WasmParser/WAT: Add support for the tail-call proposal

Sources/WAT/BinaryInstructionEncoder.swift

@@ -74,6 +74,14 @@ extension BinaryInstructionEncoder {
         try encodeInstruction([0x11])
         try encodeImmediates(typeIndex: typeIndex, tableIndex: tableIndex)
     }
+    mutating func visitReturnCall(functionIndex: UInt32) throws {
+        try encodeInstruction([0x12])
+        try encodeImmediates(functionIndex: functionIndex)
+    }
+    mutating func visitReturnCallIndirect(typeIndex: UInt32, tableIndex: UInt32) throws {
+        try encodeInstruction([0x13])
+        try encodeImmediates(typeIndex: typeIndex, tableIndex: tableIndex)
+    }
     mutating func visitDrop() throws { try encodeInstruction([0x1A]) }
     mutating func visitSelect() throws { try encodeInstruction([0x1B]) }
     mutating func visitTypedSelect(type: ValueType) throws {

Sources/WAT/ParseTextInstruction.swift

@@ -43,6 +43,12 @@ func parseTextInstruction<V: InstructionVisitor>(keyword: String, expressionPars
     case "call_indirect":
         let (typeIndex, tableIndex) = try expressionParser.visitCallIndirect(wat: &wat)
         return { return try $0.visitCallIndirect(typeIndex: typeIndex, tableIndex: tableIndex) }
+    case "return_call":
+        let (functionIndex) = try expressionParser.visitReturnCall(wat: &wat)
+        return { return try $0.visitReturnCall(functionIndex: functionIndex) }
+    case "return_call_indirect":
+        let (typeIndex, tableIndex) = try expressionParser.visitReturnCallIndirect(wat: &wat)
+        return { return try $0.visitReturnCallIndirect(typeIndex: typeIndex, tableIndex: tableIndex) }
     case "drop": return { return try $0.visitDrop() }
     case "select": return { return try $0.visitSelect() }
     case "local.get":

Sources/WAT/Parser/ExpressionParser.swift

@@ -450,6 +450,12 @@ extension ExpressionParser {
         let (_, typeIndex) = try wat.types.resolve(use: typeUse)
         return (UInt32(typeIndex), tableIndex)
     }
+    mutating func visitReturnCall(wat: inout Wat) throws -> UInt32 {
+        return try visitCall(wat: &wat)
+    }
+    mutating func visitReturnCallIndirect(wat: inout Wat) throws -> (typeIndex: UInt32, tableIndex: UInt32) {
+        return try visitCallIndirect(wat: &wat)
+    }
     mutating func visitTypedSelect(wat: inout Wat) throws -> ValueType {
         fatalError("unreachable because Instruction.json does not define the name of typed select and it is handled in parseTextInstruction() manually")
     }

Sources/WasmParser/BinaryInstructionDecoder.swift

@@ -26,6 +26,10 @@ protocol BinaryInstructionDecoder {
     @inlinable mutating func visitCall() throws -> UInt32
     /// Decode `call_indirect` immediates
     @inlinable mutating func visitCallIndirect() throws -> (typeIndex: UInt32, tableIndex: UInt32)
+    /// Decode `return_call` immediates
+    @inlinable mutating func visitReturnCall() throws -> UInt32
+    /// Decode `return_call_indirect` immediates
+    @inlinable mutating func visitReturnCallIndirect() throws -> (typeIndex: UInt32, tableIndex: UInt32)
     /// Decode `typedSelect` immediates
     @inlinable mutating func visitTypedSelect() throws -> ValueType
     /// Decode `local.get` immediates
@@ -122,6 +126,12 @@ func parseBinaryInstruction<V: InstructionVisitor, D: BinaryInstructionDecoder>(
     case 0x11:
         let (typeIndex, tableIndex) = try decoder.visitCallIndirect()
         try visitor.visitCallIndirect(typeIndex: typeIndex, tableIndex: tableIndex)
+    case 0x12:
+        let (functionIndex) = try decoder.visitReturnCall()
+        try visitor.visitReturnCall(functionIndex: functionIndex)
+    case 0x13:
+        let (typeIndex, tableIndex) = try decoder.visitReturnCallIndirect()
+        try visitor.visitReturnCallIndirect(typeIndex: typeIndex, tableIndex: tableIndex)
     case 0x1A:
         try visitor.visitDrop()
     case 0x1B:

Sources/WasmParser/InstructionVisitor.swift

@@ -187,6 +187,8 @@ public enum Instruction: Equatable {
     case `return`
     case `call`(functionIndex: UInt32)
     case `callIndirect`(typeIndex: UInt32, tableIndex: UInt32)
+    case `returnCall`(functionIndex: UInt32)
+    case `returnCallIndirect`(typeIndex: UInt32, tableIndex: UInt32)
     case `drop`
     case `select`
     case `typedSelect`(type: ValueType)
@@ -246,6 +248,8 @@ extension AnyInstructionVisitor {
     public mutating func visitReturn() throws { return try self.visit(.return) }
     public mutating func visitCall(functionIndex: UInt32) throws { return try self.visit(.call(functionIndex: functionIndex)) }
     public mutating func visitCallIndirect(typeIndex: UInt32, tableIndex: UInt32) throws { return try self.visit(.callIndirect(typeIndex: typeIndex, tableIndex: tableIndex)) }
+    public mutating func visitReturnCall(functionIndex: UInt32) throws { return try self.visit(.returnCall(functionIndex: functionIndex)) }
+    public mutating func visitReturnCallIndirect(typeIndex: UInt32, tableIndex: UInt32) throws { return try self.visit(.returnCallIndirect(typeIndex: typeIndex, tableIndex: tableIndex)) }
     public mutating func visitDrop() throws { return try self.visit(.drop) }
     public mutating func visitSelect() throws { return try self.visit(.select) }
     public mutating func visitTypedSelect(type: ValueType) throws { return try self.visit(.typedSelect(type: type)) }
@@ -316,6 +320,10 @@ public protocol InstructionVisitor {
     mutating func visitCall(functionIndex: UInt32) throws
     /// Visiting `call_indirect` instruction.
     mutating func visitCallIndirect(typeIndex: UInt32, tableIndex: UInt32) throws
+    /// Visiting `return_call` instruction.
+    mutating func visitReturnCall(functionIndex: UInt32) throws
+    /// Visiting `return_call_indirect` instruction.
+    mutating func visitReturnCallIndirect(typeIndex: UInt32, tableIndex: UInt32) throws
     /// Visiting `drop` instruction.
     mutating func visitDrop() throws
     /// Visiting `select` instruction.
@@ -409,6 +417,8 @@ extension InstructionVisitor {
         case .return: return try visitReturn()
         case let .call(functionIndex): return try visitCall(functionIndex: functionIndex)
         case let .callIndirect(typeIndex, tableIndex): return try visitCallIndirect(typeIndex: typeIndex, tableIndex: tableIndex)
+        case let .returnCall(functionIndex): return try visitReturnCall(functionIndex: functionIndex)
+        case let .returnCallIndirect(typeIndex, tableIndex): return try visitReturnCallIndirect(typeIndex: typeIndex, tableIndex: tableIndex)
         case .drop: return try visitDrop()
         case .select: return try visitSelect()
         case let .typedSelect(type): return try visitTypedSelect(type: type)
@@ -465,6 +475,8 @@ extension InstructionVisitor {
     public mutating func visitReturn() throws {}
     public mutating func visitCall(functionIndex: UInt32) throws {}
     public mutating func visitCallIndirect(typeIndex: UInt32, tableIndex: UInt32) throws {}
+    public mutating func visitReturnCall(functionIndex: UInt32) throws {}
+    public mutating func visitReturnCallIndirect(typeIndex: UInt32, tableIndex: UInt32) throws {}
     public mutating func visitDrop() throws {}
     public mutating func visitSelect() throws {}
     public mutating func visitTypedSelect(type: ValueType) throws {}

Sources/WasmParser/WasmParser.swift

@@ -193,11 +193,14 @@ public struct WasmFeatureSet: OptionSet {
     /// The WebAssembly threads proposal
     @_alwaysEmitIntoClient
     public static var threads: WasmFeatureSet { WasmFeatureSet(rawValue: 1 << 2) }
+    /// The WebAssembly tail-call proposal
+    @_alwaysEmitIntoClient
+    public static var tailCall: WasmFeatureSet { WasmFeatureSet(rawValue: 1 << 3) }
 
     /// The default feature set
     public static let `default`: WasmFeatureSet = [.referenceTypes]
     /// The feature set with all features enabled
-    public static let all: WasmFeatureSet = [.memory64, .referenceTypes, .threads]
+    public static let all: WasmFeatureSet = [.memory64, .referenceTypes, .threads, .tailCall]
 }
 
 /// An error that occurs during parsing of a WebAssembly binary
@@ -629,6 +632,16 @@ extension Parser: BinaryInstructionDecoder {
         return (typeIndex, tableIndex)
     }
 
+    @inlinable mutating func visitReturnCall() throws -> UInt32 {
+        try parseUnsigned()
+    }
+
+    @inlinable mutating func visitReturnCallIndirect() throws -> (typeIndex: UInt32, tableIndex: UInt32) {
+        let typeIndex: TypeIndex = try parseUnsigned()
+        let tableIndex: TableIndex = try parseUnsigned()
+        return (typeIndex, tableIndex)
+    }
+
     @inlinable mutating func visitTypedSelect() throws -> WasmTypes.ValueType {
         let results = try parseVector { try parseValueType() }
         guard results.count == 1 else {

Tests/WATTests/EncoderTests.swift

@@ -116,7 +116,12 @@ class EncoderTests: XCTestCase {
 
                     let wast2jsonProcess = try Process.run(
                         wast2json,
-                        arguments: [wastFile.path, "-o", json.path]
+                        arguments: [
+                            wastFile.path,
+                            "--enable-memory64",
+                            "--enable-tail-call",
+                            "-o", json.path,
+                        ]
                     )
                     wast2jsonProcess.waitUntilExit()
 

Tests/WATTests/Spectest.swift

@@ -20,6 +20,7 @@ enum Spectest {
         var allFiles = [
             testsuitePath,
             testsuitePath.appendingPathComponent("proposals/memory64"),
+            testsuitePath.appendingPathComponent("proposals/tail-call"),
             rootDirectory.appendingPathComponent("Tests/WasmKitTests/ExtraSuite"),
         ].flatMap {
             try! FileManager.default.contentsOfDirectory(at: $0, includingPropertiesForKeys: nil)

Utilities/Instructions.json

@@ -12,6 +12,8 @@
   ["mvp"                 , "return"                   , ["0x0F"]        , []                                                 , null        ],
   ["mvp"                 , "call"                     , ["0x10"]        , [["functionIndex", "UInt32"]]                      , null        ],
   ["mvp"                 , "call_indirect"            , ["0x11"]        , [["typeIndex", "UInt32"], ["tableIndex", "UInt32"]], null        ],
+  ["tailCall"            , "return_call"              , ["0x12"]        , [["functionIndex", "UInt32"]]                      , null        ],
+  ["tailCall"            , "return_call_indirect"     , ["0x13"]        , [["typeIndex", "UInt32"], ["tableIndex", "UInt32"]], null        ],
   ["mvp"                 , "drop"                     , ["0x1A"]        , []                                                 , null        ],
   ["mvp"                 , "select"                   , ["0x1B"]        , []                                                 , null        ],
   ["referenceTypes"      , {"enumCase": "typedSelect"}, ["0x1C"]        , [["type", "ValueType"]]                            , null        ],