Description Ed Maste 2015-05-19 17:29:54 UTC

/usr/lib/libcompiler_rt.a (on stable/10 after 10.1) has the following undefined symbols, which are provided by libm:

U fabs
U fabsf
U fabsl
U fmax
U fmaxf
U fmaxl
U logb
U logbf
U logbl
U scalbn
U scalbnf
U scalbnl

GCC's libgcc{.a,_s.so} intentionally avoids relying on external libm functionality. Presumably we haven't encountered an issue with this before for a few reasons:

- static libgcc.a / libcompiler_rt.a is probably used much less often
- the complex division routines that introduce these dependencies are probably not used often
- code that would generate a call to the complex division routines likely links with -lm (although the link order might be wrong?)

Here's a similar issue in Chromium:
https://code.google.com/p/nativeclient/issues/detail?id=4019

This will be a problem if we want to use compiler-rt instead of libgcc_s.so.

For reference, the other (non-math related) undef symbols are:

U _GLOBAL_OFFSET_TABLE_
U __stack_chk_fail
U __stack_chk_guard
U __stderrp
U abort
U fflush
U fprintf
U mprotect
U sysconf