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https://github.com/irmen/prog8.git
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453 lines
20 KiB
Kotlin
453 lines
20 KiB
Kotlin
package prog8.codegen.cpu6502
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import prog8.ast.Program
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import prog8.ast.expressions.NumericLiteral
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import prog8.ast.statements.VarDecl
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import prog8.ast.statements.VarDeclType
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import prog8.compilerinterface.IMachineDefinition
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// note: see https://wiki.nesdev.org/w/index.php/6502_assembly_optimisations
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internal fun optimizeAssembly(lines: MutableList<String>, machine: IMachineDefinition, program: Program): Int {
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var numberOfOptimizations = 0
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var linesByFour = getLinesBy(lines, 4)
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var mods = optimizeUselessStackByteWrites(linesByFour)
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if(mods.isNotEmpty()) {
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apply(mods, lines)
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linesByFour = getLinesBy(lines, 4)
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numberOfOptimizations++
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}
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mods = optimizeIncDec(linesByFour)
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if(mods.isNotEmpty()) {
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apply(mods, lines)
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linesByFour = getLinesBy(lines, 4)
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numberOfOptimizations++
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}
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mods = optimizeCmpSequence(linesByFour)
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if(mods.isNotEmpty()) {
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apply(mods, lines)
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linesByFour = getLinesBy(lines, 4)
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numberOfOptimizations++
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}
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mods = optimizeStoreLoadSame(linesByFour, machine, program)
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if(mods.isNotEmpty()) {
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apply(mods, lines)
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linesByFour = getLinesBy(lines, 4)
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numberOfOptimizations++
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}
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mods= optimizeJsrRts(linesByFour)
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if(mods.isNotEmpty()) {
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apply(mods, lines)
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linesByFour = getLinesBy(lines, 4)
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numberOfOptimizations++
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}
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var linesByFourteen = getLinesBy(lines, 14)
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mods = optimizeSameAssignments(linesByFourteen, machine, program)
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if(mods.isNotEmpty()) {
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apply(mods, lines)
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linesByFourteen = getLinesBy(lines, 14)
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numberOfOptimizations++
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}
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// TODO more assembly optimizations
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return numberOfOptimizations
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}
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private fun String.isBranch() = this.startsWith("b")
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private fun String.isStoreReg() = this.startsWith("sta") || this.startsWith("sty") || this.startsWith("stx")
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private fun String.isStoreRegOrZero() = this.isStoreReg() || this.startsWith("stz")
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private fun String.isLoadReg() = this.startsWith("lda") || this.startsWith("ldy") || this.startsWith("ldx")
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private class Modification(val lineIndex: Int, val remove: Boolean, val replacement: String?)
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private fun apply(modifications: List<Modification>, lines: MutableList<String>) {
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for (modification in modifications.sortedBy { it.lineIndex }.reversed()) {
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if(modification.remove)
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lines.removeAt(modification.lineIndex)
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else
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lines[modification.lineIndex] = modification.replacement!!
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}
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}
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private fun getLinesBy(lines: MutableList<String>, windowSize: Int) =
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// all lines (that aren't empty or comments) in sliding windows of certain size
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lines.withIndex().filter { it.value.isNotBlank() && !it.value.trimStart().startsWith(';') }.windowed(windowSize, partialWindows = false)
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private fun optimizeCmpSequence(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
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// when statement (on bytes) generates a sequence of:
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// lda $ce01,x
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// cmp #$20
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// beq check_prog8_s72choice_32
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// lda $ce01,x
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// cmp #$21
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// beq check_prog8_s73choice_33
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// the repeated lda can be removed
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val mods = mutableListOf<Modification>()
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for(lines in linesByFour) {
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if(lines[0].value.trim()=="lda P8ESTACK_LO+1,x" &&
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lines[1].value.trim().startsWith("cmp ") &&
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lines[2].value.trim().startsWith("beq ") &&
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lines[3].value.trim()=="lda P8ESTACK_LO+1,x") {
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mods.add(Modification(lines[3].index, true, null)) // remove the second lda
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}
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}
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return mods
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}
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private fun optimizeUselessStackByteWrites(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
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// sta on stack, dex, inx, lda from stack -> eliminate this useless stack byte write
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// this is a lot harder for word values because the instruction sequence varies.
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val mods = mutableListOf<Modification>()
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for(lines in linesByFour) {
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if(lines[0].value.trim()=="sta P8ESTACK_LO,x" &&
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lines[1].value.trim()=="dex" &&
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lines[2].value.trim()=="inx" &&
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lines[3].value.trim()=="lda P8ESTACK_LO,x") {
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mods.add(Modification(lines[1].index, true, null))
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mods.add(Modification(lines[2].index, true, null))
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mods.add(Modification(lines[3].index, true, null))
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}
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}
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return mods
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}
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private fun optimizeSameAssignments(linesByFourteen: List<List<IndexedValue<String>>>, machine: IMachineDefinition, program: Program): List<Modification> {
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// Optimize sequential assignments of the same value to various targets (bytes, words, floats)
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// the float one is the one that requires 2*7=14 lines of code to check...
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// The better place to do this is in the Compiler instead and never create these types of assembly, but hey
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val mods = mutableListOf<Modification>()
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for (lines in linesByFourteen) {
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val first = lines[0].value.trimStart()
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val second = lines[1].value.trimStart()
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val third = lines[2].value.trimStart()
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val fourth = lines[3].value.trimStart()
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val fifth = lines[4].value.trimStart()
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val sixth = lines[5].value.trimStart()
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val seventh = lines[6].value.trimStart()
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val eighth = lines[7].value.trimStart()
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if(first.startsWith("lda") && second.startsWith("ldy") && third.startsWith("sta") && fourth.startsWith("sty") &&
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fifth.startsWith("lda") && sixth.startsWith("ldy") && seventh.startsWith("sta") && eighth.startsWith("sty")) {
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val firstvalue = first.substring(4)
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val secondvalue = second.substring(4)
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val thirdvalue = fifth.substring(4)
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val fourthvalue = sixth.substring(4)
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if(firstvalue==thirdvalue && secondvalue==fourthvalue) {
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// lda/ldy sta/sty twice the same word --> remove second lda/ldy pair (fifth and sixth lines)
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val address1 = getAddressArg(first, program)
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val address2 = getAddressArg(second, program)
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if(address1==null || address2==null || (!machine.isIOAddress(address1) && !machine.isIOAddress(address2))) {
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mods.add(Modification(lines[4].index, true, null))
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mods.add(Modification(lines[5].index, true, null))
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}
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}
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}
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if(first.startsWith("lda") && second.startsWith("sta") && third.startsWith("lda") && fourth.startsWith("sta")) {
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val firstvalue = first.substring(4)
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val secondvalue = third.substring(4)
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if(firstvalue==secondvalue) {
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// lda value / sta ? / lda same-value / sta ? -> remove second lda (third line)
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val address = getAddressArg(first, program)
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if(address==null || !machine.isIOAddress(address))
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mods.add(Modification(lines[2].index, true, null))
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}
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}
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if(first.startsWith("lda") && second.startsWith("ldy") && third.startsWith("sta") && fourth.startsWith("sty") &&
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fifth.startsWith("lda") && sixth.startsWith("ldy") &&
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(seventh.startsWith("jsr floats.copy_float") || seventh.startsWith("jsr cx16flt.copy_float"))) {
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val nineth = lines[8].value.trimStart()
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val tenth = lines[9].value.trimStart()
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val eleventh = lines[10].value.trimStart()
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val twelveth = lines[11].value.trimStart()
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val thirteenth = lines[12].value.trimStart()
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val fourteenth = lines[13].value.trimStart()
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if(eighth.startsWith("lda") && nineth.startsWith("ldy") && tenth.startsWith("sta") && eleventh.startsWith("sty") &&
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twelveth.startsWith("lda") && thirteenth.startsWith("ldy") &&
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(fourteenth.startsWith("jsr floats.copy_float") || fourteenth.startsWith("jsr cx16flt.copy_float"))) {
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if(first.substring(4) == eighth.substring(4) && second.substring(4)==nineth.substring(4)) {
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// identical float init
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mods.add(Modification(lines[7].index, true, null))
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mods.add(Modification(lines[8].index, true, null))
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mods.add(Modification(lines[9].index, true, null))
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mods.add(Modification(lines[10].index, true, null))
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}
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}
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}
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var overlappingMods = false
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/*
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sta prog8_lib.retval_intermX ; remove
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sty prog8_lib.retval_intermY ; remove
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lda prog8_lib.retval_intermX ; remove
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ldy prog8_lib.retval_intermY ; remove
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sta A1
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sty A2
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*/
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if(first.isStoreReg() && second.isStoreReg()
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&& third.isLoadReg() && fourth.isLoadReg()
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&& fifth.isStoreReg() && sixth.isStoreReg()) {
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val reg1 = first[2]
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val reg2 = second[2]
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val reg3 = third[2]
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val reg4 = fourth[2]
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val reg5 = fifth[2]
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val reg6 = sixth[2]
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if (reg1 == reg3 && reg1 == reg5 && reg2 == reg4 && reg2 == reg6) {
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val firstvalue = first.substring(4)
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val secondvalue = second.substring(4)
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val thirdvalue = third.substring(4)
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val fourthvalue = fourth.substring(4)
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if(firstvalue.contains("prog8_lib.retval_interm") && secondvalue.contains("prog8_lib.retval_interm")
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&& firstvalue==thirdvalue && secondvalue==fourthvalue) {
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mods.add(Modification(lines[0].index, true, null))
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mods.add(Modification(lines[1].index, true, null))
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mods.add(Modification(lines[2].index, true, null))
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mods.add(Modification(lines[3].index, true, null))
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overlappingMods = true
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}
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}
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}
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/*
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sta A1
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sty A2
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lda A1 ; can be removed
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ldy A2 ; can be removed if not followed by a branch instuction
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*/
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if(!overlappingMods && first.isStoreReg() && second.isStoreReg()
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&& third.isLoadReg() && fourth.isLoadReg()) {
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val reg1 = first[2]
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val reg2 = second[2]
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val reg3 = third[2]
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val reg4 = fourth[2]
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if(reg1==reg3 && reg2==reg4) {
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val firstvalue = first.substring(4)
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val secondvalue = second.substring(4)
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val thirdvalue = third.substring(4)
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val fourthvalue = fourth.substring(4)
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if(firstvalue==thirdvalue && secondvalue == fourthvalue) {
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val address = getAddressArg(first, program)
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if(address==null || !machine.isIOAddress(address)) {
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overlappingMods = true
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mods.add(Modification(lines[2].index, true, null))
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if (!fifth.startsWith('b'))
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mods.add(Modification(lines[3].index, true, null))
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}
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}
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}
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}
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/*
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sta A1
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sty A2 ; ... or stz
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lda A1 ; can be removed if not followed by a branch instruction
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*/
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if(!overlappingMods && first.isStoreReg() && second.isStoreRegOrZero()
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&& third.isLoadReg() && !fourth.isBranch()) {
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val reg1 = first[2]
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val reg3 = third[2]
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if(reg1==reg3) {
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val firstvalue = first.substring(4)
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val thirdvalue = third.substring(4)
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if(firstvalue==thirdvalue) {
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val address = getAddressArg(first, program)
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if(address==null || !machine.isIOAddress(address)) {
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overlappingMods = true
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mods.add(Modification(lines[2].index, true, null))
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}
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}
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}
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}
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/*
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sta A1
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ldy A1 ; make tay
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sta A1 ; remove
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*/
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if(!overlappingMods && first.startsWith("sta") && second.isLoadReg()
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&& third.startsWith("sta") && second.length>4) {
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val firstvalue = first.substring(4)
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val secondvalue = second.substring(4)
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val thirdvalue = third.substring(4)
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if(firstvalue==secondvalue && firstvalue==thirdvalue) {
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val address = getAddressArg(first, program)
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if(address==null || !machine.isIOAddress(address)) {
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overlappingMods = true
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val reg2 = second[2]
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mods.add(Modification(lines[1].index, false, " ta$reg2"))
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mods.add(Modification(lines[2].index, true, null))
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}
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}
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}
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/*
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sta A ; or stz double store, remove this first one
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sta A ; or stz
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*/
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if(!overlappingMods && first.isStoreRegOrZero() && second.isStoreRegOrZero()) {
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if(first[2]==second[2]) {
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val firstvalue = first.substring(4)
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val secondvalue = second.substring(4)
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if(firstvalue==secondvalue) {
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val address = getAddressArg(first, program)
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if(address==null || !machine.isIOAddress(address)) {
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overlappingMods = true
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mods.add(Modification(lines[0].index, true, null))
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}
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}
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}
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}
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}
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return mods
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}
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private fun optimizeStoreLoadSame(linesByFour: List<List<IndexedValue<String>>>, machine: IMachineDefinition, program: Program): List<Modification> {
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// sta X + lda X, sty X + ldy X, stx X + ldx X -> the second instruction can OFTEN be eliminated
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val mods = mutableListOf<Modification>()
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for (lines in linesByFour) {
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val first = lines[1].value.trimStart()
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val second = lines[2].value.trimStart()
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if ((first.startsWith("sta ") && second.startsWith("lda ")) ||
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(first.startsWith("stx ") && second.startsWith("ldx ")) ||
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(first.startsWith("sty ") && second.startsWith("ldy ")) ||
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(first.startsWith("lda ") && second.startsWith("lda ")) ||
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(first.startsWith("ldy ") && second.startsWith("ldy ")) ||
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(first.startsWith("ldx ") && second.startsWith("ldx ")) ||
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(first.startsWith("sta ") && second.startsWith("lda ")) ||
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(first.startsWith("sty ") && second.startsWith("ldy ")) ||
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(first.startsWith("stx ") && second.startsWith("ldx "))
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) {
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val third = lines[3].value.trimStart()
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val attemptRemove =
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if(third.isBranch()) {
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// a branch instruction follows, we can only remove the load instruction if
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// another load instruction of the same register precedes the store instruction
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// (otherwise wrong cpu flags are used)
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val loadinstruction = second.substring(0, 3)
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lines[0].value.trimStart().startsWith(loadinstruction)
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}
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else {
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// no branch instruction follows, we can remove the load instruction
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val address = getAddressArg(lines[2].value, program)
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address==null || !machine.isIOAddress(address)
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}
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if(attemptRemove) {
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val firstLoc = first.substring(4).trimStart()
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val secondLoc = second.substring(4).trimStart()
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if (firstLoc == secondLoc)
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mods.add(Modification(lines[2].index, true, null))
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}
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}
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else if(first=="pha" && second=="pla" ||
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first=="phx" && second=="plx" ||
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first=="phy" && second=="ply" ||
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first=="php" && second=="plp") {
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mods.add(Modification(lines[1].index, true, null))
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mods.add(Modification(lines[2].index, true, null))
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} else if(first=="pha" && second=="plx") {
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mods.add(Modification(lines[1].index, true, null))
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mods.add(Modification(lines[2].index, false, " tax"))
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} else if(first=="pha" && second=="ply") {
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mods.add(Modification(lines[1].index, true, null))
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mods.add(Modification(lines[2].index, false, " tay"))
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} else if(first=="phx" && second=="pla") {
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mods.add(Modification(lines[1].index, true, null))
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mods.add(Modification(lines[2].index, false, " txa"))
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} else if(first=="phx" && second=="ply") {
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mods.add(Modification(lines[1].index, true, null))
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mods.add(Modification(lines[2].index, false, " txy"))
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} else if(first=="phy" && second=="pla") {
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mods.add(Modification(lines[1].index, true, null))
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mods.add(Modification(lines[2].index, false, " tya"))
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} else if(first=="phy" && second=="plx") {
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mods.add(Modification(lines[1].index, true, null))
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mods.add(Modification(lines[2].index, false, " tyx"))
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}
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}
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return mods
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}
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private val identifierRegex = Regex("""^([a-zA-Z_$][a-zA-Z\d_\.$]*)""")
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private fun getAddressArg(line: String, program: Program): UInt? {
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val loadArg = line.trimStart().substring(3).trim()
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return when {
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loadArg.startsWith('$') -> loadArg.substring(1).toUIntOrNull(16)
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loadArg.startsWith('%') -> loadArg.substring(1).toUIntOrNull(2)
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loadArg.startsWith('#') -> null
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loadArg.startsWith('(') -> null
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loadArg[0].isLetter() -> {
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val identMatch = identifierRegex.find(loadArg)
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if(identMatch!=null) {
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val identifier = identMatch.value
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val decl = program.toplevelModule.lookup(identifier.split(".")) as? VarDecl
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if(decl!=null) {
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when(decl.type){
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VarDeclType.VAR -> null
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VarDeclType.CONST,
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VarDeclType.MEMORY -> (decl.value as NumericLiteral).number.toUInt()
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}
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}
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else null
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} else null
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}
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else -> loadArg.substring(1).toUIntOrNull()
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}
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}
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private fun optimizeIncDec(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
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// sometimes, iny+dey / inx+dex / dey+iny / dex+inx sequences are generated, these can be eliminated.
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val mods = mutableListOf<Modification>()
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for (lines in linesByFour) {
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val first = lines[0].value
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val second = lines[1].value
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if ((" iny" in first || "\tiny" in first) && (" dey" in second || "\tdey" in second)
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|| (" inx" in first || "\tinx" in first) && (" dex" in second || "\tdex" in second)
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|| (" ina" in first || "\tina" in first) && (" dea" in second || "\tdea" in second)
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|| (" inc a" in first || "\tinc a" in first) && (" dec a" in second || "\tdec a" in second)
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|| (" dey" in first || "\tdey" in first) && (" iny" in second || "\tiny" in second)
|
|
|| (" dex" in first || "\tdex" in first) && (" inx" in second || "\tinx" in second)
|
|
|| (" dea" in first || "\tdea" in first) && (" ina" in second || "\tina" in second)
|
|
|| (" dec a" in first || "\tdec a" in first) && (" inc a" in second || "\tinc a" in second)) {
|
|
mods.add(Modification(lines[0].index, true, null))
|
|
mods.add(Modification(lines[1].index, true, null))
|
|
}
|
|
}
|
|
return mods
|
|
}
|
|
|
|
private fun optimizeJsrRts(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
|
|
// jsr Sub + rts -> jmp Sub
|
|
val mods = mutableListOf<Modification>()
|
|
for (lines in linesByFour) {
|
|
val first = lines[0].value
|
|
val second = lines[1].value
|
|
if ((" jsr" in first || "\tjsr" in first ) && (" rts" in second || "\trts" in second)) {
|
|
mods += Modification(lines[0].index, false, lines[0].value.replace("jsr", "jmp"))
|
|
mods += Modification(lines[1].index, true, null)
|
|
}
|
|
}
|
|
return mods
|
|
}
|