tweak to byte compares

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

@@ -133,7 +133,7 @@ internal class IfElseAsmGen(private val program: PtProgram,
                 else
                     translateIfElseBodies("beq", stmt)
             }
-            "<" -> translateByteGreater(condition.right, condition.left, stmt, signed, jumpAfterIf)
+            "<" -> translateByteLess(stmt, signed, jumpAfterIf)
             "<=" -> {
                 // X<=Y -> Y>=X (reverse of >=)
                 asmgen.assignExpressionToRegister(condition.right, RegisterOrPair.A, signed)
@@ -150,7 +150,7 @@ internal class IfElseAsmGen(private val program: PtProgram,
                         translateIfElseBodies("bcc", stmt)
                 }
             }
-            ">" -> translateByteGreater(condition.left, condition.right, stmt, signed, jumpAfterIf)
+            ">" -> translateByteGreater(stmt, signed, jumpAfterIf)
             ">=" -> {
                 asmgen.assignExpressionToRegister(condition.left, RegisterOrPair.A, signed)
                 cmpAwithByteValue(condition.right, false)
@@ -323,7 +323,7 @@ internal class IfElseAsmGen(private val program: PtProgram,
                 if(constIndex!=null) {
                     val offset = constIndex * program.memsizer.memorySize(value.type)
                     if(offset<256) {
-                        return asmgen.out("  ldy  #$offset |  $compare  ${asmgen.asmVariableName(value.variable.name)},y")
+                        return asmgen.out("  ldy  #$offset |  $compare  ${asmgen.asmVariableName(value.variable)},y")
                     }
                 }
                 cmpViaScratch()
@@ -337,7 +337,7 @@ internal class IfElseAsmGen(private val program: PtProgram,
                 }
             }
             is PtIdentifier -> {
-                asmgen.out("  $compare  ${asmgen.asmVariableName(value.name)}")
+                asmgen.out("  $compare  ${asmgen.asmVariableName(value)}")
             }
             is PtNumber -> {
                 if(value.number!=0.0)
@@ -349,26 +349,50 @@ internal class IfElseAsmGen(private val program: PtProgram,
         }
     }
 
-    private fun translateByteGreater(leftOperand: PtExpression, rightOperand: PtExpression, stmt: PtIfElse, signed: Boolean, jumpAfterIf: PtJump?) {
+    private fun translateByteLess(stmt: PtIfElse, signed: Boolean, jumpAfterIf: PtJump?) {
+        val condition = stmt.condition as PtBinaryExpression
+        asmgen.assignExpressionToRegister(condition.left, RegisterOrPair.A, signed)
+        cmpAwithByteValue(condition.right, false)
         if(signed) {
-            // X>Y -> Y<X
+            if(jumpAfterIf!=null)
-            asmgen.assignExpressionToRegister(rightOperand, RegisterOrPair.A, signed)
+                translateJumpElseBodies("bmi", "bpl", jumpAfterIf, stmt.elseScope)
-            cmpAwithByteValue(leftOperand, true)
+            else
+                translateIfElseBodies("bpl", stmt)
+        } else {
+            if(jumpAfterIf!=null)
+                translateJumpElseBodies("bcc", "bcs", jumpAfterIf, stmt.elseScope)
+            else
+                translateIfElseBodies("bcs", stmt)
+        }
+    }
+
+    private fun translateByteGreater(stmt: PtIfElse, signed: Boolean, jumpAfterIf: PtJump?) {
+        val condition = stmt.condition as PtBinaryExpression
+        if(signed) {
+            // TODO if compared to a number, a more optimized routine is possible (X>=Y+1)
+            // X>Y --> Y<X
+            asmgen.assignExpressionToRegister(condition.right, RegisterOrPair.A, signed)
+            cmpAwithByteValue(condition.left, true)
+            if (jumpAfterIf != null)
+                translateJumpElseBodies("bmi", "bpl", jumpAfterIf, stmt.elseScope)
+            else
+                translateIfElseBodies("bpl", stmt)
+        } else {
+            asmgen.assignExpressionToRegister(condition.left, RegisterOrPair.A, signed)
+            cmpAwithByteValue(condition.right, false)
             if(jumpAfterIf!=null) {
                 val (asmLabel, indirect) = asmgen.getJumpTarget(jumpAfterIf)
                 if(indirect) {
-                    // X>Y -> Y<X
                     asmgen.out("""
-                        bvc  +
+                        bcc  +
-                        eor  #128
+                        beq  +
-+                       bpl  +
                         jmp  ($asmLabel)
 +""")
                 } else {
                     asmgen.out("""
-                        bvc  +
+                        beq  +
-                        eor  #128
+                        bcs  $asmLabel
-+                       bmi  $asmLabel""")
++""")
                 }
                 asmgen.translate(stmt.elseScope)
             } else {
@@ -376,33 +400,18 @@ internal class IfElseAsmGen(private val program: PtProgram,
                 if(stmt.hasElse()) {
                     // if and else blocks
                     val elseLabel = asmgen.makeLabel("else")
-                    asmgen.out("""
+                    asmgen.out("  bcc  $elseLabel |  beq  $elseLabel")
-                        bvc  +
-                        eor  #128
-+                       bpl  $elseLabel""")
                     asmgen.translate(stmt.ifScope)
                     asmgen.jmp(afterIfLabel, false)
                     asmgen.out(elseLabel)
                     asmgen.translate(stmt.elseScope)
                 } else {
                     // no else block
-                    asmgen.out("""
+                    asmgen.out("  bcc  $afterIfLabel |  beq  $afterIfLabel")
-                        bvc  +
-                        eor  #128
-+                       bpl  $afterIfLabel""")
                     asmgen.translate(stmt.ifScope)
                 }
                 asmgen.out(afterIfLabel)
             }
-        } else {
-            // X>Y -> Y<X
-            asmgen.assignExpressionToRegister(rightOperand, RegisterOrPair.A, signed)
-            cmpAwithByteValue(leftOperand, false)
-            if(jumpAfterIf!=null) {
-                translateJumpElseBodies("bcc", "bcs", jumpAfterIf, stmt.elseScope)
-            } else {
-                translateIfElseBodies("bcs", stmt)
-            }
         }
     }
 

docs/source/todo.rst

@@ -1,6 +1,13 @@
 TODO
 ====
 
+fix large code for  while wptr!=&buffer
+
+explore possible optimizations when comparing to a constant number:
+X < N --> X<=N-1
+X > N --> X>=N+1   etc etc   some yield shorter code!!
+
+
 verify ifelse codegens to be shortest code:  (some are using too many scratch vars?)
 uword >=
 uword >
@@ -12,7 +19,6 @@ word <=
 word <
 
 
-plasma is a bit larger
 floatparse is a bit larger
 testgfx2 is a bit larger
 amiga is a bit larger

examples/test.p8

@@ -1,397 +1,48 @@
-
+%import math
 %import textio
-%import floats
-%import test_stack
 %zeropage dontuse
 %option no_sysinit
 
 main {
-    ubyte success = 0
-    str datatype = "uword"
-    uword @shared comparison
-
     sub start() {
-        txt.print("\ngreater-equal tests for: ")
+        uword @shared wptr
-        txt.print(datatype)
+        str buffer="    "
-        txt.nl()
+
-        test_stack.test()
+        ; TODO: these generate LARGE code
-        txt.print("\n>=number: ")
+        while wptr!=&buffer
-        test_cmp_number()
+            cx16.r0L++
-/*
+        while wptr==&buffer
-        txt.print("\n>=var: ")
+            cx16.r0L++
-        test_cmp_var()
+
-        txt.print("\n>=array[]: ")
+        ; ... these are fine:
-        test_cmp_array()
+        while wptr!=cx16.r0
-        txt.print("\n>=expr: ")
+            cx16.r0L++
-        test_cmp_expr()
+        while wptr==cx16.r0
-*/
+            cx16.r0L++
-        test_stack.test()
+
+
+        if ub() > 5
+            cx16.r0L++
+
+        if ub() < 5
+            cx16.r0L++
+
+        if sb() > 5
+            cx16.r0L++
+
+        if sb() < 5
+            cx16.r0L++
+
     }
 
-    sub verify_success(ubyte expected) {
+    sub ub() -> ubyte {
-        if success==expected {
+        cx16.r0++
-            txt.print_ub(success)
+        return cx16.r0L
-            txt.print(" successes ok")
-        } else {
-            txt.print(" **failed** ")
-            txt.print_ub(success)
-            txt.print(" success, expected ")
-            txt.print_ub(expected)
-        }
     }
 
-    sub fail_byte(uword idx) {
+    sub sb() -> byte {
-        txt.print(" **fail#")
+        cx16.r0++
-        txt.print_uw(idx)
+        return cx16.r0sL
-        txt.print(" **")
     }
-
-    sub fail_ubyte(uword idx) {
-        txt.print(" **fail#")
-        txt.print_uw(idx)
-        txt.print(" **")
-    }
-
-    sub fail_word(uword idx) {
-        txt.print(" **fail#")
-        txt.print_uw(idx)
-        txt.print(" **")
-    }
-
-    sub fail_uword(uword idx) {
-        txt.print(" **fail#")
-        txt.print_uw(idx)
-        txt.print(" **")
-    }
-
-    sub fail_float(uword idx) {
-        txt.print(" **fail#")
-        txt.print_uw(idx)
-        txt.print(" **")
-    }
-
-
-    sub test_cmp_number() {
-    uword @shared x = 65500
-        if x>=65500
-            goto lbl4a
-        goto skip4a
-lbl4a:   txt.print("should see this!\n")
-skip4a:
-}
-
-/*
-    sub test_cmp_var() {
-    uword @shared x, value
-        success = 0
-    x=0
-    value=0
-    ; direct jump
-        if x>=value
-            goto lbl1a
-        goto skip1a
-lbl1a:   success++
-skip1a:
-        ; indirect jump
-        cx16.r3 = &lbl1b
-        if x>=value
-            goto cx16.r3
-        goto skip1b
-lbl1b:   success++
-skip1b:
-        ; no else
-        if x>=value
-            success++
-
-        ; with else
-        if x>=value
-            success++
-        else
-            cx16.r0L++
-
-    value=65535
-    ; direct jump
-        if x>=value
-            goto lbl2a
-        goto skip2a
-lbl2a:   fail_uword(5)
-skip2a:
-        ; indirect jump
-        cx16.r3 = &lbl2b
-        if x>=value
-            goto cx16.r3
-        goto skip2b
-lbl2b:   fail_uword(6)
-skip2b:
-        ; no else
-        if x>=value
-            fail_uword(7)
-
-        ; with else
-        if x>=value
-            fail_uword(8)
-        else
-            success++
-
-    x=65535
-    value=0
-    ; direct jump
-        if x>=value
-            goto lbl3a
-        goto skip3a
-lbl3a:   success++
-skip3a:
-        ; indirect jump
-        cx16.r3 = &lbl3b
-        if x>=value
-            goto cx16.r3
-        goto skip3b
-lbl3b:   success++
-skip3b:
-        ; no else
-        if x>=value
-            success++
-
-        ; with else
-        if x>=value
-            success++
-        else
-            cx16.r0L++
-
-    value=65535
-    ; direct jump
-        if x>=value
-            goto lbl4a
-        goto skip4a
-lbl4a:   success++
-skip4a:
-        ; indirect jump
-        cx16.r3 = &lbl4b
-        if x>=value
-            goto cx16.r3
-        goto skip4b
-lbl4b:   success++
-skip4b:
-        ; no else
-        if x>=value
-            success++
-
-        ; with else
-        if x>=value
-            success++
-        else
-            cx16.r0L++
-
-    verify_success(13)
-}
-    sub test_cmp_array() {
-    uword @shared x
-        uword[] values = [0, 0]
-        success = 0
-    x=0
-    values[1]=0
-    ; direct jump
-        if x>=values[1]
-            goto lbl1a
-        goto skip1a
-lbl1a:   success++
-skip1a:
-        ; indirect jump
-        cx16.r3 = &lbl1b
-        if x>=values[1]
-            goto cx16.r3
-        goto skip1b
-lbl1b:   success++
-skip1b:
-        ; no else
-        if x>=values[1]
-            success++
-
-        ; with else
-        if x>=values[1]
-            success++
-        else
-            cx16.r0L++
-
-    values[1]=65535
-    ; direct jump
-        if x>=values[1]
-            goto lbl2a
-        goto skip2a
-lbl2a:   fail_uword(9)
-skip2a:
-        ; indirect jump
-        cx16.r3 = &lbl2b
-        if x>=values[1]
-            goto cx16.r3
-        goto skip2b
-lbl2b:   fail_uword(10)
-skip2b:
-        ; no else
-        if x>=values[1]
-            fail_uword(11)
-
-        ; with else
-        if x>=values[1]
-            fail_uword(12)
-        else
-            success++
-
-    x=65535
-    values[1]=0
-    ; direct jump
-        if x>=values[1]
-            goto lbl3a
-        goto skip3a
-lbl3a:   success++
-skip3a:
-        ; indirect jump
-        cx16.r3 = &lbl3b
-        if x>=values[1]
-            goto cx16.r3
-        goto skip3b
-lbl3b:   success++
-skip3b:
-        ; no else
-        if x>=values[1]
-            success++
-
-        ; with else
-        if x>=values[1]
-            success++
-        else
-            cx16.r0L++
-
-    values[1]=65535
-    ; direct jump
-        if x>=values[1]
-            goto lbl4a
-        goto skip4a
-lbl4a:   success++
-skip4a:
-        ; indirect jump
-        cx16.r3 = &lbl4b
-        if x>=values[1]
-            goto cx16.r3
-        goto skip4b
-lbl4b:   success++
-skip4b:
-        ; no else
-        if x>=values[1]
-            success++
-
-        ; with else
-        if x>=values[1]
-            success++
-        else
-            cx16.r0L++
-
-    verify_success(13)
-}
-    sub test_cmp_expr() {
-    uword @shared x
-        cx16.r4 = 1
-        cx16.r5 = 1
-        float @shared f4 = 1.0
-        float @shared f5 = 1.0
-        success = 0
-    x=0
-    ; direct jump
-        if x>=cx16.r4+0-cx16.r5
-            goto lbl1a
-        goto skip1a
-lbl1a:   success++
-skip1a:
-        ; indirect jump
-        cx16.r3 = &lbl1b
-        if x>=cx16.r4+0-cx16.r5
-            goto cx16.r3
-        goto skip1b
-lbl1b:   success++
-skip1b:
-        ; no else
-        if x>=cx16.r4+0-cx16.r5
-            success++
-
-        ; with else
-        if x>=cx16.r4+0-cx16.r5
-            success++
-        else
-            cx16.r0L++
-
-    ; direct jump
-        if x>=cx16.r4+65535-cx16.r5
-            goto lbl2a
-        goto skip2a
-lbl2a:   fail_uword(13)
-skip2a:
-        ; indirect jump
-        cx16.r3 = &lbl2b
-        if x>=cx16.r4+65535-cx16.r5
-            goto cx16.r3
-        goto skip2b
-lbl2b:   fail_uword(14)
-skip2b:
-        ; no else
-        if x>=cx16.r4+65535-cx16.r5
-            fail_uword(15)
-
-        ; with else
-        if x>=cx16.r4+65535-cx16.r5
-            fail_uword(16)
-        else
-            success++
-
-    x=65535
-    ; direct jump
-        if x>=cx16.r4+0-cx16.r5
-            goto lbl3a
-        goto skip3a
-lbl3a:   success++
-skip3a:
-        ; indirect jump
-        cx16.r3 = &lbl3b
-        if x>=cx16.r4+0-cx16.r5
-            goto cx16.r3
-        goto skip3b
-lbl3b:   success++
-skip3b:
-        ; no else
-        if x>=cx16.r4+0-cx16.r5
-            success++
-
-        ; with else
-        if x>=cx16.r4+0-cx16.r5
-            success++
-        else
-            cx16.r0L++
-
-    ; direct jump
-        if x>=cx16.r4+65535-cx16.r5
-            goto lbl4a
-        goto skip4a
-lbl4a:   success++
-skip4a:
-        ; indirect jump
-        cx16.r3 = &lbl4b
-        if x>=cx16.r4+65535-cx16.r5
-            goto cx16.r3
-        goto skip4b
-lbl4b:   success++
-skip4b:
-        ; no else
-        if x>=cx16.r4+65535-cx16.r5
-            success++
-
-        ; with else
-        if x>=cx16.r4+65535-cx16.r5
-            success++
-        else
-            cx16.r0L++
-
-    verify_success(13)
-}
-*/
-
 }