JVM_IR generate range-based loop closer to Java counter loop

KT-48435 KT-48507
This commit is contained in:
Dmitry Petrov
2021-09-01 15:31:19 +03:00
parent 9ed08438d5
commit b669de1663
137 changed files with 1518 additions and 573 deletions
@@ -1,4 +1,14 @@
// TARGET_BACKEND: JVM_IR
// IMPORTANT!
// Please, when your changes cause failures in bytecodeText tests for 'for' loops,
// examine the resulting bytecode shape carefully.
// Range and progression-based loops generated with Kotlin compiler should be
// as close as possible to Java counter loops ('for (int i = a; i < b; ++i) { ... }').
// Otherwise it may result in performance regression due to missing HotSpot optimizations.
// Run Kotlin compiler benchmarks (https://github.com/Kotlin/kotlin-benchmarks)
// with compiler built from your changes if you are not sure.
fun box(): String {
val intProgression = 1..7 step 3 // `step` ensures type is IntProgression, NOT IntRange
for (i in intProgression step 2) {
@@ -12,25 +22,7 @@ fun box(): String {
// If the step is non-constant, there is a check that it is > 0, and if not, an IllegalArgumentException is thrown. However, when the
// step is constant and > 0, this check does not need to be added.
//
// Expected lowered form of loop:
//
// // Additional statements:
// val nestedFirst = intProgression.first
// val nestedLast = intProgression.last
// val nestedStep = intProgression.step
// val maybeNegatedStep = if (nestedStep <= 0) -2 else 2
//
// // Standard form of loop over progression
// var inductionVar = nestedFirst
// val last = getProgressionLastElement(nestedFirst, nestedLast, maybeNegatedStep)
// if ((maybeNegatedStep > 0 && inductionVar <= last) || (maybeNegatedStep < 0 && last <= inductionVar)) {
// // Loop is not empty
// do {
// val i = inductionVar
// inductionVar += maybeNegatedStep
// // Loop body
// } while (i != last)
// }
// 0 iterator
// 0 getStart
@@ -43,9 +35,14 @@ fun box(): String {
// 0 ATHROW
// 1 IF_ICMPGT
// 1 IF_ICMPLE
// 1 IF_ICMPNE
// 1 IF_ICMPEQ
// 1 IFLE
// 1 IFGT
// 1 IFGE
// 6 IF
// 0 INEG
// 0 INEG
// 14 ILOAD
// 6 ISTORE
// 1 IADD
// 0 ISUB
// 0 IINC