[all-commits] [llvm/llvm-project] c25220: [DAG][ARM][MIPS][RISCV] Improve funnel shift promo...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: c252200e4de4411478fb525e93cc7ae05b189a22
      https://github.com/llvm/llvm-project/commit/c252200e4de4411478fb525e93cc7ae05b189a22
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2020-10-12 (Mon, 12 Oct 2020)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
    M llvm/test/CodeGen/ARM/funnel-shift.ll
    M llvm/test/CodeGen/Mips/funnel-shift.ll
    M llvm/test/CodeGen/RISCV/rv64Zbt.ll

  Log Message:
  -----------
  [DAG][ARM][MIPS][RISCV] Improve funnel shift promotion to use 'double shift' patterns

Based on a discussion on D88783, if we're promoting a funnel shift to a width at least twice the size as the original type, then we can use the 'double shift' patterns (shifting the concatenated sources).

Differential Revision: https://reviews.llvm.org/D89139