[Wasm] Add a basic end-to-end sourcemap generation in wasm backend

More constructions/instructions will be supported separately.

compiler/cli/cli-js/src/org/jetbrains/kotlin/cli/js/K2JsIrCompiler.kt

@@ -367,18 +367,23 @@ class K2JsIrCompiler : CLICompiler<K2JSCompilerArguments>() {
                 if (arguments.irDce) {
                     eliminateDeadDeclarations(allModules, backendContext)
                 }
+
+                val sourceMapFileName = if (configuration.getBoolean(JSConfigurationKeys.SOURCE_MAP)) "$outputName.map" else null
+
                 val res = compileWasm(
                     allModules = allModules,
                     backendContext = backendContext,
                     emitNameSection = arguments.wasmDebug,
                     allowIncompleteImplementations = arguments.irDce,
                     generateWat = true,
+                    sourceMapFileName = sourceMapFileName
                 )
 
                 writeCompilationResult(
                     result = res,
                     dir = outputDir,
-                    fileNameBase = outputName
+                    fileNameBase = outputName,
+                    sourceMapFileName = sourceMapFileName
                 )
 
                 return OK

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/compiler.kt

@@ -11,20 +11,31 @@ import org.jetbrains.kotlin.backend.common.serialization.linkerissues.checkNoUnb
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.WasmCompiledModuleFragment
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.WasmModuleFragmentGenerator
 import org.jetbrains.kotlin.backend.wasm.lower.markExportedDeclarations
+import org.jetbrains.kotlin.config.CompilerConfiguration
 import org.jetbrains.kotlin.ir.backend.js.MainModule
 import org.jetbrains.kotlin.ir.backend.js.ModulesStructure
+import org.jetbrains.kotlin.ir.backend.js.SourceMapsInfo
 import org.jetbrains.kotlin.ir.backend.js.loadIr
 import org.jetbrains.kotlin.ir.declarations.IrFactory
 import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
 import org.jetbrains.kotlin.ir.util.ExternalDependenciesGenerator
 import org.jetbrains.kotlin.ir.util.patchDeclarationParents
+import org.jetbrains.kotlin.js.sourceMap.SourceFilePathResolver
+import org.jetbrains.kotlin.js.sourceMap.SourceMap3Builder
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.wasm.ir.source.location.SourceLocation
 import org.jetbrains.kotlin.wasm.ir.convertors.WasmIrToBinary
 import org.jetbrains.kotlin.wasm.ir.convertors.WasmIrToText
+import org.jetbrains.kotlin.wasm.ir.source.location.SourceLocationMapping
 import java.io.ByteArrayOutputStream
 import java.io.File
 
-class WasmCompilerResult(val wat: String?, val js: String, val wasm: ByteArray)
+class WasmCompilerResult(
+    val wat: String?,
+    val js: String,
+    val wasm: ByteArray,
+    val sourceMap: String?
+)
 
 fun compileToLoweredIr(
     depsDescriptors: ModulesStructure,
@@ -77,6 +88,7 @@ fun compileWasm(
     emitNameSection: Boolean = false,
     allowIncompleteImplementations: Boolean = false,
     generateWat: Boolean = false,
+    sourceMapFileName: String? = null,
 ): WasmCompilerResult {
     val compiledWasmModule = WasmCompiledModuleFragment(backendContext.irBuiltIns)
     val codeGenerator = WasmModuleFragmentGenerator(backendContext, compiledWasmModule, allowIncompleteImplementations = allowIncompleteImplementations)
@@ -95,16 +107,65 @@ fun compileWasm(
     val js = compiledWasmModule.generateJs()
 
     val os = ByteArrayOutputStream()
-    WasmIrToBinary(os, linkedModule, allModules.last().descriptor.name.asString(), emitNameSection).appendWasmModule()
+
+    val sourceLocationMappings =
+        if (sourceMapFileName != null) mutableListOf<SourceLocationMapping>() else null
+
+    val wasmIrToBinary =
+        WasmIrToBinary(
+            os,
+            linkedModule,
+            allModules.last().descriptor.name.asString(),
+            emitNameSection,
+            sourceMapFileName,
+            sourceLocationMappings
+        )
+
+    wasmIrToBinary.appendWasmModule()
+
     val byteArray = os.toByteArray()
 
     return WasmCompilerResult(
         wat = wat,
         js = js,
-        wasm = byteArray
+        wasm = byteArray,
+        sourceMap = generateSourceMap(backendContext.configuration, sourceLocationMappings)
     )
 }
 
+private fun generateSourceMap(
+    configuration: CompilerConfiguration,
+    sourceLocationMappings: MutableList<SourceLocationMapping>?
+): String? {
+    if (sourceLocationMappings == null) return null
+
+    val sourceMapsInfo = SourceMapsInfo.from(configuration) ?: return null
+
+    val sourceMapBuilder =
+        SourceMap3Builder(null, { error("This should not be called for Kotlin/Wasm") }, sourceMapsInfo.sourceMapPrefix)
+
+    val pathResolver =
+        SourceFilePathResolver.create(sourceMapsInfo.sourceRoots, sourceMapsInfo.sourceMapPrefix, sourceMapsInfo.outputDir)
+
+    var prev: SourceLocation? = null
+
+    for (mapping in sourceLocationMappings) {
+        val location = mapping.sourceLocation as? SourceLocation.Location ?: continue
+
+        if (location == prev) continue
+
+        prev = location
+
+        location.apply {
+            // TODO resulting path goes too deep since temporary directory we compiled first is deeper than final destination.   
+            val relativePath = pathResolver.getPathRelativeToSourceRoots(File(file)).substring(3)
+            sourceMapBuilder.addMapping(relativePath, null, { null }, line, column, null, mapping.offset)
+        }
+    }
+
+    return sourceMapBuilder.build()
+}
+
 fun WasmCompiledModuleFragment.generateJs(): String {
     //language=js
     val runtime = """
@@ -170,7 +231,8 @@ fun generateJsWasmLoader(wasmFilePath: String, externalJs: String): String =
 fun writeCompilationResult(
     result: WasmCompilerResult,
     dir: File,
-    fileNameBase: String = "index",
+    fileNameBase: String,
+    sourceMapFileName: String?
 ) {
     dir.mkdirs()
     if (result.wat != null) {
@@ -180,4 +242,8 @@ fun writeCompilationResult(
 
     val jsWithLoader = generateJsWasmLoader("./$fileNameBase.wasm", result.js)
     File(dir, "$fileNameBase.mjs").writeText(jsWithLoader)
+
+    if (sourceMapFileName != null) {
+        File(dir, sourceMapFileName).writeText(result.sourceMap!!)
+    }
 }

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ir2wasm/BodyGenerator.kt

@@ -27,6 +27,8 @@ import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
 import org.jetbrains.kotlin.js.config.JSConfigurationKeys
 import org.jetbrains.kotlin.wasm.ir.*
+import org.jetbrains.kotlin.wasm.ir.source.location.SourceLocation
+import org.jetbrains.kotlin.wasm.ir.source.location.withLocation
 
 class BodyGenerator(
     val context: WasmFunctionCodegenContext,
@@ -420,7 +422,9 @@ class BodyGenerator(
 
         } else {
             // Static function call
-            body.buildCall(context.referenceFunction(function.symbol))
+            withLocation(call.getSourceLocation()) {
+                body.buildCall(context.referenceFunction(function.symbol), location)
+            }
         }
 
         // Unit types don't cross function boundaries
@@ -646,7 +650,7 @@ class BodyGenerator(
             body.buildGetLocal(context.referenceLocal(0))
         }
 
-        body.buildInstr(WasmOp.RETURN)
+        body.buildInstr(WasmOp.RETURN, expression.getSourceLocation())
     }
 
     internal fun generateWithExpectedType(expression: IrExpression, expectedType: IrType) {
@@ -883,4 +887,16 @@ class BodyGenerator(
 
         return false
     }
+
+    private fun IrExpression.getSourceLocation(): SourceLocation {
+        val fileEntry = context.irFunction.fileEntry
+        val path = fileEntry.name
+        val startLine = fileEntry.getLineNumber(startOffset)
+        val startColumn = fileEntry.getColumnNumber(startOffset)
+
+        if (startLine < 0 || startColumn < 0) return SourceLocation.NoLocation
+
+        return SourceLocation.Location(path, startLine, startColumn)
+    }
+
 }