[Bug c/56335] Optimization assumes __attribute__((aligned(N))) always works.

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56335

Andrew Pinski  changed:

   What|Removed |Added

   See Also||https://gcc.gnu.org/bugzill
   ||a/show_bug.cgi?id=87795,
   ||https://gcc.gnu.org/bugzill
   ||a/show_bug.cgi?id=89357
 Resolution|--- |FIXED
 Status|NEW |RESOLVED
   Target Milestone|--- |9.3

--- Comment #3 from Andrew Pinski  ---
>   .comm   a,512,134217728


The linker should fail to link if it can't link to 128 MB here.

>From JSM's email:
> MAX_OFILE_ALIGNMENT (presently just a warning),

That was PR 87795 and was fixed in r9-3979-g4c7bd36194e13c .

> an object with automatic storage duration has an alignment greater than 
> MAX_STACK_ALIGNMENT

See PR 89357 which removed the constraint for C++ _Alignas as the middle-end
supports huge alignments now.

So closing as fixed for GCC 9.3.0.

[Bug c/56335] Optimization assumes __attribute__((aligned(N))) always works.

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56335



Richard Biener rguenth at gcc dot gnu.org changed:



   What|Removed |Added



   Keywords||wrong-code

 Status|UNCONFIRMED |NEW

   Last reconfirmed||2013-02-15

  Component|tree-optimization   |c

 Ever Confirmed|0   |1



--- Comment #1 from Richard Biener rguenth at gcc dot gnu.org 2013-02-15 
09:28:12 UTC ---

That's a bug in alignment attribute processing then.  It should not communicate

alignments that can not be reached to the middle-end.



Language lawyer question: Is __alignof__ then allowed to report a lower

alignment?  Or do we have to reject a testcase with a too large alignment

specification as invalid?

[Bug c/56335] Optimization assumes __attribute__((aligned(N))) always works.

[joseph at codesourcery dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56335



--- Comment #2 from joseph at codesourcery dot com joseph at codesourcery dot 
com 2013-02-15 15:47:00 UTC ---

See http://gcc.gnu.org/ml/gcc-patches/2011-11/msg00841.html, where I 

discuss what I think would be the appropriate checks for supported 

alignment (which I deferred for the initial implementation of _Alignas / 

_Alignof).



I think the checks should be errors for both the C11 _Alignas syntax and 

the __attribute__ syntax.