LLVM exports too many symbols (on Unix like systems like Linux and Mac)

[llvmbot]

Bugzilla Link	19333
Version	trunk
OS	All
Reporter	LLVM Bugzilla Contributor
CC	@tstellar

Extended Description

This doesn't apply to Windows because by default symbols are hidden in DLLs. On Unix like systems like Linux and Mac though there are a bunch of symbols exported that shouldn't be which increase startup time. There is a long and annoying process of marking symbols to export for the libraries but for the executables (which obviously shouldn't export any symbols unless they have a plugin system) the flag -fvisibility=hidden should be a cheap and easy optimization. Note that LLVM does not use runtime type information or exceptions so I believe there shouldn't be very many problems however, according to http://gcc.gnu.org/wiki/Visibility there also some other cases (for example, static data members of templates that can cause this problem). Using #pragma push for one's own code could be one way of quickly accomplishing this.

[llvmbot]

assigned to @tstellar

[tstellar]

This patch may help: https://reviews.llvm.org/D54439