[Bug middle-end/98713] Failure to generate branch version of abs if user requested it

2021-09-26 Thread pinskia at gcc dot gnu.org via Gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98713 --- Comment #10 from Andrew Pinski --- (In reply to Martin Liška from comment #1) > I think it's fixed since r11-2588-gc072fd236dc08f99. Oh this changed from the shift/xor/sub to using cmov ...

[Bug middle-end/98713] Failure to generate branch version of abs if user requested it

2021-09-26 Thread pinskia at gcc dot gnu.org via Gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98713 Andrew Pinski changed: What|Removed |Added Target||x86_64 Keywords|

[Bug middle-end/98713] Failure to generate branch version of abs if user requested it

2021-01-18 Thread jakub at gcc dot gnu.org via Gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98713 --- Comment #8 from Jakub Jelinek --- This is specific to x86, where if the inputs are inpredictable and results aren't consumed too early that the cmov latency kills performance cmov sometimes improves performance a lot, on the other side, if th

[Bug middle-end/98713] Failure to generate branch version of abs if user requested it

2021-01-18 Thread roger at nextmovesoftware dot com via Gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98713 --- Comment #7 from Roger Sayle --- I agree in the general case, a conditional jump (that depends only on the condition flags) potentially has a shorter dependence chain than a cmov (which depends on the condition flags and two registers). But i

[Bug middle-end/98713] Failure to generate branch version of abs if user requested it

2021-01-18 Thread jakub at gcc dot gnu.org via Gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98713 Jakub Jelinek changed: What|Removed |Added CC||jakub at gcc dot gnu.org --- Comment #6

[Bug middle-end/98713] Failure to generate branch version of abs if user requested it

2021-01-18 Thread david.bolvansky at gmail dot com via Gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98713 --- Comment #5 from Dávid Bolvanský --- User knows the data better, so he/she may prefer abs with branch. Also PGO may say that branch for abs is better based on profile data.

[Bug middle-end/98713] Failure to generate branch version of abs if user requested it

2021-01-18 Thread ubizjak at gmail dot com via Gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98713 --- Comment #4 from Uroš Bizjak --- Please see PR 56309 (and PR 85559 meta bug). Quote from Honza: The decision on whether to use cmov or jmp was always tricky on x86 architectures. Cmov increase dependency chains, register pressure (both value

[Bug middle-end/98713] Failure to generate branch version of abs if user requested it

2021-01-18 Thread rguenth at gcc dot gnu.org via Gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98713 --- Comment #3 from Richard Biener --- A well-predicted branch will be faster than the cmov because of the shorter data dependence path.

[Bug middle-end/98713] Failure to generate branch version of abs if user requested it

2021-01-18 Thread roger at nextmovesoftware dot com via Gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98713 Roger Sayle changed: What|Removed |Added CC||roger at nextmovesoftware dot com --- Com

[Bug middle-end/98713] Failure to generate branch version of abs if user requested it

2021-01-18 Thread marxin at gcc dot gnu.org via Gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98713 Martin Liška changed: What|Removed |Added Ever confirmed|0 |1 Status|UNCONFIRMED