Re: [GCC RFC]A new and simple pass merging paired load store instructions

[Jeff Law <law at redhat dot com>]

On 05/20/14 01:13, Bin.Cheng wrote:
> > The idea being that common cases where a pair moves can be turned into a
> > single wider move without having to write target code to make that happen
> > much of the time.  ie 2xQI->HI, 2xHI->SI, 2xSI->DI 2xSF->DF.  For things
> > outside those simple cases, fall back to a target hook or a target expander.
> This is practicable, but the question is why we would bother with
> general cases if the hook interface is needed anyway.  Is it because
> target calls are generally more expensive?
No, it's because most (all?) targets would benefit without having to 
write target dependent code.

jeff