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

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

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

--- Comment #14 from Richard Biener <rguenth at gcc dot gnu.org> ---
Another testcase is

struct S { double a, b; } s;

void
foo (double a, double b)
{
  s.a = a;
  s.b = b;
}

which also receives the same costs and compiles vectorized to

  unpcklpd %xmm1,%xmm0
  movaps %xmm0,0x0(%rip)  
  ret

which is also smaller than unvectorized.