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added asm optimization for same pointer index

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This commit is contained in:
Irmen de Jong 2022-08-14 12:50:46 +02:00
parent 7ef4ddf0f3
commit f249ccd414
2 changed files with 49 additions and 6 deletions
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49
codeGenCpu6502/src/prog8/codegen/cpu6502/AsmOptimizer.kt
View File

@ -59,6 +59,13 @@ internal fun optimizeAssembly(lines: MutableList<String>, machine: IMachineDefin
numberOfOptimizations++
}
mods = optimizeSamePointerIndexing(linesByFourteen, machine, program)
if(mods.isNotEmpty()) {
apply(mods, lines)
linesByFourteen = getLinesBy(lines, 14)
numberOfOptimizations++
}
// TODO more assembly peephole optimizations
return numberOfOptimizations
@ -320,6 +327,48 @@ private fun optimizeSameAssignments(linesByFourteen: List<List<IndexedValue<Stri
return mods
}
private fun optimizeSamePointerIndexing(linesByFourteen: List<List<IndexedValue<String>>>, machine: IMachineDefinition, program: Program): 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:
// ldy #0
// lda (ptr),y
// ora #3 ; <-- instruction(s) that don't modify Y
// ldy #0 ; <-- can be removed
// sta (ptr),y
val mods = mutableListOf<Modification>()
for (lines in linesByFourteen) {
val first = lines[0].value.trimStart()
val second = lines[1].value.trimStart()
val third = lines[2].value.trimStart()
val fourth = lines[3].value.trimStart()
val fifth = lines[4].value.trimStart()
val sixth = lines[5].value.trimStart()
if(first.startsWith("ldy") && second.startsWith("lda") && fourth.startsWith("ldy") && fifth.startsWith("sta")) {
val firstvalue = first.substring(4)
val secondvalue = second.substring(4)
val fourthvalue = fourth.substring(4)
val fifthvalue = fifth.substring(4)
if("y" !in third && firstvalue==fourthvalue && secondvalue==fifthvalue && secondvalue.endsWith(",y") && fifthvalue.endsWith(",y")) {
mods.add(Modification(lines[3].index, true, null))
}
}
if(first.startsWith("ldy") && second.startsWith("lda") && fifth.startsWith("ldy") && sixth.startsWith("sta")) {
val firstvalue = first.substring(4)
val secondvalue = second.substring(4)
val fifthvalue = fifth.substring(4)
val sixthvalue = sixth.substring(4)
if("y" !in third && "y" !in fourth && firstvalue==fifthvalue && secondvalue==sixthvalue && secondvalue.endsWith(",y") && sixthvalue.endsWith(",y")) {
mods.add(Modification(lines[4].index, true, null))
}
}
}
return mods
}
private fun optimizeStoreLoadSame(linesByFour: List<List<IndexedValue<String>>>, machine: IMachineDefinition, program: Program): List<Modification> {
// sta X + lda X, sty X + ldy X, stx X + ldx X -> the second instruction can OFTEN be eliminated
val mods = mutableListOf<Modification>()

6
docs/source/todo.rst
View File

@ -3,12 +3,6 @@ TODO
For next release
^^^^^^^^^^^^^^^^
- @(ptr) |= 3 -> asm peephole optimize remove the second ldy if the instruction before doesn't modify y
ldy #0
lda (starfieldPtr2),y
ora #3
ldy #0
sta (starfieldPtr2),y
- vm: intermediate code: don't flatten everything. Instead, as a new intermediary step,
convert the new Ast into *structured* intermediary code.
Basically keep the blocks and subroutines structure, including full subroutine signature information,