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IR: optimize redundant labels

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This commit is contained in:
Irmen de Jong 2023-11-25 01:08:26 +01:00
parent 6a40f23578
commit 9ef9c24388
3 changed files with 41 additions and 15 deletions
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38
codeGenIntermediate/src/prog8/codegen/intermediate/IRPeepholeOptimizer.kt
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@ -87,7 +87,7 @@ class IRPeepholeOptimizer(private val irprog: IRProgram) {
/*
Empty Code chunk with label ->
If next chunk has no label -> move label to next chunk, remove original
If next chunk has label -> label name should be the same, remove original. Otherwise FOR NOW leave it in place. (TODO: merge both labels into 1)
If next chunk has label -> label name should be the same, remove original. Otherwise merge both labels into 1.
If is last chunk -> keep chunk in place because of the label.
Empty Code chunk without label ->
should not have been generated! ERROR.
@ -96,6 +96,7 @@ class IRPeepholeOptimizer(private val irprog: IRProgram) {
val relabelChunks = mutableListOf<Pair<Int, String>>()
val removeChunks = mutableListOf<Int>()
val replaceLabels = mutableMapOf<String, String>()
sub.chunks.withIndex().forEach { (index, chunk) ->
if(chunk is IRCodeChunk && chunk.instructions.isEmpty()) {
@ -109,10 +110,18 @@ class IRPeepholeOptimizer(private val irprog: IRProgram) {
relabelChunks += Pair(index + 1, chunk.label!!)
removeChunks += index
} else {
if (chunk.label == nextchunk.label)
removeChunks += index
else {
// TODO: merge labels on same chunk
// merge both labels into 1 except if this is the label chunk at the start of the subroutine
if(index>0) {
if (chunk.label == nextchunk.label)
removeChunks += index
else {
removeChunks += index
replaceLabels[chunk.label!!] = nextchunk.label!!
replaceLabels.entries.forEach { (key, value) ->
if (value == chunk.label)
replaceLabels[key] = nextchunk.label!!
}
}
}
}
}
@ -129,6 +138,25 @@ class IRPeepholeOptimizer(private val irprog: IRProgram) {
sub.chunks[index] = chunk
}
removeChunks.reversed().forEach { index -> sub.chunks.removeAt(index) }
sub.chunks.forEach { chunk ->
chunk.instructions.withIndex().forEach { (idx, instr) ->
instr.labelSymbol?.let {
if(instr.opcode in OpcodesThatBranch) {
replaceLabels.forEach { (from, to) ->
if (it == from) {
chunk.instructions[idx] = instr.copy(labelSymbol = to)
}
else {
val actualPrefix = "$from."
if (it.startsWith(actualPrefix))
chunk.instructions[idx] = instr.copy(labelSymbol = "$to.")
}
}
}
}
}
}
}
private fun joinChunks(sub: IRSubroutine) {

16
codeGenIntermediate/test/TestIRPeepholeOpt.kt
View File

@ -53,9 +53,9 @@ class TestIRPeepholeOpt: FunSpec({
test("remove jmp to label below") {
val c1 = IRCodeChunk("main.start", null)
c1 += IRInstruction(Opcode.JUMP, labelSymbol = "label") // removed, but chunk stays because of label
c1 += IRInstruction(Opcode.JUMP, labelSymbol = "label")
val c2 = IRCodeChunk("label", null)
c2 += IRInstruction(Opcode.JUMP, labelSymbol = "label2") // removed, but chunk stays because of label
c2 += IRInstruction(Opcode.JUMP, labelSymbol = "label2")
c2 += IRInstruction(Opcode.NOP) // removed
val c3 = IRCodeChunk("label2", null)
c3 += IRInstruction(Opcode.JUMP, labelSymbol = "label3")
@ -67,15 +67,13 @@ class TestIRPeepholeOpt: FunSpec({
irProg.chunks().flatMap { it.instructions }.size shouldBe 5
val opt = IRPeepholeOptimizer(irProg)
opt.optimize(true, ErrorReporterForTests())
irProg.chunks().size shouldBe 4
irProg.chunks().size shouldBe 3
irProg.chunks()[0].label shouldBe "main.start"
irProg.chunks()[1].label shouldBe "label"
irProg.chunks()[2].label shouldBe "label2"
irProg.chunks()[3].label shouldBe "label3"
irProg.chunks()[1].label shouldBe "label2"
irProg.chunks()[2].label shouldBe "label3"
irProg.chunks()[0].isEmpty() shouldBe true
irProg.chunks()[1].isEmpty() shouldBe true
irProg.chunks()[2].isEmpty() shouldBe false
irProg.chunks()[3].isEmpty() shouldBe true
irProg.chunks()[1].isEmpty() shouldBe false
irProg.chunks()[2].isEmpty() shouldBe true
val instr = irProg.chunks().flatMap { it.instructions }
instr.size shouldBe 2
instr[0].opcode shouldBe Opcode.JUMP

2
compiler/res/prog8lib/cx16/bmx.p8
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@ -1,7 +1,7 @@
; Routines to load and save "BMX" files (commander X16 bitmap format) Version 1.
; Only uncompressed images are supported for now.
; BMX Specification: https://cx16forum.com/forum/viewtopic.php?t=6945
; TODO: make read_palette() and write_palette() use a palette_buffer_ptr to store palette into system ram instead of directly into vram.
; TODO: make read_palette() and write_palette() use an optional palette_buffer_ptr to store palette into system ram instead of directly into vram.
%import diskio