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).
