Improved static value analysis to identify #<0, #>0 as identical to #0

src/main/java/dk/camelot64/kickc/asm/AsmProgramStaticRegisterValues.java

@@ -72,43 +72,37 @@ public class AsmProgramStaticRegisterValues {
             current.setA(instruction.getParameter());
             current.setaMem(null);
 
-            try {
+            Integer immValue = getImmValue(instruction.getParameter());
-               int immValue = getImmValue(instruction);
+            if (immValue != null) {
                current.setZ(immValue == 0);
                current.setN(immValue > 127);
-            } catch (NumberFormatException e) {
-               // ignore
             }
          }
-         if (instructionType.getMnemnonic().equals("sta") && (instructionType.getAddressingMode().equals(AsmAddressingMode.ZP)||instructionType.getAddressingMode().equals(AsmAddressingMode.ABS))) {
+         if (instructionType.getMnemnonic().equals("sta") && (instructionType.getAddressingMode().equals(AsmAddressingMode.ZP) || instructionType.getAddressingMode().equals(AsmAddressingMode.ABS))) {
             current.setaMem(instruction.getParameter());
          }
          if (instructionType.getMnemnonic().equals("ldx") && instructionType.getAddressingMode().equals(AsmAddressingMode.IMM)) {
             current.setX(instruction.getParameter());
             current.setxMem(null);
-            try {
+            Integer immValue = getImmValue(instruction.getParameter());
-               int immValue = getImmValue(instruction);
+            if (immValue != null) {
                current.setZ(immValue == 0);
                current.setN(immValue > 127);
-            } catch (NumberFormatException e) {
-               // ignore
             }
          }
-         if (instructionType.getMnemnonic().equals("stx") && (instructionType.getAddressingMode().equals(AsmAddressingMode.ZP)||instructionType.getAddressingMode().equals(AsmAddressingMode.ABS))) {
+         if (instructionType.getMnemnonic().equals("stx") && (instructionType.getAddressingMode().equals(AsmAddressingMode.ZP) || instructionType.getAddressingMode().equals(AsmAddressingMode.ABS))) {
             current.setxMem(instruction.getParameter());
          }
          if (instructionType.getMnemnonic().equals("ldy") && instructionType.getAddressingMode().equals(AsmAddressingMode.IMM)) {
             current.setY(instruction.getParameter());
             current.setyMem(null);
-            try {
+            Integer immValue = getImmValue(instruction.getParameter());
-               int immValue = getImmValue(instruction);
+            if (immValue != null) {
                current.setZ(immValue == 0);
                current.setN(immValue > 127);
-            } catch (NumberFormatException e) {
-               // ignore
             }
          }
-         if (instructionType.getMnemnonic().equals("sty") && (instructionType.getAddressingMode().equals(AsmAddressingMode.ZP)||instructionType.getAddressingMode().equals(AsmAddressingMode.ABS))) {
+         if (instructionType.getMnemnonic().equals("sty") && (instructionType.getAddressingMode().equals(AsmAddressingMode.ZP) || instructionType.getAddressingMode().equals(AsmAddressingMode.ABS))) {
             current.setyMem(instruction.getParameter());
          }
          if (instructionType.getMnemnonic().equals("txa")) {
@@ -137,18 +131,47 @@ public class AsmProgramStaticRegisterValues {
       return current;
    }
 
-   private int getImmValue(AsmInstruction instruction) {
+   public static Integer getImmValue(String parameter) {
-      int immValue;
+      Integer immValue = null;
-      if(instruction.getParameter().equals("<0")) {
+      if (parameter != null) {
-         immValue = 0;
+         if(parameter.startsWith("<")) {
-      } else if(instruction.getParameter().equals(">0")) {
+            try {
-         immValue = 0;
+               int parValue = Integer.parseInt(parameter.substring(1));
-      } else{
+               return 0xff & parValue;
-         immValue = Integer.parseInt(instruction.getParameter());
+            } catch (NumberFormatException e) {
+               // ignore
+            }
+         } else if(parameter.startsWith(">")) {
+            try {
+               int parValue = Integer.parseInt(parameter.substring(1));
+               return 0xff & (parValue / 0x100);
+            } catch (NumberFormatException e) {
+               // ignore
+            }
+         } else {
+            try {
+               immValue = Integer.parseInt(parameter);
+               return immValue;
+            } catch (NumberFormatException e) {
+               // ignore
+            }
+         }
       }
       return immValue;
    }
 
+   public static boolean matchImm(String immVal1, String immVal2) {
+      if (immVal1 != null && immVal2 != null && immVal1.equals(immVal2)) {
+         return true;
+      }
+      Integer immInt1 = getImmValue(immVal1);
+      Integer immInt2 = getImmValue(immVal2);
+      if (immInt1 != null && immInt2 != null && immInt1.equals(immInt2)) {
+         return true;
+      }
+      return false;
+   }
+
    /**
     * Known values of registers/flags at an instruction. null where value is unknown.
     */
@@ -260,6 +283,7 @@ public class AsmProgramStaticRegisterValues {
          this.z = z;
       }
 
+
    }
 
 }

src/main/java/dk/camelot64/kickc/passes/Pass5UnnecesaryLoadElimination.java

@@ -34,13 +34,13 @@ public class Pass5UnnecesaryLoadElimination extends Pass5AsmOptimization {
                if (instructionType.getMnemnonic().equals("lda") && instructionType.getAddressingMode().equals(AsmAddressingMode.IMM)) {
                   String immValue = instruction.getParameter();
                   AsmProgramStaticRegisterValues.AsmRegisterValues instructionValues = staticValues.getValues(instruction);
-                  if (instructionValues.getA() != null && instructionValues.getA().equals(immValue)) {
+                  if (AsmProgramStaticRegisterValues.matchImm(instructionValues.getA(), immValue)) {
                      modified = remove(lineIt);
-                  } else if (instructionValues.getX() != null && instructionValues.getX().equals(immValue)) {
+                  } else if (AsmProgramStaticRegisterValues.matchImm(instructionValues.getX(), immValue)) {
                      getLog().append("Replacing instruction "+instruction+" with TXA");
                      instruction.setType(AsmInstructionSet.getInstructionType("txa", AsmAddressingMode.NON, null, false));
                      instruction.setParameter(null);
-                  } else if (instructionValues.getY() != null && instructionValues.getY().equals(immValue)) {
+                  } else if (AsmProgramStaticRegisterValues.matchImm(instructionValues.getY(), immValue)) {
                      getLog().append("Replacing instruction "+instruction+" with TYA");
                      instruction.setType(AsmInstructionSet.getInstructionType("tya", AsmAddressingMode.NON, null, false));
                      instruction.setParameter(null);
@@ -64,9 +64,9 @@ public class Pass5UnnecesaryLoadElimination extends Pass5AsmOptimization {
                if (instructionType.getMnemnonic().equals("ldx") && instructionType.getAddressingMode().equals(AsmAddressingMode.IMM)) {
                   String immValue = instruction.getParameter();
                   AsmProgramStaticRegisterValues.AsmRegisterValues instructionValues = staticValues.getValues(instruction);
-                  if (instructionValues.getX() != null && instructionValues.getX().equals(immValue)) {
+                  if (AsmProgramStaticRegisterValues.matchImm(instructionValues.getX(), immValue)) {
                      modified = remove(lineIt);
-                  } else if (instructionValues.getA() != null && instructionValues.getA().equals(immValue)) {
+                  } else if (AsmProgramStaticRegisterValues.matchImm(instructionValues.getA(), immValue)) {
                      getLog().append("Replacing instruction "+instruction+" with TAX");
                      instruction.setType(AsmInstructionSet.getInstructionType("tax", AsmAddressingMode.NON, null, false));
                      instruction.setParameter(null);
@@ -86,9 +86,9 @@ public class Pass5UnnecesaryLoadElimination extends Pass5AsmOptimization {
                if (instructionType.getMnemnonic().equals("ldy") && instructionType.getAddressingMode().equals(AsmAddressingMode.IMM)) {
                   String immValue = instruction.getParameter();
                   AsmProgramStaticRegisterValues.AsmRegisterValues instructionValues = staticValues.getValues(instruction);
-                  if (instructionValues.getY() != null && instructionValues.getY().equals(immValue)) {
+                  if (AsmProgramStaticRegisterValues.matchImm(instructionValues.getY(), immValue)) {
                      modified = remove(lineIt);
-                  } else if (instructionValues.getA() != null && instructionValues.getA().equals(immValue)) {
+                  } else if (AsmProgramStaticRegisterValues.matchImm(instructionValues.getA(), immValue)) {
                      getLog().append("Replacing instruction "+instruction+" with TAY");
                      instruction.setType(AsmInstructionSet.getInstructionType("tay", AsmAddressingMode.NON, null, false));
                      instruction.setParameter(null);

src/main/java/dk/camelot64/kickc/test/ref/bitmap-bresenham.asm

@@ -394,9 +394,8 @@ init_plot_tables: {
     bne b1
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
-    ldx #0
+    tax
   b3:
     txa
     and #7

src/main/java/dk/camelot64/kickc/test/ref/bitmap-bresenham.log

@@ -18292,6 +18292,8 @@ Removing instruction lda yd
 Removing instruction lda yd
 Removing instruction lda yd
 Removing instruction ldy #0
+Removing instruction lda #>0
+Replacing instruction ldx #0 with TAX
 Replacing instruction lda #0 with TYA
 Succesful ASM optimization Pass5UnnecesaryLoadElimination
 ASSEMBLER
@@ -19082,10 +19084,9 @@ init_plot_tables: {
   //SEG316 [171] phi (byte*) init_plot_tables::yoffs#2 = ((byte*))(byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#0] -- zpptrby1=cowo1 
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
   //SEG317 [171] phi (byte) init_plot_tables::y#2 = (byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#1] -- xby=coby1 
-    ldx #0
+    tax
     jmp b3
   //SEG318 [171] phi from init_plot_tables::@4 to init_plot_tables::@3 [phi:init_plot_tables::@4->init_plot_tables::@3]
   b3_from_b4:
@@ -20024,10 +20025,9 @@ init_plot_tables: {
   //SEG316 [171] phi (byte*) init_plot_tables::yoffs#2 = ((byte*))(byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#0] -- zpptrby1=cowo1 
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
   //SEG317 [171] phi (byte) init_plot_tables::y#2 = (byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#1] -- xby=coby1 
-    ldx #0
+    tax
     jmp b3
   //SEG318 [171] phi from init_plot_tables::@4 to init_plot_tables::@3 [phi:init_plot_tables::@4->init_plot_tables::@3]
   //SEG319 [171] phi (byte*) init_plot_tables::yoffs#2 = (byte*) init_plot_tables::yoffs#4 [phi:init_plot_tables::@4->init_plot_tables::@3#0] -- register_copy 
@@ -20922,10 +20922,9 @@ init_plot_tables: {
   //SEG316 [171] phi (byte*) init_plot_tables::yoffs#2 = ((byte*))(byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#0] -- zpptrby1=cowo1 
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
   //SEG317 [171] phi (byte) init_plot_tables::y#2 = (byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#1] -- xby=coby1 
-    ldx #0
+    tax
     jmp b3
   //SEG318 [171] phi from init_plot_tables::@4 to init_plot_tables::@3 [phi:init_plot_tables::@4->init_plot_tables::@3]
   //SEG319 [171] phi (byte*) init_plot_tables::yoffs#2 = (byte*) init_plot_tables::yoffs#4 [phi:init_plot_tables::@4->init_plot_tables::@3#0] -- register_copy 
@@ -21769,10 +21768,9 @@ init_plot_tables: {
   //SEG316 [171] phi (byte*) init_plot_tables::yoffs#2 = ((byte*))(byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#0] -- zpptrby1=cowo1 
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
   //SEG317 [171] phi (byte) init_plot_tables::y#2 = (byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#1] -- xby=coby1 
-    ldx #0
+    tax
   //SEG318 [171] phi from init_plot_tables::@4 to init_plot_tables::@3 [phi:init_plot_tables::@4->init_plot_tables::@3]
   //SEG319 [171] phi (byte*) init_plot_tables::yoffs#2 = (byte*) init_plot_tables::yoffs#4 [phi:init_plot_tables::@4->init_plot_tables::@3#0] -- register_copy 
   //SEG320 [171] phi (byte) init_plot_tables::y#2 = (byte) init_plot_tables::y#1 [phi:init_plot_tables::@4->init_plot_tables::@3#1] -- register_copy 
@@ -22961,10 +22959,9 @@ init_plot_tables: {
   //SEG316 [171] phi (byte*) init_plot_tables::yoffs#2 = ((byte*))(byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#0] -- zpptrby1=cowo1 
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
   //SEG317 [171] phi (byte) init_plot_tables::y#2 = (byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#1] -- xby=coby1 
-    ldx #0
+    tax
   //SEG318 [171] phi from init_plot_tables::@4 to init_plot_tables::@3 [phi:init_plot_tables::@4->init_plot_tables::@3]
   //SEG319 [171] phi (byte*) init_plot_tables::yoffs#2 = (byte*) init_plot_tables::yoffs#4 [phi:init_plot_tables::@4->init_plot_tables::@3#0] -- register_copy 
   //SEG320 [171] phi (byte) init_plot_tables::y#2 = (byte) init_plot_tables::y#1 [phi:init_plot_tables::@4->init_plot_tables::@3#1] -- register_copy 

src/main/java/dk/camelot64/kickc/test/ref/bitmap-plotter.asm

@@ -118,9 +118,8 @@ init_plot_tables: {
     bne b1
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
-    ldx #0
+    tax
   b3:
     txa
     and #7

src/main/java/dk/camelot64/kickc/test/ref/bitmap-plotter.log

@@ -6849,6 +6849,8 @@ init_screen: {
 
 Removing instruction lda #0
 Removing instruction ldy #0
+Removing instruction lda #>0
+Replacing instruction ldx #0 with TAX
 Replacing instruction lda #0 with TYA
 Succesful ASM optimization Pass5UnnecesaryLoadElimination
 ASSEMBLER
@@ -7073,10 +7075,9 @@ init_plot_tables: {
   //SEG78 [47] phi (byte*) init_plot_tables::yoffs#2 = ((byte*))(byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#0] -- zpptrby1=cowo1 
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
   //SEG79 [47] phi (byte) init_plot_tables::y#2 = (byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#1] -- xby=coby1 
-    ldx #0
+    tax
     jmp b3
   //SEG80 [47] phi from init_plot_tables::@4 to init_plot_tables::@3 [phi:init_plot_tables::@4->init_plot_tables::@3]
   b3_from_b4:
@@ -7441,10 +7442,9 @@ init_plot_tables: {
   //SEG78 [47] phi (byte*) init_plot_tables::yoffs#2 = ((byte*))(byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#0] -- zpptrby1=cowo1 
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
   //SEG79 [47] phi (byte) init_plot_tables::y#2 = (byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#1] -- xby=coby1 
-    ldx #0
+    tax
     jmp b3
   //SEG80 [47] phi from init_plot_tables::@4 to init_plot_tables::@3 [phi:init_plot_tables::@4->init_plot_tables::@3]
   //SEG81 [47] phi (byte*) init_plot_tables::yoffs#2 = (byte*) init_plot_tables::yoffs#4 [phi:init_plot_tables::@4->init_plot_tables::@3#0] -- register_copy 
@@ -7790,10 +7790,9 @@ init_plot_tables: {
   //SEG78 [47] phi (byte*) init_plot_tables::yoffs#2 = ((byte*))(byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#0] -- zpptrby1=cowo1 
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
   //SEG79 [47] phi (byte) init_plot_tables::y#2 = (byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#1] -- xby=coby1 
-    ldx #0
+    tax
     jmp b3
   //SEG80 [47] phi from init_plot_tables::@4 to init_plot_tables::@3 [phi:init_plot_tables::@4->init_plot_tables::@3]
   //SEG81 [47] phi (byte*) init_plot_tables::yoffs#2 = (byte*) init_plot_tables::yoffs#4 [phi:init_plot_tables::@4->init_plot_tables::@3#0] -- register_copy 
@@ -8117,10 +8116,9 @@ init_plot_tables: {
   //SEG78 [47] phi (byte*) init_plot_tables::yoffs#2 = ((byte*))(byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#0] -- zpptrby1=cowo1 
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
   //SEG79 [47] phi (byte) init_plot_tables::y#2 = (byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#1] -- xby=coby1 
-    ldx #0
+    tax
   //SEG80 [47] phi from init_plot_tables::@4 to init_plot_tables::@3 [phi:init_plot_tables::@4->init_plot_tables::@3]
   //SEG81 [47] phi (byte*) init_plot_tables::yoffs#2 = (byte*) init_plot_tables::yoffs#4 [phi:init_plot_tables::@4->init_plot_tables::@3#0] -- register_copy 
   //SEG82 [47] phi (byte) init_plot_tables::y#2 = (byte) init_plot_tables::y#1 [phi:init_plot_tables::@4->init_plot_tables::@3#1] -- register_copy 
@@ -8583,10 +8581,9 @@ init_plot_tables: {
   //SEG78 [47] phi (byte*) init_plot_tables::yoffs#2 = ((byte*))(byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#0] -- zpptrby1=cowo1 
     lda #<0
     sta yoffs
-    lda #>0
     sta yoffs+1
   //SEG79 [47] phi (byte) init_plot_tables::y#2 = (byte/signed byte/word/signed word) 0 [phi:init_plot_tables::@2->init_plot_tables::@3#1] -- xby=coby1 
-    ldx #0
+    tax
   //SEG80 [47] phi from init_plot_tables::@4 to init_plot_tables::@3 [phi:init_plot_tables::@4->init_plot_tables::@3]
   //SEG81 [47] phi (byte*) init_plot_tables::yoffs#2 = (byte*) init_plot_tables::yoffs#4 [phi:init_plot_tables::@4->init_plot_tables::@3#0] -- register_copy 
   //SEG82 [47] phi (byte) init_plot_tables::y#2 = (byte) init_plot_tables::y#1 [phi:init_plot_tables::@4->init_plot_tables::@3#1] -- register_copy 

src/main/java/dk/camelot64/kickc/test/ref/immzero.asm

@@ -6,9 +6,8 @@ main: {
     .label w = 2
     lda #<0
     sta w
-    lda #>0
     sta w+1
-    ldx #0
+    tax
   b1:
     txa
     clc

src/main/java/dk/camelot64/kickc/test/ref/immzero.log

@@ -635,6 +635,62 @@ main: {
     rts
 }
 
+Removing instruction lda #>0
+Replacing instruction ldx #0 with TAX
+Succesful ASM optimization Pass5UnnecesaryLoadElimination
+ASSEMBLER
+//SEG0 Basic Upstart
+.pc = $801 "Basic"
+:BasicUpstart(main)
+.pc = $80d "Program"
+//SEG1 Global Constants & labels
+//SEG2 @begin
+bbegin:
+//SEG3 @1
+b1:
+//SEG4 [0] call main param-assignment [ ] ( )
+//SEG5 [1] phi from @1 to main [phi:@1->main]
+main_from_b1:
+  jsr main
+//SEG6 @end
+bend:
+//SEG7 main
+main: {
+    .label w = 2
+  //SEG8 [2] phi from main to main::@1 [phi:main->main::@1]
+  b1_from_main:
+  //SEG9 [2] phi (word) main::w#2 = ((word))(byte/signed byte/word/signed word) 0 [phi:main->main::@1#0] -- zpwo1=cowo1 
+    lda #<0
+    sta w
+    sta w+1
+  //SEG10 [2] phi (byte) main::i#1 = (byte/signed byte/word/signed word) 0 [phi:main->main::@1#1] -- xby=coby1 
+    tax
+    jmp b1
+  //SEG11 [2] phi from main::@1 to main::@1 [phi:main::@1->main::@1]
+  b1_from_b1:
+  //SEG12 [2] phi (word) main::w#2 = (word) main::w#1 [phi:main::@1->main::@1#0] -- register_copy 
+  //SEG13 [2] phi (byte) main::i#1 = (byte) main::j#1 [phi:main::@1->main::@1#1] -- register_copy 
+  //SEG14 main::@1
+  b1:
+  //SEG15 [3] (word) main::w#1 ← (word) main::w#2 + (byte) main::i#1 [ main::i#1 main::w#1 ] ( main:0 [ main::i#1 main::w#1 ] ) -- zpwo1=zpwo1_plus_xby 
+    txa
+    clc
+    adc w
+    sta w
+    bcc !+
+    inc w+1
+  !:
+  //SEG16 [4] (byte) main::j#1 ← ++ (byte) main::i#1 [ main::j#1 main::w#1 ] ( main:0 [ main::j#1 main::w#1 ] ) -- xby=_inc_xby 
+    inx
+  //SEG17 [5] if((byte) main::j#1!=(byte/signed byte/word/signed word) 11) goto main::@1 [ main::j#1 main::w#1 ] ( main:0 [ main::j#1 main::w#1 ] ) -- xby_neq_coby1_then_la1 
+    cpx #$b
+    bne b1_from_b1
+  //SEG18 main::@return
+  breturn:
+  //SEG19 [6] return  [ ] ( main:0 [ ] )
+    rts
+}
+
 Replacing label b1_from_b1 with b1
 Removing instruction bbegin:
 Removing instruction main_from_b1:
@@ -662,10 +718,9 @@ main: {
   //SEG9 [2] phi (word) main::w#2 = ((word))(byte/signed byte/word/signed word) 0 [phi:main->main::@1#0] -- zpwo1=cowo1 
     lda #<0
     sta w
-    lda #>0
     sta w+1
   //SEG10 [2] phi (byte) main::i#1 = (byte/signed byte/word/signed word) 0 [phi:main->main::@1#1] -- xby=coby1 
-    ldx #0
+    tax
     jmp b1
   //SEG11 [2] phi from main::@1 to main::@1 [phi:main::@1->main::@1]
   //SEG12 [2] phi (word) main::w#2 = (word) main::w#1 [phi:main::@1->main::@1#0] -- register_copy 
@@ -715,10 +770,9 @@ main: {
   //SEG9 [2] phi (word) main::w#2 = ((word))(byte/signed byte/word/signed word) 0 [phi:main->main::@1#0] -- zpwo1=cowo1 
     lda #<0
     sta w
-    lda #>0
     sta w+1
   //SEG10 [2] phi (byte) main::i#1 = (byte/signed byte/word/signed word) 0 [phi:main->main::@1#1] -- xby=coby1 
-    ldx #0
+    tax
     jmp b1
   //SEG11 [2] phi from main::@1 to main::@1 [phi:main::@1->main::@1]
   //SEG12 [2] phi (word) main::w#2 = (word) main::w#1 [phi:main::@1->main::@1#0] -- register_copy 
@@ -764,10 +818,9 @@ main: {
   //SEG9 [2] phi (word) main::w#2 = ((word))(byte/signed byte/word/signed word) 0 [phi:main->main::@1#0] -- zpwo1=cowo1 
     lda #<0
     sta w
-    lda #>0
     sta w+1
   //SEG10 [2] phi (byte) main::i#1 = (byte/signed byte/word/signed word) 0 [phi:main->main::@1#1] -- xby=coby1 
-    ldx #0
+    tax
   //SEG11 [2] phi from main::@1 to main::@1 [phi:main::@1->main::@1]
   //SEG12 [2] phi (word) main::w#2 = (word) main::w#1 [phi:main::@1->main::@1#0] -- register_copy 
   //SEG13 [2] phi (byte) main::i#1 = (byte) main::j#1 [phi:main::@1->main::@1#1] -- register_copy 
@@ -828,10 +881,9 @@ main: {
   //SEG9 [2] phi (word) main::w#2 = ((word))(byte/signed byte/word/signed word) 0 [phi:main->main::@1#0] -- zpwo1=cowo1 
     lda #<0
     sta w
-    lda #>0
     sta w+1
   //SEG10 [2] phi (byte) main::i#1 = (byte/signed byte/word/signed word) 0 [phi:main->main::@1#1] -- xby=coby1 
-    ldx #0
+    tax
   //SEG11 [2] phi from main::@1 to main::@1 [phi:main::@1->main::@1]
   //SEG12 [2] phi (word) main::w#2 = (word) main::w#1 [phi:main::@1->main::@1#0] -- register_copy 
   //SEG13 [2] phi (byte) main::i#1 = (byte) main::j#1 [phi:main::@1->main::@1#1] -- register_copy