[CppCodeGen] Make Reflection.Execution compile

[jkotas]

This is pre-requisite for making reflection work (#2035):

Repro:

1. Comment out if check:

   corert/src/ILCompiler.Compiler/src/Compiler/LibraryInitializers.cs

   Line 69 in 358c945

   if (_isCppCodeGen && !entry.UseWithCppCodeGen)

2. Compile "Hello world" using CppCodeGen

[jkotas]

The current problem is:

---------------------------
Assertion Failed: Abort=Quit, Retry=Debug, Ignore=Continue
---------------------------
Stack is not empty
   at Internal.IL.EvaluationStack`1.Pop()
   at Internal.IL.ILImporter.ImportStoreVar(Int32 index, Boolean argument)
   at Internal.IL.ILImporter.ImportBasicBlock(BasicBlock basicBlock)

[mikedn]

Presumably CppCodeGen has not support for exception handling and the best that can be done atm is to just push a null on the stack of the handler BB?

[jkotas]

The handlers should not be getting compiled right now. If they are getting pulled in somehow in this method (what is special about this method that pulls them in?), I agree that pushing null on the stack would be fine for now.

[mikedn]

The handlers should not be getting compiled right now

Yep, that seems to be the intention of the existing code. But this is done by not creating BBs for catch handlers and this results in nested finally BBs falling through into the catch BB code. I'll try to fix it one of these days.

PS: Actually it's the other way around, the BB is created but it's not ignored during import. Either way, EH handling needs fixing.