Release generated bytecode after each processed part

Part here means separate '.kt' file or multi-file facade
Now this memory optimization doesn't work with jar's,
because there is no simple way to write them incrementally.

compiler/backend/src/org/jetbrains/kotlin/codegen/ClassBuilderOnDemand.java

@@ -36,8 +36,12 @@ public class ClassBuilderOnDemand extends DelegatingClassBuilder {
 
     @Override
     public void done() {
-        if (classBuilder.isComputed()) {
+        if (isComputed()) {
             classBuilder.invoke().done();
         }
     }
+
+    public boolean isComputed() {
+        return classBuilder.isComputed();
+    }
 }

compiler/backend/src/org/jetbrains/kotlin/codegen/ClassFileFactory.java

@@ -92,6 +92,10 @@ public class ClassFileFactory implements OutputFileCollection {
         }
     }
 
+    public void releaseGeneratedOutput() {
+        generators.clear();
+    }
+
     private void writeModuleMappings() {
         final JvmPackageTable.PackageTable.Builder builder = JvmPackageTable.PackageTable.newBuilder();
         String outputFilePath = getMappingFileName(state.getModuleName());
@@ -144,6 +148,11 @@ public class ClassFileFactory implements OutputFileCollection {
     @Override
     public List<OutputFile> asList() {
         done();
+        return getCurrentOutput();
+    }
+
+    @NotNull
+    public List<OutputFile> getCurrentOutput() {
         return ContainerUtil.map(generators.keySet(), new Function<String, OutputFile>() {
             @Override
             public OutputFile fun(String relativeClassFilePath) {

compiler/backend/src/org/jetbrains/kotlin/codegen/MultifileClassCodegen.kt

@@ -127,6 +127,7 @@ class MultifileClassCodegen(
             ProgressIndicatorAndCompilationCanceledStatus.checkCanceled()
             try {
                 generatePart(file, generateCallableMemberTasks, partFqNames)
+                state.afterIndependentPart()
             }
             catch (e: ProcessCanceledException) {
                 throw e
@@ -292,6 +293,9 @@ class MultifileClassCodegen(
 
     private fun done() {
         classBuilder.done()
+        if (classBuilder.isComputed) {
+            state.afterIndependentPart()
+        }
     }
 
     companion object {

compiler/backend/src/org/jetbrains/kotlin/codegen/PackageCodegen.java

@@ -27,7 +27,6 @@ import org.jetbrains.kotlin.codegen.state.GenerationState;
 import org.jetbrains.kotlin.descriptors.PackageFragmentDescriptor;
 import org.jetbrains.kotlin.diagnostics.DiagnosticUtils;
 import org.jetbrains.kotlin.fileClasses.JvmFileClassInfo;
-import org.jetbrains.kotlin.load.kotlin.PackageParts;
 import org.jetbrains.kotlin.name.FqName;
 import org.jetbrains.kotlin.progress.ProgressIndicatorAndCompilationCanceledStatus;
 import org.jetbrains.kotlin.psi.*;
@@ -60,6 +59,7 @@ public class PackageCodegen {
             ProgressIndicatorAndCompilationCanceledStatus.checkCanceled();
             try {
                 generateFile(file);
+                state.afterIndependentPart();
             }
             catch (ProcessCanceledException e) {
                 throw e;

compiler/backend/src/org/jetbrains/kotlin/codegen/state/GenerationState.kt

@@ -67,7 +67,8 @@ class GenerationState @JvmOverloads constructor(
         val outDirectory: File? = null,
         val incrementalCompilationComponents: IncrementalCompilationComponents? = null,
         val generateOpenMultifileClasses: Boolean = false,
-        val progress: Progress = Progress.DEAF
+        val progress: Progress = Progress.DEAF,
+        private val onIndependentPartCompilationEnd: GenerationStateEventCallback = GenerationStateEventCallback.DO_NOTHING
 ) {
     abstract class GenerateClassFilter {
         abstract fun shouldAnnotateClass(processingClassOrObject: KtClassOrObject): Boolean
@@ -170,6 +171,10 @@ class GenerationState @JvmOverloads constructor(
         CodegenBinding.initTrace(this)
     }
 
+    fun afterIndependentPart() {
+        onIndependentPartCompilationEnd(this)
+    }
+
     private fun markUsed() {
         if (used) throw IllegalStateException("${GenerationState::class.java} cannot be used more than once")
 
@@ -197,3 +202,14 @@ private class LazyJvmDiagnostics(compute: () -> Diagnostics): Diagnostics {
 
     override fun iterator() = delegate.iterator()
 }
+
+interface GenerationStateEventCallback : (GenerationState) -> Unit {
+    companion object {
+        val DO_NOTHING = GenerationStateEventCallback {  }
+    }
+}
+
+fun GenerationStateEventCallback(block: (GenerationState) -> Unit): GenerationStateEventCallback =
+        object : GenerationStateEventCallback {
+            override fun invoke(s: GenerationState) = block(s)
+        }