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import WIT
/// A type responsible for lifting a core value representation of WasmKit to a Swift value
struct HostStaticCanonicalLifting: StaticCanonicalLifting {
typealias Operand = StaticMetaOperand
typealias Pointer = StaticMetaPointer
let printer: SourcePrinter
let builder: SwiftFunctionBuilder
let context: StaticMetaCanonicalCallContext
let definitionMapping: DefinitionMapping
func liftUInt(_ value: Operand, bitWidth: Int) -> Operand {
.call("UInt\(bitWidth)", arguments: [value])
}
func liftInt(_ value: Operand, bitWidth: Int) -> Operand {
let sourceBiWidth = bitWidth == 64 ? 64 : 32
return .call(
"Int\(bitWidth)",
arguments: [
.call("Int\(sourceBiWidth)", arguments: [("bitPattern", value)])
])
}
func liftPointer(_ value: Operand, pointeeTypeName: String) -> Operand {
return .call(
"UnsafeGuestPointer<\(pointeeTypeName)>",
arguments: [
("memorySpace", .accessField(.variable(context.contextVar), name: "guestMemory")),
("offset", value),
])
}
func liftBufferPointer(_ value: Operand, length: Operand) -> Operand {
.call(
"UnsafeGuestBufferPointer",
arguments: [
("baseAddress", value), ("count", length),
])
}
func liftList(
pointer: Operand, length: Operand,
element: WITType, loadElement: (Pointer) throws -> Operand
) throws -> Operand {
let loadElementVar = builder.variable("loadElement")
try printer.write(line: "let \(loadElementVar): (UnsafeGuestRawPointer) throws -> \(element.qualifiedSwiftName(mapping: definitionMapping)) = {")
try printer.indent {
// NOTE: `loadElement` can print statements
let loaded = try loadElement(.init(basePointerVar: "$0", offset: 0))
printer.write(line: "return \(loaded)")
}
printer.write(line: "}")
return .call(
"try CanonicalLifting.liftList",
arguments: [
("pointer", pointer),
("length", length),
("elementSize", .literal(CanonicalABI.size(type: element).description)),
("loadElement", .variable(loadElementVar)),
("context", .variable(context.contextVar)),
])
}
}
/// A type responsible for lowering a Swift value to a core value representation of WasmKit
struct HostStaticCanonicalLowering: StaticCanonicalLowering {
typealias Operand = StaticMetaOperand
typealias Pointer = StaticMetaPointer
let printer: SourcePrinter
let builder: SwiftFunctionBuilder
let context: StaticMetaCanonicalCallContext
let definitionMapping: DefinitionMapping
func lowerString(_ value: Operand, encoding: String) throws -> (pointer: Operand, length: Operand) {
let lowered = Operand.call(
"try CanonicalLowering.lowerString",
arguments: [
(nil, value), ("context", .variable(context.contextVar)),
])
let loweredVar = StaticMetaOperand.variable(builder.variable("stringLowered"))
printer.write(line: "let \(loweredVar) = \(lowered)")
return (
lowerUInt32(.accessField(loweredVar, name: "pointer")),
lowerUInt32(.accessField(loweredVar, name: "length"))
)
}
func lowerList(
_ value: Operand, element: WIT.WITType,
storeElement: (Pointer, Operand) throws -> Void
) throws -> (pointer: Operand, length: Operand) {
let storeElementVar = builder.variable("storeElement")
try printer.write(line: "let \(storeElementVar): (\(element.qualifiedSwiftName(mapping: definitionMapping)), UnsafeGuestRawPointer) throws -> Void = {")
try printer.indent {
try storeElement(Pointer(basePointerVar: "$1", offset: 0), .variable("$0"))
}
printer.write(line: "}")
let lowered = Operand.call(
"try CanonicalLowering.lowerList",
arguments: [
(nil, value),
("elementSize", .literal(CanonicalABI.size(type: element).description)),
("elementAlignment", .literal(CanonicalABI.alignment(type: element).description)),
("storeElement", .variable(storeElementVar)),
("context", .variable(context.contextVar)),
])
let loweredVar = StaticMetaOperand.variable(builder.variable("listLowered"))
printer.write(line: "let \(loweredVar) = \(lowered)")
return (
lowerUInt32(.accessField(loweredVar, name: "pointer")),
lowerUInt32(.accessField(loweredVar, name: "length"))
)
}
}
/// A type representing a function that wraps an exported function from a WebAssembly module
/// callable from host environment.
struct HostExportFunction {
let function: FunctionSyntax
let name: CanonicalFunctionName
let signatureTranslation: SignatureTranslation
let builder = SwiftFunctionBuilder()
let context: StaticMetaCanonicalCallContext
let definitionMapping: DefinitionMapping
init(
function: FunctionSyntax,
name: CanonicalFunctionName,
signatureTranslation: SignatureTranslation,
definitionMapping: DefinitionMapping
) {
self.function = function
self.name = name
self.signatureTranslation = signatureTranslation
self.definitionMapping = definitionMapping
// Reserve variables used in the function
self.context = StaticMetaCanonicalCallContext(contextVar: builder.variable("context"))
}
private func printLowerArguments(
parameterNames: some Sequence<String>,
coreSignature: CanonicalABI.CoreSignature,
typeResolver: (TypeReprSyntax) throws -> WITType,
printer: SourcePrinter
) throws -> [StaticMetaOperand] {
// TODO: Support indirect parameters
var loweredArguments: [StaticMetaOperand] = []
var coreParameters = coreSignature.parameters.makeIterator()
var lowering = HostStaticCanonicalLowering(printer: printer, builder: builder, context: context, definitionMapping: definitionMapping)
var storing = StaticCanonicalStoring(printer: printer, builder: builder, definitionMapping: definitionMapping)
for (parameter, parameterName) in zip(function.parameters, parameterNames) {
let type = try typeResolver(parameter.type)
let loweredValues = try CanonicalABI.lower(
type: type, value: StaticMetaOperand.variable(parameterName), lowering: &lowering, storing: &storing
)
for lowered in loweredValues {
let loweredVar = builder.variable(parameterName + "Lowered")
guard let coreType = coreParameters.next() else {
fatalError("insufficient number of core types!?")
}
printer.write(line: "let \(loweredVar) = \(WasmKitSourcePrinter().printNewValue(lowered, type: coreType.type))")
loweredArguments.append(.variable(loweredVar))
}
}
return loweredArguments
}
private func printReturnIndirectResult(
call: String,
typeResolver: (TypeReprSyntax) throws -> WITType,
printer: SourcePrinter
) throws {
let resultPtrVar = builder.variable("resultPtr")
var loading = StaticCanonicalLoading(printer: printer, builder: builder)
printer.write(line: "let \(resultPtrVar) = \(call)[0].i32")
var lifting = HostStaticCanonicalLifting(
printer: printer, builder: builder, context: context,
definitionMapping: definitionMapping
)
let hostPointerVar = builder.variable("guestPointer")
printer.write(
line: "let \(hostPointerVar) = UnsafeGuestRawPointer(memorySpace: \(context.contextVar).guestMemory, offset: \(resultPtrVar))"
)
var loadedResults: [StaticMetaOperand] = []
for resultType in function.results.types {
let resolvedResultType = try typeResolver(resultType)
let loaded = try CanonicalABI.load(
loading: &loading, lifting: &lifting,
type: resolvedResultType, pointer: StaticMetaPointer(basePointerVar: hostPointerVar, offset: 0)
)
loadedResults.append(loaded)
}
printer.write(line: "return (\(loadedResults.map(\.description).joined(separator: ", ")))")
}
private func printReturnDirectResult(
call: String, coreSignature: CanonicalABI.CoreSignature,
typeResolver: (TypeReprSyntax) throws -> WITType,
printer: SourcePrinter
) throws {
let resultVar = builder.variable("result")
printer.write(line: "let \(resultVar) = \(call)")
if coreSignature.results.isEmpty {
// Suppress unused variable warning
printer.write(line: "_ = \(resultVar)")
}
var resultCoreValues: [StaticMetaOperand] = []
for (idx, result) in coreSignature.results.enumerated() {
let resultElementVar = builder.variable("resultElement")
printer.write(line: "let \(resultElementVar) = \(resultVar)[\(idx)].\(result.type)")
resultCoreValues.append(.variable(resultElementVar))
}
var resultCoreValuesIterator = resultCoreValues.makeIterator()
var liftedResults: [StaticMetaOperand] = []
var lifting = HostStaticCanonicalLifting(
printer: printer, builder: builder, context: context,
definitionMapping: definitionMapping
)
var loading = StaticCanonicalLoading(printer: printer, builder: builder)
for resultType in function.results.types {
let resolvedResultType = try typeResolver(resultType)
let lifted = try WIT.CanonicalABI.lift(
type: resolvedResultType, coreValues: &resultCoreValuesIterator,
lifting: &lifting, loading: &loading
)
liftedResults.append(lifted)
}
printer.write(line: "return (\(liftedResults.map(\.description).joined(separator: ", ")))")
}
/// Prints a Swift source code of the function
///
/// - Parameters:
/// - typeResolver: A function that resolves a WIT type from a type representation syntax
/// - printer: A printer to print the source code
func print(
typeResolver: (TypeReprSyntax) throws -> WITType,
printer: SourcePrinter
) throws {
let coreSignature = try CanonicalABI.flattenSignature(
function: function,
typeResolver: typeResolver
)
var signature = try signatureTranslation.signature(function: function, name: ConvertCase.camelCase(kebab: name.apiSwiftName))
let witParameters = signature.parameters.map(\.label)
signature.parameters.insert(("runtime", "Runtime"), at: 0)
signature.hasThrows = true
printer.write(line: signature.description + " {")
try printer.indent {
let optionsVar = builder.variable("options")
printer.write(line: "let \(optionsVar) = CanonicalOptions._derive(from: moduleInstance, exportName: \"\(name.abiName)\")")
printer.write(line: "let \(context.contextVar) = CanonicalCallContext(options: \(optionsVar), moduleInstance: moduleInstance, runtime: runtime)")
// Supress unused variable warning for "context"
printer.write(line: "_ = \(context.contextVar)")
let arguments = try printLowerArguments(
parameterNames: witParameters, coreSignature: coreSignature,
typeResolver: typeResolver, printer: printer
)
var call = "try runtime.invoke(moduleInstance, function: \"\(name.abiName)\""
if !arguments.isEmpty {
call += ", with: [\(arguments.map(\.description).joined(separator: ", "))]"
}
call += ")"
if coreSignature.isIndirectResult {
try printReturnIndirectResult(call: call, typeResolver: typeResolver, printer: printer)
} else {
try printReturnDirectResult(
call: call, coreSignature: coreSignature,
typeResolver: typeResolver, printer: printer)
}
}
printer.write(line: "}")
}
}
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