On 6/15/21 6:03 AM, Jeff Law wrote:
On 6/14/2021 12:40 AM, Richard Biener wrote:
I bet it's going to be tougher to remove DOM's threader. It knows how
to do thinks like resolve memory references using temporary equivalences
and such. But I bet it's enough to drop the VRP based threaders.
Yes. In fact I am wondering if adding threading to the not iterating FRE
would make it possible to drop DOM, replacing it with instances of FRE.
I'd think so. I'd approach as:
1. Remove the VRP threader instances.
2. Drop cprop and redundancy elimination from DOM using FRE instead
3. What's left of DOM is just forward jump threading. Revamp &
simplify. Then either make it a distinct pass or as a sub-pass of FRE.
But one could just as easily look at adding threading to FRE and just
killing DOM and its jump threading.
Andrew will hopefully be contributing the relational work this week.
Once he does so, I will gather more granular stats for VRP1/VRP2 so we
can assess the situation.
Also, a bunch of tests needed to be tweaked because the new code picks
up so many threads. I'm waiting for the relational work to avoid having
to adjust the tests again.
I would personally prefer to add an item 0 to the above list: replace
current backwards threader code with the rewrite. I would hate to
replace all threaders at once and deal with the fallout. Perhaps it's
better to replace the backward threaders, and once that settles move
onto VRP[12]??
Aldy
