[all-commits] [llvm/llvm-project] d5198c: [CostModel][X86] Check for 'null op' truncations

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d5198cf92f3eeb56e41d6222996ac32578e6ad4f
      https://github.com/llvm/llvm-project/commit/d5198cf92f3eeb56e41d6222996ac32578e6ad4f
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2022-05-01 (Sun, 01 May 2022)

  Changed paths:
    M llvm/lib/Target/X86/X86TargetTransformInfo.cpp
    M llvm/test/Analysis/CostModel/X86/arith-fix.ll
    M llvm/test/Analysis/CostModel/X86/arith-overflow.ll

  Log Message:
  -----------
  [CostModel][X86] Check for 'null op' truncations

If the legalized src/dst types are the same, assume the "truncation" is free.

This fixes some edge cases such as mul lo/hi ops and bool vectors which will get legalized back to legal vector widths