From 7f26deb5e60f5d93b78858f578d3fbbcf474681d Mon Sep 17 00:00:00 2001
From: Svyatoslav Kuzmich <svyatoslav.kuzmich@jetbrains.com>
Date: Mon, 9 Nov 2020 17:18:03 +0300
Subject: [PATCH] [Wasm] Enable for loops optimization

---
 .../backend/common/lower/loops/HeaderProcessor.kt      |  4 +++-
 .../kotlin/backend/wasm/WasmLoweringPhases.kt          | 10 ++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/HeaderProcessor.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/HeaderProcessor.kt
index 8d994e425bd..0300e61cc9e 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/HeaderProcessor.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/HeaderProcessor.kt
@@ -382,7 +382,9 @@ internal class IndexedGetLoopHeader(
         with(builder) {
             // loopVariable = objectVariable[inductionVariable]
             val indexedGetFun = with(headerInfo.expressionHandler) { headerInfo.objectVariable.type.getFunction }
-            val get = irCall(indexedGetFun.symbol).apply {
+            // Making sure that expression type has type of the variable when it exists.
+            // Return type of get function can be a type parameter (for example Array<T>::get) which is not a subtype of loopVariable type.
+            val get = irCall(indexedGetFun.symbol, type = loopVariable?.type ?: indexedGetFun.returnType).apply {
                 dispatchReceiver = irGet(headerInfo.objectVariable)
                 putValueArgument(0, irGet(inductionVariable))
             }
diff --git a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt
index 78142b78ede..56b32d80129 100644
--- a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt
+++ b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt
@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.backend.wasm
 import org.jetbrains.kotlin.backend.common.FileLoweringPass
 import org.jetbrains.kotlin.backend.common.lower.*
 import org.jetbrains.kotlin.backend.common.lower.inline.FunctionInlining
+import org.jetbrains.kotlin.backend.common.lower.loops.ForLoopsLowering
 import org.jetbrains.kotlin.backend.common.phaser.*
 import org.jetbrains.kotlin.backend.wasm.lower.*
 import org.jetbrains.kotlin.ir.backend.js.lower.*
@@ -399,6 +400,12 @@ private val virtualDispatchReceiverExtractionPhase = makeWasmModulePhase(
     description = "Eliminate side-effects in dispatch receivers of virtual function calls"
 )
 
+private val forLoopsLoweringPhase = makeWasmModulePhase(
+    ::ForLoopsLowering,
+    name = "ForLoopsLowering",
+    description = "[Optimization] For loops lowering"
+)
+
 val wasmPhases = NamedCompilerPhase(
     name = "IrModuleLowering",
     description = "IR module lowering",
@@ -447,6 +454,9 @@ val wasmPhases = NamedCompilerPhase(
 
             stringConstructorLowering then
             returnableBlockLoweringPhase then
+
+            forLoopsLoweringPhase then
+
             defaultArgumentStubGeneratorPhase then
             defaultArgumentPatchOverridesPhase then
             defaultParameterInjectorPhase then