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asm optimizer: don't remove labels. remove redundant cmp/cpx/cpy instructions.

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This commit is contained in:
Irmen de Jong 2024-02-29 22:27:42 +01:00
parent ceaa4cd07d
commit 620ffe54ec
3 changed files with 76 additions and 38 deletions
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65
codeGenCpu6502/src/prog8/codegen/cpu6502/AsmOptimizer.kt
View File

@ -75,23 +75,48 @@ private fun String.isStoreReg() = this.startsWith("sta") || this.startsWith("sty
private fun String.isStoreRegOrZero() = this.isStoreReg() || this.startsWith("stz")
private fun String.isLoadReg() = this.startsWith("lda") || this.startsWith("ldy") || this.startsWith("ldx")
private class Modification(val lineIndex: Int, val remove: Boolean, val replacement: String?)
private class Modification(val lineIndex: Int, val remove: Boolean, val replacement: String?, val removeLabel: Boolean=false)
private fun apply(modifications: List<Modification>, lines: MutableList<String>) {
for (modification in modifications.sortedBy { it.lineIndex }.reversed()) {
if(modification.remove)
lines.removeAt(modification.lineIndex)
if(modification.remove) {
if(modification.removeLabel)
lines.removeAt(modification.lineIndex)
else {
val line = lines[modification.lineIndex]
if (line.length < 2 || line[0] == ';' || line.trimStart()[0] == ';')
lines.removeAt(modification.lineIndex)
else if (haslabel(line)) {
val label = keeplabel(line)
if (label.isNotEmpty())
lines[modification.lineIndex] = label
else
lines.removeAt(modification.lineIndex)
} else lines.removeAt(modification.lineIndex)
}
}
else
lines[modification.lineIndex] = modification.replacement!!
}
}
private fun haslabel(line: String): Boolean {
return line.length>1 && line[0]!=';' && (!line[0].isWhitespace() || ':' in line)
}
private fun keeplabel(line: String): String {
if(':' in line)
return line.substringBefore(':') + ':'
val splits = line.split('\t', ' ', limit=2)
return if(splits.size>1) splits[0] + ':' else ""
}
private fun getLinesBy(lines: MutableList<String>, windowSize: Int) =
// all lines (that aren't empty or comments) in sliding windows of certain size
lines.withIndex().filter { it.value.isNotBlank() && !it.value.trimStart().startsWith(';') }.windowed(windowSize, partialWindows = false)
lines.asSequence().withIndex().filter { it.value.isNotBlank() && !it.value.trimStart().startsWith(';') }.windowed(windowSize, partialWindows = false)
private fun optimizeSameAssignments(
linesByFourteen: List<List<IndexedValue<String>>>,
linesByFourteen: Sequence<List<IndexedValue<String>>>,
machine: IMachineDefinition,
symbolTable: SymbolTable
): List<Modification> {
@ -281,7 +306,7 @@ private fun optimizeSameAssignments(
return mods
}
private fun optimizeSamePointerIndexing(linesByFourteen: List<List<IndexedValue<String>>>): List<Modification> {
private fun optimizeSamePointerIndexing(linesByFourteen: Sequence<List<IndexedValue<String>>>): List<Modification> {
// Optimize same pointer indexing where for instance we load and store to the same ptr index in Y
// if Y isn't modified in between we can omit the second LDY:
@ -324,7 +349,7 @@ private fun optimizeSamePointerIndexing(linesByFourteen: List<List<IndexedValue<
}
private fun optimizeStoreLoadSame(
linesByFour: List<List<IndexedValue<String>>>,
linesByFour: Sequence<List<IndexedValue<String>>>,
machine: IMachineDefinition,
symbolTable: SymbolTable
): List<Modification> {
@ -414,7 +439,7 @@ private fun getAddressArg(line: String, symbolTable: SymbolTable): UInt? {
}
}
private fun optimizeIncDec(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
private fun optimizeIncDec(linesByFour: Sequence<List<IndexedValue<String>>>): List<Modification> {
// sometimes, iny+dey / inx+dex / dey+iny / dex+inx sequences are generated, these can be eliminated.
val mods = mutableListOf<Modification>()
for (lines in linesByFour) {
@ -435,10 +460,11 @@ private fun optimizeIncDec(linesByFour: List<List<IndexedValue<String>>>): List<
return mods
}
private fun optimizeJsrRtsAndOtherCombinations(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
private fun optimizeJsrRtsAndOtherCombinations(linesByFour: Sequence<List<IndexedValue<String>>>): List<Modification> {
// jsr Sub + rts -> jmp Sub
// rts + jmp -> remove jmp
// rts + bxx -> remove bxx
// lda + cmp #0 -> remove cmp, same for cpy and cpx.
// and some other optimizations.
val mods = mutableListOf<Modification>()
@ -472,6 +498,23 @@ private fun optimizeJsrRtsAndOtherCombinations(linesByFour: List<List<IndexedVal
mods += Modification(lines[1].index, true, null)
}
if (!haslabel(second)) {
if ((" lda" in first || "\tlda" in first) && (" cmp #0" in second || "\tcmp #0" in second) ||
(" ldx" in first || "\tldx" in first) && (" cpx #0" in second || "\tcpx #0" in second) ||
(" ldy" in first || "\tldy" in first) && (" cpy #0" in second || "\tcpy #0" in second)
) {
mods.add(Modification(lines[1].index, true, null))
}
else if(" cmp #0" in second || "\tcmp #0" in second) {
// there are many instructions that modify A and set the bits...
for(instr in arrayOf("lda", "ora", "and", "eor", "adc", "sbc", "asl", "cmp", "inc a", "lsr", "pla", "rol", "ror", "txa", "tya")) {
if(" $instr" in first || "\t$instr" in first) {
mods.add(Modification(lines[1].index, true, null))
}
}
}
}
/*
LDA NUM1
CMP NUM2
@ -501,7 +544,7 @@ private fun optimizeJsrRtsAndOtherCombinations(linesByFour: List<List<IndexedVal
return mods
}
private fun optimizeUselessPushPopStack(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
private fun optimizeUselessPushPopStack(linesByFour: Sequence<List<IndexedValue<String>>>): List<Modification> {
val mods = mutableListOf<Modification>()
fun optimize(register: Char, lines: List<IndexedValue<String>>) {
@ -538,7 +581,7 @@ private fun optimizeUselessPushPopStack(linesByFour: List<List<IndexedValue<Stri
return mods
}
private fun optimizeUnneededTempvarInAdd(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
private fun optimizeUnneededTempvarInAdd(linesByFour: Sequence<List<IndexedValue<String>>>): List<Modification> {
// sequence: sta P8ZP_SCRATCH_XX / lda something / clc / adc P8ZP_SCRATCH_XX
// this can be performed without the scratch variable: clc / adc something
val mods = mutableListOf<Modification>()

7
docs/source/todo.rst
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@ -1,14 +1,9 @@
TODO
====
add peephole asm optimizer that removes a cmp #0 directly after a lda (same for cpx cpy)
check all comparisons for split word arrays (signed+unsigned, all 4 variants)
floatparse is slightly larger
snow is a lot larger
neofetch is sligthly larger
snow example is a lot larger!
explore possible optimizations for words when comparing to a constant number (BeforeAsmAstChanger)

42
examples/test.p8
View File

@ -11,27 +11,27 @@ main {
if any(barray)
cx16.r0++
;
;
; if barray[2] == 33
; cx16.r0++
; else
; cx16.r1++
;
; if warray[2] == 3333
; cx16.r0++
; else
; cx16.r1++
;
; if barray[cx16.r0L] == 33
; cx16.r0++
; else
; cx16.r1++
;
; if warray[cx16.r0L] == 3333
; cx16.r0++
; else
; cx16.r1++
if barray[2] == 33
cx16.r0++
else
cx16.r1++
if warray[2] == 3333
cx16.r0++
else
cx16.r1++
if barray[cx16.r0L] == 33
cx16.r0++
else
cx16.r1++
if warray[cx16.r0L] == 3333
cx16.r0++
else
cx16.r1++
}
}