Hi everyone,

I've been away for a few days so I haven't
been paying too much attention to the trunk,
but I've noticed some new changes to the x86-
64 peephole optimized that look interesting.
Can someone fill me in on what they're meant
to do and the motivation behind the
additions? This is just so I fully understand
what everything is doing and don't
accidentally overwrite something.

Gareth aka. Kit

Which ones do you mean? Normally, I try to a add a reasonable commit message.

Hi Florian,

Thanks for the response.  I'm mostly referring to r44241 that introdues GetNextInstructionUsingRegTrackingUse and some restrictions on more expensive optimisations.

One thing I wanted to bring up is "RemoveCurrentP(p)" - I've been avoiding its use because it calls GetNextInstruction, which can be an expensive call, and a lot of the time, I already know what the next instruction is at that point (hence the "p := hp1;" assignments that appear after it).  I figure it might class as a micro-optimisation though and I can certainly see a call to "RemoveCurrentP(p)" being safer, lest we accidentally leave p dangling.  Can I recommend we split this into two separate commands named "RemovePAndSetNext" and "RemovePAndNil" or some such?  The former would set p to GetNextInstruction, while the latter would set p to nil.  With the aid of inlining and deadstore removal, if "p := hp1;" follows a call to RemovePAndNil(p), then the setting of p to nil will be removed by the optimiser.

Gareth aka. Kit