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asm optimization: bxx+jmp -> opposite bxx

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Irmen de Jong 2024-06-29 17:22:57 +02:00
parent 7a9dd1ac9b
commit ead8aa7800
2 changed files with 66 additions and 28 deletions
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83
codeGenCpu6502/src/prog8/codegen/cpu6502/AsmOptimizer.kt
View File

@ -446,23 +446,6 @@ private fun optimizeStoreLoadSame(
if (firstLoc == secondLoc)
mods.add(Modification(lines[2].index, true, null))
}
// phy + ldy + pla -> tya + ldy
// phx + ldx + pla -> txa + ldx
// pha + lda + pla -> nop
if(first=="phy" && second.startsWith("ldy ") && third=="pla") {
mods.add(Modification(lines[3].index, true, null))
mods.add(Modification(lines[1].index, false, " tya"))
}
else if(first=="phx" && second.startsWith("ldx ") && third=="pla") {
mods.add(Modification(lines[3].index, true, null))
mods.add(Modification(lines[1].index, false, " txa"))
}
else if(first=="pha" && second.startsWith("lda ") && third=="pla") {
mods.add(Modification(lines[1].index, true, null))
mods.add(Modification(lines[2].index, true, null))
mods.add(Modification(lines[3].index, true, null))
}
}
return mods
}
@ -525,6 +508,7 @@ private fun optimizeJsrRtsAndOtherCombinations(linesByFour: Sequence<List<Indexe
for (lines in linesByFour) {
val first = lines[0].value
val second = lines[1].value
val third = lines[2].value
if ((" jsr" in first || "\tjsr" in first ) && (" rts" in second || "\trts" in second)) {
mods += Modification(lines[0].index, false, lines[0].value.replace("jsr", "jmp"))
mods += Modification(lines[1].index, true, null)
@ -594,6 +578,48 @@ private fun optimizeJsrRtsAndOtherCombinations(linesByFour: Sequence<List<Indexe
mods += Modification(lines[3].index, true, null)
}
}
fun sameLabel(branchInstr: String, jumpInstr: String, labelInstr: String): Boolean {
if('(' in jumpInstr) return false // indirect jump cannot be replaced
val label = labelInstr.trimEnd().substringBefore(':').substringBefore(' ').substringBefore('\t')
println("label=$label")
return true
}
// beq Label + jmp Addr + Label -> bne Addr
if((" jmp" in second || "\tjmp " in second) && haslabel(third)) {
if((" beq " in first || "\tbeq " in first) && sameLabel(first, second, third)) {
val branch = second.replace("jmp", "bne")
mods.add(Modification(lines[0].index, true, null))
mods.add(Modification(lines[1].index, false, branch))
}
else if((" bne " in first || "\tbne " in first) && sameLabel(first, second, third)) {
val branch = second.replace("jmp", "beq")
mods.add(Modification(lines[0].index, true, null))
mods.add(Modification(lines[1].index, false, branch))
}
else if((" bcc " in first || "\tbcc " in first) && sameLabel(first, second, third)){
val branch = second.replace("jmp", "bcs")
mods.add(Modification(lines[0].index, true, null))
mods.add(Modification(lines[1].index, false, branch))
}
else if((" bcs " in first || "\tbcs " in first) && sameLabel(first, second, third)) {
val branch = second.replace("jmp", "bcc")
mods.add(Modification(lines[0].index, true, null))
mods.add(Modification(lines[1].index, false, branch))
}
else if((" bpl " in first || "\tbpl " in first) && sameLabel(first, second, third)) {
val branch = second.replace("jmp", "bmi")
mods.add(Modification(lines[0].index, true, null))
mods.add(Modification(lines[1].index, false, branch))
}
else if((" bmi " in first || "\tbmi " in first) && sameLabel(first, second, third)) {
val branch = second.replace("jmp", "bpl")
mods.add(Modification(lines[0].index, true, null))
mods.add(Modification(lines[1].index, false, branch))
}
}
}
return mods
}
@ -631,7 +657,30 @@ private fun optimizeUselessPushPopStack(linesByFour: Sequence<List<IndexedValue<
optimize('a', lines)
optimize('x', lines)
optimize('y', lines)
val first = lines[1].value.trimStart()
val second = lines[2].value.trimStart()
val third = lines[3].value.trimStart()
// phy + ldy + pla -> tya + ldy
// phx + ldx + pla -> txa + ldx
// pha + lda + pla -> nop
if(first=="phy" && second.startsWith("ldy ") && third=="pla") {
mods.add(Modification(lines[3].index, true, null))
mods.add(Modification(lines[1].index, false, " tya"))
}
else if(first=="phx" && second.startsWith("ldx ") && third=="pla") {
mods.add(Modification(lines[3].index, true, null))
mods.add(Modification(lines[1].index, false, " txa"))
}
else if(first=="pha" && second.startsWith("lda ") && third=="pla") {
mods.add(Modification(lines[1].index, true, null))
mods.add(Modification(lines[2].index, true, null))
mods.add(Modification(lines[3].index, true, null))
}
}
return mods
}

11
docs/source/todo.rst
View File

@ -6,17 +6,6 @@ causes compiler error for virtual: just calling txt.cls() gives compile error un
https://github.com/irmen/prog8/issues/136 (string.find register order issue)
if-optimization:
if row == NUMQUEENS {
print_solution()
return
}
compiles into this, where the bne+jmp could be a single beq instead:
cmp #8
bne label_asm_21_afterif
jmp p8b_main.p8s_print_solution
label_asm_21_afterif:
optimize signed byte/word division by powers of 2 (and shift right?), it's now using divmod routine. (also % ?)
see inplacemodificationByteVariableWithLiteralval() and inplacemodificationSomeWordWithLiteralval()