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added several more assembly-level optimizations to remove redundant instructions

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This commit is contained in:
Irmen de Jong 2021-11-14 12:23:46 +01:00
parent c858ceeb58
commit 5190594c8a
3 changed files with 119 additions and 0 deletions
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114
codeGeneration/src/prog8/compiler/target/cpu6502/codegen/AsmOptimizer.kt
View File

@ -174,7 +174,121 @@ private fun optimizeSameAssignments(linesByFourteen: List<List<IndexedValue<Stri
}
}
}
var overlappingMods = false
/*
sta prog8_lib.retval_intermX ; remove
sty prog8_lib.retval_intermY ; remove
lda prog8_lib.retval_intermX ; remove
ldy prog8_lib.retval_intermY ; remove
sta A1
sty A2
*/
if(first.startsWith("st") && second.startsWith("st")
&& third.startsWith("ld") && fourth.startsWith("ld")
&& fifth.startsWith("st") && sixth.startsWith("st")) {
val reg1 = first[2]
val reg2 = second[2]
val reg3 = third[2]
val reg4 = fourth[2]
val reg5 = fifth[2]
val reg6 = sixth[2]
if (reg1 == reg3 && reg1 == reg5 && reg2 == reg4 && reg2 == reg6) {
val firstvalue = first.substring(4)
val secondvalue = second.substring(4)
val thirdvalue = third.substring(4)
val fourthvalue = fourth.substring(4)
if(firstvalue.contains("prog8_lib.retval_interm") && secondvalue.contains("prog8_lib.retval_interm")
&& firstvalue==thirdvalue && secondvalue==fourthvalue) {
mods.add(Modification(lines[0].index, true, null))
mods.add(Modification(lines[1].index, true, null))
mods.add(Modification(lines[2].index, true, null))
mods.add(Modification(lines[3].index, true, null))
overlappingMods = true
}
}
}
/*
sta A1
sty A2
lda A1 ; can be removed
ldy A2 ; can be removed if not followed by a branch instuction
*/
if(!overlappingMods && first.startsWith("st") && second.startsWith("st")
&& third.startsWith("ld") && fourth.startsWith("ld")) {
val reg1 = first[2]
val reg2 = second[2]
val reg3 = third[2]
val reg4 = fourth[2]
if(reg1==reg3 && reg2==reg4) {
val firstvalue = first.substring(4)
val secondvalue = second.substring(4)
val thirdvalue = third.substring(4)
val fourthvalue = fourth.substring(4)
if(firstvalue==thirdvalue && secondvalue == fourthvalue) {
overlappingMods = true
mods.add(Modification(lines[2].index, true, null))
if(!fifth.startsWith('b'))
mods.add(Modification(lines[3].index, true, null))
}
}
}
/*
sta A1
sty A2
lda A1 ; can be removed if not followed by a branch instruction
*/
if(!overlappingMods && first.startsWith("st") && second.startsWith("st")
&& third.startsWith("ld") && !fourth.startsWith("b")) {
val reg1 = first[2]
val reg3 = third[2]
if(reg1==reg3) {
val firstvalue = first.substring(4)
val thirdvalue = third.substring(4)
if(firstvalue==thirdvalue) {
overlappingMods = true
mods.add(Modification(lines[2].index, true, null))
}
}
}
/*
sta A1
<other st/ld instruction not involving A1>
sta A1 ; can be removed
*/
if(!overlappingMods && first.startsWith("st") && third.startsWith("st")) {
val reg1 = first[2]
val reg3 = third[2]
if(reg1==reg3 && (second.startsWith("ld") || second.startsWith("st"))) {
val firstvalue = first.substring(4)
val secondvalue = second.substring(4)
val thirdvalue = third.substring(4)
if(firstvalue==thirdvalue && firstvalue!=secondvalue) {
overlappingMods = true
mods.add(Modification(lines[2].index, true, null))
}
}
}
/*
sta A1
ldy A1 ; make tay
sta A1 ; remove
*/
if(!overlappingMods && first.startsWith("sta") && second.startsWith("ld")
&& third.startsWith("sta") && second.length>4) {
val firstvalue = first.substring(4)
val secondvalue = second.substring(4)
val thirdvalue = third.substring(4)
if(firstvalue==secondvalue && firstvalue==thirdvalue) {
overlappingMods = true
val reg2 = second[2]
mods.add(Modification(lines[1].index, false, " ta$reg2"))
mods.add(Modification(lines[2].index, true, null))
}
}
}
return mods
}

4
compiler/src/prog8/compiler/BeforeAsmGenerationAstChanger.kt
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@ -239,6 +239,10 @@ internal class BeforeAsmGenerationAstChanger(val program: Program, private val o
var leftOperandReplacement: Expression? = null
var rightAssignment: Assignment? = null
var rightOperandReplacement: Expression? = null
// TODO don't optimize simple conditionals that are just a function call
if(!expr.left.isSimple) {
val dt = expr.left.inferType(program)
val name = when {

1
docs/source/todo.rst
View File

@ -3,6 +3,7 @@ TODO
For next compiler release (7.3)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
- simplifyConditionalExpression: don't change conditinal expressions that are just a single function call
- add expression simplification to while and until loops as well.