[Bug tree-optimization/86072] Poor codegen with atomics

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86072

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2018-06-07
     Ever confirmed|0                           |1

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Andrew is right.  Still confirmed.

Somebody has to decide if it's worth optimizing them and has to sit down and
exactly specify what kind of optimizations are valid.

I guess it's worth optimizing them if these cases appear in real-world code
(and then we'd like to see examples).

As for validity not optimizing them leads to (wanted/required) side-effects
like being a barrier for a lot of compiler optimizations.  Which may mor
may not be designed that way.  I'm sitting on patches teaching points-to
about atomics, specifically making them not escape points or uses/clobbers
for all memory.  Esp. the latter I'm not sure is a good idea to improve,
because there's nothing in the compiler making atomics "special", they
are just modeled as function calls.