Darwin: Rework handling for unwinder code in libgcc_s and specs [PR80556].
This addresses a long-standing problem where a work-around for an unwinder
issue (also a regression) regresses other functionality. The patch replaces
several work-arounds with a fix for PR80556 and a work-around for PR88590.
* The fix for PR80556 requires a bump to the SO name for libgcc_s, since we
need to remove the unwinder symbols from it. This would trigger PR88590
hence the work-around for that.
* We weaken the symbols for emulated TLS support so that it is possible
for a DSO linked with static-libgcc to interoperate with a DSO linked with
libgcc_s. Likewise main exes.
* We remove all the gcc-4.2.1 era stubs machinery and workarounds.
* libgcc is always now linked ahead of libc, which avoids fails where the
libc (libSystem) builtins implementations are not up to date.
* The unwinder now always comes from the system
- for Darwin9 from /usr/lib/libgcc_s.1.dylib
- for Darwin10 from /usr/lib/libSystem.dylib
- for Darwin11+ from /usr/lib/system/libunwind.dylib.
We still insert a shim on Darwin10 to fix an omitted unwind function, but
the underlying unwinder remains the system one.
* The work-around for PR88590 has two parts (1) we always link libgcc from
its convenience lib on affected system versions (avoiding the need to find
the DSO path); (2) we add and export the emutls functions from DSOs - this
makes a relatively small (20k) addition to a DSO. These can be backed out
when a proper fix for PR88590 is committed.
For distributions that wish to install a libgcc_s.1.dylib to satisfy linkage
from exes that linked against the stubs can use a reexported libgcc_s.1.1
(since that contains all the symbols that were previously exported via the
stubs).
projects / thirdparty / gcc.git / commit
