[PATCH] D45454: Make __gcov_flush visible outside a shared library

Xinliang David Li via cfe-commits cfe-commits at lists.llvm.org
Wed Apr 11 12:31:57 PDT 2018


On Wed, Apr 11, 2018 at 11:31 AM, Chih-Hung Hsieh via Phabricator via
llvm-commits <llvm-commits at lists.llvm.org> wrote:

> chh added a comment.
>
> Yes, calling `__gcov_flush` within .so files are different,
> but it's a revert of https://reviews.llvm.org/D38124.
> I think  https://bugs.llvm.org/show_bug.cgi?id=27224
> can be fixed by hiding only llvm_gcda_* functions,
> without any change to `__gcov_flush`.
>
>
The coverage dumping behavior for shared libraries (not dlopened) was also
wrong before D38124. D38124 fixed the crash as well as the dumping bug.

David





> (1) Before https://reviews.llvm.org/D38124:
>
> - Calling `__gcov_flush` within .so or main function dumps to main gcda
> file.
> - Android's dlsym() lookup/call of `__gcov_flush` dumps to .so file
> specific gcda files.
>
> (2) After https://reviews.llvm.org/D38124:
>
> - Android's dlsym() cannot find/call `__gcov_flush`.
> - Calling `__gcov_flush` from main works as in (1).
> - Calling `__gcov_flush` from .so works differently; it will dump to .so
> specific gcda file, not the main one.
>
> (3) With this change, we revert `__gcov_flush` behavior back to (1).
>
> Is there any application that needs to call `__gcov_flush` within .so
> and expects the output to .so specific gcda file like in (2)?
> I think the behavior of (1) is more desirable.
> If a main program wants to dump to .so specific gcda file, like Android,
> it can use dlsym() to look up .so specific `__gcov_flush`.
>
>
> https://reviews.llvm.org/D45454
>
>
>
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