[llvm-bugs] [Bug 48336] New: [X86] What AVX512 cpus should prefer 512-bit vectors?

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=48336

            Bug ID: 48336
           Summary: [X86] What AVX512 cpus should prefer 512-bit vectors?
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: llvm-dev at redking.me.uk
                CC: craig.topper at gmail.com, llvm-bugs at lists.llvm.org,
                    llvm-dev at redking.me.uk, pengfei.wang at intel.com,
                    peter at cordes.ca, spatel+llvm at rotateright.com

All avx512 capable Skylake CPUs and later currently prefer 256-bit vs 512-bit
vector generation - only the Knights Landing family always prefers 512-bit
(very different arch, no VLX support etc.).

AFAICT many of the frequency throttling issues with 512-bit ops were already
addressed by/after Icelake - so do we need to alter the tuning for later cpus
to let them vectorize to the full 512-bit alu width?

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20201130/8d4b49b2/attachment-0001.html>