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tweak the redundant beq asm optimizer a bit more

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This commit is contained in:
Irmen de Jong 2024-03-09 00:05:06 +01:00
parent f46896fd74
commit fc0fae8caf
1 changed files with 31 additions and 20 deletions
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51
codeGenCpu6502/src/prog8/codegen/cpu6502/AsmOptimizer.kt
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@ -58,7 +58,7 @@ internal fun optimizeAssembly(lines: MutableList<String>, machine: IMachineDefin
numberOfOptimizations++
}
mods = optimizeSamePointerIndexing(linesByFourteen)
mods = optimizeSamePointerIndexingAndUselessBeq(linesByFourteen)
if(mods.isNotEmpty()) {
apply(mods, lines)
linesByFourteen = getLinesBy(lines, 14)
@ -306,7 +306,7 @@ private fun optimizeSameAssignments(
return mods
}
private fun optimizeSamePointerIndexing(linesByFourteen: Sequence<List<IndexedValue<String>>>): List<Modification> {
private fun optimizeSamePointerIndexingAndUselessBeq(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:
@ -343,6 +343,35 @@ private fun optimizeSamePointerIndexing(linesByFourteen: Sequence<List<IndexedVa
mods.add(Modification(lines[4].index, true, null))
}
}
/*
beq +
lda #1
+
[ optional: label_xxxx_shortcut line here]
beq label_xxxx_shortcut / bne label_xxxx_shortcut
or *_afterif labels.
This gets generated after certain if conditions, and only the branch instruction is needed in these cases.
*/
if(first=="beq +" && second=="lda #1" && third=="+") {
if((fourth.startsWith("beq label_") || fourth.startsWith("bne label_")) &&
(fourth.endsWith("_shortcut") || fourth.endsWith("_afterif") || fourth.endsWith("_shortcut:") || fourth.endsWith("_afterif:"))) {
mods.add(Modification(lines[0].index, true, null))
mods.add(Modification(lines[1].index, true, null))
mods.add(Modification(lines[2].index, true, null))
}
else if(fourth.startsWith("label_") && (fourth.endsWith("_shortcut") || fourth.endsWith("_shortcut:"))) {
if((fifth.startsWith("beq label_") || fifth.startsWith("bne label_")) &&
(fifth.endsWith("_shortcut") || fifth.endsWith("_afterif") || fifth.endsWith("_shortcut:") || fifth.endsWith("_afterif:"))) {
mods.add(Modification(lines[0].index, true, null))
mods.add(Modification(lines[1].index, true, null))
mods.add(Modification(lines[2].index, true, null))
}
}
}
}
return mods
@ -540,24 +569,6 @@ private fun optimizeJsrRtsAndOtherCombinations(linesByFour: Sequence<List<Indexe
mods += Modification(lines[3].index, true, null)
}
}
/*
beq +
lda #1
+
beq label_xxxx_shortcut / bne label_xxxx_shortcut
or *_afterif labels.
This gets generated after certain if conditions, and only the branch instruction is needed in these cases.
*/
if(tfirst=="beq +" && tsecond=="lda #1" && tthird=="+") {
if((tfourth.startsWith("beq label_") || tfourth.startsWith("bne label_")) && (tfourth.endsWith("_shortcut") || tfourth.endsWith("_afterif"))) {
mods.add(Modification(lines[0].index, true, null))
mods.add(Modification(lines[1].index, true, null))
mods.add(Modification(lines[2].index, true, null))
}
}
}
return mods
}