[clang] [llvm] [Clang][AIX] Add -mloadtime-comment-vars flag to preserve identifying variables (PR #187986)

[Wael Yehia via llvm-commits]

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@@ -1077,6 +1077,13 @@ void CodeGenModule::Release() {
   Module *Primary = getContext().getCurrentNamedModule();
   if (CXX20ModuleInits && Primary && !Primary->isHeaderLikeModule())
     EmitModuleInitializers(Primary);
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w2yehia wrote:

Also, specifying variable names in a list for C++ programs is not straightforward. I would prefer to use mangled names, then you don't have to worry about things like:
```
> cat t.cpp
namespace { int x; }
int x;
namespace N { int x; }
class A { static int x; }

# will you need to use :: operator like so?
> clang -mloadtime-comment-vars="x,::x,N::x,A::x"
```
You either accept mangled names or put restrictions on what kind of global variables can be listed via the option.

@hubert-reinterpretcast if you have any comments/suggestions?

https://github.com/llvm/llvm-project/pull/187986