From f5b90198460fe6fbee9247166b789793a3a58a23 Mon Sep 17 00:00:00 2001
From: Tanner Gooding <tagoo@outlook.com>
Date: Thu, 25 Jul 2024 12:27:33 -0700
Subject: [PATCH] Ensure we don't reuse temps when calling fgMorphArgs on LIR
 nodes

---
 src/coreclr/jit/morph.cpp                     |  4 +-
 .../JitBlue/Runtime_105468/Runtime_105468.cs  | 45 +++++++++++++++++++
 .../Runtime_105468/Runtime_105468.csproj      |  8 ++++
 3 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 src/tests/JIT/Regression/JitBlue/Runtime_105468/Runtime_105468.cs
 create mode 100644 src/tests/JIT/Regression/JitBlue/Runtime_105468/Runtime_105468.csproj

diff --git a/src/coreclr/jit/morph.cpp b/src/coreclr/jit/morph.cpp
index 0d922459acdc4..74389eca4143f 100644
--- a/src/coreclr/jit/morph.cpp
+++ b/src/coreclr/jit/morph.cpp
@@ -3283,8 +3283,8 @@ void Compiler::fgMakeOutgoingStructArgCopy(GenTreeCall* call, CallArg* arg)
     bool                 found        = false;
 
     // Attempt to find a local we have already used for an outgoing struct and reuse it.
-    // We do not reuse within a statement.
-    if (!opts.MinOpts())
+    // We do not reuse within a statement and we don't reuse if we're in LIR
+    if (!opts.MinOpts() && (fgOrder == FGOrderTree))
     {
         found = ForEachHbvBitSet(*fgAvailableOutgoingArgTemps, [&](indexType lclNum) {
             LclVarDsc*   varDsc = lvaGetDesc((unsigned)lclNum);
diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_105468/Runtime_105468.cs b/src/tests/JIT/Regression/JitBlue/Runtime_105468/Runtime_105468.cs
new file mode 100644
index 0000000000000..c6498096c371e
--- /dev/null
+++ b/src/tests/JIT/Regression/JitBlue/Runtime_105468/Runtime_105468.cs
@@ -0,0 +1,45 @@
+// Generated by Fuzzlyn v1.7 on 2024-07-25 11:40:55
+// Run on X64 Windows
+// Seed: 418121815423725559-vectort,vector128,vector256,x86aes,x86avx,x86avx2,x86bmi1,x86bmi1x64,x86bmi2,x86bmi2x64,x86fma,x86lzcnt,x86lzcntx64,x86pclmulqdq,x86popcnt,x86popcntx64,x86sse,x86ssex64,x86sse2,x86sse2x64,x86sse3,x86sse41,x86sse41x64,x86sse42,x86sse42x64,x86ssse3,x86x86base
+// Reduced from 72.7 KiB to 1.0 KiB in 00:01:55
+// Debug: Outputs <0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0>
+// Release: Outputs <1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1>
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.X86;
+using Xunit;
+
+[module: SkipLocalsInit]
+
+public struct S3
+{
+    public byte F0;
+}
+
+public class Runtime_105468
+{
+    public static S3 s_3;
+
+    [Fact]
+    public static void TestEntryPoint()
+    {
+        if (Avx2.IsSupported)
+        {
+            var vr15 = (ushort)0;
+            var vr16 = Vector256.CreateScalar(vr15);
+            var vr17 = Vector256.Create<ushort>(1);
+            var vr18 = (ushort)0;
+            var vr19 = Vector256.CreateScalar(vr18);
+            var vr20 = s_3.F0;
+            var vr21 = Avx2.AlignRight(vr17, vr19, vr20);
+            M6(vr16, vr21);
+        }
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static void M6(Vector256<ushort> arg1, Vector256<ushort> arg3)
+    {
+        Assert.Equal(Vector256<ushort>.Zero, arg1);
+    }
+}
diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_105468/Runtime_105468.csproj b/src/tests/JIT/Regression/JitBlue/Runtime_105468/Runtime_105468.csproj
new file mode 100644
index 0000000000000..de6d5e08882e8
--- /dev/null
+++ b/src/tests/JIT/Regression/JitBlue/Runtime_105468/Runtime_105468.csproj
@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+</Project>