optimize word&=$ff00 and word&=$00ff

codeGenCpu6502/src/prog8/codegen/cpu6502/ExpressionsAsmGen.kt

@@ -798,7 +798,8 @@ internal class ExpressionsAsmGen(private val program: Program, private val asmge
             "<=" -> asmgen.out(if(dt==DataType.UWORD) "  jsr  prog8_lib.lesseq_uw" else "  jsr  prog8_lib.lesseq_w")
             ">=" -> asmgen.out(if(dt==DataType.UWORD) "  jsr  prog8_lib.greatereq_uw" else "  jsr  prog8_lib.greatereq_w")
             "==" -> asmgen.out("  jsr  prog8_lib.equal_w")
-            "!=" -> asmgen.out("  jsr  prog8_lib.notequal_w")            "&" -> asmgen.out("  jsr  prog8_lib.bitand_w")
+            "!=" -> asmgen.out("  jsr  prog8_lib.notequal_w")
+            "&" -> asmgen.out("  jsr  prog8_lib.bitand_w")
             "^" -> asmgen.out("  jsr  prog8_lib.bitxor_w")
             "|" -> asmgen.out("  jsr  prog8_lib.bitor_w")
             "and" -> asmgen.out("  jsr  prog8_lib.and_w")

codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AugmentableAssignmentAsmGen.kt

@@ -1066,6 +1066,18 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                         else
                             asmgen.out("  lda  #0 |  sta  $name |  sta  $name+1")
                     }
+                    value == 0x00ff -> {
+                        if(asmgen.isTargetCpu(CpuType.CPU65c02))
+                            asmgen.out("  stz  $name+1")
+                        else
+                            asmgen.out("  lda  #0 |  sta  $name+1")
+                    }
+                    value == 0xff00 -> {
+                        if(asmgen.isTargetCpu(CpuType.CPU65c02))
+                            asmgen.out("  stz  $name")
+                        else
+                            asmgen.out("  lda  #0 |  sta  $name")
+                    }
                     value and 255 == 0 -> {
                         if(asmgen.isTargetCpu(CpuType.CPU65c02))
                             asmgen.out("  stz  $name")

docs/source/todo.rst

@@ -3,6 +3,10 @@ TODO
 
 For next release
 ^^^^^^^^^^^^^^^^
+- fix optimization of w >>= 8 , it generates bad code when opt=on, ok when opt=off
+- fix w <<= 8 generates weird code with pha/pla in it when opt=on, ok when opt=off
+- optimize  w=msb(w)  =>  w >>=8,  w=lsb(w) ==> w &= $00ff
+
 fix the value of ww being wrong (with optimizations enabled) in :
     sub start() {
         byte ub1 = -50
@@ -17,7 +21,6 @@ fix the value of ww being wrong (with optimizations enabled) in :
         return x1
     }
 
-- optimize  w=msb(w),  w=lsb(w)
 
 ...
 
@@ -37,7 +40,7 @@ Blocked by an official Commander-x16 r39 release
 
 Future Things and Ideas
 ^^^^^^^^^^^^^^^^^^^^^^^
-- nameInAssemblyCode() should search smarter
+- nameInAssemblyCode() should search smarter (only labels in column 0? only full words, not part of a larger word?)
 - Fix: don't report as recursion if code assigns address of its own subroutine to something, rather than calling it
 - allow "xxx" * constexpr  (where constexpr is not a number literal, now gives expression error not same type)
 - can we promise a left-to-right function call argument evaluation? without sacrificing performance

examples/test.p8

@@ -1,23 +1,25 @@
 %import textio
-%import string
 %zeropage basicsafe
 
 main {
     sub start() {
-        uword xx=$ea31
-        xx = lsb(xx)
-        uword ww = plot(lsb(xx), msb(xx))
-        ww=msb(ww)
-        txt.print_uwhex(ww, true)
+        uword @shared xx=$ea31
+        xx &= $00ff
+        ;xx = lsb(xx)
+        txt.print_uwhex(xx, true)
+        xx = $ea31
+        xx &= $ff00
+        ; xx = msb(xx)
+;        %asm {{
+;            nop
+;            nop
+;        }}
+;        xx >>= 8
+;        %asm {{
+;            nop
+;            nop
+;        }}
+;        xx <<= 8
+        txt.print_uwhex(xx, true)
     }
-
-    inline asmsub  plot(uword plotx @R0, uword ploty @R1) -> uword @AY{
-        %asm {{
-            lda  cx16.r0
-            ldy  cx16.r1
-            rts
-        }}
-    }
-
-
 }