Alexander Graf wrote: > This is a resend of a mail I sent to the list on 2008/02/06. I felt it > rather disturbing, yet normal that nobody cared about Mac OS X host > support, but this concerns all x86 host OSs, so I believe this deserves > some discussion. > > Hi, > > I've been trying to get the new TCG approach running on an i386 host. It > works when I use gcc3 (miraculously as I will explain later), but fails > on gcc4. > > On boot the very first instruction that gets issued is the ljmp to the > bios: > [...] > 1. Why is gcc3 generating code, that does not use ebx? > 2. Why does movi_i64 generate code that only accesses registers? I have > not been able to find any branch in the tcg code generator for movi_ixx > that generates movs to memory addresses. > > The whole issue could be easily fixed by using registers, but putting > the call into inline assembly, telling gcc that this call clobbers all > the registers. I do not know if this is the expected behavior though, so > I think I'd rather ask before doing any patches.
The fact that it works in some cases is a miracle. The right solution is to use a global TB prologue and epilogue which saves and restores callee saved registers (it is in the tcg TODO list). A temporary solution before that would be to mark ebx, esi and edi as reserved registers if TARGET_LONG_BITS > HOST_LONG_BITS. Fabrice.
