Summary:
The complex division builtins (div?c3) use logb methods from libm to scale numbers during division and avoid rounding issues. However, these come from libm, meaning anyone that uses --rtlib=compiler-rt also has to include -lm. Implement logb* methods for standard ieee 754 floats so we can avoid -lm on those platforms, falling back to the old behavior (using either logb() or `__builtin_logb()`) when not supported.
These new methods are defined internally as `__compiler_rt_logb` so as not to conflict with the libm definitions in any way.
This fixes just the libm methods mentioned in PR32279 and PR28652. libc is still required, although that seems to not be an issue.
Note: this is proposed as an alternative to just adding -lm: D49330.
Reviewers: efriedma, compnerd, scanon, echristo
Reviewed By: echristo
Subscribers: jsji, echristo, nemanjai, dberris, mgorny, kbarton, delcypher, llvm-commits, #sanitizers
Differential Revision: https://reviews.llvm.org/D49514
llvm-svn: 342917
Avoid __attribute__((constructor)) in cpu_model.c.
Use more C99 _Complex emulation in divtc3.c. Joerg Sonnenberger added
this builtin just after the last round of C99 _Complex emulation landed
in r249514 (Oct 2015).
llvm-svn: 299784
Jordan Rupprecht