[all-commits] [llvm/llvm-project] e64f91: [TTI][X86] Recognise PMULUDQ costs for vXi64 multi...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e64f9140c583de1619c1f032abc8585b0cdc2c89
      https://github.com/llvm/llvm-project/commit/e64f9140c583de1619c1f032abc8585b0cdc2c89
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2023-06-14 (Wed, 14 Jun 2023)

  Changed paths:
    M llvm/lib/Target/X86/X86TargetTransformInfo.cpp
    M llvm/test/Analysis/CostModel/X86/mul64.ll

  Log Message:
  -----------
  [TTI][X86] Recognise PMULUDQ costs for vXi64 multiplies

Addresses part of Issue #62969 - if the upper 32-bits of the vXi64 elements are known to be zero, then a multiply simplifies to a single (fast) PMULUDQ instruction

We still have the problem that minRequiredElementSize can't determine that the upper bits are zero for the test case from Issue #62969 - I'll take a look at that next.