6502: Two fixes:

– fix writing constants to volatile variables
– fix optimizing variables to registers yet again

src/test/scala/millfork/test/VolatileSuite.scala

@@ -0,0 +1,37 @@
+package millfork.test
+
+import millfork.Cpu
+import millfork.test.emu.{EmuBenchmarkRun, EmuCrossPlatformBenchmarkRun, EmuSuperOptimizedRun, EmuUltraBenchmarkRun}
+import org.scalatest.{FunSuite, Matchers}
+
+/**
+  * @author Karol Stasiak
+  */
+class VolatileSuite extends FunSuite with Matchers {
+
+  test("Basic volatile test") {
+    EmuCrossPlatformBenchmarkRun(Cpu.Mos, Cpu.Z80)(
+      """
+        | word addr @$c000
+        | volatile byte output @$c0ea
+        | byte thing
+        | void main () {
+        |   f(55)
+        |   addr = f.addr
+        | }
+        | noinline void f(byte x) {
+        |   output = 5
+        |   thing = x
+        |   output = x
+        | }
+      """.stripMargin) { m =>
+      m.readByte(0xc0ea) should equal(55)
+      var f = m.readWord(0xc000)
+      var count = 0
+      do {
+        if (m.readWord(f) == 0xc0ea) count +=1
+        f += 1
+      } while (count < 2)
+    }
+  }
+}