FIR CLI: count lines/files and report events to perfman

compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/pipeline/buildFir.kt

@@ -5,6 +5,8 @@
 
 package org.jetbrains.kotlin.fir.pipeline
 
+import com.intellij.openapi.util.io.FileUtil
+import com.intellij.openapi.vfs.CharsetToolkit
 import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.builder.PsiHandlingMode
@@ -17,16 +19,28 @@ import org.jetbrains.kotlin.fir.session.sourcesToPathsMapper
 import org.jetbrains.kotlin.psi.KtFile
 import java.io.File
 
-fun FirSession.buildFirViaLightTree(files: Collection<File>, diagnosticsReporter: DiagnosticReporter? = null): List<FirFile> {
+fun FirSession.buildFirViaLightTree(
+    files: Collection<File>,
+    diagnosticsReporter: DiagnosticReporter? = null,
+    reportFilesAndLines: ((Int, Int) -> Unit)? = null
+): List<FirFile> {
     val firProvider = (firProvider as FirProviderImpl)
     val sourcesToPathsMapper = sourcesToPathsMapper
     val builder = LightTree2Fir(this, firProvider.kotlinScopeProvider, diagnosticsReporter)
-    return files.map {
-        builder.buildFirFile(it).also { firFile ->
+    val shouldCountLines = (reportFilesAndLines != null)
+    var linesCount = 0
+    val firFiles = files.map { file ->
+        val code = FileUtil.loadFile(file, CharsetToolkit.UTF8, true /* code below relies on conversion */)
+        if (shouldCountLines) {
+            linesCount += code.count { it == '\n' } // assuming converted line separators
+        }
+        builder.buildFirFile(code, file.name, file.path).also { firFile ->
             firProvider.recordFile(firFile)
-            sourcesToPathsMapper.registerFileSource(firFile.source!!, it.path)
+            sourcesToPathsMapper.registerFileSource(firFile.source!!, file.path)
         }
     }
+    reportFilesAndLines?.invoke(files.count(), linesCount)
+    return firFiles
 }
 
 fun FirSession.buildFirFromKtFiles(ktFiles: Collection<KtFile>): List<FirFile> {