fix failing optimization of 'not' in if statements

compiler/src/prog8/compiler/Compiler.kt

@@ -477,6 +477,14 @@ private fun optimizeAst(program: Program, compilerOptions: CompilationOptions, e
         program.constantFold(errors, compilerOptions) // because simplified statements and expressions can result in more constants that can be folded away
     }
 
+    if(errors.noErrors()) {
+        // certain optimization steps could have introduced a "not" in an if statement, postprocess those again.
+        var changer = NotExpressionAndIfComparisonExprChanger(program, errors, compilerOptions.compTarget)
+        changer.visit(program)
+        if(errors.noErrors())
+            changer.applyModifications()
+    }
+
     errors.report()
 }
 

compiler/test/TestOptimization.kt

@@ -1126,4 +1126,35 @@ other {
         compileText(VMTarget(), true, src, writeAssembly = true) shouldNotBe null
         compileText(C64Target(), true, src, writeAssembly = true) shouldNotBe null
     }
+
+    test("if-else should not have 'not' in the condition even after optimization steps") {
+        val src="""
+main {
+    sub start() {
+        if (cx16.r0 & 1) as bool == false
+            cx16.r1++
+        else
+            cx16.r2++
+
+        if (cx16.r0 & 1) as bool == true
+            cx16.r1++
+        else
+            cx16.r2++
+
+        if not((cx16.r0 & 1) as bool)
+            cx16.r1++
+        else
+            cx16.r2++
+
+        if (cx16.r0 & 1) as bool
+            cx16.r1++
+        else
+            cx16.r2++
+    }
+}"""
+        compileText(VMTarget(), false, src, writeAssembly = false) shouldNotBe null
+        compileText(C64Target(), false, src, writeAssembly = false) shouldNotBe null
+        compileText(VMTarget(), true, src, writeAssembly = true) shouldNotBe null
+        compileText(C64Target(), true, src, writeAssembly = true) shouldNotBe null
+    }
 })

examples/test.p8

@@ -1,30 +1,26 @@
 %import textio
-%import diskio
-%option no_sysinit
 %zeropage basicsafe
 
 main {
     sub start() {
+        if (cx16.r0 & 1) as bool == false
+            cx16.r1++
+        else
+            cx16.r2++
 
-        if diskio.f_open("lines.txt") {
-            defer diskio.f_close()
+        if (cx16.r0 & 1) as bool == true
+            cx16.r1++
+        else
+            cx16.r2++
 
-            if diskio.f_open_w("@:copy.txt") {
-                defer diskio.f_close_w()
+        if not((cx16.r0 & 1) as bool)
+            cx16.r1++
+        else
+            cx16.r2++
 
-                str buffer = " "*80
-                ubyte length, status
-                do {
-                    length, status = diskio.f_readline(&buffer)
-                    cbm.CLRCHN()
-                    txt.print_uw(length)
-                    txt.nl()
-                    if length!=0 {
-                        if not diskio.f_write(buffer, length)
-                            return
-                    }
-                } until status!=0
-            }
-        }
+        if (cx16.r0 & 1) as bool
+            cx16.r1++
+        else
+            cx16.r2++
     }
 }