[Bug rtl-optimization/21182] [6/7/8 Regression] gcc can use registers but uses stack instead

[law at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=21182

--- Comment #27 from Jeffrey A. Law <law at redhat dot com> ---
So for gcc-8.

UNAIL_REGS -O3  41 stack references
UNAIL_REGS -O2  41 stack referenecs

DNAIL_REGS -O3   3 stack references
DNAIL_REGS -O2   3 stack references

In the DNAIL_REGS case I think all three references are pulling arguments out
of the stack.