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Adjust bound for out-of-line call to StringUTF16.toBytes #20058

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Aug 27, 2024
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Adjust bound for out-of-line call to StringUTF16.toBytes #20058

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17 changes: 9 additions & 8 deletions runtime/compiler/optimizer/J9RecognizedCallTransformer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -287,10 +287,11 @@ void J9::RecognizedCallTransformer::process_java_lang_StringUTF16_toBytes(TR::Tr

// The implementation of java.lang.StringUTF16.toBytes(char[],int,int) will
// throw a NegativeArraySizeException or OutOfMemoryError if the specified
// length is outside the range [0,0x3fffffff]. In order to avoid deciding
// which to throw in the IL, fall back to the out-of-line call if the length
// is negative or too great. Otherwise, create the byte array and copy the
// input char array to it with java.lang.String.decompressedArrayCopy
// length is outside the range [0,0x3fffffff] or [0,0x3ffffffe], depending on
// the JDK level. In order to avoid deciding which to throw in the IL, fall
// back to the out-of-line call if the length is negative or greater than or
// equal to 0x3fffffff. Otherwise, create the byte array and copy the input
// char array to it with java.lang.String.decompressedArrayCopy
//
// Before:
//
Expand All @@ -312,7 +313,7 @@ void J9::RecognizedCallTransformer::process_java_lang_StringUTF16_toBytes(TR::Tr
// | iload off |
// | istore lenTemp |
// | iload len |
// | ifiucmpgt --> fallbackPathBlock -----------------+
// | ifiucmpge --> fallbackPathBlock -----------------+
// | iload lenTemp | |
// | iconst 0x3fffffff | |
// +--------------------+-------------------+ |
Expand Down Expand Up @@ -355,7 +356,7 @@ void J9::RecognizedCallTransformer::process_java_lang_StringUTF16_toBytes(TR::Tr
// +----------------------------------------+
//
TR::Node *upperBoundConstNode = TR::Node::iconst(node, TR::getMaxSigned<TR::Int32>() >> 1);
TR::Node *ifCmpNode = TR::Node::createif(TR::ifiucmpgt, lenNode, upperBoundConstNode);
TR::Node *ifCmpNode = TR::Node::createif(TR::ifiucmpge, lenNode, upperBoundConstNode);
TR::TreeTop *ifCmpTreeTop = TR::TreeTop::create(comp(), treetop->getPrevTreeTop(), ifCmpNode);

// Create temporary variable that will be used to hold result
Expand Down Expand Up @@ -410,7 +411,7 @@ void J9::RecognizedCallTransformer::process_java_lang_StringUTF16_toBytes(TR::Tr
TR::Node::recreate(node, comp()->il.opCodeForDirectLoad(resultDataType));
node->setSymbolReference(resultSymRef);

// Split the current block right after the ifuicmpgt
// Split the current block right after the ifiucmpge
TR::Block *ifCmpBlock = ifCmpTreeTop->getEnclosingBlock();

// Then split the inline version of the code into its own block
Expand All @@ -429,7 +430,7 @@ void J9::RecognizedCallTransformer::process_java_lang_StringUTF16_toBytes(TR::Tr
fallThroughPathBlock->getExit()->insertBefore(gotoTree);

// Now we have fall-through block, fallback block and tail/merge block.
// Set the ifuicmp's destination to the fallback block and update the CFG as well.
// Set the ifiucmp's destination to the fallback block and update the CFG as well.
ifCmpNode->setBranchDestination(fallbackPathBlock->getEntry());
cfg->addEdge(ifCmpBlock, fallbackPathBlock);
cfg->addEdge(fallThroughPathBlock, tailBlock);
Expand Down