[clang] [HLSL] Fix debug info generation for RWBuffer types (PR #119041)

[via cfe-commits]

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@@ -2021,28 +2021,10 @@ llvm::DISubroutineType *CGDebugInfo::getOrCreateInstanceMethodType(
   // ThisPtr may be null if the member function has an explicit 'this'
   // parameter.
   if (!ThisPtr.isNull()) {
-    const CXXRecordDecl *RD = ThisPtr->getPointeeCXXRecordDecl();
-    if (isa<ClassTemplateSpecializationDecl>(RD)) {
----------------
joaosaffran wrote:

Well, this is a consequence of the `this` fix, the same done in DXC. After applying the fix the code becomes:

```c++
if (isa<ClassTemplateSpecializationDecl>(RD)) {
    // HLSL Change Begin - This is a reference.
    llvm::DIType *ThisPtrType = getOrCreateType(ThisPtr, Unit);
    // HLSL Change End - This is a reference.
    TypeCache[ThisPtr.getAsOpaquePtr()].reset(ThisPtrType);
    // TODO: This and the artificial type below are misleading, the
    // types aren't artificial the argument is, but the current
    // metadata doesn't represent that.
    ThisPtrType = DBuilder.createObjectPointerType(ThisPtrType);
    Elts.push_back(ThisPtrType);
  } else {
    llvm::DIType *ThisPtrType = getOrCreateType(ThisPtr, Unit);
    TypeCache[ThisPtr.getAsOpaquePtr()].reset(ThisPtrType);
    ThisPtrType = DBuilder.createObjectPointerType(ThisPtrType);
    Elts.push_back(ThisPtrType);
  }
```

Removing the comments, if and else blocks become the same code, so I just removed the branching

https://github.com/llvm/llvm-project/pull/119041