> The DWARF debugging symbols emitted by Clang is different from what GCC is 
> emitting. While GCC produces a complete `.debug_aranges` section (which is 
> required in the DWARF parser), Clang does not. As a result, the DWARF parser 
> cannot find the necessary information to proceed and create the line number 
> information:
> 
> The `.debug_aranges` section contains address range to compilation unit 
> offset mappings. The parsing algorithm can just walk through all these 
> entries to find the correct address range that contains the library offset of 
> the current pc. This gives us the compilation unit offset into the 
> `.debug_info` section from where we can proceed to parse the line number 
> information.
> 
> Without a complete `.debug_aranges` section, we fail with an assertion that 
> we could not find the correct entry. Since 
> [JDK-8293402](https://bugs.openjdk.org/browse/JDK-8293402), we will still get 
> the complete stack trace at least. Nevertheless, we should still fix this 
> assertion failure of course. But that would require a different parsing 
> approach. We need to parse the entire `.debug_info` section instead to get to 
> the correct compilation unit. This, however, would require a lot more work. 
> 
> I therefore suggest to disable DWARF parsing for Clang for now and file an 
> RFE to support Clang in the future with a different parsing approach. I'm 
> using the `__clang__` `ifdef` to bail out in `get_source_info()` and disable 
> the `gtests`. I've noticed that we are currently running the `gtests` with 
> `NOT PRODUCT` which I think is not necessary - the gtests should also work 
> fine with product builds. I've corrected this as well but that could also be 
> done separately.
> 
> Thanks,
> Christian

Christian Hagedorn has updated the pull request incrementally with one 
additional commit since the last revision:

  Remove unused local variable

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/10287/files
  - new: https://git.openjdk.org/jdk/pull/10287/files/0b759abe..3121d380

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10287&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10287&range=04-05

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/10287.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10287/head:pull/10287

PR: https://git.openjdk.org/jdk/pull/10287

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