From 721ee18a641208174e5b8cd3458d89ecbc8ec086 Mon Sep 17 00:00:00 2001
From: LepilkinaElena <Elena.Lepilkina@jetbrains.com>
Date: Thu, 26 Dec 2019 16:15:21 +0300
Subject: [PATCH] Limit stack allocation only for array read operations with
 connection between return value  and array (#3728)

---
 .../konan/optimizations/LocalEscapeAnalysis.kt  |  6 ++++--
 backend.native/tests/build.gradle               |  5 +++++
 .../tests/runtime/collections/stack_array.kt    | 17 +++++++++++++++++
 3 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 backend.native/tests/runtime/collections/stack_array.kt

diff --git a/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/optimizations/LocalEscapeAnalysis.kt b/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/optimizations/LocalEscapeAnalysis.kt
index edc3b4adcfd..1ce38ef15aa 100644
--- a/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/optimizations/LocalEscapeAnalysis.kt
+++ b/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/optimizations/LocalEscapeAnalysis.kt
@@ -134,8 +134,10 @@ internal object LocalEscapeAnalysis {
                     }
                 }
                 is DataFlowIR.Node.ArrayRead -> {
-                    // If element of array escapes then array also should escape.
-                    connectObjects(node, node.array.node)
+                    // If element of array(return value) points to array(this value) and escapes then array also should escape.
+                    if (((node.callee.pointsTo?.elementAtOrNull(node.callee.parameters.size) ?: 0) and (1 shl 0)) != 0) {
+                        connectObjects(node, node.array.node)
+                    }
                 }
             }
         }
diff --git a/backend.native/tests/build.gradle b/backend.native/tests/build.gradle
index e707c63942a..b7f080ecaae 100644
--- a/backend.native/tests/build.gradle
+++ b/backend.native/tests/build.gradle
@@ -1789,6 +1789,11 @@ task BitSet(type: KonanLocalTest) {
     source = "runtime/collections/BitSet.kt"
 }
 
+task stack_array(type: KonanLocalTest) {
+    goldValue = "true\n3\n"
+    source = "runtime/collections/stack_array.kt"
+}
+
 task array0(type: KonanLocalTest) {
     goldValue = "5\n6\n7\n8\n9\n10\n11\n12\n13\n"
     source = "runtime/collections/array0.kt"
diff --git a/backend.native/tests/runtime/collections/stack_array.kt b/backend.native/tests/runtime/collections/stack_array.kt
new file mode 100644
index 00000000000..d68d3ad529a
--- /dev/null
+++ b/backend.native/tests/runtime/collections/stack_array.kt
@@ -0,0 +1,17 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package runtime.collections.stack_array
+
+import kotlin.test.*
+
+@Test fun runTest() {
+    val array = IntArray(2)
+    array[0] = 1
+    array[1] = 2
+    val check = array is IntArray
+    println(check)
+    println(array[0] + array[1])
+}
\ No newline at end of file