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/// > Note:
/// <https://webassembly.github.io/spec/core/exec/instructions.html#control-instructions>
extension ExecutionState {
func unreachable(runtime: Runtime) throws {
throw Trap.unreachable
}
mutating func nop(runtime: Runtime) throws {
programCounter += 1
}
private func getTypeSection(store: Store) -> [FunctionType] {
store.module(address: stack.currentFrame.module).types
}
typealias BlockType = Instruction.BlockType
mutating func block(runtime: Runtime, endRef: ExpressionRef, type: BlockType) {
enter(
jumpTo: programCounter + 1,
continuation: programCounter + endRef.relativeOffset,
arity: Int(type.results),
pushPopValues: Int(type.parameters)
)
}
mutating func loop(runtime: Runtime, type: BlockType) {
let paramSize = Int(type.parameters)
enter(jumpTo: programCounter + 1, continuation: programCounter, arity: paramSize, pushPopValues: paramSize)
}
mutating func ifThen(runtime: Runtime, endRef: ExpressionRef, type: BlockType) {
let isTrue = stack.popValue().i32 != 0
if isTrue {
enter(
jumpTo: programCounter + 1,
continuation: programCounter.advanced(by: endRef.relativeOffset),
arity: Int(type.results),
pushPopValues: Int(type.parameters)
)
} else {
programCounter += endRef.relativeOffset
}
}
mutating func ifThenElse(runtime: Runtime, elseRef: ExpressionRef, endRef: ExpressionRef, type: BlockType) {
let isTrue = stack.popValue().i32 != 0
let addendToPC: Int
if isTrue {
addendToPC = 1
} else {
addendToPC = elseRef.relativeOffset
}
enter(
jumpTo: programCounter + addendToPC,
continuation: programCounter + endRef.relativeOffset,
arity: Int(type.results),
pushPopValues: Int(type.parameters)
)
}
mutating func end(runtime: Runtime) {
if let currentLabel = self.stack.currentLabel {
stack.exit(label: currentLabel)
}
programCounter += 1
}
mutating func `else`(runtime: Runtime) {
let label = self.stack.currentLabel!
stack.exit(label: label)
programCounter = label.continuation // if-then-else's continuation points the "end"
}
private mutating func branch(labelIndex: Int, runtime: Runtime) throws {
if stack.numberOfLabelsInCurrentFrame() == labelIndex {
try self.return(runtime: runtime)
return
}
let label = stack.getLabel(index: Int(labelIndex))
let values = stack.popValues(count: label.arity)
stack.unwindLabels(upto: labelIndex)
stack.push(values: values)
programCounter = label.continuation
}
mutating func br(runtime: Runtime, labelIndex: LabelIndex) throws {
try branch(labelIndex: Int(labelIndex), runtime: runtime)
}
mutating func brIf(runtime: Runtime, labelIndex: LabelIndex) throws {
guard stack.popValue().i32 != 0 else {
programCounter += 1
return
}
try br(runtime: runtime, labelIndex: labelIndex)
}
mutating func brTable(runtime: Runtime, brTable: Instruction.BrTable) throws {
let labelIndices = brTable.labelIndices
let defaultIndex = brTable.defaultIndex
let value = stack.popValue().i32
let labelIndex: LabelIndex
if labelIndices.indices.contains(Int(value)) {
labelIndex = labelIndices[Int(value)]
} else {
labelIndex = defaultIndex
}
try branch(labelIndex: Int(labelIndex), runtime: runtime)
}
mutating func `return`(runtime: Runtime) throws {
let currentFrame = stack.currentFrame!
_ = stack.exit(frame: currentFrame)
try endOfFunction(runtime: runtime, currentFrame: currentFrame)
}
mutating func endOfFunction(runtime: Runtime) throws {
try self.endOfFunction(runtime: runtime, currentFrame: stack.currentFrame)
}
mutating func endOfExecution(runtime: Runtime) throws {
reachedEndOfExecution = true
}
private mutating func endOfFunction(runtime: Runtime, currentFrame: Frame) throws {
// When reached at "end" of function
#if DEBUG
if let address = currentFrame.address {
runtime.interceptor?.onExitFunction(address, store: runtime.store)
}
#endif
let values = stack.popValues(count: currentFrame.arity)
stack.popFrame()
stack.push(values: values)
programCounter = currentFrame.returnPC
}
mutating func call(runtime: Runtime, functionIndex: UInt32) throws {
let functionAddresses = runtime.store.module(address: stack.currentFrame.module).functionAddresses
guard functionAddresses.indices.contains(Int(functionIndex)) else {
throw Trap.invalidFunctionIndex(functionIndex)
}
try invoke(functionAddress: functionAddresses[Int(functionIndex)], runtime: runtime)
}
mutating func callIndirect(runtime: Runtime, tableIndex: TableIndex, typeIndex: TypeIndex) throws {
let moduleInstance = runtime.store.module(address: stack.currentFrame.module)
let tableAddresses = moduleInstance.tableAddresses[Int(tableIndex)]
let tableInstance = runtime.store.tables[tableAddresses]
let expectedType = moduleInstance.types[Int(typeIndex)]
let value = stack.popValue().i32
let elementIndex = Int(value)
guard elementIndex < tableInstance.elements.count else {
throw Trap.undefinedElement
}
guard case let .function(functionAddress?) = tableInstance.elements[elementIndex]
else {
throw Trap.tableUninitialized(ElementIndex(elementIndex))
}
let function = runtime.store.functions[functionAddress]
guard function.type == expectedType else {
throw Trap.callIndirectFunctionTypeMismatch(actual: function.type, expected: expectedType)
}
try invoke(functionAddress: functionAddress, runtime: runtime)
}
}
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