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add IR peephole optimization to remove redundant store

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This commit is contained in:
Irmen de Jong 2024-03-28 01:06:05 +01:00
parent 56c1035581
commit bd5abfb969
2 changed files with 16 additions and 7 deletions
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20
codeGenIntermediate/src/prog8/codegen/intermediate/IRPeepholeOptimizer.kt
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@ -433,12 +433,24 @@ class IRPeepholeOptimizer(private val irprog: IRProgram) {
}
private fun removeDoubleLoadsAndStores(chunk: IRCodeChunk, indexedInstructions: List<IndexedValue<IRInstruction>>): Boolean {
return false
/*
var changed = false
indexedInstructions.forEach { (idx, ins) ->
if(ins.opcode==Opcode.STOREM) {
val prev = indexedInstructions[idx-1].value
if(prev.opcode==Opcode.LOADM) {
// loadm.X rX,something | storem.X rX,something ?? -> get rid of the store.
if(ins.labelSymbol!=null && ins.labelSymbol==prev.labelSymbol) {
changed=true
chunk.instructions.removeAt(idx)
}
else if(ins.address!=null && ins.address==prev.address) {
changed=true
chunk.instructions.removeAt(idx)
}
}
}
/*
// TODO: detect multiple loads to the same target registers, only keep first (if source is not I/O memory)
// TODO: detect multiple stores to the same target, only keep first (if target is not I/O memory)
// TODO: detect multiple float ffrom/fto to the same target, only keep first
@ -446,8 +458,8 @@ class IRPeepholeOptimizer(private val irprog: IRProgram) {
// TODO: detect multiple same ands, ors; only keep first
// TODO: (hard) detect multiple registers being assigned the same value (and not changed) - use only 1 of them
// ...
*/
}
return changed
*/
}
}

3
docs/source/todo.rst
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@ -3,9 +3,6 @@ TODO
add docs for multi-assigns.
add IR peephole optimizer for : loadm.X rX,$address | storem.X rX,$address. (get rid of the store)
(you can generate this code by assigning a asmsub's R0 return value to R0 for instance).
...