From ab7d7c290733aceab25265cc4a71ed5162747cc8 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Thu, 26 Mar 2020 22:59:42 +0100
Subject: [PATCH] fix comparison of memory expressions (this error prevented
 some optimizations)

---
 compiler/src/prog8/ast/statements/AstStatements.kt | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/compiler/src/prog8/ast/statements/AstStatements.kt b/compiler/src/prog8/ast/statements/AstStatements.kt
index 61dd10f15..3a18af4e6 100644
--- a/compiler/src/prog8/ast/statements/AstStatements.kt
+++ b/compiler/src/prog8/ast/statements/AstStatements.kt
@@ -432,7 +432,13 @@ data class AssignTarget(val register: Register?,
 
     infix fun isSameAs(value: Expression): Boolean {
         return when {
-            this.memoryAddress!=null -> false
+            this.memoryAddress!=null -> {
+                // if the target is a memory write, and the value is a memory read, they're the same if the address matches
+                if(value is DirectMemoryRead)
+                    this.memoryAddress.addressExpression isSameAs value.addressExpression
+                else
+                    false
+            }
             this.register!=null -> value is RegisterExpr && value.register==register
             this.identifier!=null -> value is IdentifierReference && value.nameInSource==identifier!!.nameInSource
             this.arrayindexed!=null -> value is ArrayIndexedExpression &&