[release/3.1] Port fix for JIT silent bad code

src/jit/importer.cpp

@@ -10837,11 +10837,22 @@ void Compiler::impImportBlockCode(BasicBlock* block)
  }
  else if (lhs->OperIsBlk())
  {
- // Check for ADDR(LCL_VAR), or ADD(ADDR(LCL_VAR),CNS_INT))
- // (the latter may appear explicitly in the IL).
- // Local field stores will cause the stack to be spilled when
- // they are encountered.
- lclVar = lhs->AsBlk()->Addr()->IsLocalAddrExpr();
+ // Check if LHS address is within some struct local, to catch
+ // cases where we're updating the struct by something other than a stfld
+ GenTree* addr = lhs->AsBlk()->Addr();
+
+ // Catches ADDR(LCL_VAR), or ADD(ADDR(LCL_VAR),CNS_INT))
+ lclVar = addr->IsLocalAddrExpr();
+
+ // Catches ADDR(FIELD(... ADDR(LCL_VAR)))
+ if (lclVar == nullptr)
+ {
+ GenTree* lclTree = nullptr;
+ if (impIsAddressInLocal(addr, &lclTree))
+ {
+ lclVar = lclTree->AsLclVarCommon();
+ }
+ }
  }
  if (lclVar != nullptr)
  {

tests/src/JIT/Regression/JitBlue/Runtime_764/Runtime_764.cs

@@ -0,0 +1,52 @@
+// 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.
+
+using System;
+using System.Runtime.CompilerServices;
+
+// Regression test case for importer bug.
+// If Release is inlined into Main, the importer may unsafely re-order trees.
+
+public struct Ptr<T> where T: class
+{
+ public Ptr(T value)
+ {
+ _value = value;
+ }
+
+ public T Release()
+ {
+ T tmp = _value;
+ _value = null;
+ return tmp;
+ }
+
+ T _value;
+}
+
+class Runtime_764
+{
+ private static int Main(string[] args)
+ {
+ Ptr<string> ptr = new Ptr<string>("Hello, world");
+
+ bool res = false;
+ while (res)
+ {
+ }
+
+ string summary = ptr.Release();
+
+ if (summary == null)
+ {
+ Console.WriteLine("FAILED");
+ return -1;
+ }
+ else
+ {
+ Console.WriteLine("PASSED");
+ return 100;
+ }
+ }
+}

tests/src/JIT/Regression/JitBlue/Runtime_764/Runtime_764.csproj

@@ -0,0 +1,33 @@
+<?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>
+ <SchemaVersion>2.0</SchemaVersion>
+ <ProjectGuid>{95DFC527-4DC1-495E-97D7-E94EE1F7140D}</ProjectGuid>
+ <OutputType>Exe</OutputType>
+ <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+ <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
+ </PropertyGroup>
+ <!-- Default configurations to help VS understand the configurations -->
+ <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' "></PropertyGroup>
+ <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' " />
+ <ItemGroup>
+ <CodeAnalysisDependentAssemblyPaths Condition=" '$(VS100COMNTOOLS)' != '' " Include="$(VS100COMNTOOLS)..\IDE\PrivateAssemblies">
+ <Visible>False</Visible>
+ </CodeAnalysisDependentAssemblyPaths>
+ </ItemGroup>
+ <PropertyGroup>
+ <DebugType>None</DebugType>
+ <Optimize>True</Optimize>
+ </PropertyGroup>
+ <ItemGroup>
+ <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+ </ItemGroup>
+ <ItemGroup>
+ <Compile Include="$(MSBuildProjectName).cs" />
+ </ItemGroup>
+ <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
+ <PropertyGroup Condition=" '$(MsBuildProjectDirOverride)' != '' "></PropertyGroup>
+</Project>