[Bug target/98482] -mfentry creates invalid call for -mcmodel=large

[toiwoton at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98482

--- Comment #4 from Topi Miettinen <toiwoton at gmail dot com> ---
Sorry, I didn't check the ABI. It seems that %r11 and maybe %r10 should be
usable:

Figure 3.4: Register Usage

Register
 Usage
 Preserved across function calls

%r10
 temporary register, used for passing a function’s static chain pointer
 No

%r11
 temporary register
 No

Otherwise, I suppose any register could be used if it's saved:
        pushq   %reg
        movabsq $__fentry__, %reg
        call    *%reg
        popq     %reg