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Fix switch statement issue #97

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Merged
martin-henz merged 2 commits into from
Jun 24, 2026
Merged

Fix switch statement issue #97

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1b8e9a5
fix switch statement issue
kjw142857 Jun 16, 2026
be416fd
fix lookupswitch logic
kjw142857 Jun 24, 2026
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109 changes: 74 additions & 35 deletions src/compiler/code-generator.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1416,9 +1416,9 @@ const codeGenerators: { [type: string]: (node: Node, cg: CodeGenerator) => Compi
indexTracker++
}

// Add default branch (jump to default label)
cg.code.push(0, 0, 0, defaultLabel.offset)
caseLabelIndex.push(indexTracker + 3)
// Add default branch (reserve 4 bytes for default label offset)
cg.code.push(0, 0, 0, 0)
caseLabelIndex.push(indexTracker)
indexTracker += 4

// Push low and high values (min and max case values)
Expand All @@ -1436,16 +1436,11 @@ const codeGenerators: { [type: string]: (node: Node, cg: CodeGenerator) => Compi
)
indexTracker += 8

// Generate branch table (map each value to a case label)
// Generate branch table (reserve 4 bytes per entry and record start indices)
for (let i = minValue; i <= maxValue; i++) {
const caseIndex = caseValues.indexOf(i)
cg.code.push(
0,
0,
0,
caseIndex !== -1 ? caseLabels[caseIndex].offset : defaultLabel.offset
)
caseLabelIndex.push(indexTracker + 3)
// push the 4-byte placeholder for the branch target
cg.code.push(0, 0, 0, 0)
caseLabelIndex.push(indexTracker)
indexTracker += 4
}
} else {
Expand All @@ -1458,9 +1453,9 @@ const codeGenerators: { [type: string]: (node: Node, cg: CodeGenerator) => Compi
indexTracker++
}

// Add default branch (jump to default label)
cg.code.push(0, 0, 0, defaultLabel.offset)
caseLabelIndex.push(indexTracker + 3)
// Add default branch (reserve 4 bytes for default label offset)
cg.code.push(0, 0, 0, 0)
caseLabelIndex.push(indexTracker)
indexTracker += 4

// Push the number of case-value pairs
Expand All @@ -1474,9 +1469,12 @@ const codeGenerators: { [type: string]: (node: Node, cg: CodeGenerator) => Compi

// Generate lookup table (pairs of case values and corresponding labels)
caseValues.forEach((value, index) => {
cg.code.push(value >> 24, (value >> 16) & 0xff, (value >> 8) & 0xff, value & 0xff)
cg.code.push(0, 0, 0, caseLabels[index].offset)
caseLabelIndex.push(indexTracker + 7)
// push 4-byte key
cg.code.push((value >> 24) & 0xff, (value >> 16) & 0xff, (value >> 8) & 0xff, value & 0xff)
// reserve 4 bytes for the branch target
cg.code.push(0, 0, 0, 0)
// label offset starts after the 4-byte key
caseLabelIndex.push(indexTracker + 4)
indexTracker += 8
})
}
Expand Down Expand Up @@ -1523,10 +1521,38 @@ const codeGenerators: { [type: string]: (node: Node, cg: CodeGenerator) => Compi
}
}

cg.code[caseLabelIndex[0]] = caseLabels[caseLabels.length - 1].offset - positionOffset
// Patch switch target offsets (write full 4-byte signed offsets, big-endian)
// Patch default target
{
const idx = caseLabelIndex[0]
const defOff = defaultLabel.offset - positionOffset
cg.code[idx] = (defOff >> 24) & 0xff
cg.code[idx + 1] = (defOff >> 16) & 0xff
cg.code[idx + 2] = (defOff >> 8) & 0xff
cg.code[idx + 3] = defOff & 0xff
}

for (let i = 1; i < caseLabelIndex.length; i++) {
cg.code[caseLabelIndex[i]] = caseLabels[i - 1].offset - positionOffset
if (useTableSwitch) {
const range = maxValue - minValue + 1
for (let j = 0; j < range; j++) {
const idx = caseLabelIndex[1 + j]
const lbl = caseLabelMap.get(minValue + j) || defaultLabel
const off = lbl.offset - positionOffset
cg.code[idx] = (off >> 24) & 0xff
cg.code[idx + 1] = (off >> 16) & 0xff
cg.code[idx + 2] = (off >> 8) & 0xff
cg.code[idx + 3] = off & 0xff
}
} else {
for (let k = 0; k < caseValues.length; k++) {
const idx = caseLabelIndex[1 + k]
const lbl = caseLabelMap.get(caseValues[k]) || defaultLabel
const off = lbl.offset - positionOffset
cg.code[idx] = (off >> 24) & 0xff
cg.code[idx + 1] = (off >> 16) & 0xff
cg.code[idx + 2] = (off >> 8) & 0xff
cg.code[idx + 3] = off & 0xff
}
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}

endLabel.offset = cg.code.length
Expand Down Expand Up @@ -1570,9 +1596,9 @@ const codeGenerators: { [type: string]: (node: Node, cg: CodeGenerator) => Compi
indexTracker++
}

// Default jump target
cg.code.push(0, 0, 0, defaultLabel.offset)
caseLabelIndex.push(indexTracker + 3)
// Default jump target (reserve 4 bytes)
cg.code.push(0, 0, 0, 0)
caseLabelIndex.push(indexTracker)
indexTracker += 4

// Number of case-value pairs
Expand All @@ -1585,15 +1611,14 @@ const codeGenerators: { [type: string]: (node: Node, cg: CodeGenerator) => Compi
indexTracker += 4

// Populate LOOKUPSWITCH
const hashLabels: Label[] = []
hashCaseMap.forEach((label, hashCode) => {
cg.code.push(
hashCode >> 24,
(hashCode >> 16) & 0xff,
(hashCode >> 8) & 0xff,
hashCode & 0xff
)
cg.code.push(0, 0, 0, label.offset)
caseLabelIndex.push(indexTracker + 7)
cg.code.push((hashCode >> 24) & 0xff, (hashCode >> 16) & 0xff, (hashCode >> 8) & 0xff, hashCode & 0xff)
// reserve 4 bytes for the branch target
cg.code.push(0, 0, 0, 0)
// label offset starts after the 4-byte key
caseLabelIndex.push(indexTracker + 4)
hashLabels.push(label)
indexTracker += 8
})

Expand Down Expand Up @@ -1660,10 +1685,24 @@ const codeGenerators: { [type: string]: (node: Node, cg: CodeGenerator) => Compi
})
}

cg.code[caseLabelIndex[0]] = caseLabels[caseLabels.length - 1].offset - positionOffset
// Patch default target
{
const idx = caseLabelIndex[0]
const defOff = defaultLabel.offset - positionOffset
cg.code[idx] = (defOff >> 24) & 0xff
cg.code[idx + 1] = (defOff >> 16) & 0xff
cg.code[idx + 2] = (defOff >> 8) & 0xff
cg.code[idx + 3] = defOff & 0xff
}

for (let i = 1; i < caseLabelIndex.length; i++) {
cg.code[caseLabelIndex[i]] = caseLabels[i - 1].offset - positionOffset
// Patch hash-case entries in insertion order
for (let k = 0; k < hashLabels.length; k++) {
const idx = caseLabelIndex[1 + k]
const off = hashLabels[k].offset - positionOffset
cg.code[idx] = (off >> 24) & 0xff
cg.code[idx + 1] = (off >> 16) & 0xff
cg.code[idx + 2] = (off >> 8) & 0xff
cg.code[idx + 3] = off & 0xff
}

endLabel.offset = cg.code.length
Expand Down
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