optimize codegen for x += array[index] (and others)

irmen · Jan 2, 2025 · 3b4b37f · 3b4b37f
1 parent 68d5983
commit 3b4b37f
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Showing 4 changed files with 188 additions and 275 deletions.
diff --git a/codeGenCpu6502/src/prog8/codegen/cpu6502/AsmGen.kt b/codeGenCpu6502/src/prog8/codegen/cpu6502/AsmGen.kt
@@ -1115,6 +1115,21 @@ $repeatLabel""")
         }
     }
 
+    internal fun signExtendAXlsb(valueDt: BaseDataType) {
+        // sign extend signed byte in A to full word in AX
+        when(valueDt) {
+            BaseDataType.UBYTE -> out("  ldx  #0")
+            BaseDataType.BYTE -> out("""
+                ldx  #0
+                cmp  #$80
+                bcc  +
+                dex
++
+            """)
+            else -> throw AssemblyError("need byte type")
+        }
+    }
+
     internal fun signExtendVariableLsb(asmvar: String, valueDt: BaseDataType) {
         // sign extend signed byte in a var to a full word in that variable
         when(valueDt) {