Preserve VNs in fgMorphIntoHelperCall.

This method is used to transform a node into a semantically-equivalent
helper call, and should preserve any value numbers that are present on
the the node.

3 files changed, 178 insertions, 1 deletions

diff --git a/src/jit/morph.cpp b/src/jit/morph.cpp
index 92d5e0967e..308eaf04ee 100644
--- a/src/jit/morph.cpp
+++ b/src/jit/morph.cpp
@@ -60,7 +60,8 @@ GenTreePtr Compiler::fgMorphCastIntoHelper(GenTreePtr tree, int helper, GenTreeP
 
 GenTreePtr Compiler::fgMorphIntoHelperCall(GenTreePtr tree, int helper, GenTreeArgList* args)
 {
-    tree->ChangeOper(GT_CALL);
+    // The helper call ought to be semantically equivalent to the original node, so preserve its VN.
+    tree->ChangeOper(GT_CALL, GenTree::PRESERVE_VN);
 
     tree->gtFlags |= GTF_CALL;
     if (args)
diff --git a/tests/src/JIT/Regression/JitBlue/DevDiv_397793/DevDiv_397793.il b/tests/src/JIT/Regression/JitBlue/DevDiv_397793/DevDiv_397793.il
new file mode 100644
index 0000000000..0e3599566b
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/DevDiv_397793/DevDiv_397793.il
@@ -0,0 +1,142 @@
+// 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.
+
+.assembly extern mscorlib{}
+.assembly ILGEN_MODULE{}
+.class ILGEN_CLASS
+{
+    .method static float32 ILGEN_METHOD(int16, char, char, native int)
+    {
+        .maxstack  65535
+        .locals init (int8, native unsigned int, int64, int8, bool, unsigned int64, char, float64, int64, native int, float32, int64, int64, unsigned int16)
+
+        IL_0000: ldloc 0x000d
+        IL_0004: not
+        IL_0005: ldloc.s 0x06
+        IL_0007: cgt.un
+        IL_0009: ldloc.s 0x06
+        IL_000b: clt.un
+        IL_000d: conv.r4
+        IL_000e: ldloc.s 0x08
+        IL_0010: conv.r.un
+        IL_0011: mul
+        IL_0012: conv.i8
+        IL_0013: ldloc.s 0x03
+        IL_0015: conv.u1
+        IL_0016: not
+        IL_0017: ldloc.s 0x00
+        IL_0019: ldloc.s 0x07
+        IL_001b: neg
+        IL_001c: conv.u1
+        IL_001d: xor
+        IL_001e: sub
+        IL_001f: ldloc 0x000c
+        IL_0023: neg
+        IL_0024: conv.i8
+        IL_0025: ldloc.s 0x07
+        IL_0027: neg
+        IL_0028: conv.u8
+        IL_0029: conv.i8
+        IL_002a: ldc.i4 0x2487c9b5
+        IL_002f: conv.i8
+        IL_0030: rem.un
+        IL_0031: ldloc.s 0x09
+        IL_0033: conv.i8
+        IL_0034: ldloc.s 0x01
+        IL_0036: neg
+        IL_0037: not
+        IL_0038: ldloc 0x0006
+        IL_003c: mul
+        IL_003d: shr.un
+        IL_003e: add
+        IL_003f: ldloc.s 0x0b
+        IL_0041: conv.i4
+        IL_0042: shr.un
+        IL_0043: ldarg.s 0x03
+        IL_0045: conv.i4
+        IL_0046: ldloc.s 0x00
+        IL_0048: clt
+        IL_004a: neg
+        IL_004b: ldloc.s 0x09
+        IL_004d: pop
+        IL_004e: conv.r.un
+        IL_004f: conv.u8
+        IL_0050: ldloc.s 0x05
+        IL_0052: mul
+        IL_0053: ldloc.s 0x0c
+        IL_0055: conv.i8
+        IL_0056: not
+        IL_0057: cgt.un
+        IL_0059: neg
+        IL_005a: nop
+        IL_005b: shl
+        IL_005c: ldc.i8 0x6ddee7e52bcb7a50
+        IL_0065: ldloc 0x0004
+        IL_0069: shr.un
+        IL_006a: pop
+        IL_006b: and
+        IL_006c: conv.u2
+        IL_006d: add
+        IL_006e: ldarg.s 0x02
+        IL_0070: not
+        IL_0071: neg
+        IL_0072: pop
+        IL_0073: ldarg.s 0x01
+        IL_0075: ldloc 0x0008
+        IL_0079: ldloc 0x000b
+        IL_007d: clt
+        IL_007f: conv.r.un
+        IL_0080: pop
+        IL_0081: ldloc 0x000c
+        IL_0085: not
+        IL_0086: ldloc.s 0x0c
+        IL_0088: conv.u8
+        IL_0089: mul
+        IL_008a: ldloc 0x000b
+        IL_008e: add
+        IL_008f: ldloc 0x0002
+        IL_0093: ldloc.s 0x0b
+        IL_0095: rem
+        IL_0096: ldc.i8 0xfe6f83985a745065
+        IL_009f: add
+        IL_00a0: neg
+        IL_00a1: cgt.un
+        IL_00a3: shr
+        IL_00a4: conv.u8
+        IL_00a5: nop
+        IL_00a6: neg
+        IL_00a7: neg
+        IL_00a8: pop
+        IL_00a9: shr
+        IL_00aa: nop
+        IL_00ab: conv.r.un
+        IL_00ac: ret   
+    }
+
+    .method public static int32 Main()
+    {
+        .entrypoint
+
+        .try
+        {
+            ldc.i4 0
+            ldc.i4 0
+            ldc.i4 0
+            ldc.i4 0
+            conv.i
+            call float32 ILGEN_CLASS::ILGEN_METHOD(int16, char, char, native int)
+            pop
+            leave done
+        }
+        catch [mscorlib]System.Exception
+        {
+            pop
+            leave done
+        }
+
+    done:
+        ldc.i4 100
+        ret
+    }
+}
diff --git a/tests/src/JIT/Regression/JitBlue/DevDiv_397793/DevDiv_397793.ilproj b/tests/src/JIT/Regression/JitBlue/DevDiv_397793/DevDiv_397793.ilproj
new file mode 100644
index 0000000000..c722432ef9
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/DevDiv_397793/DevDiv_397793.ilproj
@@ -0,0 +1,34 @@
+<?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>
+    <AssemblyName>$(MSBuildProjectName)</AssemblyName>
+    <SchemaVersion>2.0</SchemaVersion>
+    <ProjectGuid>{95DFC527-4DC1-495E-97D7-E94EE1F7140D}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
+  </PropertyGroup>
+  <!-- Default configurations to help VS understand the configurations -->
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' "></PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' "></PropertyGroup>
+  <ItemGroup>
+    <CodeAnalysisDependentAssemblyPaths Condition=" '$(VS100COMNTOOLS)' != '' " Include="$(VS100COMNTOOLS)..\IDE\PrivateAssemblies">
+      <Visible>False</Visible>
+    </CodeAnalysisDependentAssemblyPaths>
+  </ItemGroup>
+  <PropertyGroup>
+    <DebugType>PdbOnly</DebugType>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="DevDiv_397793.il" />
+  </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
+  <PropertyGroup Condition=" '$(MsBuildProjectDirOverride)' != '' "></PropertyGroup>
+</Project>