src/compiler-rt/lib/builtins/Darwin-excludes/README.TXT

   1 This folder contains list of symbols that should be excluded from the builtin
   2 libraries for Darwin. There are two reasons symbols are excluded:
   3
   4 (1) They aren't supported on Darwin
   5 (2) They are contained within the OS on the minimum supported target
   6
   7 The builtin libraries must contain all symbols not provided by the lowest
   8 supported target OS. Meaning if minimum deployment target is iOS 6, all builtins
   9 not included in the ios6-<arch>.txt files need to be included. The one catch is
  10 that this is per-architecture. Since iOS 6 doesn't support arm64, when supporting
  11 iOS 6, the minimum deployment target for arm64 binaries is iOS 7.