On Wed, 28 Sep 2016, Yichao Yu wrote: > In particular, it seems that on all the platforms with a > arm*-*-gnueabihf triple I've checked (alarm armv7h, alarm armv6h, > debian armhf, fedora armv7hl) the __powidf2 function (and possibly > many others) are compiled with the AAPCS VFP calling convention, which > is also how it is used by gcc. However, LLVM dev (CC'd) claims that > these routines are meant to be always using soft floating point > calling convention even on platforms using hard floating point ABI.
The RTABI functions should use the base AAPCS calling conventions. That was something I dealt with when working on the implementation of the VFP ABI variant <https://gcc.gnu.org/ml/gcc-patches/2009-05/msg00591.html>. Except where an external ABI defines things like that, the normal expectation for libgcc functions is that they have the same ABI as for an ordinary C function with the same prototype. That is, since libgcc.texi gives a prototype for __powidf2 without saying anything special about its ABI, and since it is not a function defined in RTABI, it can be taken to use the VFP ABI when compiling for that ABI. -- Joseph S. Myers jos...@codesourcery.com
