JVM: separate the two kinds of source mappers

* a writing source mapper has `mapLineNumber(line, file, class)` that
   inserts a new SMAP entry and returns a fake line number from it;
 * a copying source mapper has `mapLineNumber(line)` that uses an
   existing SMAP to resolve the line number and call the former method
   on a different source mapper;
 * those two types are disjoint.

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

@@ -148,7 +148,7 @@ abstract class ClassCodegen protected constructor(
         if (writeSourceMap) {
             visitor.visitSMAP(smap, !context.state.languageVersionSettings.supportsFeature(LanguageFeature.CorrectSourceMappingSyntax))
         } else {
-            visitor.visitSource(smap.sourceInfo.source, null)
+            visitor.visitSource(smap.sourceInfo!!.source, null)
         }
 
         visitor.done()
@@ -269,7 +269,7 @@ abstract class ClassCodegen protected constructor(
 
     protected abstract fun bindMethodMetadata(method: IrFunction, signature: Method)
 
-    private fun generateMethod(method: IrFunction, classSMAP: DefaultSourceMapper) {
+    private fun generateMethod(method: IrFunction, classSMAP: SourceMapper) {
         if (method.isFakeOverride) {
             jvmSignatureClashDetector.trackFakeOverrideMethod(method)
             return
@@ -281,7 +281,7 @@ abstract class ClassCodegen protected constructor(
             method.origin == JvmLoweredDeclarationOrigin.FOR_INLINE_STATE_MACHINE_TEMPLATE_CAPTURES_CROSSINLINE
         )
         val mv = with(node) { visitor.newMethod(method.OtherOrigin, access, name, desc, signature, exceptions.toTypedArray()) }
-        val smapCopier = NestedSourceMapper(classSMAP, smap, sameFile = true)
+        val smapCopier = SourceMapCopier(classSMAP, smap, keepCallSites = true)
         val smapCopyingVisitor = object : MethodVisitor(Opcodes.API_VERSION, mv) {
             override fun visitLineNumber(line: Int, start: Label) =
                 super.visitLineNumber(smapCopier.mapLineNumber(line), start)

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

@@ -106,7 +106,7 @@ class ExpressionCodegen(
     val mv: InstructionAdapter,
     val classCodegen: ClassCodegen,
     val inlinedInto: ExpressionCodegen?,
-    val smap: DefaultSourceMapper
+    val smap: SourceMapper
 ) : IrElementVisitor<PromisedValue, BlockInfo>, BaseExpressionCodegen {
 
     var finallyDepth = 0

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

@@ -85,7 +85,7 @@ class IrSourceCompilerForInline(
             )
         }
 
-    override val lazySourceMapper: DefaultSourceMapper
+    override val lazySourceMapper: SourceMapper
         get() = codegen.smap.also { codegen.classCodegen.writeSourceMap = true }
 
     override fun generateLambdaBody(lambdaInfo: ExpressionLambda): SMAPAndMethodNode =

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

@@ -13,7 +13,7 @@ import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns.FQ_NAMES
 import org.jetbrains.kotlin.builtins.jvm.JavaToKotlinClassMap
 import org.jetbrains.kotlin.codegen.*
-import org.jetbrains.kotlin.codegen.inline.DefaultSourceMapper
+import org.jetbrains.kotlin.codegen.inline.SourceMapper
 import org.jetbrains.kotlin.codegen.signature.BothSignatureWriter
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptorWithSource
@@ -80,14 +80,14 @@ val IrDeclaration.fileParent: IrFile
 internal val DeclarationDescriptorWithSource.psiElement: PsiElement?
     get() = (source as? PsiSourceElement)?.psi
 
-fun JvmBackendContext.getSourceMapper(declaration: IrClass): DefaultSourceMapper {
+fun JvmBackendContext.getSourceMapper(declaration: IrClass): SourceMapper {
     val sourceManager = this.psiSourceManager
     val fileEntry = sourceManager.getFileEntry(declaration.fileParent)
     // NOTE: apparently inliner requires the source range to cover the
     //       whole file the class is declared in rather than the class only.
     // TODO: revise
     val endLineNumber = fileEntry?.getSourceRangeInfo(0, fileEntry.maxOffset)?.endLineNumber ?: 0
-    return DefaultSourceMapper(
+    return SourceMapper(
         SourceInfo.createInfoForIr(
             endLineNumber + 1,
             typeMapper.mapClass(declaration).internalName,