MaskRay added a comment. > There are also going to be binaries in our system build that don't use foo.h > and ideally shouldn't have any overhead since nothing inside them is > instrumented (they should behave as if -fprofile-instr-generate wasn't set > for them at all). That's not the case today because if you set > -fprofile-instr-generate, driver passes -u__llvm_profile_runtime to the > linker which "pulls in" the profile runtime introducing some extra bloat and > startup overhead I described earlier.
The overhead is just `__llvm_profile_write_file`, right? It just writes a 100+ bytes file which has very little overhead. Some sanitizers can be used in a link-only manner without instrumentation, e.g. `-fsanitize=leak` does not need instrumentation. The source code just loses `__has_feature(leak_sanitizer)` detection. Link-only `-fsanitize=address` can catch double free and mismatching new/delete. Do we expect that libclang_rt.profile- can provide other features which may be useful even if there is nothing to instrument according to `-fprofile-list`? If yes, making the library conditionally not linked can lose such features. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D98061/new/ https://reviews.llvm.org/D98061 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
