[PATCH] Add generic HAVE_RM_CTX implementation

[Joseph S. Myers]

On Tue, 20 May 2014, Wilco wrote:

> Ping
> 
> As for an additional reviewer, Joseph could you please have a look?

OK, although my comments in 
<https://sourceware.org/ml/libc-alpha/2014-03/msg00267.html> apply.  All 
these macros / functions need careful review and refactoring; the present 
set makes it far from obvious that required invariants hold such as "if 
the function used at the start of a fixed-rounding-mode block has the 
feholdexcept effects of disabling traps or clearing existing set 
exceptions, then the function at the end of that block must have the 
reverse effects of restoring previously enabled traps and set exceptions 
(possibly with new exceptions merged in, depending on the semantics of the 
function at the end)".  I suspect things might be clearer if the functions 
/ macros had extra arguments for such things as "clearing exceptions 
permitted / required / not permitted" or "new exceptions must be merged 
into the previous set / may be merged in / must be discarded", rather than 
having so many macros with similar names but different semantics.

-- 
Joseph S. Myers
joseph@codesourcery.com