JIT: fix spill logic for local structs

src/coreclr/src/jit/importer.cpp

@@ -10831,11 +10831,22 @@ 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)
  {

src/coreclr/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
+{
+ private T _value;
+
+ public Ptr(T value)
+ {
+ _value = value;
+ }
+
+ public T Release()
+ {
+ T tmp = _value;
+ _value = null;
+ return tmp;
+ }
+}
+
+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;
+ }
+ }
+}

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

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+ <PropertyGroup>
+ <OutputType>Exe</OutputType>
+ <DebugType>None</DebugType>
+ <Optimize>True</Optimize>
+ </PropertyGroup>
+ <ItemGroup>
+ <Compile Include="$(MSBuildProjectName).cs" />
+ </ItemGroup>
+</Project>