JVM IR: Improve codegen for try/catch statements

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt

@@ -519,7 +519,7 @@ class ExpressionCodegen(
     override fun visitSetVariable(expression: IrSetVariable, data: BlockInfo): PromisedValue {
         expression.markLineNumber(startOffset = true)
         setVariable(expression.symbol, expression.value, data)
-        return defaultValue(expression.type)
+        return immaterialUnitValue
     }
 
     fun setVariable(symbol: IrValueSymbol, value: IrExpression, data: BlockInfo) {
@@ -751,7 +751,7 @@ class ExpressionCodegen(
         mv.nop()
         val tryAsmType = aTry.asmType
         val tryResult = aTry.tryResult.accept(this, data)
-        val isExpression = true //TODO: more wise check is required
+        val isExpression = !aTry.type.isUnit()
         var savedValue: Int? = null
         if (isExpression) {
             tryResult.coerce(tryAsmType, aTry.type).materialize()

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/FunctionCodegen.kt

@@ -6,7 +6,6 @@
 package org.jetbrains.kotlin.backend.jvm.codegen
 
 import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
-import org.jetbrains.kotlin.backend.jvm.JvmLoweredDeclarationOrigin
 import org.jetbrains.kotlin.codegen.AsmUtil
 import org.jetbrains.kotlin.codegen.ClassBuilderMode
 import org.jetbrains.kotlin.codegen.visitAnnotableParameterCount

compiler/testData/codegen/bytecodeText/coroutines/varValueConflictsWithTableSameSort.kt

@@ -1,3 +1,4 @@
+// IGNORE_BACKEND: JVM_IR
 // WITH_COROUTINES
 
 import helpers.*
@@ -41,6 +42,9 @@ fun box(): String {
 // 1 LOCALVARIABLE i Ljava/lang/String; L.* 3
 // 1 LOCALVARIABLE s Ljava/lang/String; L.* 3
 // 1 PUTFIELD VarValueConflictsWithTableSameSortKt\$box\$1.L\$0 : Ljava/lang/Object;
-/* 1 load in try/finally */
+/* 1 load in the catch (e: Throwable) { throw e } block which is implicitly wrapped around try/finally */
+// 1 ALOAD 3\s+ATHROW
 /* 1 load in result = s */
+// 1 ALOAD 3\s+PUTFIELD kotlin/jvm/internal/Ref\$ObjectRef\.element
+/* But no further load when spilling 's' to the continuation */
 // 2 ALOAD 3

compiler/testData/codegen/bytecodeText/statements/tryCatchFinally.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun z() {}
 
 fun foo() {