On 05/04/2016 12:03 PM, Eric Botcazou wrote:
The IBM LTC team has tested the benefit of -frename-registers at -O2
and sees no net benefit for PowerPC -- some benchmarks improve
slightly but others degrade slightly (a few percent). You mentioned
no overall benefit for x86. Although you mentioned benefit for
Itanium, it is not a primary nor secondary architecture target for GCC
and continues to have limited adoption. Andreas also reported a
bootstrap comparison failure for Itanium due to the change.
...which had nothing to do with -frename-registers but was a latent issue in
the speculation support of the scheduler, see the audit trail.
Yeah, I'd forgotten to add this to the list of issues found. Also,
Alan's morestack representation issue.
Given how many latent bugs it has shown up I think that alone would make
it valuable to have enabled at -O2.
Bernd