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[JVM] Fix the nop removal optimization.

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Never remove a nop if that would cause a line number to move
across a local lifetime boundary.

This fixes KT-42725.
This commit is contained in:
Mads Ager
2020-10-16 14:52:26 +02:00
committed by Dmitry Petrov
parent 69127445a3
commit 0505bd958a
4 changed files with 18 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files
compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/RedundantNopsCleanupMethodTransformer.kt
+16 -23
View File
@@ -16,7 +16,6 @@
package org.jetbrains.kotlin.codegen.optimization
import org.jetbrains.kotlin.codegen.optimization.common.InsnSequence
import org.jetbrains.kotlin.codegen.optimization.common.findNextOrNull
import org.jetbrains.kotlin.codegen.optimization.common.isMeaningful
import org.jetbrains.kotlin.codegen.optimization.transformer.MethodTransformer
@@ -53,41 +52,35 @@ class RedundantNopsCleanupMethodTransformer : MethodTransformer() {
}
private fun recordNopsRequiredForDebugger(methodNode: MethodNode, requiredNops: MutableSet<AbstractInsnNode>) {
// We two subsets of labels that are "special" for the debugger:
// We consider two subsets of labels that are special for the debugger:
//
// 1) Labels for line numbers.
// 2) Labels for observable local variables lifetimes.
// NB this includes synthetic variables denoting inlined function bodies and arguments
// (see JvmAbi.LOCAL_VARIABLE_NAME_PREFIX_INLINE_FUNCTION, JvmAbi.LOCAL_VARIABLE_NAME_PREFIX_INLINE_ARGUMENT).
//
// If we enumerate labels in a given subset in order of occurrence in the method code:
// L[0], L[1], ..., L[n-1], L[n]
// then for each k, 1 <= k <= n-1:
// an instruction interval I[k] = [L[k]; L[k+1]) should contain at least one bytecode instruction (which can be a NOP).
for (insn in methodNode.instructions) {
if (insn is LineNumberNode) {
val nextLineNumber = insn.findNextOrNull { it is LineNumberNode && it.line != insn.line }
requiredNops.addIfNotNull(getRequiredNopInRange(insn, nextLineNumber))
}
}
val localVariableLabels = run {
val labels = hashSetOf<LabelNode>().apply {
// We must not remove nops if that leads to a line number having no instructions before the next line number
// or a linenumber crossing a local variable lifetime boundary.
//
// We enumerate all special labels, and make sure to leave nops if they are the only real
// instruction between a line number label and any other special label.
val specialLabels = run {
val localVarLables = hashSetOf<LabelNode>().apply {
for (localVariable in methodNode.localVariables) {
add(localVariable.start)
add(localVariable.end)
}
}
methodNode.instructions.toArray().filter { labels.contains(it) }
methodNode.instructions.toArray().filter { localVarLables.contains(it) || it is LineNumberNode }
}
for (i in 0..localVariableLabels.size - 2) {
val begin = localVariableLabels[i]
val end = localVariableLabels[i + 1]
if (InsnSequence(begin, end).any { it in requiredNops }) continue
requiredNops.addIfNotNull(getRequiredNopInRange(begin, end))
for (i in 0..specialLabels.size - 2) {
val begin = specialLabels[i]
val end = specialLabels[i + 1]
if (begin is LineNumberNode) {
requiredNops.addIfNotNull(getRequiredNopInRange(begin, end))
}
}
}
compiler/testData/codegen/bytecodeText/coercionToUnitOptimization/nopInlineFuns.kt
Vendored
+1 -1
View File
@@ -23,4 +23,4 @@ fun simpleFunVoid(f: () -> Unit): Unit {
return f()
}
// 3 NOP
// 0 NOP