removed faulty and too aggressive assembly optimization of double-store

codeGeneration/src/prog8/compiler/target/cpu6502/codegen/AsmOptimizer.kt

@@ -1,7 +1,7 @@
 package prog8.compiler.target.cpu6502.codegen
 
 
-// note: see https://wiki.nesdev.com/w/index.php/6502_assembly_optimisations
+// note: see https://wiki.nesdev.org/w/index.php/6502_assembly_optimisations
 
 
 fun optimizeAssembly(lines: MutableList<String>): Int {
@@ -252,24 +252,7 @@ private fun optimizeSameAssignments(linesByFourteen: List<List<IndexedValue<Stri
                 }
             }
         }
-        /*
+
-        sta  A1
-        <other st/ld instruction not involving A1>
-        sta  A1     ; can be removed
-         */
-        if(!overlappingMods && first.startsWith("st") && third.startsWith("st")) {
-            val reg1 = first[2]
-            val reg3 = third[2]
-            if(reg1==reg3 && (second.startsWith("ld") || second.startsWith("st"))) {
-                val firstvalue = first.substring(4)
-                val secondvalue = second.substring(4)
-                val thirdvalue = third.substring(4)
-                if(firstvalue==thirdvalue && firstvalue!=secondvalue) {
-                    overlappingMods = true
-                    mods.add(Modification(lines[2].index, true, null))
-                }
-            }
-        }
         /*
         sta  A1
         ldy  A1     ; make tay
@@ -295,6 +278,7 @@ private fun optimizeSameAssignments(linesByFourteen: List<List<IndexedValue<Stri
 private fun optimizeStoreLoadSame(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
     // sta X + lda X,  sty X + ldy X,   stx X + ldx X  -> the second instruction can OFTEN be eliminated
     // TODO this is not true if X is not a regular RAM memory address (but instead mapped I/O or ROM) but how does this code know?
+    //      should this optimization be removed????  or teach it about the InRegularRAM ?
     val mods = mutableListOf<Modification>()
     for (lines in linesByFour) {
         val first = lines[1].value.trimStart()

compiler/res/prog8lib/conv.p8

@@ -516,7 +516,7 @@ asmsub  uword2decimal  (uword value @AY) -> ubyte @Y, ubyte @A, ubyte @X  {
 
 ;Convert 16 bit Hex to Decimal (0-65535) Rev 2
 ;By Omegamatrix    Further optimizations by tepples
-; routine from http://forums.nesdev.com/viewtopic.php?f=2&t=11341&start=15
+; routine from https://forums.nesdev.org/viewtopic.php?f=2&t=11341&start=15
 
 ;HexToDec99
 ; start in A

docs/source/todo.rst

@@ -3,12 +3,17 @@ TODO
 
 For next compiler release (7.4)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-BUG: Fix C-64sound issue in petaxian (regression since 7.3, sound on c64 build works fine on older versions)
-
 BUG: fix "assignment isAugmented correctness" test
 
 optimize TODO in "Add assignment to initialize with zero" in StatementReorderer
 optimize TODO in after(assignment) in VariousCleanups
+optimize: bitwise operations with a negative constant number -> replace the number by its positive 2 complement
+optimize: add some more constant folders mentioned in test.p8
+
+fix: give error when initializing an integer var with a float value
+
+optimize: there is an optimizations in AsmOptimizer that can only be done correctly
+ if it knows about regular ram vs io space ram distinction.
 
 
 Blocked by an official Commander-x16 v39 release

examples/test.p8

@@ -11,7 +11,8 @@ main {
         byte bb
         float fl
 
-        ; TODO:  bitwise operations with a negative constant number -> replace the number by its positive 2 complement
+
+; TODO add these constant folders:
 
 ; (X + C1) + (Y + C2)  =>  (X + Y) + (C1 + C2)
 ; (X + C1) - (Y + C2)  =>  (X - Y) + (C1 - C2)
@@ -24,16 +25,13 @@ main {
         xx=6
         yy=8
 
-
         yy = (xx+5)+(yy+10)
-        ; yy = (xx+yy)+(5+10)     ; TODO crashes compiler
         txt.print_ub(yy)        ; 29
         txt.nl()
 
         xx=100
         yy=8
-        ;yy = (xx+5)-(yy+10)
+        yy = (xx+5)-(yy+10)
-        yy = (xx-yy)+(5-10) as ubyte
         txt.print_ub(yy)        ; 87
         txt.nl()