Emit conversions between native integers and pointers directly (#47708)

src/Compilers/CSharp/Portable/Binder/Semantics/Conversions/ConversionsBase.cs

@@ -1917,16 +1917,20 @@ private static bool HasSpecialIntPtrConversion(TypeSymbol source, TypeSymbol tar
             var s0 = source.StrippedType();
             var t0 = target.StrippedType();
 
-            if (s0.SpecialType != SpecialType.System_UIntPtr &&
-                s0.SpecialType != SpecialType.System_IntPtr &&
-                t0.SpecialType != SpecialType.System_UIntPtr &&
-                t0.SpecialType != SpecialType.System_IntPtr)
+            TypeSymbol otherType;
+            if (isIntPtrOrUIntPtr(s0))
+            {
+                otherType = t0;
+            }
+            else if (isIntPtrOrUIntPtr(t0))
+            {
+                otherType = s0;
+            }
+            else
             {
                 return false;
             }
 
-            TypeSymbol otherType = (s0.SpecialType == SpecialType.System_UIntPtr || s0.SpecialType == SpecialType.System_IntPtr) ? t0 : s0;
-
             if (otherType.IsPointerOrFunctionPointer())
             {
                 return true;
@@ -1955,6 +1959,9 @@ private static bool HasSpecialIntPtrConversion(TypeSymbol source, TypeSymbol tar
             }
 
             return false;
+
+            static bool isIntPtrOrUIntPtr(TypeSymbol type) =>
+                (type.SpecialType == SpecialType.System_IntPtr || type.SpecialType == SpecialType.System_UIntPtr) && !type.IsNativeIntegerType;
         }
 
         private static bool HasExplicitEnumerationConversion(TypeSymbol source, TypeSymbol destination)
@@ -3494,20 +3501,7 @@ private static bool HasPointerToIntegerConversion(TypeSymbol source, TypeSymbol
             // The spec should state that any pointer type is convertible to
             // sbyte, byte, ... etc, or any corresponding nullable type.
 
-            switch (destination.StrippedType().SpecialType)
-            {
-                case SpecialType.System_SByte:
-                case SpecialType.System_Byte:
-                case SpecialType.System_Int16:
-                case SpecialType.System_UInt16:
-                case SpecialType.System_Int32:
-                case SpecialType.System_UInt32:
-                case SpecialType.System_Int64:
-                case SpecialType.System_UInt64:
-                    return true;
-            }
-
-            return false;
+            return IsIntegerTypeSupportingPointerConversions(destination.StrippedType());
         }
 
         private static bool HasIntegerToPointerConversion(TypeSymbol source, TypeSymbol destination)
@@ -3521,8 +3515,12 @@ private static bool HasIntegerToPointerConversion(TypeSymbol source, TypeSymbol
             }
 
             // Note that void* is convertible to int?, but int? is not convertible to void*.
+            return IsIntegerTypeSupportingPointerConversions(source);
+        }
 
-            switch (source.SpecialType)
+        private static bool IsIntegerTypeSupportingPointerConversions(TypeSymbol type)
+        {
+            switch (type.SpecialType)
             {
                 case SpecialType.System_SByte:
                 case SpecialType.System_Byte:
@@ -3533,6 +3531,9 @@ private static bool HasIntegerToPointerConversion(TypeSymbol source, TypeSymbol
                 case SpecialType.System_Int64:
                 case SpecialType.System_UInt64:
                     return true;
+                case SpecialType.System_IntPtr:
+                case SpecialType.System_UIntPtr:
+                    return type.IsNativeIntegerType;
             }
 
             return false;

src/Compilers/CSharp/Portable/CodeGen/EmitConversion.cs

@@ -143,8 +143,8 @@ private void EmitConversion(BoundConversion conversion)
 #if DEBUG
                     switch (fromPredefTypeKind)
                     {
-                        case Microsoft.Cci.PrimitiveTypeCode.IntPtr:
-                        case Microsoft.Cci.PrimitiveTypeCode.UIntPtr:
+                        case Microsoft.Cci.PrimitiveTypeCode.IntPtr when !fromType.IsNativeIntegerType:
+                        case Microsoft.Cci.PrimitiveTypeCode.UIntPtr when !fromType.IsNativeIntegerType:
                         case Microsoft.Cci.PrimitiveTypeCode.Pointer:
                         case Microsoft.Cci.PrimitiveTypeCode.FunctionPointer:
                             Debug.Assert(IsNumeric(toType));
@@ -152,8 +152,7 @@ private void EmitConversion(BoundConversion conversion)
                         default:
                             Debug.Assert(IsNumeric(fromType));
                             Debug.Assert(
-                                toPredefTypeKind == Microsoft.Cci.PrimitiveTypeCode.IntPtr ||
-                                toPredefTypeKind == Microsoft.Cci.PrimitiveTypeCode.UIntPtr ||
+                                (toPredefTypeKind == Microsoft.Cci.PrimitiveTypeCode.IntPtr || toPredefTypeKind == Microsoft.Cci.PrimitiveTypeCode.UIntPtr) && !toType.IsNativeIntegerType ||
                                 toPredefTypeKind == Microsoft.Cci.PrimitiveTypeCode.Pointer ||
                                 toPredefTypeKind == Microsoft.Cci.PrimitiveTypeCode.FunctionPointer);
                             break;

src/Compilers/CSharp/Test/Semantic/Semantics/NativeIntegerTests.cs

@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
 using Microsoft.CodeAnalysis.CSharp.Symbols;
@@ -6963,16 +6962,8 @@ .maxstack  1
   IL_0006:  ret
 }");
             conversions(sourceType: "string", destType: "nint", expectedImplicitIL: null, expectedExplicitIL: null);
-            conversions(sourceType: "void*", destType: "nint", expectedImplicitIL: null,
-// https://github.com/dotnet/roslyn/issues/42457: Investigate whether this conversion (and other
-// conversions to/from void*) can use conv.i or conv.u instead of explicit operators on System.[U]IntPtr.
-@"{
-  // Code size        7 (0x7)
-  .maxstack  1
-  IL_0000:  ldarg.0
-  IL_0001:  call       ""System.IntPtr System.IntPtr.op_Explicit(void*)""
-  IL_0006:  ret
-}");
+            conversions(sourceType: "void*", destType: "nint", expectedImplicitIL: null, expectedExplicitIL: convNone, expectedCheckedIL: conv("conv.ovf.i.un"));
+            conversions(sourceType: "delegate*<void>", destType: "nint", expectedImplicitIL: null, expectedExplicitIL: convNone, expectedCheckedIL: conv("conv.ovf.i.un"));
             conversions(sourceType: "bool", destType: "nint", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "char", destType: "nint", expectedImplicitIL: conv("conv.u"), expectedExplicitIL: conv("conv.u"));
             conversions(sourceType: "sbyte", destType: "nint", expectedImplicitIL: conv("conv.i"), expectedExplicitIL: conv("conv.i"));
@@ -7066,12 +7057,35 @@ .maxstack  1
             conversions(sourceType: "string", destType: "nint?", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "void*", destType: "nint?", expectedImplicitIL: null,
 @"{
-  // Code size       12 (0xc)
+  // Code size        7 (0x7)
   .maxstack  1
   IL_0000:  ldarg.0
-  IL_0001:  call       ""System.IntPtr System.IntPtr.op_Explicit(void*)""
-  IL_0006:  newobj     ""nint?..ctor(nint)""
-  IL_000b:  ret
+  IL_0001:  newobj     ""nint?..ctor(nint)""
+  IL_0006:  ret
+}",
+@"{
+  // Code size        8 (0x8)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  conv.ovf.i.un
+  IL_0002:  newobj     ""nint?..ctor(nint)""
+  IL_0007:  ret
+}");
+            conversions(sourceType: "delegate*<void>", destType: "nint?", expectedImplicitIL: null,
+@"{
+  // Code size        7 (0x7)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  newobj     ""nint?..ctor(nint)""
+  IL_0006:  ret
+}",
+@"{
+  // Code size        8 (0x8)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  conv.ovf.i.un
+  IL_0002:  newobj     ""nint?..ctor(nint)""
+  IL_0007:  ret
 }");
             conversions(sourceType: "bool", destType: "nint?", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "char", destType: "nint?", expectedImplicitIL: convToNullableT("conv.u", "nint"), expectedExplicitIL: convToNullableT("conv.u", "nint"));
@@ -7211,14 +7225,8 @@ .maxstack  1
   IL_0006:  ret
 }");
             conversions(sourceType: "nint", destType: "string", expectedImplicitIL: null, expectedExplicitIL: null);
-            conversions(sourceType: "nint", destType: "void*", expectedImplicitIL: null,
-@"{
-  // Code size        7 (0x7)
-  .maxstack  1
-  IL_0000:  ldarg.0
-  IL_0001:  call       ""void* System.IntPtr.op_Explicit(System.IntPtr)""
-  IL_0006:  ret
-}");
+            conversions(sourceType: "nint", destType: "void*", expectedImplicitIL: null, expectedExplicitIL: convNone, expectedCheckedIL: conv("conv.ovf.u"));
+            conversions(sourceType: "nint", destType: "delegate*<void>", expectedImplicitIL: null, expectedExplicitIL: convNone, expectedCheckedIL: conv("conv.ovf.u"));
             conversions(sourceType: "nint", destType: "bool", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "nint", destType: "char", expectedImplicitIL: null, expectedExplicitIL: conv("conv.u2"), expectedCheckedIL: conv("conv.ovf.u2"));
             conversions(sourceType: "nint", destType: "sbyte", expectedImplicitIL: null, expectedExplicitIL: conv("conv.i1"), expectedCheckedIL: conv("conv.ovf.i1"));
@@ -7315,15 +7323,8 @@ .maxstack  1
   IL_0006:  ret
 }");
             conversions(sourceType: "nint?", destType: "string", expectedImplicitIL: null, expectedExplicitIL: null);
-            conversions(sourceType: "nint?", destType: "void*", expectedImplicitIL: null,
-@"{
-  // Code size       13 (0xd)
-  .maxstack  1
-  IL_0000:  ldarga.s   V_0
-  IL_0002:  call       ""nint nint?.Value.get""
-  IL_0007:  call       ""void* System.IntPtr.op_Explicit(System.IntPtr)""
-  IL_000c:  ret
-}");
+            conversions(sourceType: "nint?", destType: "void*", expectedImplicitIL: null, expectedExplicitIL: null);
+            conversions(sourceType: "nint?", destType: "delegate*<void>", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "nint?", destType: "bool", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "nint?", destType: "char", expectedImplicitIL: null, expectedExplicitIL: convFromNullableT("conv.u2", "nint"), expectedCheckedIL: convFromNullableT("conv.ovf.u2", "nint"));
             conversions(sourceType: "nint?", destType: "sbyte", expectedImplicitIL: null, expectedExplicitIL: convFromNullableT("conv.i1", "nint"), expectedCheckedIL: convFromNullableT("conv.ovf.i1", "nint"));
@@ -7421,14 +7422,8 @@ .maxstack  1
   IL_0006:  ret
 }");
             conversions(sourceType: "string", destType: "nuint", expectedImplicitIL: null, expectedExplicitIL: null);
-            conversions(sourceType: "void*", destType: "nuint", expectedImplicitIL: null,
-@"{
-  // Code size        7 (0x7)
-  .maxstack  1
-  IL_0000:  ldarg.0
-  IL_0001:  call       ""System.UIntPtr System.UIntPtr.op_Explicit(void*)""
-  IL_0006:  ret
-}");
+            conversions(sourceType: "void*", destType: "nuint", expectedImplicitIL: null, expectedExplicitIL: convNone);
+            conversions(sourceType: "delegate*<void>", destType: "nuint", expectedImplicitIL: null, expectedExplicitIL: convNone);
             conversions(sourceType: "bool", destType: "nuint", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "char", destType: "nuint", expectedImplicitIL: conv("conv.u"), expectedExplicitIL: conv("conv.u"));
             conversions(sourceType: "sbyte", destType: "nuint", expectedImplicitIL: conv("conv.i"), expectedExplicitIL: conv("conv.i"), expectedCheckedIL: conv("conv.ovf.u"));
@@ -7522,12 +7517,19 @@ .maxstack  1
             conversions(sourceType: "string", destType: "nuint?", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "void*", destType: "nuint?", expectedImplicitIL: null,
 @"{
-  // Code size       12 (0xc)
+  // Code size        7 (0x7)
   .maxstack  1
   IL_0000:  ldarg.0
-  IL_0001:  call       ""System.UIntPtr System.UIntPtr.op_Explicit(void*)""
-  IL_0006:  newobj     ""nuint?..ctor(nuint)""
-  IL_000b:  ret
+  IL_0001:  newobj     ""nuint?..ctor(nuint)""
+  IL_0006:  ret
+}");
+            conversions(sourceType: "delegate*<void>", destType: "nuint?", expectedImplicitIL: null,
+@"{
+  // Code size        7 (0x7)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  newobj     ""nuint?..ctor(nuint)""
+  IL_0006:  ret
 }");
             conversions(sourceType: "bool", destType: "nuint?", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "char", destType: "nuint?", expectedImplicitIL: convToNullableT("conv.u", "nuint"), expectedExplicitIL: convToNullableT("conv.u", "nuint"));
@@ -7667,14 +7669,8 @@ .maxstack  1
   IL_0006:  ret
 }");
             conversions(sourceType: "nuint", destType: "string", expectedImplicitIL: null, expectedExplicitIL: null);
-            conversions(sourceType: "nuint", destType: "void*", expectedImplicitIL: null,
-@"{
-  // Code size        7 (0x7)
-  .maxstack  1
-  IL_0000:  ldarg.0
-  IL_0001:  call       ""void* System.UIntPtr.op_Explicit(System.UIntPtr)""
-  IL_0006:  ret
-}");
+            conversions(sourceType: "nuint", destType: "void*", expectedImplicitIL: null, expectedExplicitIL: convNone);
+            conversions(sourceType: "nuint", destType: "delegate*<void>", expectedImplicitIL: null, expectedExplicitIL: convNone);
             conversions(sourceType: "nuint", destType: "bool", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "nuint", destType: "char", expectedImplicitIL: null, expectedExplicitIL: conv("conv.u2"), expectedCheckedIL: conv("conv.ovf.u2.un"));
             conversions(sourceType: "nuint", destType: "sbyte", expectedImplicitIL: null, expectedExplicitIL: conv("conv.i1"), expectedCheckedIL: conv("conv.ovf.i1.un"));
@@ -7769,15 +7765,8 @@ .maxstack  1
   IL_0006:  ret
 }");
             conversions(sourceType: "nuint?", destType: "string", expectedImplicitIL: null, expectedExplicitIL: null);
-            conversions(sourceType: "nuint?", destType: "void*", expectedImplicitIL: null,
-@"{
-  // Code size       13 (0xd)
-  .maxstack  1
-  IL_0000:  ldarga.s   V_0
-  IL_0002:  call       ""nuint nuint?.Value.get""
-  IL_0007:  call       ""void* System.UIntPtr.op_Explicit(System.UIntPtr)""
-  IL_000c:  ret
-}");
+            conversions(sourceType: "nuint?", destType: "void*", expectedImplicitIL: null, expectedExplicitIL: null);
+            conversions(sourceType: "nuint?", destType: "delegate*<void>", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "nuint?", destType: "bool", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "nuint?", destType: "char", expectedImplicitIL: null, expectedExplicitIL: convFromNullableT("conv.u2", "nuint"), expectedCheckedIL: convFromNullableT("conv.ovf.u2.un", "nuint"));
             conversions(sourceType: "nuint?", destType: "sbyte", expectedImplicitIL: null, expectedExplicitIL: convFromNullableT("conv.i1", "nuint"), expectedCheckedIL: convFromNullableT("conv.ovf.i1.un", "nuint"));
@@ -7883,6 +7872,7 @@ .maxstack  1
 }");
             conversions(sourceType: "System.IntPtr", destType: "string", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "System.IntPtr", destType: "void*", expectedImplicitIL: null, expectedExplicitIL: convAndExplicit("void* System.IntPtr.op_Explicit(System.IntPtr)"));
+            conversions(sourceType: "System.IntPtr", destType: "delegate*<void>", expectedImplicitIL: null, expectedExplicitIL: convAndExplicit("void* System.IntPtr.op_Explicit(System.IntPtr)"));
             conversions(sourceType: "System.IntPtr", destType: "bool", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "System.IntPtr", destType: "char", expectedImplicitIL: null, expectedExplicitIL: convAndExplicit("int System.IntPtr.op_Explicit(System.IntPtr)", "conv.u2"), expectedCheckedIL: convAndExplicit("int System.IntPtr.op_Explicit(System.IntPtr)", "conv.ovf.u2"));
             conversions(sourceType: "System.IntPtr", destType: "sbyte", expectedImplicitIL: null, expectedExplicitIL: convAndExplicit("int System.IntPtr.op_Explicit(System.IntPtr)", "conv.i1"), expectedCheckedIL: convAndExplicit("int System.IntPtr.op_Explicit(System.IntPtr)", "conv.ovf.i1"));
@@ -8020,6 +8010,7 @@ .maxstack  1
 }");
             conversions(sourceType: "string", destType: "System.IntPtr", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "void*", destType: "System.IntPtr", expectedImplicitIL: null, expectedExplicitIL: explicitAndConv("System.IntPtr System.IntPtr.op_Explicit(void*)"));
+            conversions(sourceType: "delegate*<void>", destType: "System.IntPtr", expectedImplicitIL: null, expectedExplicitIL: explicitAndConv("System.IntPtr System.IntPtr.op_Explicit(void*)"));
             conversions(sourceType: "bool", destType: "System.IntPtr", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "char", destType: "System.IntPtr", expectedImplicitIL: null, expectedExplicitIL: explicitAndConv("System.IntPtr System.IntPtr.op_Explicit(int)"));
             conversions(sourceType: "sbyte", destType: "System.IntPtr", expectedImplicitIL: null, expectedExplicitIL: explicitAndConv("System.IntPtr System.IntPtr.op_Explicit(int)"));
@@ -8135,6 +8126,7 @@ .maxstack  1
 }");
             conversions(sourceType: "System.UIntPtr", destType: "string", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "System.UIntPtr", destType: "void*", expectedImplicitIL: null, expectedExplicitIL: convAndExplicit("void* System.UIntPtr.op_Explicit(System.UIntPtr)"));
+            conversions(sourceType: "System.UIntPtr", destType: "delegate*<void>", expectedImplicitIL: null, expectedExplicitIL: convAndExplicit("void* System.UIntPtr.op_Explicit(System.UIntPtr)"));
             conversions(sourceType: "System.UIntPtr", destType: "bool", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "System.UIntPtr", destType: "char", expectedImplicitIL: null, expectedExplicitIL: convAndExplicit("uint System.UIntPtr.op_Explicit(System.UIntPtr)", "conv.u2"), expectedCheckedIL: convAndExplicit("uint System.UIntPtr.op_Explicit(System.UIntPtr)", "conv.ovf.u2.un"));
             conversions(sourceType: "System.UIntPtr", destType: "sbyte", expectedImplicitIL: null, expectedExplicitIL: convAndExplicit("uint System.UIntPtr.op_Explicit(System.UIntPtr)", "conv.i1"), expectedCheckedIL: convAndExplicit("uint System.UIntPtr.op_Explicit(System.UIntPtr)", "conv.ovf.i1.un"));
@@ -8330,6 +8322,7 @@ .maxstack  1
 }");
             conversions(sourceType: "string", destType: "System.UIntPtr", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "void*", destType: "System.UIntPtr", expectedImplicitIL: null, expectedExplicitIL: explicitAndConv("System.UIntPtr System.UIntPtr.op_Explicit(void*)"));
+            conversions(sourceType: "delegate*<void>", destType: "System.UIntPtr", expectedImplicitIL: null, expectedExplicitIL: explicitAndConv("System.UIntPtr System.UIntPtr.op_Explicit(void*)"));
             conversions(sourceType: "bool", destType: "System.UIntPtr", expectedImplicitIL: null, expectedExplicitIL: null);
             conversions(sourceType: "char", destType: "System.UIntPtr", expectedImplicitIL: null, expectedExplicitIL: explicitAndConv("System.UIntPtr System.UIntPtr.op_Explicit(uint)"));
             conversions(sourceType: "sbyte", destType: "System.UIntPtr", expectedImplicitIL: null, expectedExplicitIL: explicitAndConv("System.UIntPtr System.UIntPtr.op_Explicit(ulong)", "conv.i8"), expectedCheckedIL: explicitAndConv("System.UIntPtr System.UIntPtr.op_Explicit(ulong)", "conv.ovf.u8"));
@@ -8481,7 +8474,7 @@ .maxstack  1
                     verifier.VerifyIL("Program.Convert", expectedIL);
                 }
 
-                static bool useUnsafe(string type) => type == "void*";
+                static bool useUnsafe(string type) => type == "void*" || type == "delegate*<void>";
             }
         }
 
@@ -12243,5 +12236,142 @@ static object Execute(Func<object> f)
 0
 {(IntPtr.Size == 4 ? "System.OverflowException" : "0")}");
         }
+
+        [WorkItem(44810, "https://github.com/dotnet/roslyn/issues/44810")]
+        [Theory]
+        [InlineData("void*")]
+        [InlineData("byte*")]
+        [InlineData("delegate*<void>")]
+        public void PointerConversions(string pointerType)
+        {
+            string source =
+$@"using System;
+unsafe class Program
+{{
+    static {pointerType} ToPointer1(nint i) => ({pointerType})i;
+    static {pointerType} ToPointer2(nuint u) => ({pointerType})u;
+    static {pointerType} ToPointer3(nint i) => checked(({pointerType})i);
+    static {pointerType} ToPointer4(nuint u) => checked(({pointerType})u);
+    static nint FromPointer1({pointerType} p) => (nint)p;
+    static nuint FromPointer2({pointerType} p) => (nuint)p;
+    static nint FromPointer3({pointerType} p) => checked((nint)p);
+    static nuint FromPointer4({pointerType} p) => checked((nuint)p);
+    static object Execute(Func<object> f)
+    {{
+        try
+        {{
+            return f();
+        }}
+        catch (Exception e)
+        {{
+            return e.GetType().FullName;
+        }}
+    }}
+    static void Execute({pointerType} p)
+    {{
+        Console.WriteLine((int)p);
+        Console.WriteLine(Execute(() => FromPointer1(p)));
+        Console.WriteLine(Execute(() => FromPointer2(p)));
+        Console.WriteLine(Execute(() => FromPointer3(p)));
+        Console.WriteLine(Execute(() => FromPointer4(p)));
+    }}
+    static void Main()
+    {{
+        Execute(ToPointer1(-42));
+        Execute(ToPointer2(42));
+        Execute(ToPointer1(int.MinValue));
+        Execute(ToPointer2(uint.MaxValue));
+        Console.WriteLine(Execute(() => (ulong)ToPointer3(-42)));
+        Console.WriteLine(Execute(() => (ulong)ToPointer4(42)));
+        Console.WriteLine(Execute(() => (ulong)ToPointer3(int.MinValue)));
+        Console.WriteLine(Execute(() => (ulong)ToPointer4(uint.MaxValue)));
+    }}
+}}";
+            var comp = CreateCompilation(source, options: TestOptions.UnsafeReleaseExe, parseOptions: TestOptions.Regular9);
+            string expectedOutput =
+$@"-42
+-42
+{(IntPtr.Size == 4 ? "4294967254" : "18446744073709551574")}
+System.OverflowException
+{(IntPtr.Size == 4 ? "4294967254" : "18446744073709551574")}
+42
+42
+42
+42
+42
+-2147483648
+-2147483648
+{(IntPtr.Size == 4 ? "2147483648" : "18446744071562067968")}
+System.OverflowException
+{(IntPtr.Size == 4 ? "2147483648" : "18446744071562067968")}
+-1
+{(IntPtr.Size == 4 ? "-1" : "4294967295")}
+4294967295
+{(IntPtr.Size == 4 ? "System.OverflowException" : "4294967295")}
+4294967295
+System.OverflowException
+42
+System.OverflowException
+4294967295";
+            var verifier = CompileAndVerify(comp, verify: Verification.Skipped, expectedOutput: expectedOutput);
+            verifier.VerifyIL("Program.ToPointer1",
+@"{
+  // Code size        2 (0x2)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  ret
+}");
+            verifier.VerifyIL("Program.ToPointer2",
+@"{
+  // Code size        2 (0x2)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  ret
+}");
+            verifier.VerifyIL("Program.ToPointer3",
+@"{
+  // Code size        3 (0x3)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  conv.ovf.u
+  IL_0002:  ret
+}");
+            verifier.VerifyIL("Program.ToPointer4",
+@"{
+  // Code size        2 (0x2)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  ret
+}");
+            verifier.VerifyIL("Program.FromPointer1",
+@"{
+  // Code size        2 (0x2)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  ret
+}");
+            verifier.VerifyIL("Program.FromPointer2",
+@"{
+  // Code size        2 (0x2)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  ret
+}");
+            verifier.VerifyIL("Program.FromPointer3",
+@"{
+  // Code size        3 (0x3)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  conv.ovf.i.un
+  IL_0002:  ret
+}");
+            verifier.VerifyIL("Program.FromPointer4",
+@"{
+  // Code size        2 (0x2)
+  .maxstack  1
+  IL_0000:  ldarg.0
+  IL_0001:  ret
+}");
+        }
     }
 }

src/Compilers/Core/Portable/CodeGen/ILBuilderConversions.cs

@@ -7,7 +7,6 @@
 using System;
 using System.Diagnostics;
 using System.Reflection.Metadata;
-using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CodeGen
@@ -151,6 +150,11 @@ public void EmitNumericConversion(Microsoft.Cci.PrimitiveTypeCode fromPredefType
                                 // Don't want to sign extend if this is a widening conversion.
                                 this.EmitOpCode(ILOpCode.Conv_u); // potentially widening, so not NOP
                             break;
+                        case Microsoft.Cci.PrimitiveTypeCode.Pointer:
+                        case Microsoft.Cci.PrimitiveTypeCode.FunctionPointer:
+                            if (@checked)
+                                goto default;
+                            break; // NOP
                         default:
                             if (@checked)
                                 this.EmitOpCode(fromUnsigned ? ILOpCode.Conv_ovf_i_un : ILOpCode.Conv_ovf_i);
@@ -164,6 +168,8 @@ public void EmitNumericConversion(Microsoft.Cci.PrimitiveTypeCode fromPredefType
                     switch (fromPredefTypeKind)
                     {
                         case Microsoft.Cci.PrimitiveTypeCode.UIntPtr:
+                        case Microsoft.Cci.PrimitiveTypeCode.Pointer:
+                        case Microsoft.Cci.PrimitiveTypeCode.FunctionPointer:
                             break; // NOP
                         case Microsoft.Cci.PrimitiveTypeCode.UInt8:
                         case Microsoft.Cci.PrimitiveTypeCode.UInt16:
@@ -306,6 +312,11 @@ public void EmitNumericConversion(Microsoft.Cci.PrimitiveTypeCode fromPredefType
                             case Microsoft.Cci.PrimitiveTypeCode.Int64:
                                 this.EmitOpCode(ILOpCode.Conv_ovf_u);
                                 break;
+                            case Microsoft.Cci.PrimitiveTypeCode.IntPtr:
+                                this.EmitOpCode(ILOpCode.Conv_ovf_u);
+                                break;
+                            case Microsoft.Cci.PrimitiveTypeCode.UIntPtr:
+                                break; // NOP
                             default:
                                 throw ExceptionUtilities.UnexpectedValue(fromPredefTypeKind);
                         }
@@ -328,6 +339,9 @@ public void EmitNumericConversion(Microsoft.Cci.PrimitiveTypeCode fromPredefType
                                 // rather than conv_u, to sign-extend the value.
                                 this.EmitOpCode(ILOpCode.Conv_i);
                                 break;
+                            case Microsoft.Cci.PrimitiveTypeCode.IntPtr:
+                            case Microsoft.Cci.PrimitiveTypeCode.UIntPtr:
+                                break; // NOP
                             default:
                                 throw ExceptionUtilities.UnexpectedValue(fromPredefTypeKind);
                         }