diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt
index 7d3d159e3c9..149507390cb 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt
@@ -127,6 +127,7 @@ class ExpressionCodegen(
         get() = typeMapper.typeSystem
 
     override var lastLineNumber: Int = -1
+    var noLineNumberScope: Boolean = false
 
     private val closureReifiedMarkers = hashMapOf<IrClass, ReifiedTypeParametersUsages>()
 
@@ -151,6 +152,7 @@ class ExpressionCodegen(
     private fun getLineNumberForOffset(offset: Int): Int = fileEntry?.getLineNumber(offset)?.plus(1) ?: -1
 
     private fun IrElement.markLineNumber(startOffset: Boolean) {
+        if (noLineNumberScope) return
         val offset = if (startOffset) this.startOffset else endOffset
         if (offset < 0) {
             return
@@ -167,6 +169,13 @@ class ExpressionCodegen(
 
     fun markLineNumber(element: IrElement) = element.markLineNumber(true)
 
+    fun noLineNumberScope(block: () -> Unit) {
+        val previousState = noLineNumberScope
+        noLineNumberScope = true
+        block()
+        noLineNumberScope = previousState
+    }
+
     // TODO remove
     fun gen(expression: IrExpression, type: Type, irType: IrType, data: BlockInfo): StackValue {
         if (expression.attributeOwnerId === context.fakeContinuation) {
@@ -365,7 +374,7 @@ class ExpressionCodegen(
     private fun visitStatementContainer(container: IrStatementContainer, data: BlockInfo) =
         container.statements.fold(unitValue) { prev, exp ->
             prev.discard()
-            exp.accept(this, data).also { (exp as? IrExpression)?.markEndOfStatementIfNeeded() }
+            exp.accept(this, data)
         }
 
     override fun visitBlockBody(body: IrBlockBody, data: BlockInfo): PromisedValue {
@@ -767,7 +776,18 @@ class ExpressionCodegen(
     override fun visitWhen(expression: IrWhen, data: BlockInfo): PromisedValue {
         expression.markLineNumber(startOffset = true)
         SwitchGenerator(expression, data, this).generate()?.let { return it }
-
+        // When a lookup/table switch instruction is not generate, output a nop
+        // for the line number of the when itself. Otherwise, there will be
+        // no option of breaking on the line of the `when` if there is no
+        // subject:
+        //
+        // when {
+        //   cond1 -> exp1
+        //   else -> exp2
+        // }
+        if (expression.origin == IrStatementOrigin.WHEN) {
+            mv.nop()
+        }
         val endLabel = Label()
         val exhaustive = expression.branches.any { it.condition.isTrueConst() } && !expression.type.isUnit()
         assert(exhaustive || expression.type.isUnit()) {
@@ -849,19 +869,6 @@ class ExpressionCodegen(
         }
     }
 
-    private fun IrExpression.markEndOfStatementIfNeeded() {
-        when (this) {
-            is IrWhen -> if (this.branches.size > 1) {
-                this.markLineNumber(false)
-            }
-            is IrTry -> this.markLineNumber(false)
-            is IrContainerExpression -> when (this.origin) {
-                IrStatementOrigin.WHEN, IrStatementOrigin.IF ->
-                    this.markLineNumber(false)
-            }
-        }
-    }
-
     override fun visitWhileLoop(loop: IrWhileLoop, data: BlockInfo): PromisedValue {
         val continueLabel = markNewLabel()
         val endLabel = Label()
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/SwitchGenerator.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/SwitchGenerator.kt
index 3dd3b57a181..1d5f54635bb 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/SwitchGenerator.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/SwitchGenerator.kt
@@ -348,7 +348,27 @@ class SwitchGenerator(private val expression: IrWhen, private val data: BlockInf
         override fun shouldOptimize() = cases.size > 1
 
         override fun genSwitch() {
-            subject.accept(codegen, data).materialize()
+            // Do not generate line numbers for the table switching. In particular,
+            // the subject is extracted from the condition of the first branch which
+            // will give the wrong stepping behavior for code such as:
+            //
+            // when {
+            //   x == 42 -> 1
+            //   x == 32 -> 2
+            //   x == 24 -> 3
+            //   ...
+            // }
+            //
+            // If the subject line number is generated, we will not stop on the line
+            // of the `when` but instead stop on the `x == 42` line. When x is 24,
+            // we would stop on the line `x == 42` and then step to the line `x == 24`.
+            // That is confusing and we prefer to stop on the `when` line and then step
+            // to the `x == 24` line. This is accomplished by ignoring the line number
+            // information for the subject as the `when` line number has already been
+            // emitted.
+            codegen.noLineNumberScope {
+                subject.accept(codegen, data).materialize()
+            }
             genIntSwitch(cases)
         }
     }
@@ -419,13 +439,33 @@ class SwitchGenerator(private val expression: IrWhen, private val data: BlockInf
 
         override fun genSwitch() {
             with(codegen) {
-                if (subject.type.isNullableString()) {
+                // Do not generate line numbers for the table switching. In particular,
+                // the subject is extracted from the condition of the first branch which
+                // will give the wrong stepping behavior for code such as:
+                //
+                // when {
+                //   x == "x" -> 1
+                //   x == "y" -> 2
+                //   x == "z" -> 3
+                //   ...
+                // }
+                //
+                // If the subject line number is generated, we will not stop on the line
+                // of the `when` but instead stop on the `x == "x"` line. When x is "z",
+                // we would stop on the line `x == "x"` and then step to the line `x == "z"`.
+                // That is confusing and we prefer to stop on the `when` line and then step
+                // to the `x == "z"` line. This is accomplished by ignoring the line number
+                // information for the subject as the `when` line number has already been
+                // emitted.
+                noLineNumberScope {
+                    if (subject.type.isNullableString()) {
+                        subject.accept(codegen, data).materialize()
+                        mv.ifnull(cases.find { it.value == null }?.label ?: defaultLabel)
+                    }
+                    // Reevaluating the subject is fine here because it is a read of a temporary.
                     subject.accept(codegen, data).materialize()
-                    mv.ifnull(cases.find { it.value == null }?.label ?: defaultLabel)
+                    mv.invokevirtual("java/lang/String", "hashCode", "()I", false)
                 }
-                // Reevaluating the subject is fine here because it is a read of a temporary.
-                subject.accept(codegen, data).materialize()
-                mv.invokevirtual("java/lang/String", "hashCode", "()I", false)
                 genIntSwitch(hashAndSwitchLabels)
 
                 // Multiple strings can be hashed into the same bucket.
@@ -433,7 +473,9 @@ class SwitchGenerator(private val expression: IrWhen, private val data: BlockInf
                 for ((hash, switchLabel) in hashAndSwitchLabels) {
                     mv.visitLabel(switchLabel)
                     for ((string, label) in hashToStringAndExprLabels[hash]!!) {
-                        subject.accept(codegen, data).materialize()
+                        noLineNumberScope {
+                            subject.accept(codegen, data).materialize()
+                        }
                         mv.aconst(string)
                         mv.invokevirtual("java/lang/String", "equals", "(Ljava/lang/Object;)Z", false)
                         mv.ifne(label)
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/InheritedDefaultMethodsOnClassesLowering.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/InheritedDefaultMethodsOnClassesLowering.kt
index f64052dd0fd..728a29acdb7 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/InheritedDefaultMethodsOnClassesLowering.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/InheritedDefaultMethodsOnClassesLowering.kt
@@ -88,7 +88,8 @@ private class InheritedDefaultMethodsOnClassesLowering(val context: JvmBackendCo
 
         val superMethod = firstSuperMethodFromKotlin(irFunction, interfaceImplementation).owner
         val defaultImplFun = context.cachedDeclarations.getDefaultImplsFunction(superMethod)
-        context.createIrBuilder(irFunction.symbol, UNDEFINED_OFFSET, UNDEFINED_OFFSET).apply {
+        val classStartOffset = classOverride.parentAsClass.startOffset
+        context.createIrBuilder(irFunction.symbol, classStartOffset, classStartOffset).apply {
             irFunction.body = irBlockBody {
                 +irReturn(
                     irCall(defaultImplFun.symbol, irFunction.returnType).apply {
diff --git a/compiler/testData/codegen/bytecodeText/controlStructures/kt17110.kt b/compiler/testData/codegen/bytecodeText/controlStructures/kt17110.kt
index 8d2527c6fd4..bb3125d0fe9 100644
--- a/compiler/testData/codegen/bytecodeText/controlStructures/kt17110.kt
+++ b/compiler/testData/codegen/bytecodeText/controlStructures/kt17110.kt
@@ -21,6 +21,5 @@ fun infiniteLoop() {
 // 1 GOTO L1
 
 // JVM_IR_TEMPLATES
-// 1 GOTO L6
-// 1 GOTO L7
+// 2 GOTO L6
 // 1 GOTO L0
\ No newline at end of file
diff --git a/compiler/testData/debug/stepping/stringSwitches.kt b/compiler/testData/debug/stepping/stringSwitches.kt
new file mode 100644
index 00000000000..edbb32e6c0f
--- /dev/null
+++ b/compiler/testData/debug/stepping/stringSwitches.kt
@@ -0,0 +1,113 @@
+// FILE: test.kt
+
+fun stringSwitch(x: String) {
+    val l = when {
+        x == "x" -> 1
+        x == "xy" -> 2
+        x == "xyz" -> 3
+        else -> -1
+    }
+
+    val l2 = when (x) {
+        "x" -> 1
+        "xy" -> 2
+        "xyz" -> 3
+        else -> -1
+    }
+
+    val l3 = when
+        (x)
+    {
+        "x" -> 1
+        "xy" -> 2
+        "xyz" -> 3
+        else -> -1
+    }
+}
+
+fun box() {
+    stringSwitch("x")
+    stringSwitch("xy")
+    stringSwitch("xyz")
+    stringSwitch("nope")
+}
+
+// JVM_IR uses the line number of the start of the `when` as the line number
+// for the lookup/table switch. Therefore when the subject and the when is
+// on separate lines the first step is on the subject, then steop to the when,
+// then to the right branch.
+
+// JVM_IR uses optimized lookup/table switches for all these cases. JVM
+// does not. So on JVM there are steps on each condition evaluation for
+// the first `when`.
+
+// LINENUMBERS
+// test.kt:29 box
+// test.kt:4 stringSwitch
+// test.kt:5 stringSwitch
+// test.kt:4 stringSwitch
+// test.kt:11 stringSwitch
+// test.kt:12 stringSwitch
+// test.kt:11 stringSwitch
+// test.kt:19 stringSwitch
+// LINENUMBERS JVM_IR
+// test.kt:18 stringSwitch
+// LINENUMBERS
+// test.kt:21 stringSwitch
+// test.kt:18 stringSwitch
+// test.kt:26 stringSwitch
+// test.kt:30 box
+// test.kt:4 stringSwitch
+// LINENUMBERS JVM
+// test.kt:5 stringSwitch
+// LINENUMBERS
+// test.kt:6 stringSwitch
+// test.kt:4 stringSwitch
+// test.kt:11 stringSwitch
+// test.kt:13 stringSwitch
+// test.kt:11 stringSwitch
+// test.kt:19 stringSwitch
+// LINENUMBERS JVM_IR
+// test.kt:18 stringSwitch
+// LINENUMBERS
+// test.kt:22 stringSwitch
+// test.kt:18 stringSwitch
+// test.kt:26 stringSwitch
+// test.kt:31 box
+// test.kt:4 stringSwitch
+// LINENUMBERS JVM
+// test.kt:5 stringSwitch
+// test.kt:6 stringSwitch
+// LINENUMBERS
+// test.kt:7 stringSwitch
+// test.kt:4 stringSwitch
+// test.kt:11 stringSwitch
+// test.kt:14 stringSwitch
+// test.kt:11 stringSwitch
+// test.kt:19 stringSwitch
+// LINENUMBERS JVM_IR
+// test.kt:18 stringSwitch
+// LINENUMBERS
+// test.kt:23 stringSwitch
+// test.kt:18 stringSwitch
+// test.kt:26 stringSwitch
+// test.kt:32 box
+// test.kt:4 stringSwitch
+// LINENUMBERS JVM
+// test.kt:5 stringSwitch
+// test.kt:6 stringSwitch
+// test.kt:7 stringSwitch
+// LINENUMBERS
+// test.kt:8 stringSwitch
+// test.kt:4 stringSwitch
+// test.kt:11 stringSwitch
+// test.kt:15 stringSwitch
+// test.kt:11 stringSwitch
+// test.kt:19 stringSwitch
+// LINENUMBERS JVM_IR
+// test.kt:18 stringSwitch
+// LINENUMBERS
+// test.kt:24 stringSwitch
+// test.kt:18 stringSwitch
+// test.kt:26 stringSwitch
+// test.kt:33 box
\ No newline at end of file
diff --git a/compiler/testData/debug/stepping/stringSwitchesSmall.kt b/compiler/testData/debug/stepping/stringSwitchesSmall.kt
new file mode 100644
index 00000000000..9ce227760d4
--- /dev/null
+++ b/compiler/testData/debug/stepping/stringSwitchesSmall.kt
@@ -0,0 +1,96 @@
+// FILE: test.kt
+
+fun stringSwitch(x: String) {
+    val l = when {
+        x == "x" -> 1
+        x == "xy" -> 2
+        else -> -1
+    }
+
+    val l2 = when (x) {
+        "x" -> 1
+        "xy" -> 2
+        else -> -1
+    }
+
+    val l3 = when
+        (x)
+    {
+        "x" -> 1
+        "xy" -> 2
+        else -> -1
+    }
+}
+
+fun box() {
+    stringSwitch("x")
+    stringSwitch("xy")
+    stringSwitch("nope")
+}
+
+// JVM_IR uses the line number of the start of the `when` as the line number
+// for the lookup/table switch. Therefore when the subject and the when is
+// on separate lines the first step is on the subject, then steop to the when,
+// then to the right branch.
+
+// JVM_IR uses unoptimized lookup/table switches for all these cases. JVM
+// does not. So on JVM there are direct jumps to the right branch for the
+// last two whens.
+
+// LINENUMBERS
+// test.kt:26 box
+// test.kt:4 stringSwitch
+// test.kt:5 stringSwitch
+// test.kt:4 stringSwitch
+// test.kt:10 stringSwitch
+// test.kt:11 stringSwitch
+// test.kt:10 stringSwitch
+// test.kt:17 stringSwitch
+// LINENUMBERS JVM_IR
+// test.kt:16 stringSwitch
+// LINENUMBERS
+// test.kt:19 stringSwitch
+// test.kt:16 stringSwitch
+// test.kt:23 stringSwitch
+// test.kt:27 box
+// test.kt:4 stringSwitch
+// test.kt:5 stringSwitch
+// test.kt:6 stringSwitch
+// test.kt:4 stringSwitch
+// test.kt:10 stringSwitch
+// LINENUMBERS JVM_IR
+// test.kt:11 stringSwitch
+// LINENUMBERS
+// test.kt:12 stringSwitch
+// test.kt:10 stringSwitch
+// test.kt:17 stringSwitch
+// LINENUMBERS JVM_IR
+// test.kt:16 stringSwitch
+// test.kt:19 stringSwitch
+// LINENUMBERS
+// test.kt:20 stringSwitch
+// test.kt:16 stringSwitch
+// test.kt:23 stringSwitch
+// test.kt:28 box
+// test.kt:4 stringSwitch
+// test.kt:5 stringSwitch
+// test.kt:6 stringSwitch
+// test.kt:7 stringSwitch
+// test.kt:4 stringSwitch
+// test.kt:10 stringSwitch
+// LINENUMBERS JVM_IR
+// test.kt:11 stringSwitch
+// test.kt:12 stringSwitch
+// LINENUMBERS
+// test.kt:13 stringSwitch
+// test.kt:10 stringSwitch
+// test.kt:17 stringSwitch
+// LINENUMBERS JVM_IR
+// test.kt:16 stringSwitch
+// test.kt:19 stringSwitch
+// test.kt:20 stringSwitch
+// LINENUMBERS
+// test.kt:21 stringSwitch
+// test.kt:16 stringSwitch
+// test.kt:23 stringSwitch
+// test.kt:29 box
\ No newline at end of file
diff --git a/compiler/testData/debug/stepping/trait.kt b/compiler/testData/debug/stepping/trait.kt
index bb56e290cec..1293dada46d 100644
--- a/compiler/testData/debug/stepping/trait.kt
+++ b/compiler/testData/debug/stepping/trait.kt
@@ -8,34 +8,38 @@ interface A {
     }
 }
 
+class B : A
+
 fun box() {
     (object : A {}).bar()
+    B().bar()
 }
 
-// The JVM backend generates non-synthetic overrides of foo and bar
-// in the object both with line number 12. That means that there will
-// be steps on line number 12 on entry and exit to both bar and foo.
-
-// TODO: Is this what we want? Should they be marked as bridges instead?
-// Doesn't look like the intellij debugger skips non-synthetic bridges?
-// There seems to be some heuristics in intellij dealing with this as
-// the stepping behavior with repeated step-into is mostly OK.
-
-// IGNORE_BACKEND: JVM_IR
-// The JVM_IR backend generates non-synthetic overrides of foo and bar
-// with no line numbers. That leads to steps on line -1 but only on
-// exit from bar and foo.
+// The dispatch methods added to classes directly implementing
+// interfaces with default methods (forwarding to the actual implementation
+// on A$DefaultImpls) have the line number of the class declaration.
 
 // LINENUMBERS
-// test.kt:12 box
-// test.kt:12 <init>
-// test.kt:12 box
-// test.kt:12 bar
+// test.kt:14 box
+// test.kt:14 <init>
+// test.kt:14 box
+// test.kt:14 bar
 // test.kt:7 bar
-// test.kt:12 foo
+// test.kt:14 foo
 // test.kt:4 foo
-// test.kt:12 foo
+// test.kt:14 foo
 // test.kt:7 bar
-// test.kt:12 bar
-// test.kt:12 box
-// test.kt:13 box
+// test.kt:14 bar
+// test.kt:14 box
+// test.kt:15 box
+// test.kt:11 <init>
+// test.kt:15 box
+// test.kt:11 bar
+// test.kt:7 bar
+// test.kt:11 foo
+// test.kt:4 foo
+// test.kt:11 foo
+// test.kt:7 bar
+// test.kt:11 bar
+// test.kt:15 box
+// test.kt:16 box
\ No newline at end of file
diff --git a/compiler/testData/debug/stepping/when.kt b/compiler/testData/debug/stepping/when.kt
index 16eb234d4d5..1c2c94557ed 100644
--- a/compiler/testData/debug/stepping/when.kt
+++ b/compiler/testData/debug/stepping/when.kt
@@ -18,41 +18,51 @@ fun box() {
     foo(21)
 }
 
-// IGNORE_BACKEND: JVM_IR
-
-// The JVM_IR backend has line number 8 when leaving the first
-// when. Also, the stepping is different, probably because the when
-// is compiled to a switch which it isn't with JVM? The stepping
-// behavior is likely OK, but should be double checked.
+// JVM_IR backend optimized the when to a switch in the java bytecode.
+// Therefore, the stepping for JVM_IR does not step through the evaluation
+// of each of the conditions, but goes directly to the right body. The
+// JVM_IR stepping behavior here is the same as for `whenSubject.kt`.
 
 // LINENUMBERS
 // test.kt:18 box
 // test.kt:4 foo
 // test.kt:5 foo
 // test.kt:4 foo
+// LINENUMBERS JVM
 // test.kt:5 foo
+// LINENUMBERS
 // test.kt:6 foo
 // test.kt:4 foo
+// LINENUMBERS JVM
 // test.kt:5 foo
 // test.kt:6 foo
+// LINENUMBERS
 // test.kt:7 foo
 // test.kt:10 foo
+// LINENUMBERS JVM
 // test.kt:11 foo
 // test.kt:12 foo
+// LINENUMBERS
 // test.kt:13 foo
 // test.kt:10 foo
 // test.kt:15 foo
 // test.kt:6 foo
 // test.kt:10 foo
+// LINENUMBERS JVM
 // test.kt:11 foo
+// LINENUMBERS
 // test.kt:12 foo
 // test.kt:4 foo
+// LINENUMBERS JVM
 // test.kt:5 foo
 // test.kt:6 foo
+// LINENUMBERS
 // test.kt:7 foo
 // test.kt:10 foo
+// LINENUMBERS JVM
 // test.kt:11 foo
 // test.kt:12 foo
+// LINENUMBERS
 // test.kt:13 foo
 // test.kt:10 foo
 // test.kt:15 foo
@@ -63,29 +73,41 @@ fun box() {
 // test.kt:10 foo
 // test.kt:11 foo
 // test.kt:4 foo
+// LINENUMBERS JVM
 // test.kt:5 foo
+// LINENUMBERS
 // test.kt:6 foo
 // test.kt:4 foo
+// LINENUMBERS JVM
 // test.kt:5 foo
 // test.kt:6 foo
+// LINENUMBERS
 // test.kt:7 foo
 // test.kt:10 foo
+// LINENUMBERS JVM
 // test.kt:11 foo
 // test.kt:12 foo
+// LINENUMBERS
 // test.kt:13 foo
 // test.kt:10 foo
 // test.kt:15 foo
 // test.kt:6 foo
 // test.kt:10 foo
+// LINENUMBERS JVM
 // test.kt:11 foo
+// LINENUMBERS
 // test.kt:12 foo
 // test.kt:4 foo
+// LINENUMBERS JVM
 // test.kt:5 foo
 // test.kt:6 foo
+// LINENUMBERS
 // test.kt:7 foo
 // test.kt:10 foo
+// LINENUMBERS JVM
 // test.kt:11 foo
 // test.kt:12 foo
+// LINENUMBERS
 // test.kt:13 foo
 // test.kt:10 foo
 // test.kt:15 foo
@@ -95,4 +117,4 @@ fun box() {
 // test.kt:11 foo
 // test.kt:10 foo
 // test.kt:15 foo
-// test.kt:19 box
+// test.kt:19 box
\ No newline at end of file
diff --git a/compiler/testData/debug/stepping/whenComplicatedSubject.kt b/compiler/testData/debug/stepping/whenComplicatedSubject.kt
new file mode 100644
index 00000000000..912b177be15
--- /dev/null
+++ b/compiler/testData/debug/stepping/whenComplicatedSubject.kt
@@ -0,0 +1,49 @@
+// FILE: test.kt
+
+fun foo(x: Int) {
+   when (val y =
+           when {
+             x == 0 -> 1
+             x == 1 -> 2
+             else -> 0
+         }) {
+       0 -> 3
+       1 -> 4
+   }
+}
+
+fun box() {
+    foo(0)
+    foo(1)
+    foo(2)
+}
+
+// The JVM_IR backend optimizes the inner when to a switch and therefore goes directly to the
+// right case without stepping through evaluation of each condition.
+
+// LINENUMBERS
+// test.kt:16 box
+// test.kt:5 foo
+// test.kt:6 foo
+// test.kt:4 foo
+// test.kt:11 foo
+// test.kt:13 foo
+// test.kt:17 box
+// test.kt:5 foo
+// LINENUMBERS JVM
+// test.kt:6 foo
+// LINENUMBERS
+// test.kt:7 foo
+// test.kt:4 foo
+// test.kt:13 foo
+// test.kt:18 box
+// test.kt:5 foo
+// LINENUMBERS JVM
+// test.kt:6 foo
+// test.kt:7 foo
+// LINENUMBERS
+// test.kt:8 foo
+// test.kt:4 foo
+// test.kt:10 foo
+// test.kt:13 foo
+// test.kt:19 box
\ No newline at end of file
diff --git a/compiler/testData/debug/stepping/whenMultiLine.kt b/compiler/testData/debug/stepping/whenMultiLine.kt
new file mode 100644
index 00000000000..bd792eb5b41
--- /dev/null
+++ b/compiler/testData/debug/stepping/whenMultiLine.kt
@@ -0,0 +1,83 @@
+// FILE: test.kt
+
+fun foo(x: Int): Int {
+    when {
+        x == 21 ->
+            1
+        x == 42 ->
+            2
+        else ->
+            3
+    }
+
+    val t = when {
+        x == 21 ->
+            1
+        x == 42 ->
+            2
+        else ->
+            3
+    }
+
+    return t
+}
+
+fun box() {
+    foo(21)
+    foo(42)
+    foo(63)
+}
+
+// JVM_IR backend optimized the when to a switch in the java bytecode.
+// Therefore, the stepping for JVM_IR does not step through the evaluation
+// of each of the conditions, but goes directly to the right body.
+// JVM_IR stepping behavior here is the same as for `whenMultiLineSubject.kt`.
+
+// LINENUMBERS
+// test.kt:26 box
+// test.kt:4 foo
+// LINENUMBERS JVM
+// test.kt:5 foo
+// LINENUMBERS
+// test.kt:6 foo
+// test.kt:13 foo
+// LINENUMBERS JVM
+// test.kt:14 foo
+// LINENUMBERS
+// test.kt:15 foo
+// test.kt:13 foo
+// test.kt:22 foo
+// test.kt:26 box
+// test.kt:27 box
+// test.kt:4 foo
+// LINENUMBERS JVM
+// test.kt:5 foo
+// test.kt:7 foo
+// LINENUMBERS
+// test.kt:8 foo
+// test.kt:13 foo
+// LINENUMBERS JVM
+// test.kt:14 foo
+// test.kt:16 foo
+// LINENUMBERS
+// test.kt:17 foo
+// test.kt:13 foo
+// test.kt:22 foo
+// test.kt:27 box
+// test.kt:28 box
+// test.kt:4 foo
+// LINENUMBERS JVM
+// test.kt:5 foo
+// test.kt:7 foo
+// LINENUMBERS
+// test.kt:10 foo
+// test.kt:13 foo
+// LINENUMBERS JVM
+// test.kt:14 foo
+// test.kt:16 foo
+// LINENUMBERS
+// test.kt:19 foo
+// test.kt:13 foo
+// test.kt:22 foo
+// test.kt:28 box
+// test.kt:29 box
\ No newline at end of file
diff --git a/compiler/testData/debug/stepping/whenMultiLineSubject.kt b/compiler/testData/debug/stepping/whenMultiLineSubject.kt
new file mode 100644
index 00000000000..d672f8a1b3f
--- /dev/null
+++ b/compiler/testData/debug/stepping/whenMultiLineSubject.kt
@@ -0,0 +1,56 @@
+// FILE: test.kt
+
+fun foo(x: Int): Int {
+    when (x) {
+        21 ->
+            1
+        42 ->
+            2
+        else ->
+            3
+    }
+
+    val t = when (x) {
+        21 ->
+            1
+        42 ->
+            2
+        else ->
+            3
+    }
+
+    return t
+}
+
+fun box() {
+    foo(21)
+    foo(42)
+    foo(63)
+}
+
+// LINENUMBERS
+// test.kt:26 box
+// test.kt:4 foo
+// test.kt:6 foo
+// test.kt:13 foo
+// test.kt:15 foo
+// test.kt:13 foo
+// test.kt:22 foo
+// test.kt:26 box
+// test.kt:27 box
+// test.kt:4 foo
+// test.kt:8 foo
+// test.kt:13 foo
+// test.kt:17 foo
+// test.kt:13 foo
+// test.kt:22 foo
+// test.kt:27 box
+// test.kt:28 box
+// test.kt:4 foo
+// test.kt:10 foo
+// test.kt:13 foo
+// test.kt:19 foo
+// test.kt:13 foo
+// test.kt:22 foo
+// test.kt:28 box
+// test.kt:29 box
\ No newline at end of file
diff --git a/compiler/testData/debug/stepping/whenSubject.kt b/compiler/testData/debug/stepping/whenSubject.kt
index 10d08c8f366..972dfebee6e 100644
--- a/compiler/testData/debug/stepping/whenSubject.kt
+++ b/compiler/testData/debug/stepping/whenSubject.kt
@@ -18,8 +18,6 @@ fun box() {
     foo(21)
 }
 
-// JVM_IR stops on line 8 when exiting the first when.
-
 // LINENUMBERS
 // test.kt:18 box
 // test.kt:4 foo
@@ -28,24 +26,15 @@ fun box() {
 // test.kt:6 foo
 // test.kt:4 foo
 // test.kt:7 foo
-// LINENUMBERS JVM_IR
-// test.kt:8 foo
-// LINENUMBERS
 // test.kt:10 foo
 // test.kt:13 foo
 // test.kt:10 foo
 // test.kt:15 foo
 // test.kt:6 foo
-// LINENUMBERS JVM_IR
-// test.kt:8 foo
-// LINENUMBERS
 // test.kt:10 foo
 // test.kt:12 foo
 // test.kt:4 foo
 // test.kt:7 foo
-// LINENUMBERS JVM_IR
-// test.kt:8 foo
-// LINENUMBERS
 // test.kt:10 foo
 // test.kt:13 foo
 // test.kt:10 foo
@@ -54,33 +43,21 @@ fun box() {
 // test.kt:10 foo
 // test.kt:15 foo
 // test.kt:5 foo
-// LINENUMBERS JVM_IR
-// test.kt:8 foo
-// LINENUMBERS
 // test.kt:10 foo
 // test.kt:11 foo
 // test.kt:4 foo
 // test.kt:6 foo
 // test.kt:4 foo
 // test.kt:7 foo
-// LINENUMBERS JVM_IR
-// test.kt:8 foo
-// LINENUMBERS
 // test.kt:10 foo
 // test.kt:13 foo
 // test.kt:10 foo
 // test.kt:15 foo
 // test.kt:6 foo
-// LINENUMBERS JVM_IR
-// test.kt:8 foo
-// LINENUMBERS
 // test.kt:10 foo
 // test.kt:12 foo
 // test.kt:4 foo
 // test.kt:7 foo
-// LINENUMBERS JVM_IR
-// test.kt:8 foo
-// LINENUMBERS
 // test.kt:10 foo
 // test.kt:13 foo
 // test.kt:10 foo
diff --git a/compiler/testData/debug/stepping/whenSubject2.kt b/compiler/testData/debug/stepping/whenSubject2.kt
new file mode 100644
index 00000000000..d164d802564
--- /dev/null
+++ b/compiler/testData/debug/stepping/whenSubject2.kt
@@ -0,0 +1,121 @@
+// FILE: test.kt
+
+fun foo(x: Int) {
+    when
+        (x)
+    {
+        21 -> foo(42)
+        42 -> foo(63)
+        else -> 1
+    }
+
+    val t = when
+        (x)
+    {
+        21 -> foo(42)
+        42 -> foo(63)
+        else -> 2
+    }
+}
+
+fun box() {
+    foo(21)
+}
+
+// JVM_IR uses the line number of the when for the table switch and therefore,
+// it stops on the subject line first, then on the when line (line 4 and 12), and
+// then goes to the right branch.
+
+// LINENUMBERS
+// test.kt:22 box
+// test.kt:5 foo
+// LINENUMBERS JVM_IR
+// test.kt:4 foo
+// LINENUMBERS
+// test.kt:7 foo
+// test.kt:5 foo
+// LINENUMBERS JVM_IR
+// test.kt:4 foo
+// LINENUMBERS
+// test.kt:8 foo
+// test.kt:5 foo
+// LINENUMBERS JVM_IR
+// test.kt:4 foo
+// LINENUMBERS
+// test.kt:9 foo
+// test.kt:13 foo
+// LINENUMBERS JVM_IR
+// test.kt:12 foo
+// LINENUMBERS
+// test.kt:17 foo
+// test.kt:12 foo
+// test.kt:19 foo
+// test.kt:8 foo
+// test.kt:13 foo
+// LINENUMBERS JVM_IR
+// test.kt:12 foo
+// LINENUMBERS
+// test.kt:16 foo
+// test.kt:5 foo
+// LINENUMBERS JVM_IR
+// test.kt:4 foo
+// LINENUMBERS
+// test.kt:9 foo
+// test.kt:13 foo
+// LINENUMBERS JVM_IR
+// test.kt:12 foo
+// LINENUMBERS
+// test.kt:17 foo
+// test.kt:12 foo
+// test.kt:19 foo
+// test.kt:16 foo
+// test.kt:12 foo
+// test.kt:19 foo
+// test.kt:7 foo
+// test.kt:13 foo
+// LINENUMBERS JVM_IR
+// test.kt:12 foo
+// LINENUMBERS
+// test.kt:15 foo
+// test.kt:5 foo
+// LINENUMBERS JVM_IR
+// test.kt:4 foo
+// LINENUMBERS
+// test.kt:8 foo
+// test.kt:5 foo
+// LINENUMBERS JVM_IR
+// test.kt:4 foo
+// LINENUMBERS
+// test.kt:9 foo
+// test.kt:13 foo
+// LINENUMBERS JVM_IR
+// test.kt:12 foo
+// LINENUMBERS
+// test.kt:17 foo
+// test.kt:12 foo
+// test.kt:19 foo
+// test.kt:8 foo
+// test.kt:13 foo
+// LINENUMBERS JVM_IR
+// test.kt:12 foo
+// LINENUMBERS
+// test.kt:16 foo
+// test.kt:5 foo
+// LINENUMBERS JVM_IR
+// test.kt:4 foo
+// LINENUMBERS
+// test.kt:9 foo
+// test.kt:13 foo
+// LINENUMBERS JVM_IR
+// test.kt:12 foo
+// LINENUMBERS
+// test.kt:17 foo
+// test.kt:12 foo
+// test.kt:19 foo
+// test.kt:16 foo
+// test.kt:12 foo
+// test.kt:19 foo
+// test.kt:15 foo
+// test.kt:12 foo
+// test.kt:19 foo
+// test.kt:23 box
diff --git a/compiler/tests-common/tests/org/jetbrains/kotlin/codegen/debugInformation/AbstractSteppingTest.kt b/compiler/tests-common/tests/org/jetbrains/kotlin/codegen/debugInformation/AbstractSteppingTest.kt
index 878fbbc2e27..e10e061b6e5 100644
--- a/compiler/tests-common/tests/org/jetbrains/kotlin/codegen/debugInformation/AbstractSteppingTest.kt
+++ b/compiler/tests-common/tests/org/jetbrains/kotlin/codegen/debugInformation/AbstractSteppingTest.kt
@@ -85,7 +85,7 @@ abstract class AbstractSteppingTest : AbstractDebugTest() {
                     LINENUMBERS_MARKER -> TargetBackend.ANY
                     JVM_LINENUMBER_MARKER -> TargetBackend.JVM
                     JVM_IR_LINENUMBER_MARKER -> TargetBackend.JVM_IR
-                    else -> error("Expected JVM backend")
+                    else -> error("Expected JVM backend: $line")
                 }
                 continue
             }
diff --git a/compiler/tests/org/jetbrains/kotlin/codegen/debugInformation/IrSteppingTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/codegen/debugInformation/IrSteppingTestGenerated.java
index f9f42064f67..9924d704a2f 100644
--- a/compiler/tests/org/jetbrains/kotlin/codegen/debugInformation/IrSteppingTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/codegen/debugInformation/IrSteppingTestGenerated.java
@@ -349,6 +349,18 @@ public class IrSteppingTestGenerated extends AbstractIrSteppingTest {
         runTest("compiler/testData/debug/stepping/smapInlineInIntrinsicArgument.kt");
     }
 
+    @Test
+    @TestMetadata("stringSwitches.kt")
+    public void testStringSwitches() throws Exception {
+        runTest("compiler/testData/debug/stepping/stringSwitches.kt");
+    }
+
+    @Test
+    @TestMetadata("stringSwitchesSmall.kt")
+    public void testStringSwitchesSmall() throws Exception {
+        runTest("compiler/testData/debug/stepping/stringSwitchesSmall.kt");
+    }
+
     @Test
     @TestMetadata("throwException.kt")
     public void testThrowException() throws Exception {
@@ -409,12 +421,36 @@ public class IrSteppingTestGenerated extends AbstractIrSteppingTest {
         runTest("compiler/testData/debug/stepping/when.kt");
     }
 
+    @Test
+    @TestMetadata("whenComplicatedSubject.kt")
+    public void testWhenComplicatedSubject() throws Exception {
+        runTest("compiler/testData/debug/stepping/whenComplicatedSubject.kt");
+    }
+
+    @Test
+    @TestMetadata("whenMultiLine.kt")
+    public void testWhenMultiLine() throws Exception {
+        runTest("compiler/testData/debug/stepping/whenMultiLine.kt");
+    }
+
+    @Test
+    @TestMetadata("whenMultiLineSubject.kt")
+    public void testWhenMultiLineSubject() throws Exception {
+        runTest("compiler/testData/debug/stepping/whenMultiLineSubject.kt");
+    }
+
     @Test
     @TestMetadata("whenSubject.kt")
     public void testWhenSubject() throws Exception {
         runTest("compiler/testData/debug/stepping/whenSubject.kt");
     }
 
+    @Test
+    @TestMetadata("whenSubject2.kt")
+    public void testWhenSubject2() throws Exception {
+        runTest("compiler/testData/debug/stepping/whenSubject2.kt");
+    }
+
     @Test
     @TestMetadata("while.kt")
     public void testWhile() throws Exception {
diff --git a/compiler/tests/org/jetbrains/kotlin/codegen/debugInformation/SteppingTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/codegen/debugInformation/SteppingTestGenerated.java
index 445546ea7e9..7ce96d3c1a4 100644
--- a/compiler/tests/org/jetbrains/kotlin/codegen/debugInformation/SteppingTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/codegen/debugInformation/SteppingTestGenerated.java
@@ -349,6 +349,18 @@ public class SteppingTestGenerated extends AbstractSteppingTest {
         runTest("compiler/testData/debug/stepping/smapInlineInIntrinsicArgument.kt");
     }
 
+    @Test
+    @TestMetadata("stringSwitches.kt")
+    public void testStringSwitches() throws Exception {
+        runTest("compiler/testData/debug/stepping/stringSwitches.kt");
+    }
+
+    @Test
+    @TestMetadata("stringSwitchesSmall.kt")
+    public void testStringSwitchesSmall() throws Exception {
+        runTest("compiler/testData/debug/stepping/stringSwitchesSmall.kt");
+    }
+
     @Test
     @TestMetadata("throwException.kt")
     public void testThrowException() throws Exception {
@@ -409,12 +421,36 @@ public class SteppingTestGenerated extends AbstractSteppingTest {
         runTest("compiler/testData/debug/stepping/when.kt");
     }
 
+    @Test
+    @TestMetadata("whenComplicatedSubject.kt")
+    public void testWhenComplicatedSubject() throws Exception {
+        runTest("compiler/testData/debug/stepping/whenComplicatedSubject.kt");
+    }
+
+    @Test
+    @TestMetadata("whenMultiLine.kt")
+    public void testWhenMultiLine() throws Exception {
+        runTest("compiler/testData/debug/stepping/whenMultiLine.kt");
+    }
+
+    @Test
+    @TestMetadata("whenMultiLineSubject.kt")
+    public void testWhenMultiLineSubject() throws Exception {
+        runTest("compiler/testData/debug/stepping/whenMultiLineSubject.kt");
+    }
+
     @Test
     @TestMetadata("whenSubject.kt")
     public void testWhenSubject() throws Exception {
         runTest("compiler/testData/debug/stepping/whenSubject.kt");
     }
 
+    @Test
+    @TestMetadata("whenSubject2.kt")
+    public void testWhenSubject2() throws Exception {
+        runTest("compiler/testData/debug/stepping/whenSubject2.kt");
+    }
+
     @Test
     @TestMetadata("while.kt")
     public void testWhile() throws Exception {
diff --git a/plugins/kotlin-serialization/kotlin-serialization-compiler/testData/codegen/Basic.ir.txt b/plugins/kotlin-serialization/kotlin-serialization-compiler/testData/codegen/Basic.ir.txt
index 19dc50f7fa1..87553282beb 100644
--- a/plugins/kotlin-serialization/kotlin-serialization-compiler/testData/codegen/Basic.ir.txt
+++ b/plugins/kotlin-serialization/kotlin-serialization-compiler/testData/codegen/Basic.ir.txt
@@ -113,8 +113,8 @@ public final class ListOfUsers$$serializer : java/lang/Object, kotlinx/serializa
         LABEL (L4)
           ICONST_0
           ISTORE (3)
-          GOTO (L5)
-        LABEL (L6)
+          GOTO (L2)
+        LABEL (L5)
           ALOAD (7)
           ALOAD (2)
           ICONST_0
@@ -131,21 +131,16 @@ public final class ListOfUsers$$serializer : java/lang/Object, kotlinx/serializa
           ICONST_1
           IOR
           ISTORE (5)
-          GOTO (L5)
-        LABEL (L7)
+          GOTO (L2)
+        LABEL (L6)
           NEW
           DUP
           ILOAD (4)
           INVOKESPECIAL (kotlinx/serialization/UnknownFieldException, <init>, (I)V)
           ATHROW
-        LABEL (L5)
-        LINENUMBER (13)
-          GOTO (L2)
         LABEL (L3)
           ALOAD (7)
           ALOAD (2)
-        LABEL (L8)
-        LINENUMBER (12)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeDecoder, endStructure, (Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
           NEW
           DUP
@@ -156,7 +151,7 @@ public final class ListOfUsers$$serializer : java/lang/Object, kotlinx/serializa
           CHECKCAST
           INVOKESPECIAL (ListOfUsers, <init>, (ILjava/util/List;Lkotlinx/serialization/internal/SerializationConstructorMarker;)V)
           ARETURN
-        LABEL (L9)
+        LABEL (L7)
     }
 
     public java.lang.Object deserialize(kotlinx.serialization.encoding.Decoder decoder) {
@@ -295,10 +290,8 @@ public final class ListOfUsers : java/lang/Object {
           ALOAD (0)
           ALOAD (2)
           PUTFIELD (list, Ljava/util/List;)
-        LABEL (L2)
-        LINENUMBER (13)
           RETURN
-        LABEL (L3)
+        LABEL (L2)
     }
 
     public final java.util.List getList()
@@ -411,8 +404,8 @@ public final class OptionalUser$$serializer : java/lang/Object, kotlinx/serializ
         LABEL (L4)
           ICONST_0
           ISTORE (3)
-          GOTO (L5)
-        LABEL (L6)
+          GOTO (L2)
+        LABEL (L5)
           ALOAD (7)
           ALOAD (2)
           ICONST_0
@@ -425,21 +418,16 @@ public final class OptionalUser$$serializer : java/lang/Object, kotlinx/serializ
           ICONST_1
           IOR
           ISTORE (5)
-          GOTO (L5)
-        LABEL (L7)
+          GOTO (L2)
+        LABEL (L6)
           NEW
           DUP
           ILOAD (4)
           INVOKESPECIAL (kotlinx/serialization/UnknownFieldException, <init>, (I)V)
           ATHROW
-        LABEL (L5)
-        LINENUMBER (10)
-          GOTO (L2)
         LABEL (L3)
           ALOAD (7)
           ALOAD (2)
-        LABEL (L8)
-        LINENUMBER (9)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeDecoder, endStructure, (Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
           NEW
           DUP
@@ -450,7 +438,7 @@ public final class OptionalUser$$serializer : java/lang/Object, kotlinx/serializ
           CHECKCAST
           INVOKESPECIAL (OptionalUser, <init>, (ILUser;Lkotlinx/serialization/internal/SerializationConstructorMarker;)V)
           ARETURN
-        LABEL (L9)
+        LABEL (L7)
     }
 
     public java.lang.Object deserialize(kotlinx.serialization.encoding.Decoder decoder) {
@@ -636,7 +624,6 @@ public final class OptionalUser : java/lang/Object {
           ALOAD (2)
           PUTFIELD (user, LUser;)
         LABEL (L4)
-        LINENUMBER (10)
           RETURN
         LABEL (L5)
     }
@@ -779,8 +766,8 @@ public final class User$$serializer : java/lang/Object, kotlinx/serialization/in
         LABEL (L4)
           ICONST_0
           ISTORE (3)
-          GOTO (L5)
-        LABEL (L6)
+          GOTO (L2)
+        LABEL (L5)
           ALOAD (8)
           ALOAD (2)
           ICONST_0
@@ -790,8 +777,8 @@ public final class User$$serializer : java/lang/Object, kotlinx/serialization/in
           ICONST_1
           IOR
           ISTORE (5)
-          GOTO (L5)
-        LABEL (L7)
+          GOTO (L2)
+        LABEL (L6)
           ALOAD (8)
           ALOAD (2)
           ICONST_1
@@ -801,21 +788,16 @@ public final class User$$serializer : java/lang/Object, kotlinx/serialization/in
           ICONST_2
           IOR
           ISTORE (5)
-          GOTO (L5)
-        LABEL (L8)
+          GOTO (L2)
+        LABEL (L7)
           NEW
           DUP
           ILOAD (4)
           INVOKESPECIAL (kotlinx/serialization/UnknownFieldException, <init>, (I)V)
           ATHROW
-        LABEL (L5)
-        LINENUMBER (7)
-          GOTO (L2)
         LABEL (L3)
           ALOAD (8)
           ALOAD (2)
-        LABEL (L9)
-        LINENUMBER (6)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeDecoder, endStructure, (Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
           NEW
           DUP
@@ -826,7 +808,7 @@ public final class User$$serializer : java/lang/Object, kotlinx/serialization/in
           CHECKCAST
           INVOKESPECIAL (User, <init>, (ILjava/lang/String;Ljava/lang/String;Lkotlinx/serialization/internal/SerializationConstructorMarker;)V)
           ARETURN
-        LABEL (L10)
+        LABEL (L8)
     }
 
     public java.lang.Object deserialize(kotlinx.serialization.encoding.Decoder decoder) {
@@ -973,29 +955,24 @@ public final class User : java/lang/Object {
           ALOAD (0)
           ALOAD (2)
           PUTFIELD (firstName, Ljava/lang/String;)
-        LABEL (L2)
-        LINENUMBER (7)
-        LINENUMBER (6)
           ILOAD (1)
           ICONST_2
           IAND
-          IFNE (L3)
+          IFNE (L2)
           NEW
           DUP
           LDC (lastName)
           INVOKESPECIAL (kotlinx/serialization/MissingFieldException, <init>, (Ljava/lang/String;)V)
           ATHROW
-        LABEL (L3)
+        LABEL (L2)
           ALOAD (0)
           ALOAD (3)
           PUTFIELD (lastName, Ljava/lang/String;)
-        LABEL (L4)
-        LINENUMBER (7)
           RETURN
-        LABEL (L5)
+        LABEL (L3)
     }
 
     public final java.lang.String getFirstName()
 
     public final java.lang.String getLastName()
-}
+}
\ No newline at end of file