wacc_37/src/main/wacc/backend/Stack.scala

91 lines
2.6 KiB
Scala

package wacc
import scala.collection.mutable.LinkedHashMap
import cats.data.Chain
class Stack {
import assemblyIR._
import assemblyIR.Size._
import sizeExtensions.size
import microWacc as mw
private val RSP = Register(Q64, RegName.SP)
private class StackValue(val size: Size, val offset: Int) {
def bottom: Int = offset + elemBytes
}
private val stack = LinkedHashMap[mw.Expr | Int, StackValue]()
private val elemBytes: Int = Q64.toInt
private def sizeBytes: Int = stack.size * elemBytes
/** The stack's size in bytes. */
def size: Int = stack.size
/** Push an expression onto the stack. */
def push(expr: mw.Expr, src: Register): AsmLine = {
stack += expr -> StackValue(src.size, sizeBytes)
Push(src)
}
/** Push a value onto the stack. */
def push(itemSize: Size, addr: Src): AsmLine = {
stack += stack.size -> StackValue(itemSize, sizeBytes)
Push(addr)
}
/** Reserve space for a variable on the stack. */
def reserve(ident: mw.Ident): AsmLine = {
stack += ident -> StackValue(ident.ty.size, sizeBytes)
Subtract(RSP, ImmediateVal(elemBytes))
}
/** Reserve space for a register on the stack. */
def reserve(src: Register): AsmLine = {
stack += stack.size -> StackValue(src.size, sizeBytes)
Subtract(RSP, ImmediateVal(src.size.toInt))
}
/** Reserve space for values on the stack.
*
* @param sizes
* The sizes of the values to reserve space for.
*/
def reserve(sizes: List[Size]): AsmLine = {
sizes.foreach { itemSize =>
stack += stack.size -> StackValue(itemSize, sizeBytes)
}
Subtract(RSP, ImmediateVal(elemBytes * sizes.size))
}
/** Pop a value from the stack into a register. Sizes MUST match. */
def pop(dest: Register): AsmLine = {
stack.remove(stack.last._1)
Pop(dest)
}
/** Drop the top n values from the stack. */
def drop(n: Int = 1): AsmLine = {
(1 to n).foreach { _ =>
stack.remove(stack.last._1)
}
Add(RSP, ImmediateVal(n * elemBytes))
}
/** Generate AsmLines within a scope, which is reset after the block. */
def withScope(block: () => Chain[AsmLine]): Chain[AsmLine] = {
val resetToSize = stack.size
var lines = block()
lines :+= drop(stack.size - resetToSize)
lines
}
/** Get an IndexAddress for a variable in the stack. */
def accessVar(ident: mw.Ident): IndexAddress =
IndexAddress(RSP, sizeBytes - stack(ident).bottom)
def contains(ident: mw.Ident): Boolean = stack.contains(ident)
def head: MemLocation = MemLocation(RSP, stack.last._2.size)
override def toString(): String = stack.toString
}