From 457041e022a89023bda57b306d71d02c0db8fbd7 Mon Sep 17 00:00:00 2001
From: EgorBo <egorbo@gmail.com>
Date: Fri, 12 Apr 2024 17:23:09 +0200
Subject: [PATCH] JIT: Track sideness of arrOp in GetCheckedBoundArithInfo

---
 src/coreclr/jit/optcse.cpp                    |  7 ++++--
 src/coreclr/jit/valuenum.cpp                  | 14 ++++++-----
 src/coreclr/jit/valuenum.h                    |  3 ++-
 .../JitBlue/Runtime_100809/Runtime_100809.cs  | 23 +++++++++++++++++++
 .../Runtime_100809/Runtime_100809.csproj      |  5 ++++
 5 files changed, 43 insertions(+), 9 deletions(-)
 create mode 100644 src/tests/JIT/Regression/JitBlue/Runtime_100809/Runtime_100809.cs
 create mode 100644 src/tests/JIT/Regression/JitBlue/Runtime_100809/Runtime_100809.csproj

diff --git a/src/coreclr/jit/optcse.cpp b/src/coreclr/jit/optcse.cpp
index 4e7fc81df64bc..505352250f4ec 100644
--- a/src/coreclr/jit/optcse.cpp
+++ b/src/coreclr/jit/optcse.cpp
@@ -3066,8 +3066,11 @@ class CSE_Heuristic
 
                                 assert(vnStore->IsVNCompareCheckedBoundArith(oldCmpVN));
                                 vnStore->GetCompareCheckedBoundArithInfo(oldCmpVN, &info);
-                                newCmpArgVN = vnStore->VNForFunc(vnStore->TypeOfVN(info.arrOp), (VNFunc)info.arrOper,
-                                                                 info.arrOp, theConservativeVN);
+                                ValueNum arrOp1 = info.arrOpLHS ? info.arrOp : theConservativeVN;
+                                ValueNum arrOp2 = info.arrOpLHS ? theConservativeVN : info.arrOp;
+
+                                newCmpArgVN =
+                                    vnStore->VNForFunc(vnStore->TypeOfVN(info.arrOp), (VNFunc)info.arrOper, arrOp1, arrOp2);
                             }
                             ValueNum newCmpVN = vnStore->VNForFunc(vnStore->TypeOfVN(oldCmpVN), (VNFunc)info.cmpOper,
                                                                    info.cmpOp, newCmpArgVN);
diff --git a/src/coreclr/jit/valuenum.cpp b/src/coreclr/jit/valuenum.cpp
index fa60633afbc23..fbc80330eb92f 100644
--- a/src/coreclr/jit/valuenum.cpp
+++ b/src/coreclr/jit/valuenum.cpp
@@ -6576,15 +6576,17 @@ void ValueNumStore::GetCheckedBoundArithInfo(ValueNum vn, CompareCheckedBoundAri
     bool isOp1CheckedBound = IsVNCheckedBound(funcArith.m_args[1]);
     if (isOp1CheckedBound)
     {
-        info->arrOper = funcArith.m_func;
-        info->arrOp   = funcArith.m_args[0];
-        info->vnBound = funcArith.m_args[1];
+        info->arrOper  = funcArith.m_func;
+        info->arrOp    = funcArith.m_args[0];
+        info->vnBound  = funcArith.m_args[1];
+        info->arrOpLHS = true;
     }
     else
     {
-        info->arrOper = funcArith.m_func;
-        info->arrOp   = funcArith.m_args[1];
-        info->vnBound = funcArith.m_args[0];
+        info->arrOper  = funcArith.m_func;
+        info->arrOp    = funcArith.m_args[1];
+        info->vnBound  = funcArith.m_args[0];
+        info->arrOpLHS = false;
     }
 }
 
diff --git a/src/coreclr/jit/valuenum.h b/src/coreclr/jit/valuenum.h
index 04fed7bfbc1f6..af6ba52901483 100644
--- a/src/coreclr/jit/valuenum.h
+++ b/src/coreclr/jit/valuenum.h
@@ -920,9 +920,10 @@ class ValueNumStore
         ValueNum vnBound;
         unsigned arrOper;
         ValueNum arrOp;
+        bool     arrOpLHS; // arrOp is on the left side of cmpOp expression
         unsigned cmpOper;
         ValueNum cmpOp;
-        CompareCheckedBoundArithInfo() : vnBound(NoVN), arrOper(GT_NONE), arrOp(NoVN), cmpOper(GT_NONE), cmpOp(NoVN)
+        CompareCheckedBoundArithInfo() : vnBound(NoVN), arrOper(GT_NONE), arrOp(NoVN), arrOpLHS(false), cmpOper(GT_NONE), cmpOp(NoVN)
         {
         }
 #ifdef DEBUG
diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_100809/Runtime_100809.cs b/src/tests/JIT/Regression/JitBlue/Runtime_100809/Runtime_100809.cs
new file mode 100644
index 0000000000000..e7c94f11ac2dc
--- /dev/null
+++ b/src/tests/JIT/Regression/JitBlue/Runtime_100809/Runtime_100809.cs
@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Runtime.CompilerServices;
+using Xunit;
+
+public static class Runtime_100809
+{
+    [Fact]
+    public static int TestEntryPoint()
+    {
+        return AlwaysFalse(96) ? -1 : 100;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static bool AlwaysFalse(int x)
+    {
+        var result = new byte[x];
+        int count = result.Length - 2;
+        return (x < 0 || result.Length - count < 0);
+    }
+}
\ No newline at end of file
diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_100809/Runtime_100809.csproj b/src/tests/JIT/Regression/JitBlue/Runtime_100809/Runtime_100809.csproj
new file mode 100644
index 0000000000000..197767e2c4e24
--- /dev/null
+++ b/src/tests/JIT/Regression/JitBlue/Runtime_100809/Runtime_100809.csproj
@@ -0,0 +1,5 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+</Project>