Re: [PATCH][combine] PR rtl-optimization/68651 Try changing rtx from (r + r) to (r << 1) to aid recognition

[Bernd Schmidt]

On 12/15/2015 03:33 PM, Richard Earnshaw wrote:

It's also possible that this would explicitly break some other
optimization passes (such as the way in which multiplies are synthesised
with shift/add operations).

How so? IMO such a change would make cost calculations more accurate and 
should help rather than break anything.


Bernd