From dfe33c9b7ab0011b65a054fde258c2608f7c9f26 Mon Sep 17 00:00:00 2001
From: Karol Stasiak <karol.m.stasiak@gmail.com>
Date: Thu, 26 Mar 2020 18:52:46 +0100
Subject: [PATCH] 6502: Pointers should have priority when allocating to the
 zeropage

---
 src/main/scala/millfork/env/Environment.scala | 11 ++++++++--
 .../scala/millfork/test/PointerSuite.scala    | 22 +++++++++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/main/scala/millfork/env/Environment.scala b/src/main/scala/millfork/env/Environment.scala
index 0d9b7aa1..8a1f5d12 100644
--- a/src/main/scala/millfork/env/Environment.scala
+++ b/src/main/scala/millfork/env/Environment.scala
@@ -186,7 +186,13 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
             } else Nil
           case VariableAllocationMethod.Auto | VariableAllocationMethod.Register | VariableAllocationMethod.Static =>
             if (m.alloc == VariableAllocationMethod.Register && options.flag(CompilationFlag.FallbackValueUseWarning)) {
-              log.warn(s"Failed to inline variable `${m.name}` into a register", None)
+              options.platform.cpuFamily match {
+                case CpuFamily.M6502 if m.sizeInBytes == 1 =>
+                  log.warn(s"Failed to inline variable `${m.name}` into a register", None)
+                case CpuFamily.I80 | CpuFamily.I80 | CpuFamily.I86 | CpuFamily.M6809 if m.sizeInBytes <= 2 =>
+                  log.warn(s"Failed to inline variable `${m.name}` into a register", None)
+                case _ =>
+              }
             }
             if (m.sizeInBytes == 0) Nil else {
               val graveName = m.name.stripPrefix(prefix) + "`"
@@ -1471,7 +1477,8 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
     stmt.assemblyParamPassingConvention match {
       case ByVariable(name) =>
         val zp = pointies(name) // TODO
-        val v = UninitializedMemoryVariable(prefix + name, typ, if (zp) VariableAllocationMethod.Zeropage else VariableAllocationMethod.Auto, None, defaultVariableAlignment(options, 2), isVolatile = false)
+        val allocationMethod = if (pointies(name)) VariableAllocationMethod.Zeropage else if (typ.isPointy) 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))
         val addr = v.toAddress
diff --git a/src/test/scala/millfork/test/PointerSuite.scala b/src/test/scala/millfork/test/PointerSuite.scala
index b7163bf7..12a944ea 100644
--- a/src/test/scala/millfork/test/PointerSuite.scala
+++ b/src/test/scala/millfork/test/PointerSuite.scala
@@ -453,4 +453,26 @@ class PointerSuite extends FunSuite with Matchers with AppendedClues {
     m.readWord(0xc000) should be <(256)
 
   }
+
+  test ("Pointers should have priority when allocating to the zeropage") {
+    val m = EmuUnoptimizedRun(
+      """
+        | word output1 @$c000
+        | word output2 @$c000
+        |
+        | array arr [252]
+        |
+        | noinline word f(pointer p, pointer q) {
+        |   output1 = p.addr
+        |   output2 = q.addr
+        |   return p + q
+        | }
+        |
+        | void main () {
+        |   f(0,1)
+        | }
+        |""".stripMargin)
+    m.readWord(0xc000) should be <(256)
+    m.readWord(0xc002) should be <(256)
+  }
 }