[PATCH] D60974: Clang IFSO driver action.

Mon Apr 29 15:33:54 PDT 2019

jakehehrlich added a comment.

I think I know the format that I'd like *roughly*. I haven't worked out how to handle COMDAT and section groups yet. Roland seems to think that COMDAT and section groups will be an issue but I'm working out the details with him to make sure I understand it. I'll get back to you soon.

  Version: 1.0
  Arch: AArch64
  Symbols:
    - Name: foo
      Type: Function
      Weak: true
    - Name: bar
      Type: Function
      Defined: false
    - Name: baz
      Type: Object
      Size: 256
      Alignment: 32

Only Arch is used other details from your header can be inferred as defaults but are not needed here. I think binding is not needed beyond Weak vs. Not Weak. I spoke with Roland about this and he pointed out STB_GNU_UNIQUE. This would motivate allowing Global, Weak, and GNU_UNIQUE as valid bindings. The only cases for viability that we care are protected and default. Internal and hidden will never appear in the public interface. We can treat protected and default as the same as they just mean that the symbol will appear in the public interface and their difference is related to how the linker resolves symbols relative to module itself not other external modules.

We don't have to worry about symbol version (and the TextAPI types don't support that yet either) but Warnings are another case to think about. Each symbol can have a warning string associated with it. This will be one of the last features (before symbol versions but after almost everyhing else) that support is added for in llvm-elfabi so I think we can ignore it here for now.

One thing we forgot to add in llvm-elfabi that we now know we need to add is Alignment. Alignment can be computed from the section and the offset within the section. This is the one bit of information that comes from the section itself and not the symbol table.

Absolute symbols probably aren't needed but if we ever need them they're easy enough to add via a new symbol type.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60974/new/

https://reviews.llvm.org/D60974