Fix VSO280120.

st.lclFld decomposition was splitting a st.lclFld into two of the same
without bumping the destination var's ref count.

diff --git a/src/jit/decomposelongs.cpp b/src/jit/decomposelongs.cpp
index a9fc6b8..ec5c2e1 100644 (file)
--- a/src/jit/decomposelongs.cpp
+++ b/src/jit/decomposelongs.cpp
@@ -538,6 +538,9 @@ GenTree* DecomposeLongs::DecomposeStoreLclFld(LIR::Use& use)
     hiStore->gtOp1 = value->gtOp2;
     hiStore->gtFlags |= (GTF_VAR_DEF | GTF_VAR_USEASG);
 
+    // Bump the ref count for the destination.
+    m_compiler->lvaIncRefCnts(hiStore);
+
     Range().InsertAfter(loStore, hiStore);
 
     return hiStore->gtNext;

diff --git a/tests/src/JIT/Regression/JitBlue/DevDiv_280120/DevDiv_280120.cs b/tests/src/JIT/Regression/JitBlue/DevDiv_280120/DevDiv_280120.cs
new file mode 100644 (file)
index 0000000..39888b1
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/DevDiv_280120/DevDiv_280120.cs
@@ -0,0 +1,22 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+// This test was originally a repro for an assertion regarding incorrect lclVar ref counts due to a bug in the
+// decomposition of a long-typed st.lclFld node. The repro requires that a dead store of this type survives until
+// decomposition. We must therefore avoid running liveness before decomposition as part of this test, which requires
+// skipping SSA (and dependent optimizations). This pass is disabled in the project file by setting JitDoSsa to 0
+// before running the test.
+
+struct S
+{
+    long m_fld;
+    int m_a, m_b, m_c, m_d;
+
+    static int Main(string[] args)
+    {
+        S s;
+        s.m_fld = (long)args.Length;
+        return 100;
+    }
+}

diff --git a/tests/src/JIT/Regression/JitBlue/DevDiv_280120/DevDiv_280120.csproj b/tests/src/JIT/Regression/JitBlue/DevDiv_280120/DevDiv_280120.csproj
new file mode 100644 (file)
index 0000000..bcbdc0f
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/DevDiv_280120/DevDiv_280120.csproj
@@ -0,0 +1,56 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <AssemblyName>$(MSBuildProjectName)</AssemblyName>
+    <SchemaVersion>2.0</SchemaVersion>
+    <ProjectGuid>{95DFC527-4DC1-495E-97D7-E94EE1F7140D}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <FileAlignment>512</FileAlignment>
+    <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <ReferencePath>$(ProgramFiles)\Common Files\microsoft shared\VSTT\11.0\UITestExtensionPackages</ReferencePath>
+    <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
+
+    <NuGetPackageImportStamp>7a9bfb7d</NuGetPackageImportStamp>
+  </PropertyGroup>
+  <!-- Default configurations to help VS understand the configurations -->
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+  </PropertyGroup>
+  <ItemGroup>
+    <CodeAnalysisDependentAssemblyPaths Condition=" '$(VS100COMNTOOLS)' != '' " Include="$(VS100COMNTOOLS)..\IDE\PrivateAssemblies">
+      <Visible>False</Visible>
+    </CodeAnalysisDependentAssemblyPaths>
+  </ItemGroup>
+  <PropertyGroup>
+    <DebugType></DebugType>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="DevDiv_280120.cs" />
+  </ItemGroup>
+  <PropertyGroup>
+    <CLRTestBatchPreCommands><![CDATA[
+$(CLRTestBatchPreCommands)
+set COMPlus_JitDoSsa=0
+]]></CLRTestBatchPreCommands>
+  <BashCLRTestPreCommands><![CDATA[
+$(BashCLRTestPreCommands)
+export COMPlus_JitDoSsa=0
+]]></BashCLRTestPreCommands>
+  </PropertyGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
+  <PropertyGroup>
+    <ProjectJson>$(JitPackagesConfigFileDirectory)minimal\project.json</ProjectJson>
+    <ProjectLockJson>$(JitPackagesConfigFileDirectory)minimal\project.lock.json</ProjectLockJson>
+  </PropertyGroup>
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
+  <PropertyGroup Condition=" '$(MsBuildProjectDirOverride)' != '' ">
+  </PropertyGroup> 
+</Project>