[llvm] r196607 - Integrated assembler incorrectly lexes ARM-style comments

[David Peixotto]

> >> URL: http://llvm.org/viewvc/llvm-project?rev=196607&view=rev
> >> Log:
> >> Integrated assembler incorrectly lexes ARM-style comments
> >>
> >> The integrated assembler fails to properly lex arm comments when they
> >> are adjacent to an identifier in the input stream. The reason is that
> >> the arm comment symbol '@' is also used as symbol variant in other
> >> assembly languages so when lexing an identifier it allows the '@'
> >> symbol as part of the identifier.
> >
> > This has broken .symver for ELF targets on ARM. Do you plan to fix this?
> > Otherwise I'd ask for a revert.
> 
> Ugh. Yet another example of why I hate the comment character choice of '@'
> on ARM (no, I don't think we should/can change it; too much history).
> 
> I agree it's important that symver work as documented. We should:
> 
> a) fix this bug, it's nasty
> b) write some better test cases for .symver as we obviously have crappy
> ones since they're passing even with this change in the tree.
> 
> David, do you think you'll have a change to have a look at this soon?

I've attached a patch that fixes the issue. I added a test for .symver based
on the one for x86. To get the expected output I first undid my change to
allow @ in identifiers and then captured the output. I am not familiar with
what that directive is trying to do, so it would be good if someone could
sanity-check the test.

Modifying the Lexer to allow @ in the symbol for that one directive was
relatively easy. The harder part was only doing it for ARM in the
ELFAsmParser. Any feedback to improve the patch is appreciated.






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