[lanai] Add ELF enum value and relocations

[jpienaar]

Summary

Add ELF enum value and relocations for Lanai backed.

General Lanai backend discussion on llvm-dev thread "[RFC] Lanai backend" (http://lists.llvm.org/pipermail/llvm-dev/2016-February/095118.html).

[jyknight]

include/llvm/MC/MCExpr.h

294

It looks like half the backends put target specific expr kinds in a subclass of MCTargetExpr, instead of in here. I'm not sure, but maybe that's the way you're supposed to do it now?

include/llvm/Object/RelocVisitor.h

324

No call to getELFAddend needed here?

lib/MC/MCExpr.cpp

316

This, in particular, seems an unfortunate consequence of not using a LanaiMCExpr: a very generic name, assigned a target-specific variant.

[jpienaar]

Moved MCExpr changes to subclass of MCTargetExpr and use that instead in the backend.

[jpienaar]

Good suggestion on subclassing instead.

[eliben]

include/llvm/Support/ELFRelocs/Lanai.def

7

Would this be a good place for a few lines of comments explaining each relocation type?

[jpienaar]

include/llvm/Support/ELFRelocs/Lanai.def

7

Looking at the other backends, the relocation types are not normally documented in ELFRelocs/X.def. Rather the explanation of relocation types is commonly done in lib/Target/X/MCTargetDesc/XFixupKinds.h.

[echristo]

One inline comment. Are there any more testcases to test RelocToApply, readobj, etc?

-eric

include/llvm/Support/ELF.h

322

Add the extra comma at the end here...

[t.p.northover]

include/llvm/Object/RelocVisitor.h

323

What's the user of this function? It appears to be untested.

include/llvm/Support/ELFRelocs/Lanai.def

7

Fixups aren't usually in 1-1 correspondence with relocations. Normally relocs are documented in a platform's ABI document, but I Lanai's intending to do it in-tree isn't it?

If so, this file looks like a reasonable place since they're all together here.

test/Object/Lanai/yaml2obj-elf-lanai-rel.yaml

6 ↗

(On Diff #47463)

The other relocs should probably be tested too. It'd be good to test the actual numbers as well, if Lanai has any ABI stability expectations.

[jpienaar]

Addressed comments, added readobj and dwarfdump tests.

[jpienaar]

Updated, thanks

include/llvm/Object/RelocVisitor.h

323

It is used by dwarfdump. Adding test for it.

[t.p.northover]

Thanks, this looks fine now.

Tim.

[jpienaar]

Thanks, if none of the other reviewers have an objection, I'll submit this tomorrow.

[echristo]

It's good. Go ahead. :)