[Mono-bugs] [Bug 322485] Invalid IL code in System.Nullable::Equals

[bugzilla_noreply at novell.com]

https://bugzilla.novell.com/show_bug.cgi?id=322485#c2


Rodrigo Kumpera <rkumpera at novell.com> changed:

           What    |Removed                                         |Added
----------------------------------------------------------------------------
                 CC|                                                |rkumpera at novell.com
          Component|CORLIB                                          |C#
            Product|Mono: Class Libraries                           |Mono: Compilers
            Version|1.1                                             |1.2




--- Comment #2 from Rodrigo Kumpera <rkumpera at novell.com>  2007-11-08 11:20:16 MST ---
It looks like a compiler bug.

gmcs generates the following IL for System.Nullable.Equals<T>. The code seens
to be wrong as you cannot pass an unboxed valuetype to a parameter of type
object.

  .method public hidebysig static bool  Equals<valuetype T>(valuetype
System.Nullable`1<!!T> value1,                                                 
          valuetype System.Nullable`1<!!T> value2) cil managed
  {
    // Code size       9 (0x9)
    .maxstack  8
    IL_0000:  ldarga.s   value1
    IL_0002:  ldarg.1
    IL_0003:  call       instance bool valuetype
System.Nullable`1<!!T>::Equals(object)
    IL_0008:  ret
  } // end of method Nullable::Equals


Interesting enough, if the same method is compiled on a class outside corlib,
the generated IL is correct:

  .method public hidebysig static bool  Equals<valuetype T>(valuetype
[mscorlib] System.Nullable`1<!!T> value1, valuetype [mscorlib]
System.Nullable`1<!!T> value2) cil managed
  {
    // Code size       14 (0xe)
    .maxstack  8
    IL_0000:  ldarga.s   value1
    IL_0002:  ldarg.1
    IL_0003:  box        valuetype [mscorlib]System.Nullable`1<!!T>
    IL_0008:  call       instance bool valuetype
[mscorlib]System.Nullable`1<!!T>::Equals(object)
    IL_000d:  ret
  } // end of method Driver::Equals


CSC generates a slightly diferent IL from the above:


  .method public hidebysig static bool  Equals<valuetype .ctor
([mscorlib]System
ValueType) T>(valuetype [mscorlib]System.Nullable`1<!!T> value1,

               valuetype [mscorlib]System.Nullable`1<!!T> value2) cil managed
  {
    // Code size       25 (0x19)
    .maxstack  2
    .locals init (bool V_0)
    IL_0000:  nop
    IL_0001:  ldarga.s   value1
    IL_0003:  ldarg.1
    IL_0004:  box        valuetype [mscorlib]System.Nullable`1<!!T>
    IL_0009:  constrained. valuetype [mscorlib]System.Nullable`1<!!T>
    IL_000f:  callvirt   instance bool [mscorlib]System.Object::Equals(object)
    IL_0014:  stloc.0
    IL_0015:  br.s       IL_0017

    IL_0017:  ldloc.0
    IL_0018:  ret
  } // end of method Driver::Equals


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