Enable range check code in MDArray accessors

The code was already there, but ILEmitter didn't support labels at the
time it was written.

We now emit IL to check the bounds of multidimensional arrays in
Get/Set/Address methods and throw an IndexOutOfRangeException if an out
of bounds access was made.

Fixes half of what's in scope for issue #89.

2 files changed, 39 insertions, 0 deletions

diff --git a/src/ILCompiler.Compiler/src/IL/HelperExtensions.cs b/src/ILCompiler.Compiler/src/IL/HelperExtensions.cs
new file mode 100644
index 000000000..a16595f0b
--- /dev/null
+++ b/src/ILCompiler.Compiler/src/IL/HelperExtensions.cs
@@ -0,0 +1,38 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+
+using ILCompiler;
+using Internal.TypeSystem;
+
+namespace Internal.IL
+{
+    static class HelperExtensions
+    {
+        public static MetadataType GetHelperType(this TypeSystemContext context, string name)
+        {
+            MetadataType helperType = ((CompilerTypeSystemContext)context).SystemModule.GetType("Internal.Runtime.CompilerHelpers", name, false);
+            if (helperType == null)
+            {
+                // TODO: throw the exception that means 'Core Library doesn't have a required thing in it'
+                throw new NotImplementedException();
+            }
+
+            return helperType;
+        }
+
+        public static MethodDesc GetHelperEntryPoint(this TypeSystemContext context, string typeName, string methodName)
+        {
+            MetadataType helperType = context.GetHelperType(typeName);
+            MethodDesc helperMethod = helperType.GetMethod(methodName, null);
+            if (helperMethod == null)
+            {
+                // TODO: throw the exception that means 'Core Library doesn't have a required thing in it'
+                throw new NotImplementedException();
+            }
+
+            return helperMethod;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/ILCompiler.Compiler/src/ILCompiler.Compiler.csproj b/src/ILCompiler.Compiler/src/ILCompiler.Compiler.csproj
index 7213aa62e..01a1404fe 100644
--- a/src/ILCompiler.Compiler/src/ILCompiler.Compiler.csproj
+++ b/src/ILCompiler.Compiler/src/ILCompiler.Compiler.csproj
@@ -81,6 +81,7 @@
     <Compile Include="Compiler\RvaFieldData.cs" />
     <Compile Include="Compiler\IntrinsicMethods.cs" />
     <Compile Include="CppCodeGen\CppWriter.cs" />
+    <Compile Include="IL\HelperExtensions.cs" />
   </ItemGroup>
   <ItemGroup>
     <Compile Include="..\..\Common\src\System\Collections\Generic\ArrayBuilder.cs">