From 84e59f14030de84d69937212204b35bf3840e8b7 Mon Sep 17 00:00:00 2001
From: Dmitry Bushev <bushevdv@gmail.com>
Date: Tue, 2 May 2023 15:22:06 +0100
Subject: [PATCH] DataflowAnalysis preserves dependencies order (#6493)

close #6324

Changelog
- feat: DataflowAnalysis compiler pass preserves the order of dependencies. This way when attaching the visualization to the sub-expression, the engine can find the first cached parent node, and properly invalidate it.
- update: runtime visualization test is updated to reproduce the issue

# Important Notes
The dropdown for the column `"LOCATION"` is available right after the Restaurants project startup.

![2023-05-01-171700_1386x975_scrot](https://user-images.githubusercontent.com/357683/235466166-9d25cfa5-0e39-49a3-9c41-93cda59edb81.png)
---
 .../RuntimeVisualizationsTest.scala           | 25 +++++++++--
 .../pass/analyse/DataflowAnalysis.scala       | 41 +++++++++++++------
 2 files changed, 50 insertions(+), 16 deletions(-)

diff --git a/engine/runtime-with-polyglot/src/test/scala/org/enso/interpreter/test/instrument/RuntimeVisualizationsTest.scala b/engine/runtime-with-polyglot/src/test/scala/org/enso/interpreter/test/instrument/RuntimeVisualizationsTest.scala
index 9a755b3b1ce..bc574d48802 100644
--- a/engine/runtime-with-polyglot/src/test/scala/org/enso/interpreter/test/instrument/RuntimeVisualizationsTest.scala
+++ b/engine/runtime-with-polyglot/src/test/scala/org/enso/interpreter/test/instrument/RuntimeVisualizationsTest.scala
@@ -3138,8 +3138,12 @@ class RuntimeVisualizationsTest
     val moduleName      = "Enso_Test.Test.Main"
     val metadata        = new Metadata
 
-    val idX = metadata.addItem(65, 1, "aa")
-    val idY = metadata.addItem(65, 7, "ab")
+    val idX      = metadata.addItem(65, 1, "aa")
+    val idY      = metadata.addItem(65, 7, "ab")
+    val idS      = metadata.addItem(81, 1)
+    val idZ      = metadata.addItem(91, 5, "ac")
+    val idZexprS = metadata.addItem(93, 1)
+    val idZexpr1 = metadata.addItem(95, 1)
 
     val code =
       """type T
@@ -3150,7 +3154,11 @@ class RuntimeVisualizationsTest
         |main =
         |    x = T.C
         |    y = x.inc 7
-        |    y
+        |    s = 1
+        |    z = p y s
+        |    z
+        |
+        |p x y = x + y
         |""".stripMargin.linesIterator.mkString("\n")
     val contents = metadata.appendToCode(code)
     val mainFile = context.writeMain(contents)
@@ -3177,7 +3185,7 @@ class RuntimeVisualizationsTest
       Api.Request(requestId, Api.PushContextRequest(contextId, item1))
     )
     context.receiveNIgnorePendingExpressionUpdates(
-      5
+      9
     ) should contain theSameElementsAs Seq(
       Api.Response(Api.BackgroundJobsStartedNotification()),
       Api.Response(requestId, Api.PushContextResponse(contextId)),
@@ -3188,6 +3196,15 @@ class RuntimeVisualizationsTest
         ConstantsGen.INTEGER_BUILTIN,
         Api.MethodPointer(moduleName, s"$moduleName.T", "inc")
       ),
+      TestMessages.update(contextId, idS, ConstantsGen.INTEGER_BUILTIN),
+      TestMessages.update(
+        contextId,
+        idZ,
+        ConstantsGen.INTEGER_BUILTIN,
+        Api.MethodPointer(moduleName, moduleName, "p")
+      ),
+      TestMessages.update(contextId, idZexprS, ConstantsGen.INTEGER_BUILTIN),
+      TestMessages.update(contextId, idZexpr1, ConstantsGen.INTEGER_BUILTIN),
       context.executionComplete(contextId)
     )
 
diff --git a/engine/runtime/src/main/scala/org/enso/compiler/pass/analyse/DataflowAnalysis.scala b/engine/runtime/src/main/scala/org/enso/compiler/pass/analyse/DataflowAnalysis.scala
index 3e6a170c44c..0ba001c66d5 100644
--- a/engine/runtime/src/main/scala/org/enso/compiler/pass/analyse/DataflowAnalysis.scala
+++ b/engine/runtime/src/main/scala/org/enso/compiler/pass/analyse/DataflowAnalysis.scala
@@ -10,6 +10,7 @@ import org.enso.compiler.exception.CompilerError
 import org.enso.compiler.pass.IRPass
 import org.enso.compiler.pass.analyse.DataflowAnalysis.DependencyInfo.Type.asStatic
 
+import scala.collection.immutable.ListSet
 import scala.collection.mutable
 
 /** This pass implements dataflow analysis for Enso.
@@ -826,23 +827,39 @@ case object DataflowAnalysis extends IRPass {
       * @return the set of all associations with `key`, if key exists
       */
     def get(key: DependencyInfo.Type): Option[Set[DependencyInfo.Type]] = {
-      val visited = mutable.LinkedHashSet[DependencyInfo.Type]()
 
-      def go(key: DependencyInfo.Type): Set[DependencyInfo.Type] = {
-        if (!visited.contains(key)) {
-          visited += key
-
-          mapping.get(key) match {
-            case Some(deps) => deps ++ deps.map(go).reduceLeft(_ ++ _)
-            case None       => Set()
+      @scala.annotation.tailrec
+      def go(
+        queue: mutable.Queue[DependencyInfo.Type],
+        visited: mutable.Set[DependencyInfo.Type],
+        result: mutable.Set[DependencyInfo.Type]
+      ): Set[DependencyInfo.Type] =
+        if (queue.isEmpty) result.to(ListSet)
+        else {
+          val elem = queue.dequeue()
+          if (visited.contains(elem)) go(queue, visited, result)
+          else {
+            mapping.get(elem) match {
+              case Some(deps) =>
+                go(
+                  queue.enqueueAll(deps),
+                  visited.addOne(elem),
+                  result.addAll(deps)
+                )
+              case None =>
+                go(queue, visited.addOne(elem), result)
+            }
           }
-        } else {
-          Set()
         }
-      }
 
       if (mapping.contains(key)) {
-        Some(go(key))
+        Some(
+          go(
+            mutable.Queue(key),
+            mutable.HashSet(),
+            mutable.LinkedHashSet()
+          )
+        )
       } else {
         None
       }