[Bug middle-end/82885] memcpy does not propagate aliasing knowledge

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82885

Richard Biener  changed:

   What|Removed |Added

 CC||david.bolvansky at gmail dot 
com

--- Comment #3 from Richard Biener  ---
*** Bug 90373 has been marked as a duplicate of this bug. ***

[Bug middle-end/82885] memcpy does not propagate aliasing knowledge

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82885

Richard Biener  changed:

   What|Removed |Added

   Keywords||alias, missed-optimization
 Status|UNCONFIRMED |NEW
   Last reconfirmed||2017-11-08
 CC||rguenth at gcc dot gnu.org
 Ever confirmed|0   |1

--- Comment #2 from Richard Biener  ---
It's also difficult because there's no representation for "[ch1, ch1 +
1024*1024[ and [ch2, ch2 + 1024+1024[" do not overlap.

[Bug middle-end/82885] memcpy does not propagate aliasing knowledge

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82885

--- Comment #1 from Marc Glisse  ---
gcc (illegally) generates some calls to memcpy(p,q,n) where p and q may be the
same pointer, although they mustn't overlap in any more complicated way. That
makes such an optimization problematic (although this memcpy generation seems
to happen at expansion time, so doing the optimization earlier might be ok).