From ba8223218fa3994d7966d789e77e5ae17fae7791 Mon Sep 17 00:00:00 2001
From: Svyatoslav Kuzmich <svyatoslav.kuzmich@jetbrains.com>
Date: Tue, 15 Dec 2020 16:54:47 +0300
Subject: [PATCH] [Wasm] Add inline property accessors optimization

---
 .../optimizations/PropertyAccessorInlineLowering.kt | 13 +++++++++++--
 .../kotlin/backend/wasm/WasmLoweringPhases.kt       |  8 ++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/optimizations/PropertyAccessorInlineLowering.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/optimizations/PropertyAccessorInlineLowering.kt
index dea400679fc..4e44e216030 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/optimizations/PropertyAccessorInlineLowering.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/optimizations/PropertyAccessorInlineLowering.kt
@@ -10,8 +10,9 @@ import org.jetbrains.kotlin.backend.common.CommonBackendContext
 import org.jetbrains.kotlin.backend.common.ir.isTopLevel
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.common.lower.irBlock
-import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
+import org.jetbrains.kotlin.descriptors.Modality
+import org.jetbrains.kotlin.ir.builders.irImplicitCast
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetFieldImpl
@@ -83,9 +84,17 @@ class PropertyAccessorInlineLowering(private val context: CommonBackendContext)
         private fun tryInlineSimpleGetter(call: IrCall, callee: IrSimpleFunction, backingField: IrField): IrExpression? {
             if (!isSimpleGetter(callee, backingField)) return null
 
-            return call.run {
+            val builder = context.createIrBuilder(call.symbol, call.startOffset, call.endOffset)
+
+            val getField = call.run {
                 IrGetFieldImpl(startOffset, endOffset, backingField.symbol, backingField.type, call.dispatchReceiver, origin)
             }
+
+            // Preserve call types when backingField have different type. This usually happens with generic field types.
+            return if (backingField.type != call.type)
+                builder.irImplicitCast(getField, call.type)
+            else
+                getField
         }
 
         private fun isSimpleGetter(callee: IrSimpleFunction, backingField: IrField): Boolean {
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 2cf8c5ba990..eb46d02bbe0 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
@@ -9,6 +9,7 @@ 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.lower.optimizations.PropertyAccessorInlineLowering
 import org.jetbrains.kotlin.backend.common.phaser.*
 import org.jetbrains.kotlin.backend.wasm.lower.*
 import org.jetbrains.kotlin.ir.backend.js.lower.*
@@ -406,6 +407,12 @@ private val forLoopsLoweringPhase = makeWasmModulePhase(
     description = "[Optimization] For loops lowering"
 )
 
+private val propertyAccessorInlinerLoweringPhase = makeWasmModulePhase(
+    ::PropertyAccessorInlineLowering,
+    name = "PropertyAccessorInlineLowering",
+    description = "[Optimization] Inline property accessors"
+)
+
 val wasmPhases = NamedCompilerPhase(
     name = "IrModuleLowering",
     description = "IR module lowering",
@@ -456,6 +463,7 @@ val wasmPhases = NamedCompilerPhase(
             returnableBlockLoweringPhase then
 
             forLoopsLoweringPhase then
+            propertyAccessorInlinerLoweringPhase then
 
             defaultArgumentStubGeneratorPhase then
             defaultArgumentPatchOverridesPhase then