Regarding LRA, I saw this coming and started working on it here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90785 Judging from the similar SH4 PR, I understand this isn't a trivial thing to fix. Is there any reason I couldn't become the ia64 maintainer, assuming there was someone available to act as my general gcc mentor?
Jason On Thu, Jun 13, 2019 at 5:24 PM Jim Wilson <j...@sifive.com> wrote: > On Thu, Jun 13, 2019 at 1:35 PM John Paul Adrian Glaubitz > <glaub...@physik.fu-berlin.de> wrote: > > I know that argument and I have heard it before but whenever I asked > > for a particular example which code in question of a backend would > > block something else, I never received an answer. > > It is hard to produce good examples on demand, as some of these things > tend to be temporary problems, and someone just gets impatient enough > that they just make a blind fix to the targets that can't be properly > tested. > > A possible example here is LRA. This is a new local register > allocation pass that is intended to replace the very old reload pass. > For now, some ports are continuing to use reload. Some ports are > using LRA. Generally, the well maintained ports are using LRA because > it has a number of advantages, and the poorly maintained ports are > still using reload. We would like to eventually obsolete the reload > code, but we can't do that until every port switches over. Meanwhile, > we have to maintain two very different register allocation passes that > do the same thing, which is twice as much work as only having one of > them. So we'd really like to see all ports switch over to LRA. IA-64 > is one of the ports that hasn't switched yet. Most of the unfixed > ports are embedded targets, and eventually someone will get impatient > enough to fix them even though they don't care about the target, using > a simulator to test it. But IA-64 is a server part, not an embedded > part, so in theory requires more testing. Also, there is no free > simulator for IA-64 that I know of which makes the testing harder. > However, there are over 20 targets that don't have LRA support yet, so > the IA-64 port is not a blocking factor here yet. There are people > slowly converting random embedded ports over though, so eventually > IA-64 will be a blocking factor if it doesn't get fixed. > > Jim > >
