From db80417bd7da1a877c698c8644cf39253e61add1 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Tue, 9 Apr 2024 22:09:29 +0200
Subject: [PATCH] fix a problem with const fold optimization in if expressions,
 and IR compilation of that

---
 .../prog8/codegen/intermediate/IRCodeGen.kt   |  4 +++
 compiler/src/prog8/compiler/Compiler.kt       |  7 ++++-
 examples/test.p8                              | 26 +++++--------------
 3 files changed, 17 insertions(+), 20 deletions(-)

diff --git a/codeGenIntermediate/src/prog8/codegen/intermediate/IRCodeGen.kt b/codeGenIntermediate/src/prog8/codegen/intermediate/IRCodeGen.kt
index 0684086d7..6add55339 100644
--- a/codeGenIntermediate/src/prog8/codegen/intermediate/IRCodeGen.kt
+++ b/codeGenIntermediate/src/prog8/codegen/intermediate/IRCodeGen.kt
@@ -1451,6 +1451,10 @@ class IRCodeGen(
         }
 
         when(val cond=ifElse.condition) {
+            is PtBool -> {
+                // normally this will be optimized away, but not with -noopt
+                translateSimple(cond, Opcode.BSTEQ)
+            }
             is PtTypeCast -> {
                 require(cond.type==DataType.BOOL && cond.value.type in NumericDatatypes)
                 translateSimple(cond, Opcode.BSTEQ)
diff --git a/compiler/src/prog8/compiler/Compiler.kt b/compiler/src/prog8/compiler/Compiler.kt
index 70129fe06..6deb2752f 100644
--- a/compiler/src/prog8/compiler/Compiler.kt
+++ b/compiler/src/prog8/compiler/Compiler.kt
@@ -458,8 +458,13 @@ private fun optimizeAst(program: Program, compilerOptions: CompilationOptions, e
             break
     }
     removeUnusedCode(program, errors, compilerOptions)
-    if(errors.noErrors())
+    if(errors.noErrors()) {
+        // last round of optimizations because constFold may have enabled more...
+        program.simplifyExpressions(errors, compilerOptions)
+        program.optimizeStatements(errors, functions, compilerOptions)
         program.constantFold(errors, compilerOptions) // because simplified statements and expressions can result in more constants that can be folded away
+    }
+
     errors.report()
 }
 
diff --git a/examples/test.p8 b/examples/test.p8
index b745d7f55..1eb783641 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -1,28 +1,16 @@
-%import bmx
-%import diskio
-%import emudbg
-%import floats
-%import gfx2
-%import graphics
-%import monogfx
-%import palette
-%import psg
-%import sprites
-%import syslib
 %import textio
-%import verafx
-%import conv
-%import cx16logo
-%import math
-%import prog8_lib
-%import string
-%import test_stack
-
 %zeropage basicsafe
 %option no_sysinit
 
 main {
     sub start() {
+        const ubyte x=0
+
+        if x==3 {
+            txt.print("three")
+        } else if x==4 {
+            txt.print("four")
+        }
     }
 }