[Bug target/68690] PowerPC64: TOC save in PHP core loop results in load hit store

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68690

--- Comment #3 from Segher Boessenkool <segher at gcc dot gnu.org> ---
This now compiles to

main:
.LCF1:
0:      addis 2,12,.TOC.-.LCF1@ha
        addi 2,2,.TOC.-.LCF1@l
        .localentry     main,.-main
        addis 9,2,.LC0@toc@ha           # gpr load fusion, type long
        ld 9,.LC0@toc@l(9)
        addis 10,2,do_nothing@toc@ha
        li 3,0
        addi 10,10,do_nothing@toc@l
        std 10,0(9)
        blr

but the problem is still there, just this testcase is defeated; remove
the assignment to fn to make the problem pop up again.