rjmccall added a comment.

In D113107#3602478 <https://reviews.llvm.org/D113107#3602478>, @zahiraam wrote:

> Do we want to add an -fexcess-precision option?

Well, generally we try to offer the same options GCC does.  However, it looks 
like GCC's `-fexcess-precision` does not line up with the options we're 
thinking of offering: GCC offers only `-fexcess-precision=standard` 
(essentially what you're implementing) and `-fexcess-precision=fast` (which I 
think would require some sort of optimizer annotation to permit folding 
truncations across statement boundaries), with no option to get 
operation-by-operation fidelity (our current behavior).  And I think we're very 
unlikely to default to `-fexcess-precision=fast` the way that GCC apparently 
does.  I'm also not sure if anyone cares enough to enable this for anything 
other than `_Float16`; on GCC, `-fexcess-precision` is much broader, e.g. 
affecting `float` and `double` math on non-SSE x86 targets.  So I think we 
should hold off on adding this option until we know what behavior we actually 
want to expose via it.


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https://reviews.llvm.org/D113107

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