Since there are more platforms that do not have symbols present, we need
to use `rustc_apfloat` for more conversion tests. Make use of the
fallback like other tests, and refactor so each test gets its own
function.
Previously we were testing both apfloat and system conversion methods
when possible. This changes to only test one or the other, depending on
whether or not the system version is available. This seems reasonable
because it is consistent with all other tests, but we should consider
updating all tests to check both at some point.
This also includes an adjustment of PowerPC configuration to account for
the linking errors at [1].
[1]: https://github.com/rust-lang/compiler-builtins/issues/655
This adds comparisons among the compiler-builtins function, system
functions if available, and optionally handwritten assembly.
These also help us identify inconsistencies between this crate and
system functions, which may otherwise go unnoticed if intrinsics get
lowered to inline operations rather than library calls.
