From 68da661edc47725c26df1a09eef40aaf364e7345 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Mon, 11 Jul 2022 15:46:14 +0200
Subject: [PATCH] optimize comparison to true/1 into comparison to zero,
 optimize while/until conditions

---
 .../prog8/optimizer/ExpressionSimplifier.kt   | 22 ++++++++++++
 .../compiler/astprocessing/CodeDesugarer.kt   | 15 ++++----
 docs/source/todo.rst                          |  4 ---
 examples/test.p8                              | 34 ++++---------------
 4 files changed, 35 insertions(+), 40 deletions(-)

diff --git a/codeOptimizers/src/prog8/optimizer/ExpressionSimplifier.kt b/codeOptimizers/src/prog8/optimizer/ExpressionSimplifier.kt
index 9bbd21a63..120572859 100644
--- a/codeOptimizers/src/prog8/optimizer/ExpressionSimplifier.kt
+++ b/codeOptimizers/src/prog8/optimizer/ExpressionSimplifier.kt
@@ -249,6 +249,28 @@ class ExpressionSimplifier(private val program: Program) : AstWalker() {
             else -> null
         }
 
+        if(rightVal!=null && leftDt==DataType.BOOL) {
+            // see if we can replace comparison against true/1 with simpler comparison against zero
+            if (expr.operator == "==") {
+                if (rightVal.number == 1.0) {
+                    val zero = NumericLiteral(DataType.UBYTE, 0.0, expr.right.position)
+                    return listOf(
+                        IAstModification.SetExpression({expr.operator="!="}, expr, parent),
+                        IAstModification.ReplaceNode(expr.right, zero, expr)
+                    )
+                }
+            }
+            if (expr.operator == "!=") {
+                if (rightVal.number == 1.0) {
+                    val zero = NumericLiteral(DataType.UBYTE, 0.0, expr.right.position)
+                    return listOf(
+                        IAstModification.SetExpression({expr.operator="=="}, expr, parent),
+                        IAstModification.ReplaceNode(expr.right, zero, expr)
+                    )
+                }
+            }
+        }
+
         if(newExpr != null)
             return listOf(IAstModification.ReplaceNode(expr, newExpr, parent))
 
diff --git a/compiler/src/prog8/compiler/astprocessing/CodeDesugarer.kt b/compiler/src/prog8/compiler/astprocessing/CodeDesugarer.kt
index 51f0158a8..a5ba6374f 100644
--- a/compiler/src/prog8/compiler/astprocessing/CodeDesugarer.kt
+++ b/compiler/src/prog8/compiler/astprocessing/CodeDesugarer.kt
@@ -1,10 +1,7 @@
 package prog8.compiler.astprocessing
 
 import prog8.ast.*
-import prog8.ast.expressions.BinaryExpression
-import prog8.ast.expressions.DirectMemoryRead
-import prog8.ast.expressions.FunctionCallExpression
-import prog8.ast.expressions.NumericLiteral
+import prog8.ast.expressions.*
 import prog8.ast.statements.*
 import prog8.ast.walk.AstWalker
 import prog8.ast.walk.IAstModification
@@ -64,11 +61,12 @@ if CONDITION==0
          */
         val pos = untilLoop.position
         val loopLabel = program.makeLabel("untilloop", pos)
-        val equalsZero = BinaryExpression(untilLoop.condition, "==", NumericLiteral(DataType.UBYTE, 0.0, pos), pos)
+        val ifCondition = invertCondition(untilLoop.condition)
+            ?: BinaryExpression(untilLoop.condition, "==", NumericLiteral(DataType.UBYTE, 0.0, pos), pos)
         val replacement = AnonymousScope(mutableListOf(
             loopLabel,
             untilLoop.body,
-            IfElse(equalsZero,
+            IfElse(ifCondition,
                 AnonymousScope(mutableListOf(program.jumpLabel(loopLabel)), pos),
                 AnonymousScope(mutableListOf(), pos),
                 pos)
@@ -89,10 +87,11 @@ _after:
         val pos = whileLoop.position
         val loopLabel = program.makeLabel("whileloop", pos)
         val afterLabel = program.makeLabel("afterwhile", pos)
-        val equalsZero = BinaryExpression(whileLoop.condition, "==", NumericLiteral(DataType.UBYTE, 0.0, pos), pos)
+        val ifCondition = invertCondition(whileLoop.condition)
+            ?: BinaryExpression(whileLoop.condition, "==", NumericLiteral(DataType.UBYTE, 0.0, pos), pos)
         val replacement = AnonymousScope(mutableListOf(
             loopLabel,
-            IfElse(equalsZero,
+            IfElse(ifCondition,
                 AnonymousScope(mutableListOf(program.jumpLabel(afterLabel)), pos),
                 AnonymousScope(mutableListOf(), pos),
                 pos),
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index 21916b66c..1a6588fb3 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -3,10 +3,6 @@ TODO
 
 For next release
 ^^^^^^^^^^^^^^^^
-- petaxian has become larger (18630) why so much larger.   problematic lines:
-    gun.p8 95,110 if ( x <= GUN_MAX_LEFT and leftmost ) ...
-    enemy.p8 456 + bombs.p8 33 (while i<value)...
-
 - have a proper option to move the evalstack rather than just assembly symbol redefine
 - then make the cx16 virtual registers in syslib.p8 use that definition to be able to shift them around on non-cx16 targets
 
diff --git a/examples/test.p8 b/examples/test.p8
index 5b8599035..41e8cef5b 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -3,36 +3,14 @@
 
 
 main {
-  ubyte key
-
-  sub pushing_fire() -> ubyte {
-    return key == 'z'
-  }
-
-  sub pushing_left() -> ubyte {
-    return key == 'k' or key == 157
-  }
-
-  sub pushing_right() -> ubyte {
-    return key == 'l' or key == 29
-  }
-
     sub start() {
-        void pushing_fire()
-        void pushing_left()
-        void pushing_right()
+        bool @shared zz
+        ubyte xx
 
-        ubyte rnr = $99
-        ubyte wordNr = ((rnr >= $33) as ubyte) +
-            ((rnr >= $66) as ubyte) +
-            ((rnr >= $99) as ubyte) +
-            ((rnr >= $CC) as ubyte)
+        while xx<42 {
+            xx++
+        }
 
-        ubyte wordNr2 = (rnr >= $33) as ubyte + (rnr >= $66) as ubyte + (rnr >= $99) as ubyte + (rnr >= $CC) as ubyte
-
-        txt.print_uw(wordNr)
-        txt.nl()
-        txt.print_uw(wordNr2)
-        txt.nl()
+        txt.print_ub(xx)
     }
 }