[Bug tree-optimization/104582] [11/12 Regression] Unoptimal code for __negdi2 (and others) from libgcc2 due to unwanted vectorization

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104582

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
What slp does is just
-  w.s.low = _1;
-  w.s.high = _5;
+  _14 = {_1, _5};
+  MEM[(union  *)&w] = _14;
I must say I don't really see that as a beneficial optimization, construction
of a vector from scalars just to store it in memory doesn't look ever like a
win.