[llvm] r328805 - Reapply "[DWARFv5] Emit file 0 to the line table."

[via llvm-commits]

My clang problems turned out to be pilot error.  Try r352541 and let me know.
--paulr

From: David Blaikie [mailto:dblaikie at gmail.com]
Sent: Monday, January 28, 2019 7:47 PM
To: Robinson, Paul
Cc: llvm-commits at lists.llvm.org
Subject: Re: [llvm] r328805 - Reapply "[DWARFv5] Emit file 0 to the line table."


On Mon, Jan 28, 2019, 4:27 PM <paul.robinson at sony.com<mailto:paul.robinson at sony.com> wrote:
I have llvm-mc working on empty (or comment-only) source, but not clang yet.
Are you possibly using a Release build? the crashes I see are assertions.
I've been running on a full debug build, including assertions. :/
Will keep on it tomorrow.
--paulr

From: David Blaikie [mailto:dblaikie at gmail.com<mailto:dblaikie at gmail.com>]
Sent: Monday, January 28, 2019 2:44 PM
To: Robinson, Paul
Cc: llvm-commits at lists.llvm.org<mailto:llvm-commits at lists.llvm.org>
Subject: Re: [llvm] r328805 - Reapply "[DWARFv5] Emit file 0 to the line table."


On Mon, Jan 28, 2019 at 11:12 AM <paul.robinson at sony.com<mailto:paul.robinson at sony.com>> wrote:
Hey Paul,

I've been experimenting with DWARFv5 broadly applied to some code at Google & found that clang crashes when trying to emit DWARFv5 on an empty assembly file. Turns out llvm-mc does not because of the above code block.

Seems this support is here for llvm-mc, but missing from clang's initialization of MCContext for cc1as.

Could you refactor/common/add equivalent functionality to Clang's cc1as? (looks like somewhere near clang/tools/driver/cc1as_main.cpp:400? (since that is where "setMainFileName" is, which is near this block in llvm-mc too))

- Dave
You mean, like a zero-length file?  For me, `llvm-mc –g t.s` also crashes with that.  Or a .s file with only a comment in it.

Hmm, llvm-mc doesn't seem to crash for me...

Looks like clang and llvm-mc crash in different places too.

Maybe different default targets, etc? Not sure.

 I'll take a look.

Thanks!

--paulr
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