[all-commits] [llvm/llvm-project] 31ec72: [llvm][CodeGen] DAG Combiner folds for vscale.

[Francesco Petrogalli via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 31ec721516b5ed36f7dbed180a903e269f29716d
      https://github.com/llvm/llvm-project/commit/31ec721516b5ed36f7dbed180a903e269f29716d
  Author: Francesco Petrogalli <francesco.petrogalli at arm.com>
  Date:   2020-02-21 (Fri, 21 Feb 2020)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/test/CodeGen/AArch64/sve-gep.ll
    A llvm/test/CodeGen/AArch64/sve-vscale-combine.ll

  Log Message:
  -----------
  [llvm][CodeGen] DAG Combiner folds for vscale.

Summary:
This patch simplifies the DAGs generated when using the intrinsic `@llvm.vscale.*` as follows:

* Fold (add (vscale * C0), (vscale * C1)) to (vscale * (C0 + C1)).
* Canonicalize (sub X, (vscale * C)) to (add X,  (vscale * -C)).
* Fold (mul (vscale * C0), C1) to (vscale * (C0 * C1)).
* Fold (shl (vscale * C0), C1) to (vscale * (C0 << C1)).

The test `sve-gep-ll` have been updated to reflect the folding introduced by this patch.

Reviewers: efriedma, sdesmalen, andwar, rengolin

Reviewed By: sdesmalen

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74782