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avoid excessive comparisons for certain comparison expressions against zero

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This commit is contained in:
Irmen de Jong 2020-09-27 03:55:59 +02:00
parent bec9cc7047
commit 446fc35d5c
2 changed files with 69 additions and 0 deletions
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66
compiler/src/prog8/compiler/target/c64/codegen/ExpressionsAsmGen.kt
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@ -53,6 +53,39 @@ internal class ExpressionsAsmGen(private val program: Program, private val asmge
val dt = left.inferType(program).typeOrElse(DataType.STRUCT)
when (operator) {
"==" -> {
// if the left operand is an expression, and the right is 0, we can just evaluate that expression.
// (the extra comparison is not required as the result of the expression is already the required boolean value)
if(rightConstVal?.number?.toDouble() == 0.0) {
when(left) {
is PrefixExpression,
is BinaryExpression,
is ArrayIndexedExpression,
is TypecastExpression,
is AddressOf,
is RangeExpr,
is FunctionCall -> {
translateExpression(left)
if(dt in ByteDatatypes) {
asmgen.out("""
inx
lda P8ESTACK_LO,x
bne $jumpIfFalseLabel""")
return
}
else if(dt in WordDatatypes) {
asmgen.out("""
inx
lda P8ESTACK_LO,x
clc
adc P8ESTACK_HI,x
bne $jumpIfFalseLabel""")
return
}
}
else -> {}
}
}
when (dt) {
in ByteDatatypes -> translateByteEquals(left, right, leftConstVal, rightConstVal, jumpIfFalseLabel)
in WordDatatypes -> translateWordEquals(left, right, leftConstVal, rightConstVal, jumpIfFalseLabel)
@ -61,6 +94,39 @@ internal class ExpressionsAsmGen(private val program: Program, private val asmge
}
}
"!=" -> {
// if the left operand is an expression, and the right is 0, we can just evaluate that expression.
// (the extra comparison is not required as the result of the expression is already the required boolean value)
if(rightConstVal?.number?.toDouble() == 0.0) {
when(left) {
is PrefixExpression,
is BinaryExpression,
is ArrayIndexedExpression,
is TypecastExpression,
is AddressOf,
is RangeExpr,
is FunctionCall -> {
translateExpression(left)
if(dt in ByteDatatypes) {
asmgen.out("""
inx
lda P8ESTACK_LO,x
beq $jumpIfFalseLabel""")
return
}
else if(dt in WordDatatypes) {
asmgen.out("""
inx
lda P8ESTACK_LO,x
clc
adc P8ESTACK_HI,x
beq $jumpIfFalseLabel""")
return
}
}
else -> {}
}
}
when (dt) {
in ByteDatatypes -> translateByteNotEquals(left, right, leftConstVal, rightConstVal, jumpIfFalseLabel)
in WordDatatypes -> translateWordNotEquals(left, right, leftConstVal, rightConstVal, jumpIfFalseLabel)

3
examples/balloonflight.p8
View File

@ -3,6 +3,9 @@
%import textio
%zeropage basicsafe
; TODO balloon only goes down now
main {
ubyte perform_scroll = false