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Merge pull request #19444 from hzongaro/indexOf-latin1-encoded-0.44
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(0.44) Use signed comparisons for Latin-1 encoded indexOf in VP
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@pshipton
pshipton authored May 3, 2024
2 parents 8d018d6 + 98d2c0a commit 85b3f7c
Showing 1 changed file with 79 additions and 2 deletions.
81 changes: 79 additions & 2 deletions runtime/compiler/optimizer/J9ValuePropagation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -376,6 +376,15 @@ bool J9::ValuePropagation::transformIndexOfKnownString(
}
else if (targetIsConstChar)
{
if (!is16Bit)
{
// The implementations of the 8-bit indexOf operations cast the character for
// which they are searching to a signed byte value, and the characters in the
// String themselves are stored in a signed byte array. Make sure that folding
// at compile-time takes into account that operations are on signed bytes.
targetChar = (int32_t)(int8_t) targetChar;
}

for (int32_t i = start; i < length; ++i)
{
int32_t ch;
Expand All @@ -397,6 +406,15 @@ bool J9::ValuePropagation::transformIndexOfKnownString(
// getStringCharacter should handle both 8 bit and 16 bit strings
ch = TR::Compiler->cls.getStringCharacter(comp(), string, i);
}
if (!is16Bit)
{
// The implementations of the 8-bit indexOf operations cast the character for
// which they are searching to a signed byte value, and the characters in the
// String themselves are stored in a signed byte array. Make sure that folding
// at compile-time takes into account that operations are on signed bytes.
ch = (int32_t)(int8_t) ch;
}

if (ch == targetChar)
{
if (performTransformation(comp(), "%sReplacing indexOf call node [" POINTER_PRINTF_FORMAT "] on known string receiver with constant value of %d\n", OPT_DETAILS, indexOfNode, i))
Expand Down Expand Up @@ -433,8 +451,37 @@ bool J9::ValuePropagation::transformIndexOfKnownString(
// getStringCharacter should handle both 8 bit and 16 bit strings
ch = TR::Compiler->cls.getStringCharacter(comp(), string, start);
}

if (!is16Bit)
{
// The implementations of the 8-bit indexOf operations cast the character for
// which they are searching to a signed byte value, and the characters in the
// String themselves are stored in a signed byte array. Make sure that the
// inlined version similarly operates on signed bytes.
ch = (int32_t)(int8_t) ch;
}

if (!performTransformation(comp(), "%sReplacing indexOf call node [" POINTER_PRINTF_FORMAT "] on known string receiver with equivalent icmpeq tree\n", OPT_DETAILS, indexOfNode))
return false;

// The implementations of the 8-bit indexOf operations cast the character for
// which they are searching to a signed byte value. In some cases that happens
// at the call to the known method that's being processed here, and in some
// cases that happens within the known method itself. If targetCharNode is not
// known to be the result of a b2i operation and is not already known to be in
// the required range for a signed byte value, force that. Otherwise, this
// could end up looking for the degree symbol, U+00B0, say, as an unsigned
// value 176 rather than the signed value -80.
if (!is16Bit
&& (targetCharNode->getOpCodeValue() != TR::b2i)
&& ((targetConstraint == NULL)
|| (targetConstraint->getLowInt() < -128)
|| (targetConstraint->getHighInt() > 127)))
{
targetCharNode = TR::Node::create(indexOfNode, TR::b2i, 1,
TR::Node::create(indexOfNode, TR::i2b, 1, targetCharNode));
}

transformCallToNodeDelayedTransformations(
_curTree,
TR::Node::create(indexOfNode, TR::isub, 2,
Expand All @@ -448,7 +495,29 @@ bool J9::ValuePropagation::transformIndexOfKnownString(
}
else if (length < 4)
{
if (!performTransformation(comp(), "%sReplacing indexOf call node [" POINTER_PRINTF_FORMAT "] on known string receiver with equivalent iselect tree\n", OPT_DETAILS, indexOfNode))
return false;

TR::Node *root = TR::Node::iconst(indexOfNode, -1);

// The implementations of the 8-bit indexOf operations cast the character for
// which they are searching to a signed byte value. In some cases that happens
// at the call to the known method that's being processed here, and in some
// cases that happens within the known method itself. If targetCharNode is not
// known to be the result of a b2i operation and is not already known to be in
// the required range for a signed byte value, force that. Otherwise, this
// could end up looking for the degree symbol, U+00B0, say, as an unsigned
// value 176 rather than the signed value -80.
if (!is16Bit
&& (targetCharNode->getOpCodeValue() != TR::b2i)
&& ((targetConstraint == NULL)
|| (targetConstraint->getLowInt() < -128)
|| (targetConstraint->getHighInt() > 127)))
{
targetCharNode = TR::Node::create(indexOfNode, TR::b2i, 1,
TR::Node::create(indexOfNode, TR::i2b, 1, targetCharNode));
}

for (int32_t i = length - 1; i >= start; --i)
{
int32_t ch;
Expand All @@ -470,8 +539,16 @@ bool J9::ValuePropagation::transformIndexOfKnownString(
// getStringCharacter should handle both 8 bit and 16 bit strings
ch = TR::Compiler->cls.getStringCharacter(comp(), string, i);
}
if (!performTransformation(comp(), "%sReplacing indexOf call node [" POINTER_PRINTF_FORMAT "] on known string receiver with equivalent iselect tree\n", OPT_DETAILS, indexOfNode))
return false;

if (!is16Bit)
{
// The implementations of the 8-bit indexOf operations cast the character for
// which they are searching to a signed byte value, and the characters in the
// String themselves are stored in a signed byte array. Make sure that the
// inlined version similarly operates on signed bytes.
ch = (int32_t)(int8_t) ch;
}

root = TR::Node::create(TR::iselect, 3,
TR::Node::create(indexOfNode, TR::icmpeq, 2,
targetCharNode,
Expand Down

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