[PATCH] D58952: [llvm] Skip over empty line table entries.

Fri Mar 15 07:58:13 PDT 2019

mtrofin added a comment.

In D58952#1430291 <https://reviews.llvm.org/D58952#1430291>, @dblaikie wrote:

> Thanks a bunch - looks good  to me.
>
> I take it the added test coverage covers the case that was broken the firstn time this was committed? But were you also able to reproduce that original failure locally with compiler-rt or wherever it was? & have you verified that scenario (check-compiler-rt, or, again, whatever it was - I'm just guessing roughly from the emails I saw) is completely passing now with this change? (in case there were other "interesting" situations that scenario trips over)

Vitaly helped me with getting the aarch64 binary involved in the test built locally (thanks again!), and from there, I was able to identify this issue by inspecting the bot report and symbols in the local binary. I don't have an arm/ppc 'test rig' so I didn't do a real, full repro (meaning, running the binary with asan enabled, etc). The arm/ppc failures appeared to come from the same root cause (this one), based on the error. I feel comfortable submitting this at this point.

================
Comment at: llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp:882-883
+  }
+  // In some cases, e.g. first instruction in a function, the compiler generates
+  // two entries, both with the same address. We want the last one.
+  // There are 2 cases wrte RowPos and the addresses in records before/after it:
----------------
dblaikie wrote:
> I'd still be inclined to describe this as "a zero-length address range" or similar, rather than two entries for the same address - though I realize that gets into the weird semantic debate murky waters so maybe it's not worth worrying about.
I'd have to tie it back to the fact that there are successive entries with the same address, which explains the following loop. Leaving it as-is.

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  https://reviews.llvm.org/D58952/new/

https://reviews.llvm.org/D58952