[patch,target] Fix ppc-darwin issue with long double intrinsics (PR25477)

[Janne Blomqvist]

FX Coudert wrote:
> Thanks to Andrew's code, Mike's and Geoff's comments in the PR, help 
> from Uros, Paolo and Jack, and Dominique's machine for testing, here is 
> a patch for fixing this PR. It has three independent parts, joined 
> together because I regtested them together:
> 
>   1. the target part, in gcc/config/darwin* and gcc/config/rs6000, that 
> takes care of setting correct assembler names for the builtins, if needed
>   2. the Fortran front-end part, bordering on obvious, that makes 
> cpow{f,,l} builtins instead of simply considering them library functions 
> (otherwise, they don't benefit from the patch above)
>   3. the Fortran testsuite part, splitting testing of ERF/ERFC from 
> large_real_kind_2.F90 into its separate test case, which still fails on 
> Darwin at -O0 because Apple's PowerPC erfl() and ercl() are plain useless.
> 
> The patch was bootstrapped on powerpc-apple-darwin9.2.0 with C and 
> Fortran, and regtested with both -m32 and -m64 for these same languages. 
> OK for trunk? (I need a Darwin maintainer approval for the target stuff, 
> and a Fortran maintainer for Fortran parts.)

Fortran parts are OK. As an aside, this should also allow gfortran to 
constant fold cpow* calls.

-- 
Janne Blomqvist