http://bugzilla.suse.com/show_bug.cgi?id=994985 http://bugzilla.suse.com/show_bug.cgi?id=994985#c3 Richard Biener <rguenther@suse.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |mgalbraith@suse.com Flags| |needinfo?(mgalbraith@suse.c | |om) --- Comment #3 from Richard Biener <rguenther@suse.com> --- Well, you obviously get what you ask for if marking this kind of regs or too many regs as fixed... they are no longer available for register allocation and at some point first your asm()s and then regular code will no longer be reg-allocatable. For example GCC needs %rbp when it needs to do dynamic stack alignment which IIRC the kernel requires for some functions. Without a frame pointer %rbp is just a regular register available for allocation so yes, it's "the cost of losing a register", esp. a "low" one, using r8-r11 result in larger instruction encoding (IIRC). Can't reproduce with the preprocessed source - please specify all compiler options you use (tried -ffixed-rbp -O[s] -g). But as said, I consider this a non-bug. -ffixed-X is not applicable for all code. -- You are receiving this mail because: You are on the CC list for the bug.