8080: Some minor improvements

src/main/scala/millfork/compiler/z80/ZBuiltIns.scala

@@ -177,6 +177,8 @@ object ZBuiltIns {
           }
         case NumericConstant(n, _) if n < 0 && !decimal =>
           result += ZLine.imm8(SUB, (-n.toInt) & 0xff)
+        case NumericConstant(0, _) =>
+          // nothing
         case _ =>
           result += ZLine.imm8(ADD, const.loByte)
           if (decimal) {

src/main/scala/millfork/env/Environment.scala

@@ -1480,7 +1480,10 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
     stmt.assemblyParamPassingConvention match {
       case ByVariable(name) =>
         val zp = pointies(name) // TODO
-        val allocationMethod = if (pointies(name)) VariableAllocationMethod.Zeropage else if (typ.isPointy) VariableAllocationMethod.Register else VariableAllocationMethod.Auto
+        val allocationMethod =
+          if (pointies(name)) VariableAllocationMethod.Zeropage
+          else if (typ.isPointy && options.platform.cpuFamily == CpuFamily.M6502) VariableAllocationMethod.Register
+          else VariableAllocationMethod.Auto
         val v = UninitializedMemoryVariable(prefix + name, typ, allocationMethod, None, defaultVariableAlignment(options, 2), isVolatile = false)
         addThing(v, stmt.position)
         registerAddressConstant(v, stmt.position, options, Some(typ))

src/main/scala/millfork/output/AbstractAssembler.scala

@@ -730,6 +730,7 @@ abstract class AbstractAssembler[T <: AbstractCode](private val program: Program
         inlinedFunctions,
         options.jobContext))
     unoptimizedCodeSize += unoptimized.map(_.sizeInBytes).sum
+    // unoptimized.foreach(l => log.trace(l.toString))
     val code = optimizations.foldLeft(quickSimplify(unoptimized)) { (c, opt) =>
       val code = opt.optimize(f, c, OptimizationContext(options, labelMap, env.maybeGet[ThingInMemory]("__reg"), niceFunctionProperties))
       if (code eq c) code else quickSimplify(code)