[PATCH] D84265: [AIX][XCOFF] emit symbol visibility for xcoff object file.

[Jason Liu via Phabricator via llvm-commits]

jasonliu added inline comments.


================
Comment at: llvm/lib/MC/MCXCOFFStreamer.cpp:39
+      MCSect->setVisibilityType(Symbol->getVisibilityType());
+  }
+}
----------------
Some thoughts on how to implement this for object generation:
If we want to follow existing practice, the closest thing we could find is `StorageClass`. 
Both symbol and section have storage class, but how we set them are different.
For sections, we set the storage class when we create them. For symbols, we set it using `emitSymbolAttribute`.
So if we want to follow existing practice, we want to set the visibility with `getXCOFFSection`.

But if we want to break the existing practice (which could be a bigger change), we could consider using `getQualNameSymbol` as proxy of the MCSection. 
So we only set attribute or property on MCSymbolXCOFF when possible, and in obj gen, we use `getQualNameSymbol` to get the property that we need for the section. 
But the problem with that is the external symbols. We use external function entry point symbols as if they are labels, but in fact, they are csects. So getQualNameSymbol for an external function entry point symbol would not return the symbol that have the correct settings on it. So maybe this is one motivation for us to change `.bl .foo` to `.bl .foo[PR]` for external symbols.

As it is right now, if we seeking for minimum work and keep things consistent, we could set the visibility using getXCOFFSection. And if later we think it's important enough to pursue using `getQualNameSymbol` as proxy of the MCSection, we could do a refactoring at that time?


Repository:
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  https://reviews.llvm.org/D84265/new/

https://reviews.llvm.org/D84265