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extension VMGen {
static let CodeSlotSize: Int = 8
/// A primitive type less than or equal to 64 bits.
struct PrimitiveType {
var name: String
var size: Int
var alignment: Int { size }
var bitWidth: Int { size * 8 }
}
/// A field in an immediate type.
struct ImmediateField {
var name: String
var type: PrimitiveType
}
/// A layout for an immediate type of VM instructions.
struct ImmediateLayout {
var name: String
var fields: [ImmediateField] = []
init(name: String) {
self.name = name
}
init(name: String, _ build: (inout Self) -> Void) {
self.name = name
build(&self)
}
mutating func field(name: String, type: PrimitiveType) {
fields.append(ImmediateField(name: name, type: type))
}
typealias SlotLayout = [ImmediateField]
/// Splits the fields into CodeSlot sized slots.
func slots() -> [SlotLayout] {
let slotSize = VMGen.CodeSlotSize
var slots: [SlotLayout] = []
var currentSlot: SlotLayout = []
var currentSize = 0
for field in fields {
currentSize = VMGen.alignUp(currentSize, to: field.type.alignment)
if currentSize + field.type.size > slotSize {
slots.append(currentSlot)
currentSlot = []
currentSize = 0
}
currentSlot.append(field)
currentSize += field.type.size
}
if !currentSlot.isEmpty {
slots.append(currentSlot)
}
return slots
}
/// Builds the type declaration derived from the layout.
func buildDeclaration() -> String {
let fieldDeclarations = fields.map { field in
" var \(field.name): \(field.type.name)"
}.joined(separator: "\n")
var output = """
struct \(name): Equatable, InstructionImmediate {
\(fieldDeclarations)
"""
// Emit `load` method
output += """
@inline(__always) static func load(from pc: inout Pc) -> Self {
"""
let slots = self.slots()
func makeSlotTupleType(slot: SlotLayout) -> (tupleName: String, elements: [(type: String, name: String?)]) {
var elemenets: [(type: String, String?)] = slot.map { ($0.type.name, $0.name) }
var elementsSize = slot.reduce(0) {
VMGen.alignUp($0, to: $1.type.alignment) + $1.type.size
}
// Padding to make the tuple size CodeSlotSize
while elementsSize < VMGen.CodeSlotSize {
elemenets.append(("UInt8", nil))
elementsSize += 1
}
return ("(" + elemenets.map { $0.type }.joined(separator: ", ") + ")", elemenets)
}
for slot in slots {
let (tupleTy, elements) = makeSlotTupleType(slot: slot)
output += """
let (\(elements.map { $0.name ?? "_" }.joined(separator: ", "))) = pc.read(\(tupleTy).self)
"""
}
output += """
return Self(\(fields.map { "\($0.name): \($0.name)" }.joined(separator: ", ")))
}
"""
// Emit `emit` method
output += """
@inline(__always) static func emit(to emitSlot: ((Self) -> CodeSlot) -> Void) {
"""
for slot in slots {
let (tupleTy, elements) = makeSlotTupleType(slot: slot)
if slot.count == 1, slot[0].type.size == VMGen.CodeSlotSize {
// Special case for a single field that is the size of a CodeSlot
// to avoid suspicious warning diagnostic from the compiler.
switch slot[0].type.name {
case "UInt64":
output += """
emitSlot { $0.\(slot[0].name) }
"""
continue
default: break
}
}
output += """
emitSlot { unsafeBitCast((\(elements.map { $0.name.flatMap { "$0.\($0)" } ?? "0" }.joined(separator: ", "))) as \(tupleTy), to: CodeSlot.self) }
"""
}
output += """
}
"""
output += """
}
"""
return output
}
}
}
extension VMGen.ImmediateLayout {
static let binary = Self(name: "BinaryOperand") {
$0.field(name: "result", type: .LVReg)
$0.field(name: "lhs", type: .VReg)
$0.field(name: "rhs", type: .VReg)
}
static let unary = Self(name: "UnaryOperand") {
$0.field(name: "result", type: .LVReg)
$0.field(name: "input", type: .LVReg)
}
static let load = Self(name: "LoadOperand") {
$0.field(name: "offset", type: .UInt64)
$0.field(name: "pointer", type: .VReg)
$0.field(name: "result", type: .VReg)
}
static let store = Self(name: "StoreOperand") {
$0.field(name: "offset", type: .UInt64)
$0.field(name: "pointer", type: .VReg)
$0.field(name: "value", type: .VReg)
}
static let globalAndVRegOperand = Self(name: "GlobalAndVRegOperand") {
$0.field(name: "reg", type: .LLVReg)
$0.field(name: "rawGlobal", type: .UInt64)
}
static let brIfOperand = Self(name: "BrIfOperand") {
$0.field(name: "condition", type: .LVReg)
$0.field(name: "offset", type: .Int32)
}
static let call = Self(name: "CallOperand") {
$0.field(name: "rawCallee", type: .UInt64)
$0.field(name: "spAddend", type: .VReg)
}
}
extension VMGen.PrimitiveType {
static let VReg = Self(name: "VReg", size: 2)
static let LVReg = Self(name: "LVReg", size: 4)
static let LLVReg = Self(name: "LLVReg", size: 8)
static let Int32 = Self(name: "Int32", size: 4)
static let UInt8 = Self(name: "UInt8", size: 1)
static let UInt16 = Self(name: "UInt16", size: 2)
static let UInt32 = Self(name: "UInt32", size: 4)
static let UInt64 = Self(name: "UInt64", size: 8)
static let UntypedValue = Self(name: "UntypedValue", size: 8)
static let MemoryIndex = Self.UInt32
static let FunctionIndex = Self.UInt32
static let ElementIndex = Self.UInt32
}
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