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Re: [PATCH] PPC remove use of phased-out mftb instructions


Steven Munroe writes:

> the POWER ISA-2.03 has marked the move from time base instruction
> "Phased-out" in favor of the equivalent move from SPR 268.
> 
> To continue support for processors I conditioned this on the _ARCH_PWR4.
> which defined for --with-cpu= or CFLAGS='-mcpu=' power4 and higher.

I am pretty sure there were never any PowerPC processor
implementations that implemented mftb, that implemented it any
differently from mfspr.  I recall checking at least the 603, 604,
7400, 7410 and 7455, and IIRC they all executed mfspr rn,268 as
mftb rn.

So I don't think it's necessary to condition it.  I could repeat the
tests and do them across a broader range of processors if that would
be helpful.

Paul.


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