Previously the default was long, which is 32-bit on AVR. But avr-gcc
expects a smaller value: it reads the return value from r24.
This is actually a regression from https://reviews.llvm.org/D98205.
Before D98205, the return value was an enum (which was 2 bytes in size)
which was compatible with the 1-byte return value that avr-gcc was
expecting. But long is 4 bytes and thus places the significant return
value in a different register.
Differential Revision: https://reviews.llvm.org/D124939
While implementing support for the float128 routines on x86_64, I noticed
that __builtin_isinf() was returning true for 128-bit floating point
values that are not infinite when compiling with GCC and using the
compiler-rt implementation of the soft-float comparison functions.
After stepping through the assembly, I discovered that this was caused by
GCC assuming a sign-extended 64-bit -1 result, but our implementation
returns an enum (which then has zeroes in the upper bits) and therefore
causes the comparison with -1 to fail.
Fix this by using a CMP_RESULT typedef and add a static_assert that it
matches the GCC soft-float comparison return type when compiling with GCC
(GCC has a __libgcc_cmp_return__ mode that can be used for this purpose).
Also move the 3 copies of the same code to a shared .inc file.
Reviewed By: compnerd
Differential Revision: https://reviews.llvm.org/D98205
Ayke van Laethem