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added asm optimizer for <= byte (bcc+beq->bcs)

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This commit is contained in:
Irmen de Jong 2024-03-02 14:26:02 +01:00
parent 58d9463f16
commit a282b17286
3 changed files with 49 additions and 30 deletions
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31
codeGenCpu6502/src/prog8/codegen/cpu6502/AsmOptimizer.kt
View File

@ -439,6 +439,7 @@ private fun optimizeJsrRtsAndOtherCombinations(linesByFour: List<List<IndexedVal
// jsr Sub + rts -> jmp Sub
// rts + jmp -> remove jmp
// rts + bxx -> remove bxx
// and some other optimizations.
val mods = mutableListOf<Modification>()
for (lines in linesByFour) {
@ -470,6 +471,32 @@ private fun optimizeJsrRtsAndOtherCombinations(linesByFour: List<List<IndexedVal
else if (" bvc" in second || "\tbvc" in second)
mods += Modification(lines[1].index, true, null)
}
/*
LDA NUM1
CMP NUM2
BCC LABEL
BEQ LABEL
(or something similar) which branches to LABEL when NUM1 <= NUM2. (In this case NUM1 and NUM2 are unsigned numbers.) However, consider the following sequence:
LDA NUM2
CMP NUM1
BCS LABEL
*/
val tfirst = first.trimStart()
val tsecond = second.trimStart()
val tthird = lines[2].value.trimStart()
val tfourth = lines[3].value.trimStart()
if(tfirst.startsWith("lda") && tsecond.startsWith("cmp") && tthird.startsWith("bcc") && tfourth.startsWith("beq")) {
val label = tthird.substring(4)
if(label==tfourth.substring(4)) {
mods += Modification(lines[0].index, false, " lda ${tsecond.substring(4)}")
mods += Modification(lines[1].index, false, " cmp ${tfirst.substring(4)}")
mods += Modification(lines[2].index, false, " bcs $label")
mods += Modification(lines[3].index, true, null)
}
}
}
return mods
}
@ -523,8 +550,8 @@ private fun optimizeUnneededTempvarInAdd(linesByFour: List<List<IndexedValue<Str
val fourth = lines[3].value.trimStart()
if(first.startsWith("sta P8ZP_SCRATCH_") && second.startsWith("lda") && third.startsWith("clc") && fourth.startsWith("adc P8ZP_SCRATCH_") ) {
if(fourth.substring(4)==first.substring(4)) {
mods.add(Modification(lines[0].index, false, " clc"))
mods.add(Modification(lines[1].index, false, " adc ${second.substring(3).trimStart()}"))
mods.add(Modification(lines[0].index, false, " clc"))
mods.add(Modification(lines[1].index, false, " adc ${second.substring(3).trimStart()}"))
mods.add(Modification(lines[2].index, true, null))
mods.add(Modification(lines[3].index, true, null))
}

15
docs/source/todo.rst
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@ -1,21 +1,6 @@
TODO
====
add asm optimizer:
LDA NUM1
CMP NUM2
BCC LABEL
BEQ LABEL
(or something similar) which branches to LABEL when NUM1 <= NUM2. (In this case NUM1 and NUM2 are unsigned numbers.) However, consider the following sequence:
LDA NUM2
CMP NUM1
BCS LABEL
larger programs:
automatons
mandelbrot (quite a bit larger)

33
examples/test.p8
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@ -3,21 +3,28 @@
%zeropage basicsafe
main {
sub rrrr() -> ubyte {
cx16.r0L++
return cx16.r0L
}
sub start() {
ubyte[] flakes = [1,2,3]
cx16.r0L = rrrr() >= 128
ubyte @shared idx = 2
if flakes[idx]==239 {
txt.print("yes")
} else {
txt.print("nope")
}
ubyte @shared xx = 16
ubyte @shared yy = 20
txt.print_ub(xx>79 or yy > 49)
; ubyte[] flakes = [1,2,3]
;
; ubyte @shared idx = 2
;
; if flakes[idx]==239 {
; txt.print("yes")
; } else {
; txt.print("nope")
; }
;
; ubyte @shared xx = 16
; ubyte @shared yy = 20
;
; txt.print_ub(xx>79 or yy > 49)
; if xx>79 or yy > 49 {
; if xx>79 or yy > 49 {