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tweak if statement handling

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This commit is contained in:
Irmen de Jong 2021-12-27 15:04:25 +01:00
parent 9906b58818
commit 97e84d0977
3 changed files with 114 additions and 47 deletions
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78
codeGeneration/src/prog8/compiler/target/cpu6502/codegen/AsmGen.kt
View File

@ -1098,16 +1098,21 @@ class AsmGen(private val program: Program,
val booleanCondition = stmt.condition as BinaryExpression
if (stmt.elsepart.isEmpty()) {
val endLabel = makeLabel("if_end")
translateComparisonExpressionWithJumpIfFalse(booleanCondition, endLabel)
translate(stmt.truepart)
out(endLabel)
// TODO specialize this
// if(stmt.truepart.statements.singleOrNull() is Jump) {
// translateCompareAndJumpIfTrue(booleanCondition, stmt.truepart.statements[0] as Jump)
// } else {
val endLabel = makeLabel("if_end")
translateCompareAndJumpIfFalse(booleanCondition, endLabel)
translate(stmt.truepart)
out(endLabel)
// }
}
else {
// both true and else parts
val elseLabel = makeLabel("if_else")
val endLabel = makeLabel("if_end")
translateComparisonExpressionWithJumpIfFalse(booleanCondition, elseLabel)
translateCompareAndJumpIfFalse(booleanCondition, elseLabel)
translate(stmt.truepart)
jmp(endLabel)
out(elseLabel)
@ -1607,44 +1612,39 @@ $label nop""")
return false
}
private fun translateComparisonExpressionWithJumpIfFalse(expr: BinaryExpression, jumpIfFalseLabel: String) {
// This is a helper routine called from if expressions to generate optimized conditional branching code.
// First, if it is of the form: <constvalue> <comparison> X , then flip the expression so the constant is always the right operand.
var left = expr.left
var right = expr.right
var operator = expr.operator
var leftConstVal = left.constValue(program)
var rightConstVal = right.constValue(program)
// make sure the constant value is on the right of the comparison expression
if(leftConstVal!=null) {
val tmp = left
left = right
right = tmp
val tmp2 = leftConstVal
leftConstVal = rightConstVal
rightConstVal = tmp2
when(expr.operator) {
"<" -> operator = ">"
"<=" -> operator = ">="
">" -> operator = "<"
">=" -> operator = "<="
}
}
private fun translateCompareAndJumpIfTrue(expr: BinaryExpression, jump: Jump) {
val left = expr.left
val right = expr.right
val operator = expr.operator
val leftConstVal = left.constValue(program)
val rightConstVal = right.constValue(program)
if (rightConstVal!=null && rightConstVal.number == 0.0)
jumpIfZeroOrNot(left, operator, jumpIfFalseLabel)
testZeroAndJump(left, operator, jump, null)
else
jumpIfComparison(left, operator, right, jumpIfFalseLabel, leftConstVal, rightConstVal)
testNonzeroComparisonAndJump(left, operator, right, jump, null, leftConstVal, rightConstVal)
}
private fun jumpIfZeroOrNot(
private fun translateCompareAndJumpIfFalse(expr: BinaryExpression, jumpIfFalseLabel: String) {
val left = expr.left
val right = expr.right
val operator = expr.operator
val leftConstVal = left.constValue(program)
val rightConstVal = right.constValue(program)
if (rightConstVal!=null && rightConstVal.number == 0.0)
testZeroAndJump(left, operator, null, jumpIfFalseLabel)
else
testNonzeroComparisonAndJump(left, operator, right, null, jumpIfFalseLabel, leftConstVal, rightConstVal)
}
private fun testZeroAndJump(
left: Expression,
operator: String,
jumpIfFalseLabel: String
jumpIfTrue: Jump?,
jumpIfFalseLabel: String?
) {
require(jumpIfTrue!=null || jumpIfFalseLabel!=null)
when(val dt = left.inferType(program).getOr(DataType.UNDEFINED)) {
DataType.UBYTE, DataType.UWORD -> {
if(operator=="<") {
@ -1729,16 +1729,20 @@ $label nop""")
}
}
private fun jumpIfComparison(
private fun testNonzeroComparisonAndJump(
left: Expression,
operator: String,
right: Expression,
jumpIfFalseLabel: String,
jumpIfTrue: Jump?,
jumpIfFalseLabel: String?,
leftConstVal: NumericLiteralValue?,
rightConstVal: NumericLiteralValue?
) {
require(jumpIfTrue!=null || jumpIfFalseLabel!=null)
val dt = left.inferType(program).getOrElse { throw AssemblyError("unknown dt") }
jumpIfFalseLabel!! // TODO jump if true... or rewrite everything to use just jump-if-false
when (operator) {
"==" -> {
when (dt) {

50
codeOptimizers/src/prog8/optimizer/ExpressionSimplifier.kt
View File

@ -1,5 +1,6 @@
package prog8.optimizer
import prog8.ast.IStatementContainer
import prog8.ast.Node
import prog8.ast.Program
import prog8.ast.base.DataType
@ -7,7 +8,10 @@ import prog8.ast.base.FatalAstException
import prog8.ast.base.IntegerDatatypes
import prog8.ast.base.NumericDatatypes
import prog8.ast.expressions.*
import prog8.ast.statements.AnonymousScope
import prog8.ast.statements.Assignment
import prog8.ast.statements.IfStatement
import prog8.ast.statements.Jump
import prog8.ast.walk.AstWalker
import prog8.ast.walk.IAstModification
import kotlin.math.abs
@ -54,6 +58,31 @@ class ExpressionSimplifier(private val program: Program) : AstWalker() {
return mods
}
override fun after(ifStatement: IfStatement, parent: Node): Iterable<IAstModification> {
val truepart = ifStatement.truepart
val elsepart = ifStatement.elsepart
if(truepart.isNotEmpty() && elsepart.isNotEmpty()) {
if(truepart.statements.singleOrNull() is Jump) {
return listOf(
IAstModification.InsertAfter(ifStatement, elsepart, parent as IStatementContainer),
IAstModification.ReplaceNode(elsepart, AnonymousScope(mutableListOf(), elsepart.position), ifStatement)
)
}
if(elsepart.statements.singleOrNull() is Jump) {
val invertedCondition = invertCondition(ifStatement.condition)
if(invertedCondition!=null) {
return listOf(
IAstModification.ReplaceNode(ifStatement.condition, invertedCondition, ifStatement),
IAstModification.InsertAfter(ifStatement, truepart, parent as IStatementContainer),
IAstModification.ReplaceNode(elsepart, AnonymousScope(mutableListOf(), elsepart.position), ifStatement),
IAstModification.ReplaceNode(truepart, elsepart, ifStatement)
)
}
}
}
return noModifications
}
override fun after(expr: BinaryExpression, parent: Node): Iterable<IAstModification> {
val leftVal = expr.left.constValue(program)
val rightVal = expr.right.constValue(program)
@ -696,3 +725,24 @@ class ExpressionSimplifier(private val program: Program) : AstWalker() {
private data class BinExprWithConstants(val expr: BinaryExpression, val leftVal: NumericLiteralValue?, val rightVal: NumericLiteralValue?)
}
fun invertCondition(cond: Expression): BinaryExpression? {
if(cond is BinaryExpression) {
val invertedOperator = invertedComparisonOperator(cond.operator)
if (invertedOperator != null)
return BinaryExpression(cond.left, invertedOperator, cond.right, cond.position)
}
return null
}
fun invertedComparisonOperator(operator: String) =
when (operator) {
"==" -> "!="
"!=" -> "=="
"<" -> ">="
">" -> "<="
"<=" -> ">"
">=" -> "<"
else -> null
}

33
compiler/src/prog8/compiler/astprocessing/VariousCleanups.kt
View File

@ -9,6 +9,7 @@ import prog8.ast.statements.*
import prog8.ast.walk.AstWalker
import prog8.ast.walk.IAstModification
import prog8.compilerinterface.IErrorReporter
import prog8.optimizer.invertedComparisonOperator
internal class VariousCleanups(val program: Program, val errors: IErrorReporter): AstWalker() {
@ -81,16 +82,7 @@ internal class VariousCleanups(val program: Program, val errors: IErrorReporter)
val comparison = expr.expression as? BinaryExpression
if (comparison != null) {
// NOT COMPARISON ==> inverted COMPARISON
val invertedOperator =
when (comparison.operator) {
"==" -> "!="
"!=" -> "=="
"<" -> ">="
">" -> "<="
"<=" -> ">"
">=" -> "<"
else -> null
}
val invertedOperator = invertedComparisonOperator(comparison.operator)
if (invertedOperator != null) {
comparison.operator = invertedOperator
return listOf(IAstModification.ReplaceNode(expr, comparison, parent))
@ -99,4 +91,25 @@ internal class VariousCleanups(val program: Program, val errors: IErrorReporter)
}
return noModifications
}
override fun after(expr: BinaryExpression, parent: Node): Iterable<IAstModification> {
if(expr.operator in ComparisonOperators) {
val leftConstVal = expr.left.constValue(program)
val rightConstVal = expr.right.constValue(program)
// make sure the constant value is on the right of the comparison expression
if(rightConstVal==null && leftConstVal!=null) {
val newOperator =
when(expr.operator) {
"<" -> ">"
"<=" -> ">="
">" -> "<"
">=" -> "<="
else -> expr.operator
}
val replacement = BinaryExpression(expr.right, newOperator, expr.left, expr.position)
return listOf(IAstModification.ReplaceNode(expr, replacement, parent))
}
}
return noModifications
}
}