wacc_37/src/main/wacc/backend/asmGenerator.scala
2025-02-25 18:20:50 +00:00

409 lines
12 KiB
Scala

package wacc
import scala.collection.mutable.LinkedHashMap
import scala.collection.mutable.ListBuffer
object asmGenerator {
import microWacc._
import assemblyIR._
import wacc.types._
import lexer.escapedChars
val RAX = Register(RegSize.R64, RegName.AX)
val EAX = Register(RegSize.E32, RegName.AX)
val ESP = Register(RegSize.E32, RegName.SP)
val EDX = Register(RegSize.E32, RegName.DX)
val RDI = Register(RegSize.R64, RegName.DI)
val RIP = Register(RegSize.R64, RegName.IP)
val RBP = Register(RegSize.R64, RegName.BP)
val RSI = Register(RegSize.R64, RegName.SI)
val RDX = Register(RegSize.R64, RegName.DX)
val RCX = Register(RegSize.R64, RegName.CX)
val R8 = Register(RegSize.R64, RegName.Reg8)
val R9 = Register(RegSize.R64, RegName.Reg9)
val _8_BIT_MASK = 0xff
def generateAsm(microProg: Program): List[AsmLine] = {
given stack: Stack = Stack()
given strings: ListBuffer[String] = ListBuffer[String]()
given labelGenerator: LabelGenerator = LabelGenerator()
val Program(funcs, main) = microProg
val progAsm =
LabelDef("main") ::
funcPrologue() ++
List(stack.align()) ++
main.flatMap(generateStmt) ++
List(Move(RAX, ImmediateVal(0))) ++
funcEpilogue() ++
generateBuiltInFuncs()
val strDirs = strings.toList.zipWithIndex.flatMap { case (str, i) =>
List(
Directive.Int(str.size),
LabelDef(s".L.str$i"),
Directive.Asciz(str.escaped)
)
}
List(Directive.IntelSyntax, Directive.Global("main"), Directive.RoData) ++
strDirs ++
List(Directive.Text) ++
progAsm
}
def wrapFunc(labelName: String, funcBody: List[AsmLine])(using
stack: Stack,
strings: ListBuffer[String]
): List[AsmLine] = {
LabelDef(labelName) ::
funcPrologue() ++
funcBody ++
funcEpilogue()
}
def generateBuiltInFuncs()(using
stack: Stack,
strings: ListBuffer[String],
labelGenerator: LabelGenerator
): List[AsmLine] = {
wrapFunc(
labelGenerator.getLabel(Builtin.Exit),
List(stack.align(), assemblyIR.Call(CLibFunc.Exit))
) ++
wrapFunc(
labelGenerator.getLabel(Builtin.Printf),
List(
stack.align(),
assemblyIR.Call(CLibFunc.PrintF),
Move(RDI, ImmediateVal(0)),
assemblyIR.Call(CLibFunc.Fflush)
)
) ++
wrapFunc(
labelGenerator.getLabel(Builtin.Malloc),
List(
stack.align()
)
) ++
wrapFunc(labelGenerator.getLabel(Builtin.Free), List()) ++
wrapFunc(
labelGenerator.getLabel(Builtin.Read),
List(
stack.align(),
stack.reserve(),
stack.push(RSI),
Load(RSI, stack.head),
assemblyIR.Call(CLibFunc.Scanf),
stack.pop(RAX),
stack.drop()
)
)
}
def generateStmt(
stmt: Stmt
)(using
stack: Stack,
strings: ListBuffer[String],
labelGenerator: LabelGenerator
): List[AsmLine] =
stmt match {
case Assign(lhs, rhs) =>
var dest: () => IndexAddress =
() => IndexAddress(RAX, 0) // gets overrwitten
(lhs match {
case ident: Ident =>
dest = stack.accessVar(ident)
if (!stack.contains(ident)) {
List(stack.reserve(ident))
} else Nil
// TODO lhs = arrayElem
case _ =>
// dest = ???
List()
}) ++
evalExprOntoStack(rhs) ++
List(
stack.pop(RAX),
Move(dest(), RAX)
)
case If(cond, thenBranch, elseBranch) => {
val elseLabel = labelGenerator.getLabel()
val endLabel = labelGenerator.getLabel()
evalExprOntoStack(cond) ++
List(
Compare(stack.head(SizeDir.Word), ImmediateVal(0)),
stack.drop(),
Jump(LabelArg(elseLabel), Cond.Equal)
) ++
thenBranch.flatMap(generateStmt) ++
List(Jump(LabelArg(endLabel)), LabelDef(elseLabel)) ++
elseBranch.flatMap(generateStmt) ++
List(LabelDef(endLabel))
}
case While(cond, body) => {
val startLabel = labelGenerator.getLabel()
val endLabel = labelGenerator.getLabel()
List(LabelDef(startLabel)) ++
evalExprOntoStack(cond) ++
List(
Compare(stack.head(SizeDir.Word), ImmediateVal(0)),
stack.drop(),
Jump(LabelArg(endLabel), Cond.Equal)
) ++
body.flatMap(generateStmt) ++
List(Jump(LabelArg(startLabel)), LabelDef(endLabel))
}
case microWacc.Return(expr) =>
evalExprOntoStack(expr) ++
List(stack.pop(RAX), assemblyIR.Return())
case call: microWacc.Call => generateCall(call)
}
def evalExprOntoStack(expr: Expr)(using
stack: Stack,
strings: ListBuffer[String],
labelGenerator: LabelGenerator
): List[AsmLine] = {
val out = expr match {
case IntLiter(v) =>
List(stack.push(ImmediateVal(v)))
case CharLiter(v) =>
List(stack.push(ImmediateVal(v.toInt)))
case ident: Ident =>
List(stack.push(stack.accessVar(ident)()))
case ArrayLiter(elems) =>
expr.ty match {
case KnownType.String =>
strings += elems.map {
case CharLiter(v) => v
case _ => ""
}.mkString
List(
Load(
RAX,
IndexAddress(
RIP,
LabelArg(s".L.str${strings.size - 1}")
)
),
stack.push(RAX)
)
// TODO other array types
case _ => List()
}
case BoolLiter(v) => List(stack.push(ImmediateVal(if (v) 1 else 0)))
case NullLiter() => List(stack.push(ImmediateVal(0)))
case ArrayElem(value, indices) => List()
case UnaryOp(x, op) =>
evalExprOntoStack(x) ++
(op match {
// TODO: chr and ord are TYPE CASTS. They do not change the internal value,
// but will need bound checking e.t.c.
case UnaryOperator.Chr => List()
case UnaryOperator.Ord => List()
case UnaryOperator.Len => List()
case UnaryOperator.Negate =>
List(
Negate(stack.head(SizeDir.Word))
)
case UnaryOperator.Not =>
evalExprOntoStack(x) ++
List(
Xor(stack.head(SizeDir.Word), ImmediateVal(1))
)
})
case BinaryOp(x, y, op) =>
op match {
case BinaryOperator.Add =>
evalExprOntoStack(x) ++
evalExprOntoStack(y) ++
List(
stack.pop(RAX),
Add(stack.head(SizeDir.Word), EAX)
// TODO OVERFLOWING
)
case BinaryOperator.Sub =>
evalExprOntoStack(x) ++
evalExprOntoStack(y) ++
List(
stack.pop(RAX),
Subtract(stack.head(SizeDir.Word), EAX)
// TODO OVERFLOWING
)
case BinaryOperator.Mul =>
evalExprOntoStack(x) ++
evalExprOntoStack(y) ++
List(
stack.pop(RAX),
Multiply(EAX, stack.head(SizeDir.Word)),
stack.drop(),
stack.push(RAX)
// TODO OVERFLOWING
)
case BinaryOperator.Div =>
evalExprOntoStack(y) ++
evalExprOntoStack(x) ++
List(
stack.pop(RAX),
Divide(stack.head(SizeDir.Word)),
stack.drop(),
stack.push(RAX)
// TODO CHECK DIVISOR IS NOT 0
)
case BinaryOperator.Mod =>
evalExprOntoStack(y) ++
evalExprOntoStack(x) ++
List(
stack.pop(RAX),
Divide(stack.head(SizeDir.Word)),
stack.drop(),
stack.push(RDX)
// TODO CHECK DIVISOR IS NOT 0
)
case BinaryOperator.Eq =>
generateComparison(x, y, Cond.Equal)
case BinaryOperator.Neq =>
generateComparison(x, y, Cond.NotEqual)
case BinaryOperator.Greater =>
generateComparison(x, y, Cond.Greater)
case BinaryOperator.GreaterEq =>
generateComparison(x, y, Cond.GreaterEqual)
case BinaryOperator.Less =>
generateComparison(x, y, Cond.Less)
case BinaryOperator.LessEq =>
generateComparison(x, y, Cond.LessEqual)
case BinaryOperator.And =>
evalExprOntoStack(x) ++
evalExprOntoStack(y) ++
List(
stack.pop(RAX),
And(stack.head(SizeDir.Word), EAX)
)
case BinaryOperator.Or =>
evalExprOntoStack(x) ++
evalExprOntoStack(y) ++
List(
stack.pop(RAX),
Or(stack.head(SizeDir.Word), EAX)
)
}
case call: microWacc.Call =>
generateCall(call) ++
List(stack.push(RAX))
}
if out.isEmpty then List(stack.push(ImmediateVal(0))) else out
}
def generateCall(call: microWacc.Call)(using
stack: Stack,
strings: ListBuffer[String],
labelGenerator: LabelGenerator
): List[AsmLine] = {
val argRegs = List(RDI, RSI, RDX, RCX, R8, R9)
val microWacc.Call(target, args) = call
argRegs.zip(args).flatMap { (reg, expr) =>
evalExprOntoStack(expr) ++
List(stack.pop(reg))
} ++
args.drop(argRegs.size).flatMap(evalExprOntoStack) ++
List(assemblyIR.Call(LabelArg(labelGenerator.getLabel(target)))) ++
(if (args.size > argRegs.size) {
List(stack.drop(args.size - argRegs.size))
} else Nil)
}
def generateComparison(x: Expr, y: Expr, cond: Cond)(using
stack: Stack,
strings: ListBuffer[String],
labelGenerator: LabelGenerator
): List[AsmLine] = {
evalExprOntoStack(x) ++
evalExprOntoStack(y) ++
List(
stack.pop(RAX),
Compare(stack.head(SizeDir.Word), EAX),
Set(Register(RegSize.Byte, RegName.AL), cond),
And(RAX, ImmediateVal(_8_BIT_MASK)),
stack.drop(),
stack.push(RAX)
)
}
// Missing a sub instruction but dont think we need it
def funcPrologue()(using stack: Stack): List[AsmLine] = {
List(
stack.push(RBP),
Move(RBP, Register(RegSize.R64, RegName.SP))
)
}
def funcEpilogue()(using stack: Stack): List[AsmLine] = {
List(
Move(Register(RegSize.R64, RegName.SP), RBP),
stack.pop(RBP),
assemblyIR.Return()
)
}
class LabelGenerator {
var labelVal = -1
def getLabel(): String = {
labelVal += 1
s".L$labelVal"
}
def getLabel(target: CallTarget): String = target match {
case Ident(v, _) => s"wacc_$v"
case Builtin(name) => s"_$name"
}
}
class Stack {
private val stack = LinkedHashMap[Expr | Int, Int]()
private val RSP = Register(RegSize.R64, RegName.SP)
def next: Int = stack.size + 1
def push(expr: Expr, src: Src): AsmLine = {
stack += expr -> next
Push(src)
}
def push(src: Src): AsmLine = {
stack += stack.size -> next
Push(src)
}
def pop(dest: Src): AsmLine = {
stack.remove(stack.last._1)
Pop(dest)
}
def reserve(ident: Ident): AsmLine = {
stack += ident -> next
Subtract(RSP, ImmediateVal(8))
}
def reserve(n: Int = 1): AsmLine = {
(1 to n).foreach(_ => stack += stack.size -> next)
Subtract(RSP, ImmediateVal(n * 8))
}
def drop(n: Int = 1): AsmLine = {
(1 to n).foreach(_ => stack.remove(stack.last._1))
Add(RSP, ImmediateVal(n * 8))
}
def accessVar(ident: Ident): () => IndexAddress = () => {
IndexAddress(RSP, (stack.size - stack(ident)) * 8)
}
def head: MemLocation = MemLocation(RSP)
def head(size: SizeDir): MemLocation = MemLocation(RSP, size)
def contains(ident: Ident): Boolean = stack.contains(ident)
// TODO: Might want to actually properly handle this with the LinkedHashMap too
def align(): AsmLine = And(RSP, ImmediateVal(-16))
}
private val escapedCharsMapping = escapedChars.map { case (k, v) => v -> s"\\$k" }
extension (s: String) {
private def escaped: String =
s.flatMap(c => escapedCharsMapping.getOrElse(c, c.toString))
}
}