[Bug target/94393] Powerpc suboptimal 64-bit constant comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94393 Jiu Fu Guo changed: What|Removed |Added Resolution|--- |FIXED CC||guojiufu at gcc dot gnu.org Status|NEW |RESOLVED --- Comment #9 from Jiu Fu Guo --- After r14-4470, trunk generates better code for this case.
[Bug target/94393] Powerpc suboptimal 64-bit constant comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94393 Alan Modra changed: What|Removed |Added Status|ASSIGNED|NEW URL||https://gcc.gnu.org/piperma ||il/gcc-patches/2020-October ||/555760.html Assignee|amodra at gmail dot com|unassigned at gcc dot gnu.org --- Comment #8 from Alan Modra --- Patch posted at given URL above. I'm taking myself off as assignee because it is clear to me the patch is going nowhere. Someone more capable than me will need to take up the task, sorry.
[Bug target/94393] Powerpc suboptimal 64-bit constant comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94393 --- Comment #7 from Alan Modra --- (In reply to Peter Bergner from comment #5) > Alan, I think you pushed some changes to help with 1) above, correct? > Is there more to do for 1)? Possibly, I haven't looked at what needs to be done (if anything) for pli. > As for 2), we're in stage1 now. Do you have ideas about what must be done > there? Do we still want to do something for 2)? I wrote a series of patches in early April.
[Bug target/94393] Powerpc suboptimal 64-bit constant comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94393 --- Comment #6 from Segher Boessenkool --- It certainly would be nice to improve this :-) It won't help most code very much -- how often do two-word values happen at all -- but we have to revisit how all this is decided anyway (for prefixed instructions), so now would be a good time :-)
[Bug target/94393] Powerpc suboptimal 64-bit constant comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94393 --- Comment #5 from Peter Bergner --- (In reply to Alan Modra from comment #3) > There are two parts to fixing this PR. > 1) We can do better in the sequences generated for some constants. > 2) rs6000_rtx_costs needs to be accurate, so that expensive constants are > put in memory and stay there with optimisation. > > Having looked at part 2 a little, I'd say fixes for that are definitely not > stage 4 material. Alan, I think you pushed some changes to help with 1) above, correct? Is there more to do for 1)? As for 2), we're in stage1 now. Do you have ideas about what must be done there? Do we still want to do something for 2)?
[Bug target/94393] Powerpc suboptimal 64-bit constant comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94393 --- Comment #4 from Nicholas Piggin --- (In reply to Alan Modra from comment #3) > There are two parts to fixing this PR. > 1) We can do better in the sequences generated for some constants. > 2) rs6000_rtx_costs needs to be accurate, so that expensive constants are > put in memory and stay there with optimisation. > > Having looked at part 2 a little, I'd say fixes for that are definitely not > stage 4 material. Well the other part I thought is that different branch test could be chosen in order to use the cheapest constant. If you generate the 0xbfff... constant more cheaply it'd still be more expensive than 0xc000... That was my intention opening the two bugs but I didn't explain myself so well.
[Bug target/94393] Powerpc suboptimal 64-bit constant comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94393 --- Comment #3 from Alan Modra --- There are two parts to fixing this PR. 1) We can do better in the sequences generated for some constants. 2) rs6000_rtx_costs needs to be accurate, so that expensive constants are put in memory and stay there with optimisation. Having looked at part 2 a little, I'd say fixes for that are definitely not stage 4 material.
[Bug target/94393] Powerpc suboptimal 64-bit constant comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94393 Alan Modra changed: What|Removed |Added CC||amodra at gmail dot com --- Comment #2 from Alan Modra --- *** Bug 57836 has been marked as a duplicate of this bug. ***
[Bug target/94393] Powerpc suboptimal 64-bit constant comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94393 --- Comment #1 from Alan Modra --- Created attachment 48146 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48146=edit teach gcc more two insn sequences for constants
[Bug target/94393] Powerpc suboptimal 64-bit constant comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94393 Alan Modra changed: What|Removed |Added Ever confirmed|0 |1 Assignee|unassigned at gcc dot gnu.org |amodra at gmail dot com Last reconfirmed||2020-03-30 CC|amodra at gmail dot com| Status|UNCONFIRMED |ASSIGNED
