Can i understand from the answer that asm instructions (not mnemonics) won't be replaced ? On Mon, Mar 18, 2019 at 12:22 PM David Brown <david@xxxxxxxxxxxxxxx> wrote: > On 18/03/2019 10:08, Florian Weimer wrote: > > * ilya german: > > > >> I have a quastion regarding reading TBR registers on PPC p2020 e500v2 > CPU. > >> > >> I wrote the following asm instructions to read the TBR: > >> > >> mftbu r5 /* Read upper Time Base */ > >> mftb r6 /* Read lower Time Base */ > >> mftbu r7 /* Read upper Time Base again */ > >> > >> When I compiled (using GNU 4) and viewed the asm instruction I saw that > >> *mftbu* and *mftb* were replaced with *mfspr* instruction. > > > > How did you determine that it was replaced? > > > > I expect he could see it from looking at a disassembly. > > On The PPC cores, mftb and mftbu are simplified mnemonics, not > instructions - they are implemented as "mfspr" instructions on the > appropriate SPR registers (268 and 269). > >
