Re: [mips-tls] A couple of potential changes to the MIPS TLS ABI

[Daniel Jacobowitz <dan@xxxxxxxxxxxxxxxx>]

On Wed, Feb 09, 2005 at 04:04:51PM -0800, Mark Mitchell wrote:
> Michael Uhler wrote:
> >Both points are valid.  But they assume that if we DO have a performance
> >problem, we'll be able to go back and fix that problem with an alternative
> >method (something other than a new ABI).  It was my impression that we were
> >discussing something that was not going to be easy to change once defined.
> 
> That's why I suggested, as a possible compromise, that we require that 
> compilers/linkers mark the rdhwr instruction with a relocation.  That 
> would allow dynamic linkers to make appropriate changes to the code, if 
> appropriate.
> 
> To me, this seems like a very practical way of moving forward with our 
> current implementation, while hedging our bets; what do you and others 
> think?

I don't think it's worthwhile, since it doesn't hedge bets very well. 
An alternative sequence could easily turn out to be more than one
instruction, but still faster than a trap.

-- 
Daniel Jacobowitz
CodeSourcery, LLC