[PATCH] D83494: [libFuzzer] Link libFuzzer's own interceptors when other compiler runtimes are not linked.

Mon Jul 13 11:38:21 PDT 2020

hctim added a comment.

In D83494#2147608 <https://reviews.llvm.org/D83494#2147608>, @dokyungs wrote:

> Builtin libfunc optimizations may transform memcmp and strcmp-like functions. To disable such optimizations, -fno-builtin= flag was additionally added in compiling new test cases. FWIW, the original test cases didn't require such flags since other sanitizers including ASan disables those optimizations in their LLVM pass by dropping libfunc attribute in the call instructions.

It sounds like we need to add `-fno-builtin` in the clang driver when building with sancov as well. Otherwise, users won't get any benefit of this patch without doing `clang++ -fsanitize=fuzzer my_fuzz_target.cpp -fno-builtin-strstr -fno-builtin-strncmp  -fno-builtin-strcmp  -fno-builtin-memcmp`?

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D83494/new/

https://reviews.llvm.org/D83494