On 09/14/2016 03:55 PM, Segher Boessenkool wrote:
On Wed, Sep 14, 2016 at 03:08:21PM +0200, Bernd Schmidt wrote:
The data that was posted showed a code size decrease on a number of
targets. I'm really not sure where this irrational hate for regrename
comes from.
It increases the number of active, "young" registers per thread.
There is no irrational hate. Regrename is simply a de-optimisation on
some (heavily) out-of-order targets.
Can you point me at a processor manual for such a chip that explains why
this would be the case?
(It also makes the generated code much harder to read, but you know that).
Can't say I do, really. I imagine it could be the case if it enables
more aggressive scheduling but that's kind of one of the intended effects.
Bernd
