From 7a50b43361692906680d99985e08a9e9884ce317 Mon Sep 17 00:00:00 2001
From: Aman Khalid <amankhalid@microsoft.com>
Date: Tue, 20 Aug 2024 18:51:37 +0000
Subject: [PATCH] JIT: Cast UInt64 to Single directly during const folding
 (#106419)

---
 src/coreclr/jit/gentree.cpp                   |  2 +-
 src/coreclr/jit/utils.cpp                     |  3 +-
 .../JitBlue/Runtime_106338/Runtime_106338.cs  | 36 +++++++++++++++++++
 .../Runtime_106338/Runtime_106338.csproj      |  8 +++++
 4 files changed, 46 insertions(+), 3 deletions(-)
 create mode 100644 src/tests/JIT/Regression/JitBlue/Runtime_106338/Runtime_106338.cs
 create mode 100644 src/tests/JIT/Regression/JitBlue/Runtime_106338/Runtime_106338.csproj

diff --git a/src/coreclr/jit/gentree.cpp b/src/coreclr/jit/gentree.cpp
index f687f9139f598..50adf99687d37 100644
--- a/src/coreclr/jit/gentree.cpp
+++ b/src/coreclr/jit/gentree.cpp
@@ -15607,7 +15607,7 @@ GenTree* Compiler::gtFoldExprConst(GenTree* tree)
 
                             case TYP_FLOAT:
                             {
-#if defined(TARGET_64BIT)
+#ifdef TARGET_64BIT
                                 if (tree->IsUnsigned() && (lval1 < 0))
                                 {
                                     f1 = FloatingPointUtils::convertUInt64ToFloat((uint64_t)lval1);
diff --git a/src/coreclr/jit/utils.cpp b/src/coreclr/jit/utils.cpp
index 209b23ac6f46a..cbee0be015818 100644
--- a/src/coreclr/jit/utils.cpp
+++ b/src/coreclr/jit/utils.cpp
@@ -2272,8 +2272,7 @@ double FloatingPointUtils::convertUInt64ToDouble(uint64_t uIntVal)
 
 float FloatingPointUtils::convertUInt64ToFloat(uint64_t u64)
 {
-    double d = convertUInt64ToDouble(u64);
-    return (float)d;
+    return (float)u64;
 }
 
 uint64_t FloatingPointUtils::convertDoubleToUInt64(double d)
diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_106338/Runtime_106338.cs b/src/tests/JIT/Regression/JitBlue/Runtime_106338/Runtime_106338.cs
new file mode 100644
index 0000000000000..5cc1b75d42fda
--- /dev/null
+++ b/src/tests/JIT/Regression/JitBlue/Runtime_106338/Runtime_106338.cs
@@ -0,0 +1,36 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+// Generated by Fuzzlyn v2.2 on 2024-08-13 00:04:04
+// Run on Arm64 MacOS
+// Seed: 13207615092246842583-vectort,vector64,vector128,armadvsimd,armadvsimdarm64,armaes,armarmbase,armarmbasearm64,armcrc32,armcrc32arm64,armdp,armrdm,armrdmarm64,armsha1,armsha256
+// Reduced from 226.8 KiB to 0.4 KiB in 00:02:12
+// Debug: Outputs 1600094603
+// Release: Outputs 1600094604
+using System;
+using System.Runtime.InteropServices;
+using System.Runtime.Intrinsics.X86;
+using Xunit;
+
+public class Runtime_106338
+{
+    [Fact]
+    [SkipOnMono("https://github.com/dotnet/runtime/issues/100368", TestPlatforms.Any)]
+    public static void TestEntryPoint()
+    {
+        ulong vr10 = 16105307123914158031UL;
+        float vr11 = 4294967295U | vr10;
+        uint result = BitConverter.SingleToUInt32Bits(vr11);
+
+        if ((RuntimeInformation.ProcessArchitecture == Architecture.Arm64) || ((RuntimeInformation.ProcessArchitecture == Architecture.X64) && Avx512F.IsSupported))
+        {
+            // Expected to cast ulong -> float directly
+            Assert.Equal(1600094603U, result);
+        }
+        else
+        {
+            // Expected to cast ulong -> double -> float
+            Assert.Equal(1600094604U, result);
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_106338/Runtime_106338.csproj b/src/tests/JIT/Regression/JitBlue/Runtime_106338/Runtime_106338.csproj
new file mode 100644
index 0000000000000..de6d5e08882e8
--- /dev/null
+++ b/src/tests/JIT/Regression/JitBlue/Runtime_106338/Runtime_106338.csproj
@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+</Project>