[all-commits] [llvm/llvm-project] e503fe: [AArch64] Fix MUL/SUB fusing

[Sanne Wouda via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: e503fee904d8c17c089d27ab928bc72eeeece649
      https://github.com/llvm/llvm-project/commit/e503fee904d8c17c089d27ab928bc72eeeece649
  Author: Sanne Wouda <Sanne.Wouda at arm.com>
  Date:   2019-12-05 (Thu, 05 Dec 2019)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
    M llvm/test/CodeGen/AArch64/neon-mla-mls.ll

  Log Message:
  -----------
  [AArch64] Fix MUL/SUB fusing

Summary:
When MUL is the first operand to SUB, we can't use MLS because the accumulator
should be negated.  Emit a NEG of the accumulator and an MLA instead, similar to
what we do for FMUL / FSUB fusing.

Reviewers: dmgreen, SjoerdMeijer, fhahn, Gerolf, mstorsjo, asbirlea

Reviewed By: asbirlea

Subscribers: kristof.beyls, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71067