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More aggressive DCE should honor debugger invariants

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- A LINENUMEBER node is "dead" if the corresponding instruction interval
 contains at least one "dead" bytecode instruction
 and no live bytecode instructions

- Observable local variable lifetimes should be taken into account
 when determining if a NOP is required for debugger.
This commit is contained in:
Dmitry Petrov
2017-05-15 14:59:50 +03:00
parent 65799a5cb4
commit 84e54124a2
8 changed files with 121 additions and 44 deletions
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compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/DeadCodeEliminationMethodTransformer.kt
+47 -13
View File
@@ -16,11 +16,13 @@
package org.jetbrains.kotlin.codegen.optimization
import org.jetbrains.kotlin.codegen.inline.remove
import org.jetbrains.kotlin.codegen.optimization.common.OptimizationBasicInterpreter
import org.jetbrains.kotlin.codegen.optimization.common.isMeaningful
import org.jetbrains.kotlin.codegen.optimization.common.removeEmptyCatchBlocks
import org.jetbrains.kotlin.codegen.optimization.transformer.MethodTransformer
import org.jetbrains.org.objectweb.asm.tree.AbstractInsnNode
import org.jetbrains.org.objectweb.asm.tree.LabelNode
import org.jetbrains.org.objectweb.asm.tree.LineNumberNode
import org.jetbrains.org.objectweb.asm.tree.MethodNode
class DeadCodeEliminationMethodTransformer : MethodTransformer() {
@@ -34,24 +36,56 @@ class DeadCodeEliminationMethodTransformer : MethodTransformer() {
}
fun removeDeadCodeByFrames(methodNode: MethodNode, frames: Array<out Any?>): Result {
val removedNodes = HashSet<AbstractInsnNode>()
val insnsToRemove = ArrayList<AbstractInsnNode>()
val insnList = methodNode.instructions
val insnsArray = insnList.toArray()
// Do not remove not meaningful nodes (labels/linenumbers) because they can be referred
// by try/catch blocks or local variables table.
insnsArray.zip(frames).filter {
it.second == null && it.first.isMeaningful
}.forEach {
insnList.remove(it.first)
removedNodes.add(it.first)
val insns = methodNode.instructions.toArray()
for (i in insns.indices) {
val insn = insns[i]
if (shouldRemove(insn, i, frames)) {
insnsToRemove.add(insn)
}
}
methodNode.remove(insnsToRemove)
// Remove empty try-catch blocks to make sure we don't break data flow analysis invariants by dead code elimination.
methodNode.removeEmptyCatchBlocks()
return Result(removedNodes)
return Result(insnsToRemove.toSet())
}
private fun shouldRemove(insn: AbstractInsnNode, index: Int, frames: Array<out Any?>): Boolean =
when (insn) {
is LabelNode ->
// Do not remove label nodes because they can be referred by try/catch blocks or local variables table
false
is LineNumberNode ->
isDeadLineNumber(insn, index, frames)
else ->
frames[index] == null
}
private fun isDeadLineNumber(insn: LineNumberNode, index: Int, frames: Array<out Any?>): Boolean {
// Line number node is "dead" if the corresponding line number interval
// contains at least one "dead" meaningful instruction and no "live" meaningful instructions.
var finger: AbstractInsnNode = insn
var fingerIndex = index
var hasDeadInsn = false
loop@ while (true) {
finger = finger.next ?: break
fingerIndex++
when (finger) {
is LabelNode ->
continue@loop
is LineNumberNode ->
if (finger.line != insn.line) return hasDeadInsn
else -> {
if (frames[fingerIndex] != null) return false
hasDeadInsn = true
}
}
}
return true
}
class Result(val removedNodes: Set<AbstractInsnNode>) {
compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/RedundantNopsCleanupMethodTransformer.kt
+42 -24
View File
@@ -16,26 +16,30 @@
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
import org.jetbrains.kotlin.utils.addIfNotNull
import org.jetbrains.org.objectweb.asm.Opcodes
import org.jetbrains.org.objectweb.asm.tree.AbstractInsnNode
import org.jetbrains.org.objectweb.asm.tree.LabelNode
import org.jetbrains.org.objectweb.asm.tree.LineNumberNode
import org.jetbrains.org.objectweb.asm.tree.MethodNode
import java.util.*
class RedundantNopsCleanupMethodTransformer : MethodTransformer() {
override fun transform(internalClassName: String, methodNode: MethodNode) {
// NOP instruction is required, iff one of the following conditions is true:
// (a) it is a sole bytecode instruction in a try-catch block (TCB)
// (b) it is a sole bytecode instruction is a source code line
LabelNormalizationMethodTransformer().transform(internalClassName, methodNode)
val requiredNops = HashSet<AbstractInsnNode>()
recordNopsRequiredForSourceCodeLines(methodNode.instructions.first, requiredNops)
// NOP instruction is required, if it is a sole bytecode instruction in a try-catch block (TCB)
recordNopsRequiredForTryCatchBlocks(methodNode, requiredNops)
// NOP instruction is required, if it is a sole bytecode instruction in a debugger stepping interval
recordNopsRequiredForDebugger(methodNode, requiredNops)
var current: AbstractInsnNode? = methodNode.instructions.first
while (current != null) {
if (current.opcode == Opcodes.NOP && !requiredNops.contains(current)) {
@@ -49,17 +53,42 @@ class RedundantNopsCleanupMethodTransformer : MethodTransformer() {
}
}
private fun recordNopsRequiredForSourceCodeLines(first: AbstractInsnNode, requiredNops: MutableSet<AbstractInsnNode>) {
var current: AbstractInsnNode? = first
while (current != null) {
if (current is LineNumberNode) {
val nextLineNumberNode = current.getNextLineNumberNode()
requiredNops.addIfNotNull(getRequiredNopInRange(current, nextLineNumberNode))
current = nextLineNumberNode
private fun recordNopsRequiredForDebugger(methodNode: MethodNode, requiredNops: MutableSet<AbstractInsnNode>) {
// We 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))
}
else {
current = current.next
}
val localVariableLabels = run {
val labels = hashSetOf<LabelNode>().apply {
for (localVariable in methodNode.localVariables) {
add(localVariable.start)
add(localVariable.end)
}
}
methodNode.instructions.toArray().filter { labels.contains(it) }
}
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))
}
}
@@ -74,17 +103,6 @@ class RedundantNopsCleanupMethodTransformer : MethodTransformer() {
}
internal fun LineNumberNode.getNextLineNumberNode(): LineNumberNode? {
var current: AbstractInsnNode? = this
while (current != null) {
if (current is LineNumberNode && current.line != this.line) {
return current
}
current = current.next
}
return null
}
internal fun getRequiredNopInRange(firstInclusive: AbstractInsnNode, lastExclusive: AbstractInsnNode?): AbstractInsnNode? {
var lastNop: AbstractInsnNode? = null
var current: AbstractInsnNode? = firstInclusive
compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/boxing/PopBackwardPropagationTransformer.kt
+3 -4
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@@ -20,7 +20,6 @@ import org.jetbrains.kotlin.codegen.optimization.common.isLoadOperation
import org.jetbrains.kotlin.codegen.optimization.common.isMeaningful
import org.jetbrains.kotlin.codegen.optimization.fixStack.top
import org.jetbrains.kotlin.codegen.optimization.removeNodeGetNext
import org.jetbrains.kotlin.codegen.optimization.replaceNodeGetNext
import org.jetbrains.kotlin.codegen.optimization.transformer.MethodTransformer
import org.jetbrains.org.objectweb.asm.Opcodes
import org.jetbrains.org.objectweb.asm.tree.*
@@ -47,9 +46,9 @@ class PopBackwardPropagationTransformer : MethodTransformer() {
}
}
private val REPLACE_WITH_NOP = Transformation { insnList.replaceNodeGetNext(it, createRemovableNopInsn()) }
private val REPLACE_WITH_POP1 = Transformation { insnList.replaceNodeGetNext(it, InsnNode(Opcodes.POP)) }
private val REPLACE_WITH_POP2 = Transformation { insnList.replaceNodeGetNext(it, InsnNode(Opcodes.POP2)) }
private val REPLACE_WITH_NOP = Transformation { insnList.set(it, createRemovableNopInsn()) }
private val REPLACE_WITH_POP1 = Transformation { insnList.set(it, InsnNode(Opcodes.POP)) }
private val REPLACE_WITH_POP2 = Transformation { insnList.set(it, InsnNode(Opcodes.POP2)) }
private val INSERT_POP1_AFTER = Transformation { insnList.insert(it, InsnNode(Opcodes.POP)) }
private val INSERT_POP2_AFTER = Transformation { insnList.insert(it, InsnNode(Opcodes.POP2)) }
compiler/testData/codegen/bytecodeText/coercionToUnitOptimization/nopInlineFuns.kt
Vendored
+1 -1
View File
@@ -23,4 +23,4 @@ fun simpleFunVoid(f: () -> Unit): Unit {
return f()
}
// 4 NOP
// 5 NOP
compiler/testData/codegen/bytecodeText/constantConditions/inlineIfFalse.kt
Vendored
+20
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@@ -0,0 +1,20 @@
package inlineInIfFalseDex
fun inlineIfFalse() {
val bar = ""
//Breakpoint!
if (inlineCall { true }) {
foo()
}
foo()
}
fun foo() {}
inline fun inlineCall(predicate: (String?) -> Boolean): Boolean {
return false
}
// 0 LINENUMBER 7
// 0 LINENUMBER 8
// 1 LINENUMBER 9
compiler/testData/codegen/bytecodeText/forLoop/loopVarInterval.kt
Vendored
+1 -1
View File
@@ -6,4 +6,4 @@ fun f() {
// 1 ISTORE 0\s+L3
// 1 ILOAD 0\s+INVOKEVIRTUAL java/io/PrintStream.print \(C\)V
// 1 LOCALVARIABLE c C L3 L8 0
// 1 LOCALVARIABLE c C L3 L6 0
compiler/testData/codegen/bytecodeText/jackAndJill/inlinedConstuctorWithSuperCallParams.kt
Vendored
+1 -1
View File
@@ -14,4 +14,4 @@ fun main(args: Array<String>) {
}
/*Threre are two constuctors so we should be sure that we check LOCALVARIABLEs from same method*/
// 1 LOCALVARIABLE this LInlinedConstuctorWithSuperCallParamsKt\$main\$\$inlined\$test\$1; L0 L7 0\s+LOCALVARIABLE \$super_call_param\$1 Ljava/lang/String; L0 L7 1
// 1 LOCALVARIABLE this LInlinedConstuctorWithSuperCallParamsKt\$main\$\$inlined\$test\$1; L0 L6 0\s+LOCALVARIABLE \$super_call_param\$1 Ljava/lang/String; L0 L6 1
compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java
+6
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@@ -911,6 +911,12 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
doTest(fileName);
}
@TestMetadata("inlineIfFalse.kt")
public void testInlineIfFalse() throws Exception {
String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/constantConditions/inlineIfFalse.kt");
doTest(fileName);
}
@TestMetadata("kt3098.kt")
public void testKt3098() throws Exception {
String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/constantConditions/kt3098.kt");