http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47602
--- Comment #13 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-02-04 15:23:22 UTC --- > In what way are we helping them by forcing them to know about it? How does > that help them write inline assembler which, e.g., uses the cpuid instruction, > or makes a kernel system call which passes a parameter in %ebx? In these cases, that won't probably help them indeed. But, in other cases, like someone wanting to write very efficiently a hot loop in asm for a library, making it explicit that the %ebx register is not freely available like the others might help him to find the most efficient approach. Maybe we could just warn though.
