9RAMConstantDynamicRef *) slotPtr)->exception);
}
result = scanCondySlot(slotPtr, &nextSlot);
break;
default:
continue;
break;
}

}

if (nextSlot) {
/* Adjust the CP slot and description information */
_cpEntry = (j9object_t *) (((U_8 *) _cpEntry)
+ sizeof(J9RAMConstantPoolItem));
_cpEntryCount -= 1;

_cpDescription >>= J9_CP_BITS_PER_DESCRIPTION;
_cpDescriptionIndex -= 1;
}

if (NULL != result) {
break;
}

return result;
}
return NULL;
return result;
}

bool
Expand Down
54 changes: 50 additions & 4 deletions runtime/gc_structs/ConstantPoolObjectSlotIterator.hpp
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@

/*******************************************************************************
* Copyright (c) 1991, 2014 IBM Corp. and others
* Copyright (c) 1991, 2018 IBM Corp. and others
*
* This program and the accompanying materials are made available under
* the terms of the Eclipse Public License 2.0 which accompanies this
Expand Down Expand Up @@ -33,6 +33,13 @@
#include "j9cfg.h"
#include "j9cp.h"
#include "modron.h"
#include "j2sever.h"
#include "ModronAssertions.h"

typedef enum {
condy_slot_value,
condy_slot_exception
} CondySlot;

/**
* Iterate over object references (but not class references) in the constant pool of a class.
Expand All @@ -48,18 +55,56 @@ class GC_ConstantPoolObjectSlotIterator
U_32 *_cpDescriptionSlots;
U_32 _cpDescription;
UDATA _cpDescriptionIndex;
bool _condyOnly;
bool _condyEnabled;
CondySlot _condySlotState;


private:
/**
* Scan the current constant dynamic slot
* @return slot value if it is not NULL
* @return exception otherwise
*/
MMINLINE
j9object_t* scanCondySlot(j9object_t *slotPtr, bool *nextSlot) {
j9object_t *result;
switch (_condySlotState) {
case condy_slot_value:
result = &(((J9RAMConstantDynamicRef *) slotPtr)->value);
_condySlotState = condy_slot_exception;
*nextSlot = false;
break;
case condy_slot_exception:
result = &(((J9RAMConstantDynamicRef *) slotPtr)->exception);
_condySlotState = condy_slot_value;
break;
default:
Assert_MM_unreachable();
break;
}
return result;
}

public:
GC_ConstantPoolObjectSlotIterator(J9Class *clazz) :

GC_ConstantPoolObjectSlotIterator(J9JavaVM *vm, J9Class *clazz, bool condyOnly = false) :
_cpEntry((j9object_t *)J9_CP_FROM_CLASS(clazz)),
_cpEntryCount(clazz->romClass->ramConstantPoolCount)
_cpEntryCount(clazz->romClass->ramConstantPoolCount),
_condySlotState(condy_slot_value)
{
_condyOnly = condyOnly;
_cpEntryTotal = _cpEntryCount;
if(_cpEntryCount) {
_cpDescriptionSlots = SRP_PTR_GET(&clazz->romClass->cpShapeDescription, U_32 *);
_cpDescriptionIndex = 0;
}

/* Check if the system is condy-enabled */
if (J2SE_VERSION(vm) < J2SE_V11) {
_condyEnabled = false;
} else {
_condyEnabled = true;
}
};

/**
Expand Down Expand Up @@ -90,6 +135,7 @@ class GC_ConstantPoolObjectSlotIterator
* @param slot[in] The slot pointer which is to be returned by the next call to nextSlot
*/
void setNextSlot(j9object_t *slot);

};

#endif /* CONSTANTPOOLOBJECTSLOTITERATOR_HPP_ */
2 changes: 1 addition & 1 deletion runtime/gc_vlhgc/CopyForwardScheme.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4670,7 +4670,7 @@ MM_CopyForwardScheme::verifyClassObjectSlots(MM_EnvironmentVLHGC *env, J9Object
/* we can safely ignore any classes referenced by the constant pool, since
* these are guaranteed to be referenced by our class loader
*/
GC_ConstantPoolObjectSlotIterator constantPoolIterator(classPtr);
GC_ConstantPoolObjectSlotIterator constantPoolIterator(_javaVM, classPtr);
while(NULL != (slotPtr = constantPoolIterator.nextSlot())) {
J9Object *dstObject = *slotPtr;
if(!_abortInProgress && verifyIsPointerInEvacute(env, dstObject)) {
Expand Down

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