[PATCH] D44972: [X86] Add SchedRW for PMULLD

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: RKSimon, GGanesh, courbet.

It seems many CPUs don't implement this instruction as well as the other vector multiplies. Often using a multi uop flow. Silvermont in particular has a 7 uop flow with 11 cycle throughput. Sandy Bridge implements it as a single uop with 5 cycle latency and 1 cycle throughput. But Haswell and later use 2 uops with 10 cycle latency and 2 cycle throughput.

This patch adds a new X86SchedWritePair we can use to tag this instruction separately. I've provided correct information for Silvermont, Btver2, and Sandy Bridge. I've removed the InstRWs for SandyBridge. I've left Haswell/Broadwell/Skylake InstRWs in place because I wasn't sure how to account for the different load latency between 128 and 256 bits. I also left Znver1 InstRWs in place because the existing values don't match Agner's spreadsheet.

I also left a FIXME in the SandyBridge model because it being used for the "generic" model is too optimistic for the 256/512-bit versions since those are multiple uops on all known CPUs.


https://reviews.llvm.org/D44972

Files:
  lib/Target/X86/X86InstrAVX512.td
  lib/Target/X86/X86InstrSSE.td
  lib/Target/X86/X86SchedBroadwell.td
  lib/Target/X86/X86SchedHaswell.td
  lib/Target/X86/X86SchedSandyBridge.td
  lib/Target/X86/X86SchedSkylakeClient.td
  lib/Target/X86/X86SchedSkylakeServer.td
  lib/Target/X86/X86Schedule.td
  lib/Target/X86/X86ScheduleBtVer2.td
  lib/Target/X86/X86ScheduleSLM.td
  lib/Target/X86/X86ScheduleZnver1.td
  test/CodeGen/X86/avx2-schedule.ll
  test/CodeGen/X86/slow-pmulld.ll
  test/CodeGen/X86/sse41-schedule.ll

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