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Merge pull request #16399 from a7ehuo/fix-callTransformer-ramStatics-2
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Fix unsafe call transformation
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@vijaysun-omr
vijaysun-omr authored Dec 6, 2022
2 parents a938b8f + 5d03563 commit 7a8923b
Showing 1 changed file with 148 additions and 43 deletions.
191 changes: 148 additions & 43 deletions runtime/compiler/optimizer/J9RecognizedCallTransformer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -344,44 +344,52 @@ void J9::RecognizedCallTransformer::process_java_lang_StrictMath_and_Math_sqrt(T
Transform an Unsafe atomic call to diamonds with equivalent semantics
yes
isObjectNull ------------------------------------------>
| |
| no |
| yes |
isNotLowTagged ---------------------------------------->
| |
| no |
| no |
isFinal ----------------------> |
| | |
| yes | |
| | |
call the calculate address calculate address
original method for static field for instance field
| | and absolute address
| | |
| |________________________|
| |
| xcall atomic method helper
| |
|_____________________________________|
|
program after the original call
isObjectNull [A] ------------------------------------------>
| |
| no |
| yes |
isNotLowTagged [B] ---------------------------------------->
| |
| no |
| no |
isFinal [C] --------------------> |
| | |
| yes | |
jitReportFinalFieldModified [F] | |
| | |
+---------------------------> |
| |
calculate address [D] calculate address
for static field for instance field
(non collected reference) and absolute address
| (collected reference)
| |
xcall atomic method helper [G] xcall atomic method helper [E]
| |
+-----------+--------------+
|
v
program after the original call [H]
Block before the transformation: ===>
start Block_A
...
xcall Unsafe.xxx
...
<load of unsafe call argX>
...
end Block_A
Blocks after the transformation: ===>
start Block_A
...
astore object-1
<load of unsafe call argX>
...
ifacmpeq -> <Block_E>
object
object-1
aconst null
end Block_A
Expand All @@ -402,29 +410,50 @@ iflcmpeq -> <Block_F>
end Block_C
start Block_D
astore <object>
astore <object-2>
aloadi ramStaticsFromClass
...
aloadi <classFromJavaLangClass>
aload <object-1>
lstore <offset>
land
lload <offset>
lconst ~J9_SUN_FIELD_OFFSET_MASK
end Block_D
start Block_G
xcall atomic method helper
aladd
aload <object-2>
lload <offset>
xload value
xstore
==>xcall
goto --> block_H
end Block_G
start Block_E
xcall atomic method helper
aladd
aload <object>
aload <object-1>
lload <offset>
xload value
xstore
==>xcall
end Block_E
start Block_H
xreturn
xload
end Block_H
...
start Block_F
call jitReportFinalFieldModified
go to <Block_E>
aloadi <classFromJavaLangClass>
aload <object-1>
go to <Block_D>
end Block_F
*/
void J9::RecognizedCallTransformer::processUnsafeAtomicCall(TR::TreeTop* treetop, TR::SymbolReferenceTable::CommonNonhelperSymbol helper, bool needsNullCheck)
{
Expand All @@ -436,6 +465,13 @@ void J9::RecognizedCallTransformer::processUnsafeAtomicCall(TR::TreeTop* treetop
TR::Node* offsetNode = unsafeCall->getChild(2);
TR::Node* address = NULL;

TR::SymbolReference* newSymbolReference = NULL;
TR::CFG* cfg = comp()->getMethodSymbol()->getFlowGraph();
TR::Node* isObjectNullNode = NULL;
TR::TreeTop* isObjectNullTreeTop = NULL;
TR::Node* isNotLowTaggedNode = NULL;
TR::TreeTop* isNotLowTaggedTreeTop = NULL;

// Preserve null check on the unsafe object
if (treetop->getNode()->getOpCode().isNullCheck())
{
Expand Down Expand Up @@ -464,7 +500,6 @@ void J9::RecognizedCallTransformer::processUnsafeAtomicCall(TR::TreeTop* treetop
// Save all the children to temps before splitting the block
TR::TransformUtil::createTempsForCall(this, treetop);

auto cfg = comp()->getMethodSymbol()->getFlowGraph();
objectNode = unsafeCall->getChild(1);
offsetNode = unsafeCall->getChild(2);

Expand All @@ -480,20 +515,20 @@ void J9::RecognizedCallTransformer::processUnsafeAtomicCall(TR::TreeTop* treetop
}

// Test if object is null
auto isObjectNullNode = TR::Node::createif(TR::ifacmpeq, objectNode->duplicateTree(), TR::Node::aconst(0), NULL);
auto isObjectNullTreeTop = TR::TreeTop::create(comp(), isObjectNullNode);
isObjectNullNode = TR::Node::createif(TR::ifacmpeq, objectNode->duplicateTree(), TR::Node::aconst(0), NULL);
isObjectNullTreeTop = TR::TreeTop::create(comp(), isObjectNullNode);
treetop->insertBefore(isObjectNullTreeTop);
treetop->getEnclosingBlock()->split(treetop, cfg, fixupCommoning);

if (enableTrace)
traceMsg(comp(), "Created isObjectNull test node n%dn, non-null object will fall through to Block_%d\n", isObjectNullNode->getGlobalIndex(), treetop->getEnclosingBlock()->getNumber());

// Test if low tag is set
auto isNotLowTaggedNode = TR::Node::createif(TR::iflcmpne,
isNotLowTaggedNode = TR::Node::createif(TR::iflcmpne,
TR::Node::create(TR::land, 2, offsetNode->duplicateTree(), TR::Node::lconst(J9_SUN_STATIC_FIELD_OFFSET_TAG)),
TR::Node::lconst(J9_SUN_STATIC_FIELD_OFFSET_TAG),
NULL);
auto isNotLowTaggedTreeTop = TR::TreeTop::create(comp(), isNotLowTaggedNode);
isNotLowTaggedTreeTop = TR::TreeTop::create(comp(), isNotLowTaggedNode);
treetop->insertBefore(isNotLowTaggedTreeTop);
treetop->getEnclosingBlock()->split(treetop, cfg, fixupCommoning);

Expand Down Expand Up @@ -529,35 +564,33 @@ void J9::RecognizedCallTransformer::processUnsafeAtomicCall(TR::TreeTop* treetop

}

// ramStatics is not collected. We cannot reuse objectNode->getSymbolReference()
newSymbolReference = comp()->getSymRefTab()->createTemporary(comp()->getMethodSymbol(), TR::Address);
newSymbolReference->getSymbol()->setNotCollected();

// Calculate static address
auto objectAdjustmentNode = TR::Node::createWithSymRef(TR::astore, 1, 1,
TR::Node::createWithSymRef(TR::aloadi, 1, 1,
TR::Node::createWithSymRef(TR::aloadi, 1, 1,
objectNode->duplicateTree(),
comp()->getSymRefTab()->findOrCreateClassFromJavaLangClassSymbolRef()),
comp()->getSymRefTab()->findOrCreateRamStaticsFromClassSymbolRef()),
objectNode->getSymbolReference());
newSymbolReference);
auto offsetAdjustmentNode = TR::Node::createWithSymRef(TR::lstore, 1, 1,
TR::Node::create(TR::land, 2,
offsetNode->duplicateTree(),
TR::Node::lconst(~J9_SUN_FIELD_OFFSET_MASK)),
offsetNode->getSymbolReference());

if (enableTrace)
traceMsg(comp(), "Created node n%dn and n%dn to adjust object and offset for static field\n", objectAdjustmentNode->getGlobalIndex(), offsetAdjustmentNode->getGlobalIndex());
traceMsg(comp(), "Created node objectAdjustmentNode n%dn #%d and offsetAdjustmentNode #%d n%dn to adjust object and offset for static field\n",
objectAdjustmentNode->getGlobalIndex(), objectAdjustmentNode->getOpCode().hasSymbolReference() ? objectAdjustmentNode->getSymbolReference()->getReferenceNumber() : -1,
offsetAdjustmentNode->getGlobalIndex(), offsetAdjustmentNode->getOpCode().hasSymbolReference() ? offsetAdjustmentNode->getSymbolReference()->getReferenceNumber() : -1);

treetop->insertBefore(TR::TreeTop::create(comp(), objectAdjustmentNode));
treetop->insertBefore(TR::TreeTop::create(comp(), offsetAdjustmentNode));
treetop->getEnclosingBlock()->split(treetop, cfg, fixupCommoning);

if (enableTrace)
traceMsg(comp(), "Block_%d contains call to atomic method helper, and is the target of isObjectNull and isNotLowTagged tests\n", treetop->getEnclosingBlock()->getNumber());

// Setup CFG edges
isObjectNullNode->setBranchDestination(treetop->getEnclosingBlock()->getEntry());
cfg->addEdge(TR::CFGEdge::createEdge(isObjectNullTreeTop->getEnclosingBlock(), treetop->getEnclosingBlock(), comp()->trMemory()));
isNotLowTaggedNode->setBranchDestination(treetop->getEnclosingBlock()->getEntry());
cfg->addEdge(TR::CFGEdge::createEdge(isNotLowTaggedTreeTop->getEnclosingBlock(), treetop->getEnclosingBlock(), comp()->trMemory()));
address = comp()->target().is32Bit() ? TR::Node::create(TR::aiadd, 2, objectNode->duplicateTree(), TR::Node::create(TR::l2i, 1, offsetNode->duplicateTree())) :
TR::Node::create(TR::aladd, 2, objectNode->duplicateTree(), offsetNode->duplicateTree());
}
Expand All @@ -568,6 +601,78 @@ void J9::RecognizedCallTransformer::processUnsafeAtomicCall(TR::TreeTop* treetop
unsafeCall->removeChild(2); // remove offset node
unsafeCall->removeChild(1); // remove object node
unsafeCall->setSymbolReference(comp()->getSymRefTab()->findOrCreateCodeGenInlinedHelper(helper));

if (!isNotStaticField)
{
// Split so that the return value from the atomic method helper call will be stored into a temp if required
TR::TreeTop *nextTreeTop = treetop->getNextTreeTop();
TR::Block *returnBlock = nextTreeTop->getEnclosingBlock()->split(nextTreeTop, cfg, fixupCommoning);

// Check if the return value from the atomic method helper call is stored into a temp
nextTreeTop = treetop->getNextTreeTop();
TR::Node *storeReturnNode = NULL;
if (nextTreeTop)
{
storeReturnNode = nextTreeTop->getNode();
if (!storeReturnNode->getOpCode().isStore() || !(storeReturnNode->getFirstChild() == unsafeCall))
{
storeReturnNode = NULL;
}
else if (enableTrace)
{
traceMsg(comp(), "storeNode n%dn #%d for the return value of atomic method helper\n", storeReturnNode->getGlobalIndex(), storeReturnNode->getSymbolReference()->getReferenceNumber());
}
}

/* Example of the atomic method helper
* n92n treetop
* n93n icall <atomicFetchAndAdd>
* n94n aladd
* n95n aload <temp slot 5>
* n96n lload <temp slot 3>
* n97n iload <temp slot 4>
*/
// Create another helper call that loads from ramStatics
TR::TreeTop *unsafeCallRamStaticsTT = treetop->duplicateTree();
TR::Node *unsafeCallRamStaticsNode = unsafeCallRamStaticsTT->getNode()->getFirstChild();
TR::Node *addressNode = unsafeCallRamStaticsNode->getFirstChild();
TR::Node *loadNode = addressNode->getFirstChild();

loadNode->setSymbolReference(newSymbolReference); // Use the same symRef as the objectAdjustmentNode
treetop->insertBefore(unsafeCallRamStaticsTT);

// Store the return value from the helper call that loads from ramStatics
if (storeReturnNode)
{
TR::Node *storeNode = TR::Node::createStore(unsafeCall, storeReturnNode->getSymbolReference(), unsafeCallRamStaticsNode);
treetop->insertBefore(TR::TreeTop::create(comp(), storeNode));
}

// Insert goto from the helper call that loads from ramStatics to the final return block
TR::Node *gotoNode = TR::Node::create(unsafeCall, TR::Goto);
gotoNode->setBranchDestination(returnBlock->getEntry());
treetop->insertBefore(TR::TreeTop::create(comp(), gotoNode));

if (enableTrace)
traceMsg(comp(), "Created atomic method helper block_%d that loads from ramStatics treetop n%dn. returnBlock block_%d\n",
unsafeCallRamStaticsTT->getEnclosingBlock()->getNumber(), unsafeCallRamStaticsTT->getNode()->getGlobalIndex(), returnBlock->getNumber());

// Split the block that contains the original helper call into a separate block
treetop->getEnclosingBlock()->split(treetop, cfg, fixupCommoning);

// Setup CFG edges
cfg->addEdge(unsafeCallRamStaticsTT->getEnclosingBlock(), returnBlock);

if (enableTrace)
traceMsg(comp(), "Block_%d contains call to atomic method helper, and is the target of isObjectNull and isNotLowTagged tests\n", treetop->getEnclosingBlock()->getNumber());

isObjectNullNode->setBranchDestination(treetop->getEnclosingBlock()->getEntry());
cfg->addEdge(TR::CFGEdge::createEdge(isObjectNullTreeTop->getEnclosingBlock(), treetop->getEnclosingBlock(), comp()->trMemory()));
isNotLowTaggedNode->setBranchDestination(treetop->getEnclosingBlock()->getEntry());
cfg->addEdge(TR::CFGEdge::createEdge(isNotLowTaggedTreeTop->getEnclosingBlock(), treetop->getEnclosingBlock(), comp()->trMemory()));

cfg->removeEdge(unsafeCallRamStaticsTT->getEnclosingBlock(), treetop->getEnclosingBlock());
}
}

#if defined(J9VM_OPT_OPENJDK_METHODHANDLE)
Expand Down

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