[PATCH] D105169: [Clang/Test]: Rename enable_noundef_analysis to disable-noundef-analysis and turn it off by default

[Nathan Chancellor via Phabricator via cfe-commits]

nathanchance added a comment.

In D105169#3236484 <https://reviews.llvm.org/D105169#3236484>, @hyeongyukim wrote:

> @nathanchance
>
> I tried to reproduce the last warning (intelfbhw_validate_mode), but I failed to produce it.
> I think my reproducer is correct, but it does not make any warning.
> Can you tell me which part was wrong?
>
>   clang -O2 -flto=thin -fsanitize=integer-divide-by-zero -c -o intelfb.o intelfb.i
>   ld.lld -m elf_x86_64 -r -o intelfb.lto.o --whole-archive intelfb.o
>   objtool orc generate --module --no-fp --no-unreachable --uaccess --mcount intelfb.lto.o
>
> I use these commands, and I attached the `intelfb.i` file.F21595840: intelfb.i <https://reviews.llvm.org/F21595840>

It looks like this particular case also needs `-fsanitize-coverage=trace-pc` (which comes from `CONFIG_KCOV`). Once I add that with your reduced reproducer, I see the initial warning.

  $ clang -O2 -flto=thin -fsanitize=integer-divide-by-zero -fsanitize-coverage=trace-pc -c -o intelfb.{o,i}
  
  $ ld.lld -m elf_x86_64 -r -o intelfb.lto.o --whole-archive intelfb.o
  
  $ ./objtool orc generate --module --no-fp --no-unreachable --uaccess --mcount intelfb.lto.o
  intelfb.lto.o: warning: objtool: .text.intelfbhw_validate_mode: unexpected end of section


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