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Merge pull request #20019 from hzongaro/string-constructor-exception-v0.47.0
(0.47.0) Fall back to out-of-line call to StringUTF16.toBytes
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‎runtime/compiler/optimizer/J9RecognizedCallTransformer.cpp

Lines changed: 139 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -275,27 +275,110 @@ void J9::RecognizedCallTransformer::process_java_lang_StringUTF16_toBytes(TR::Tr
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{
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TR_J9VMBase* fej9 = static_cast<TR_J9VMBase*>(comp()->fe());
277277

278+
// Place arguments to StringUTF16.toBytes in temporaries
279+
// to allow for control flow
280+
TransformUtil::createTempsForCall(this, treetop);
281+
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TR::Node* valueNode = node->getChild(0);
279283
TR::Node* offNode = node->getChild(1);
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TR::Node* lenNode = node->getChild(2);
281285

282-
anchorAllChildren(node, treetop);
283-
prepareToReplaceNode(node);
286+
TR::CFG *cfg = comp()->getFlowGraph();
284287

285-
int32_t byteArrayType = fej9->getNewArrayTypeFromClass(fej9->getByteArrayClass());
288+
// The implementation of java.lang.StringUTF16.toBytes(char[],int,int) will
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// throw a NegativeArraySizeException or OutOfMemoryError if the specified
290+
// length is outside the range [0,0x3fffffff]. In order to avoid deciding
291+
// which to throw in the IL, fall back to the out-of-line call if the length
292+
// is negative or too great. Otherwise, create the byte array and copy the
293+
// input char array to it with java.lang.String.decompressedArrayCopy
294+
//
295+
// Before:
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//
297+
// +----------------------------------------+
298+
// | treetop |
299+
// | acall java/lang/StringUTF16.toBytes |
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// | aload charArr |
301+
// | iload off |
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// | iload len |
303+
// +----------------------------------------+
304+
//
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// After:
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//
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// ifCmpblock
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// +----------------------------------------+
309+
// | astore charArrTemp |
310+
// | aload charArr |
311+
// | istore offTemp |
312+
// | iload off |
313+
// | istore lenTemp |
314+
// | iload len |
315+
// | ifiucmpgt --> fallbackPathBlock -----------------+
316+
// | iload lenTemp | |
317+
// | iconst 0x3fffffff | |
318+
// +--------------------+-------------------+ |
319+
// | |
320+
// fallThroughPathBlock V |
321+
// +----------------------------------------+ |
322+
// | astore result | |
323+
// | newarray jitNewArray | |
324+
// | ishl | |
325+
// | iload lenTemp | |
326+
// | icosnt 1 | |
327+
// | iconst 8 ; array type is byte | |
328+
// | treetop | |
329+
// | call java/lang/String.decompressedArrayCopy |
330+
// | aload charArrTemp | |
331+
// | iload offTemp | |
332+
// | ==>newarray | |
333+
// | iconst 0 | |
334+
// | iload lenTemp | |
335+
// | goto joinBlock ----------------------------+ |
336+
// +----------------------------------------+ | |
337+
// | |
338+
// +------------------------------+
339+
// | |
340+
// fallbackPathBlock V (freq 0) (cold) |
341+
// +----------------------------------------+ |
342+
// | astore result | |
343+
// | acall java/lang/StringUTF16.toBytes | |
344+
// | aload charArrTemp | |
345+
// | iload offTemp | |
346+
// | iload lenTemp | |
347+
// +--------------------+-------------------+ |
348+
// | |
349+
// +-------------------------+
350+
// |
351+
// joinBlock V
352+
// +----------------------------------------+
353+
// | treetop |
354+
// | aload result ; Replaces acall StringUTF16.toBytes
355+
// +----------------------------------------+
356+
//
357+
TR::Node *upperBoundConstNode = TR::Node::iconst(node, TR::getMaxSigned<TR::Int32>() >> 1);
358+
TR::Node *ifCmpNode = TR::Node::createif(TR::ifiucmpgt, lenNode, upperBoundConstNode);
359+
TR::TreeTop *ifCmpTreeTop = TR::TreeTop::create(comp(), treetop->getPrevTreeTop(), ifCmpNode);
286360

287-
TR::Node::recreateWithoutProperties(node, TR::newarray, 2,
288-
TR::Node::create(TR::ishl, 2,
289-
lenNode,
290-
TR::Node::iconst(1)),
291-
TR::Node::iconst(byteArrayType),
361+
// Create temporary variable that will be used to hold result
362+
TR::DataType resultDataType = node->getDataType();
363+
TR::SymbolReference *resultSymRef = comp()->getSymRefTab()->createTemporary(comp()->getMethodSymbol(), resultDataType);
292364

293-
getSymRefTab()->findOrCreateNewArraySymbolRef(node->getSymbolReference()->getOwningMethodSymbol(comp())));
365+
// Create result byte array and copy input char array to it with String.decompressedArrayCopy
366+
int32_t byteArrayType = fej9->getNewArrayTypeFromClass(fej9->getByteArrayClass());
294367

295-
TR::Node* newByteArrayNode = node;
368+
TR::Node *newByteArrayNode = TR::Node::createWithSymRef(TR::newarray, 2, 2,
369+
TR::Node::create(TR::ishl, 2, lenNode,
370+
TR::Node::iconst(1)),
371+
TR::Node::iconst(byteArrayType),
372+
getSymRefTab()->findOrCreateNewArraySymbolRef(
373+
node->getSymbolReference()->getOwningMethodSymbol(comp())));
374+
375+
newByteArrayNode->copyByteCodeInfo(node);
296376
newByteArrayNode->setCanSkipZeroInitialization(true);
297377
newByteArrayNode->setIsNonNull(true);
298378

379+
TR::Node *newByteArrayStoreNode = TR::Node::createStore(node, resultSymRef, newByteArrayNode);
380+
TR::TreeTop *newByteArraryTreeTop = TR::TreeTop::create(comp(), ifCmpTreeTop, newByteArrayStoreNode);
381+
299382
TR::Node* newCallNode = TR::Node::createWithSymRef(node, TR::call, 5,
300383
getSymRefTab()->methodSymRefFromName(comp()->getMethodSymbol(), "java/lang/String", "decompressedArrayCopy", "([CI[BII)V", TR::MethodSymbol::Static));
301384
newCallNode->setAndIncChild(0, valueNode);
@@ -304,14 +387,58 @@ void J9::RecognizedCallTransformer::process_java_lang_StringUTF16_toBytes(TR::Tr
304387
newCallNode->setAndIncChild(3, TR::Node::iconst(0));
305388
newCallNode->setAndIncChild(4, lenNode);
306389

307-
TR::TreeTop* newTT = treetop->insertAfter(TR::TreeTop::create(comp(), TR::Node::create(node, TR::treetop, 1, newCallNode)));
390+
TR::TreeTop* lastFallThroughTreeTop = TR::TreeTop::create(comp(), newByteArraryTreeTop,
391+
TR::Node::create(node, TR::treetop, 1, newCallNode));
392+
308393
// Insert the allocationFence after the arraycopy because the array can be allocated from the non-zeroed TLH
309394
// and therefore we need to make sure no other thread sees stale memory from the array element section.
310395
if (cg()->getEnforceStoreOrder())
311396
{
312397
TR::Node *allocationFence = TR::Node::createAllocationFence(newByteArrayNode, newByteArrayNode);
313-
newTT->insertAfter(TR::TreeTop::create(comp(), allocationFence));
398+
lastFallThroughTreeTop = TR::TreeTop::create(comp(), lastFallThroughTreeTop, allocationFence);
314399
}
400+
401+
// Copy the original call tree for the fallback path, and store the
402+
// result into the temporary that was created.
403+
TR::Node *fallbackCallNode = node->duplicateTree();
404+
TR::Node *fallbackStoreNode = TR::Node::createStore(node, resultSymRef, fallbackCallNode);
405+
TR::TreeTop *fallbackTreeTop = TR::TreeTop::create(comp(), lastFallThroughTreeTop, fallbackStoreNode);
406+
407+
// Replace original call node with the load of the temporary
408+
// variable that is stored on both sides of the if branch.
409+
prepareToReplaceNode(node);
410+
TR::Node::recreate(node, comp()->il.opCodeForDirectLoad(resultDataType));
411+
node->setSymbolReference(resultSymRef);
412+
413+
// Split the current block right after the ifuicmpgt
414+
TR::Block *ifCmpBlock = ifCmpTreeTop->getEnclosingBlock();
415+
416+
// Then split the inline version of the code into its own block
417+
TR::Block *fallThroughPathBlock = ifCmpBlock->split(newByteArraryTreeTop, cfg, true /* fixUpCommoning */, true /* copyExceptionSuccessors */);
418+
419+
// Then split the fallback, out-of-line call into its own block
420+
TR::Block *fallbackPathBlock = fallThroughPathBlock->split(fallbackTreeTop, cfg, true /* fixUpCommoning */, true /* copyExceptionSuccessors */);
421+
422+
// Then split again at the original call TreeTop to create the tail block
423+
TR::Block *tailBlock = fallbackPathBlock->split(treetop, cfg, true /* fixUpCommoning */, true /* copyExceptionSuccessors */);
424+
425+
// Now create a node to go to the merge (i.e. tail) block.
426+
TR::Node *gotoNode = TR::Node::create(node, TR::Goto);
427+
TR::TreeTop *gotoTree = TR::TreeTop::create(comp(), gotoNode, NULL, NULL);
428+
gotoNode->setBranchDestination(tailBlock->getEntry());
429+
fallThroughPathBlock->getExit()->insertBefore(gotoTree);
430+
431+
// Now we have fall-through block, fallback block and tail/merge block.
432+
// Set the ifuicmp's destination to the fallback block and update the CFG as well.
433+
ifCmpNode->setBranchDestination(fallbackPathBlock->getEntry());
434+
cfg->addEdge(ifCmpBlock, fallbackPathBlock);
435+
cfg->addEdge(fallThroughPathBlock, tailBlock);
436+
cfg->removeEdge(fallThroughPathBlock, fallbackPathBlock);
437+
438+
// The original call to StringUTF16.toBytes will only be used
439+
// if an exception needs to be thrown. Mark it as cold.
440+
fallbackPathBlock->setFrequency(UNKNOWN_COLD_BLOCK_COUNT);
441+
fallbackPathBlock->setIsCold();
315442
}
316443

317444
void J9::RecognizedCallTransformer::process_jdk_internal_util_ArraysSupport_vectorizedMismatch(TR::TreeTop* treetop, TR::Node* node)

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