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add more const foldings

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This commit is contained in:
Irmen de Jong 2021-11-17 00:57:00 +01:00
parent 5d362047e2
commit 6af3209d4d
4 changed files with 66 additions and 21 deletions
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27
codeOptimizers/src/prog8/optimizer/ConstantFoldingOptimizer.kt
View File

@ -101,6 +101,33 @@ class ConstantFoldingOptimizer(private val program: Program) : AstWalker() {
val rightconst = expr.right.constValue(program)
val modifications = mutableListOf<IAstModification>()
if(expr.operator=="==" && rightconst!=null) {
val leftExpr = expr.left as? BinaryExpression
if(leftExpr!=null) {
val leftRightConst = leftExpr.right.constValue(program)
if(leftRightConst!=null) {
when (leftExpr.operator) {
"+" -> {
// X + С1 == C2 --> X == C2 - C1
val newRightConst = NumericLiteralValue(rightconst.type, rightconst.number - leftRightConst.number, rightconst.position)
return listOf(
IAstModification.ReplaceNode(leftExpr, leftExpr.left, expr),
IAstModification.ReplaceNode(expr.right, newRightConst, expr)
)
}
"-" -> {
// X - С1 == C2 --> X == C2 + C1
val newRightConst = NumericLiteralValue(rightconst.type, rightconst.number + leftRightConst.number, rightconst.position)
return listOf(
IAstModification.ReplaceNode(leftExpr, leftExpr.left, expr),
IAstModification.ReplaceNode(expr.right, newRightConst, expr)
)
}
}
}
}
}
if(expr.operator == "**" && leftconst!=null) {
// optimize various simple cases of ** :
// optimize away 1 ** x into just 1 and 0 ** x into just 0

6
codeOptimizers/src/prog8/optimizer/ExpressionSimplifier.kt
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@ -19,12 +19,6 @@ import kotlin.math.pow
Investigate what optimizations binaryen has, also see https://egorbo.com/peephole-optimizations.html
Add some const foldings (that may already be done as well):
X + С1 == C2 => X == C2 - C1
((X + C1) + C2) => (X + (C1 + C2))
((X + C1) + (Y + C2)) => ((X + Y) + (C1 + C2))
*/

5
docs/source/todo.rst
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@ -3,7 +3,10 @@ TODO
For next compiler release (7.4)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
BUG: Fix C-64sound issue in petaxian (regression since 7.3, sound on c64 build works fine on older versions)
BUG: ubyte z1
ubyte z2
z2=z1+z2+5 CRASHES COMPILER
Blocked by an official Commander-x16 v39 release

49
examples/test.p8
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@ -13,22 +13,43 @@ main {
; TODO: bitwise operations with a negative constant number -> replace the number by its positive 2 complement
if aw<1
yy++
if aw<=0
yy++
; (X + C1) + (Y + C2) => (X + Y) + (C1 + C2)
; (X + C1) - (Y + C2) => (X - Y) + (C1 - C2)
; ---> together: (X + C1) <plusmin> (Y + C2) => (X <plusmin> Y) + (C1 <plusmin> C2)
if yy<1
yy++
if yy<=0
yy++
if bb<1
yy++
if bb<=0
yy++
txt.print_ub(yy)
txt.print_uw(aw)
; (X - C1) + (Y - C2) => (X + Y) - (C1 + C2)
; (X - C1) - (Y - C2) => (X - Y) - (C1 - C2)
xx=6
yy=8
yy = (xx+5)+(yy+10)
; yy = (xx+yy)+(5+10) ; TODO crashes compiler
txt.print_ub(yy) ; 29
txt.nl()
xx=100
yy=8
;yy = (xx+5)-(yy+10)
yy = (xx-yy)+(5-10) as ubyte
txt.print_ub(yy) ; 87
txt.nl()
xx=50
yy=40
yy = (xx-5)+(yy-10)
txt.print_ub(yy) ; 75
txt.nl()
xx=50
yy=20
yy = (xx-5)-(yy-10)
txt.print_ub(yy) ; 35
txt.nl()
repeat {
}
}
}