[Bug target/79436] [ARM Cortex-M4F] VFMA used in place of subtraction gives inexact results

[rearnsha at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79436

--- Comment #7 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
double __attribute__((optimize("fp-contract=off"))) x (double a, double b,
double c)
{
  return a*b + c;
}

You might also need to mark the function as no-inline to prevent it being
inlined into functions where the default still applies.