On December 13, 2016 11:44:06 PM GMT+01:00, "H. Peter Anvin" <h...@zytor.com> wrote: >When compiling with -fPIC gcc treats ebx as a "fixed register". A >fixed >register can't be spilled, and so a clobber of a fixed register is a >fatal error. > >Like it or not, it's how it works. > > -hpa
In the meantime I talked to my gcc guy and here's the deal: There are gcc versions (4.x and earlier) which do not save/restore the PIC register around an inline asm even if it is one of the registers that the inline asm clobbers. Therefore the saving/restoring needs to be done by the inline asm itself. 5.x and later handle that fine. Thus I was thinking of adding a build-time check for the gcc version but that might turn out to be more code in the end than those ugly ifnc clauses. -- Sent from a small device: formatting sux and brevity is inevitable.
