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Re: [Patch] rtx_cost of SUBREG

> Could you outline the gory details?  The clock is ticking on the 48 hour
> rule, but in stage3 its clearly better to address the "real problem"
> that was exposed by this change rather than leave it latent to potentially
> cause problems elsewhere before a release.

Sure, see my answer to Ulrich.  But every generic change like this is very 
likely to uncover latent problems.  That's why I think they should not be done 
at the end of stage3.

> There's also the compromise suggested in my review of Mark's patch that
> allows the backends to override the code of REG and SUBREG themselves.
> This would allow the sparc (in 64-bit mode) to specify a cost for a
> SUBREG and avoid the problem.  But you'll appreciate this is also just
> a (target-specific) workaround as the cost of the SUBREGs in the RTL
> you give really should be the same as the cost of a REG.

For any SUBREGs?

> I'm building a tree to sparc64-sun-solaris2.8 to investigate the issue.
> Whatever the outcome, this should be resolved by Monday morning.
> Sorry for the inconvenience,

A cross is enough, I'll send you a testcase privately.

Eric Botcazou

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