Provide names of local variables via FramePointerAnalysis (#10906)

(cherry picked from commit d37b8f3)

docs/runtime/compiler-ir.md

@@ -11,8 +11,8 @@ for future goals.
 
 ## Visualization
 
-The IR can be visualized using `-Denso.compiler.dumpIr` system property. This
-will output a `.dot` file in [GraphViz](www.graphviz.org) format in the
+The IR can be visualized using `--vm.D=enso.compiler.dumpIr` system property.
+This will output a `.dot` file in [GraphViz](www.graphviz.org) format in the
 `ir-dumps` directory for each IR in the program. The _dot_ file format is a
 minimal textual format, that can be converted to a graphical representation
 using the `dot` command from the GraphViz package. For example, on Ubuntu,

engine/runtime-compiler/src/main/java/org/enso/compiler/context/ContextUtils.java

@@ -0,0 +1,22 @@
+package org.enso.compiler.context;
+
+import java.util.Objects;
+import java.util.function.Supplier;
+
+final class ContextUtils {
+  private ContextUtils() {}
+
+  static <V> V assertSame(String msg, V actual, Supplier<V> expectedSupplier) {
+    assert checkEquality(actual, expectedSupplier)
+        : msg + "\nexpected: " + expectedSupplier.get() + "\nactual: " + actual;
+    return actual;
+  }
+
+  private static <V> boolean checkEquality(V actual, Supplier<V> expectedSupplier) {
+    if (!Objects.equals(expectedSupplier.get(), actual)) {
+      return false;
+    } else {
+      return true;
+    }
+  }
+}

engine/runtime-compiler/src/main/java/org/enso/compiler/pass/analyse/FrameAnalysisMeta.java

@@ -0,0 +1,6 @@
+package org.enso.compiler.pass.analyse;
+
+import org.enso.compiler.core.ir.ProcessingPass;
+
+public sealed interface FrameAnalysisMeta extends ProcessingPass.Metadata
+    permits FramePointer, FrameVariableNames {}

engine/runtime-compiler/src/main/java/org/enso/compiler/pass/analyse/FramePointer.java

@@ -0,0 +1,38 @@
+package org.enso.compiler.pass.analyse;
+
+import org.enso.compiler.core.CompilerStub;
+import org.enso.compiler.core.ir.ProcessingPass;
+import org.enso.persist.Persistable;
+import scala.Option;
+
+/**
+ * A representation of a pointer into a stack frame at a given number of levels above the current.
+ */
+@Persistable(clazz = FramePointer.class, id = 1283)
+public record FramePointer(int parentLevel, int frameSlotIdx) implements FrameAnalysisMeta {
+
+  public FramePointer {
+    assert parentLevel >= 0;
+    assert frameSlotIdx >= 0;
+  }
+
+  @Override
+  public String metadataName() {
+    return getClass().getSimpleName();
+  }
+
+  @Override
+  public ProcessingPass.Metadata prepareForSerialization(CompilerStub compiler) {
+    return this;
+  }
+
+  @Override
+  public Option<ProcessingPass.Metadata> restoreFromSerialization(CompilerStub compiler) {
+    return Option.apply(this);
+  }
+
+  @Override
+  public Option<ProcessingPass.Metadata> duplicate() {
+    return Option.apply(this);
+  }
+}

engine/runtime-compiler/src/main/java/org/enso/compiler/pass/analyse/FrameVariableNames.java

@@ -0,0 +1,45 @@
+package org.enso.compiler.pass.analyse;
+
+import java.util.List;
+import org.enso.compiler.core.CompilerStub;
+import org.enso.compiler.core.ir.ProcessingPass;
+import org.enso.persist.Persistable;
+import scala.Option;
+import scala.jdk.javaapi.CollectionConverters;
+
+@Persistable(id = 1286)
+public final class FrameVariableNames implements FrameAnalysisMeta {
+  private final List<String> names;
+
+  public FrameVariableNames(List<String> variableNames) {
+    this.names = variableNames;
+  }
+
+  public static FrameVariableNames create(scala.collection.immutable.List<String> names) {
+    return new FrameVariableNames(CollectionConverters.asJava(names));
+  }
+
+  public List<String> variableNames() {
+    return names;
+  }
+
+  @Override
+  public String metadataName() {
+    return getClass().getSimpleName();
+  }
+
+  @Override
+  public ProcessingPass.Metadata prepareForSerialization(CompilerStub compiler) {
+    return this;
+  }
+
+  @Override
+  public Option<ProcessingPass.Metadata> restoreFromSerialization(CompilerStub compiler) {
+    return Option.apply(this);
+  }
+
+  @Override
+  public Option<ProcessingPass.Metadata> duplicate() {
+    return Option.apply(new FrameVariableNames(names));
+  }
+}

engine/runtime-compiler/src/main/java/org/enso/compiler/pass/analyse/PassPersistance.java

@@ -1,7 +1,6 @@
 package org.enso.compiler.pass.analyse;
 
 import java.io.IOException;
-import org.enso.compiler.context.FramePointer;
 import org.enso.compiler.pass.analyse.alias.AliasMetadata;
 import org.enso.compiler.pass.analyse.alias.graph.Graph;
 import org.enso.compiler.pass.analyse.alias.graph.GraphOccurrence;
@@ -67,8 +66,6 @@
 @Persistable(clazz = Graph.Link.class, id = 1266, allowInlining = false)
 @Persistable(clazz = TypeInference.class, id = 1280)
 @Persistable(clazz = FramePointerAnalysis$.class, id = 1281)
-@Persistable(clazz = FramePointerAnalysis.FramePointerMeta.class, id = 1282)
-@Persistable(clazz = FramePointer.class, id = 1283)
 public final class PassPersistance {
   private PassPersistance() {}
 
@@ -155,19 +152,16 @@ public PersistAliasAnalysisGraph() {
 
     @SuppressWarnings("unchecked")
     protected Graph readObject(Input in) throws IOException {
-      var g = new Graph();
 
       var rootScope = (Graph.Scope) in.readObject();
       assignParents(rootScope);
-      g.rootScope_$eq(rootScope);
 
       var links =
           (scala.collection.immutable.Set) in.readInline(scala.collection.immutable.Set.class);
-      g.initLinks(links);
 
       var nextIdCounter = in.readInt();
-      g.nextIdCounter_$eq(nextIdCounter);
-
+      var g = new Graph(rootScope, nextIdCounter, links);
+      g.freeze();
       return g;
     }
 

engine/runtime-compiler/src/main/scala/org/enso/compiler/context/LocalScope.scala

@@ -1,12 +1,16 @@
 package org.enso.compiler.context
 
+import org.enso.compiler.pass.analyse.FrameAnalysisMeta
+import org.enso.compiler.pass.analyse.FramePointer
+import org.enso.compiler.pass.analyse.FrameVariableNames
 import org.enso.compiler.pass.analyse.DataflowAnalysis
 import org.enso.compiler.pass.analyse.alias.graph.{
   GraphOccurrence,
   Graph => AliasGraph
 }
 
 import scala.jdk.CollectionConverters._
+import java.util.function.BiFunction
 
 /** A representation of an Enso local scope.
   *
@@ -34,20 +38,55 @@ class LocalScope(
   final val aliasingGraph: () => AliasGraph,
   final private val scopeProvider: () => AliasGraph.Scope,
   final private val dataflowInfoProvider: () => DataflowAnalysis.Metadata,
-  final val flattenToParent: Boolean                       = false,
-  private val parentFrameSlotIdxs: Map[AliasGraph.Id, Int] = Map()
+  final private val symbolsProvider: () => FrameAnalysisMeta     = null,
+  final val flattenToParent: Boolean                             = false,
+  private val parentFrameSlotIdxs: () => Map[AliasGraph.Id, Int] = () => Map()
 ) {
   lazy val scope: AliasGraph.Scope                 = scopeProvider()
   lazy val dataflowInfo: DataflowAnalysis.Metadata = dataflowInfoProvider()
 
+  /** Computes allSymbols needed by this scope. Either the value is obtained
+    * from symbolsProvider or (as a fallback) a computation from aliasingGraph
+    * is performed - the latter situation is logged, when log is not null.
+    *
+    * @param where human "friendly" identification of the caller
+    * @param log function to log or null if no logging is needed
+    */
+  def allSymbols(
+    where: String,
+    log: BiFunction[String, Array[Object], Void]
+  ): java.util.List[String] = {
+    def symbols(): java.util.List[String] = {
+      val r = scope.allDefinitions.map(_.symbol)
+      r.asJava
+    }
+    val meta = if (symbolsProvider == null) null else symbolsProvider()
+    if (meta.isInstanceOf[FrameVariableNames]) {
+      val cached = meta.asInstanceOf[FrameVariableNames].variableNames()
+      if (log != null) {
+        ContextUtils.assertSame(where, cached, () => symbols())
+      }
+      cached
+    } else {
+      val result = symbols()
+      if (log != null) {
+        log(
+          "Scope computed from AliasAnalysis at {0} = {1}",
+          Array(where, result)
+        )
+      }
+      result
+    }
+  }
+
   private lazy val localFrameSlotIdxs: Map[AliasGraph.Id, Int] =
     gatherLocalFrameSlotIdxs()
 
   /** All frame slot indexes, including local and all the parents.
     * Useful for quick searching for [[FramePointer]] of parent scopes.
     */
   private lazy val allFrameSlotIdxs: Map[AliasGraph.Id, Int] =
-    parentFrameSlotIdxs ++ localFrameSlotIdxs
+    parentFrameSlotIdxs() ++ localFrameSlotIdxs
 
   /** Creates a new child with a new aliasing scope.
     *
@@ -64,15 +103,23 @@ class LocalScope(
     */
   def createChild(
     childScope: () => AliasGraph.Scope,
-    flattenToParent: Boolean = false
+    flattenToParent: Boolean                  = false,
+    symbolsProvider: () => FrameVariableNames = null
   ): LocalScope = {
+    val sp = if (flattenToParent) {
+      assert(symbolsProvider == null)
+      this.symbolsProvider
+    } else {
+      symbolsProvider
+    }
     new LocalScope(
       Some(this),
       aliasingGraph,
       childScope,
       () => dataflowInfo,
+      sp,
       flattenToParent,
-      allFrameSlotIdxs
+      () => allFrameSlotIdxs
     )
   }
 
@@ -125,11 +172,27 @@ class LocalScope(
 }
 object LocalScope {
 
-  /** Constructs a local scope for an [[EnsoRootNode]].
+  /** Empty and immutable singleton scope.
+    */
+  val empty: LocalScope = {
+    val graph = new AliasGraph
+    graph.freeze()
+    val info               = DataflowAnalysis.DependencyInfo()
+    val emptyVariableNames = FrameVariableNames.create(List())
+    new LocalScope(
+      None,
+      () => graph,
+      () => graph.rootScope,
+      () => info,
+      () => emptyVariableNames
+    )
+  }
+
+  /** Constructs a new local scope for an [[EnsoRootNode]] that can then be modified.
     *
-    * @return a defaulted local scope
+    * @return a new empty scope ready for additional modifications.
     */
-  def root: LocalScope = {
+  def createEmpty: LocalScope = {
     val graph = new AliasGraph
     val info  = DataflowAnalysis.DependencyInfo()
     new LocalScope(