https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68937
--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
There is
static bool
ix86_function_ok_for_sibcall (tree decl, tree exp)
{
tree type, decl_or_type;
rtx a, b;
/* If we are generating position-independent code, we cannot sibcall
optimize direct calls to global functions, as the PLT requires
%ebx be live. (Darwin does not have a PLT.) */
if (!TARGET_MACHO
&& !TARGET_64BIT
&& flag_pic
&& flag_plt
&& decl && !targetm.binds_local_p (decl))
return false;
Why dos RA pick callee-saved register as GOT base in jmp?
