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On Tuesday, December 14, 2010 17:00:13 Mike Frysinger wrote: > On Tuesday, December 14, 2010 16:31:22 Pedro Alves wrote: > > Can you explain why are the PC and CC registers pseudo > > registers, but supported as being raw registers anyway? Couldn't > > gdb compute them itself from the other registers, with > > gdb's pseudo register support (gdbarch_pseudo_register_read|write)? > > googling I found you mentioning that the "CC pseudo register can > > be deduced from the ASTAT register", though further googling doesn't > > find any mention of what ASTAT is. I'm sure there's a good reason, > > I'm probably just missing a comment somewhere. > > CC is actually a single bit in the ASTAT (arithmetic status) register, but > often is treated as an actual register in much of the ISA. such as > assignments or logical tests. you can do "<reg> = CC" and "CC = <reg>", > but you cant do this with any other ASTAT bit (like AZ, AN, etc...). another data point: gcc itself treats CC as a register. btw, the name is short for "Control Code" -mike
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