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Generate CHECKCAST after ACONST_NULL in coroutines

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If we do not do this, the state-machine builder will not know the type
of the ACONST_NULL, defaulting to Object, leading to VerifyError.
Alternatively, we could use LVT to deduce the type, but getting types
from LVT is something I got rid of long time ago, and I have no desire
to return it back.

Generating CHECKCAST hints the state-machine builder the type of the
variable avoiding the issue of VerifyError. However, this CHECKCAST
replaces StrictBasicValue.NULL_VALUE with BasicValue in
OptimizationBasicInterpreter. To preserve optimization on not-spilling
known nulls, introduce BasicValues, which represent typed nulls and
create BasicInterpreter, which is aware of them. This way we have the
best of two worlds - we do not spill known nulls, and we know the type
of ACONST_NULL.

 #KT-51718 Fixed
This commit is contained in:
Ilmir Usmanov
2022-03-30 03:34:07 +02:00
committed by teamcity
parent 9b103b35cd
commit 7579be6c68
15 changed files with 136 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/CoroutineTransformerMethodVisitor.kt
+1 -1
View File
@@ -643,7 +643,7 @@ class CoroutineTransformerMethodVisitor(
val value = frame.getLocal(slot)
if (value.type == null || !livenessFrame.isAlive(slot)) continue
if (value == StrictBasicValue.NULL_VALUE) {
if (value == StrictBasicValue.NULL_VALUE || value is TypedNullValue) {
referencesToSpill += slot to null
continue
}
compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/SpilledVariableFieldTypesAnalysis.kt
+15 -1
View File
@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.codegen.coroutines
import org.jetbrains.kotlin.codegen.StackValue
import org.jetbrains.kotlin.codegen.optimization.common.FastMethodAnalyzer
import org.jetbrains.kotlin.codegen.optimization.common.OptimizationBasicInterpreter
import org.jetbrains.kotlin.codegen.optimization.common.StrictBasicValue
import org.jetbrains.org.objectweb.asm.Label
import org.jetbrains.org.objectweb.asm.Opcodes
import org.jetbrains.org.objectweb.asm.Type
@@ -134,7 +135,7 @@ internal fun performSpilledVariableFieldTypesAnalysis(
for ((insn, type) in interpreter.needsToBeCoerced) {
methodNode.instructions.insert(insn, withInstructionAdapter { coerceInt(type, this) })
}
return FastMethodAnalyzer(thisName, methodNode, OptimizationBasicInterpreter()).analyze()
return FastMethodAnalyzer(thisName, methodNode, NullCheckcastAwareOptimizationBasicInterpreter()).analyze()
}
private fun coerceInt(to: Type, v: InstructionAdapter) {
@@ -157,4 +158,17 @@ private fun coerceInt(to: Type, v: InstructionAdapter) {
private fun Type.isIntLike(): Boolean = when (sort) {
Type.BOOLEAN, Type.BYTE, Type.CHAR, Type.SHORT -> true
else -> false
}
// Represents [ACONST_NULL, CHECKCAST Type] sequence result.
internal class TypedNullValue(type: Type) : BasicValue(type)
// Preserves nulls through CHECKCASTS.
private class NullCheckcastAwareOptimizationBasicInterpreter : OptimizationBasicInterpreter() {
override fun unaryOperation(insn: AbstractInsnNode, value: BasicValue?): BasicValue? {
if (insn.opcode == Opcodes.CHECKCAST && (value == StrictBasicValue.NULL_VALUE || value is TypedNullValue)) {
return TypedNullValue(Type.getObjectType((insn as TypeInsnNode).desc))
}
return super.unaryOperation(insn, value)
}
}