[all-commits] [llvm/llvm-project] 705d00: [DAGCombiner][RISCV] Don't use vector types in DAG...

[Craig Topper via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 705d00578128c6089fe05adb175a5306f46c695c
      https://github.com/llvm/llvm-project/commit/705d00578128c6089fe05adb175a5306f46c695c
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2021-08-30 (Mon, 30 Aug 2021)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    A llvm/test/CodeGen/RISCV/rvv/fixed-vectors-store-merge-crash.ll

  Log Message:
  -----------
  [DAGCombiner][RISCV] Don't use vector types in DAGCombiner::tryStoreMergeOfLoads if we need a rotate.

The check for whether a rotate is possible occurs before the
memory legality checks for the integer type. So it's possible we
decide we can use a rotate, but then fail the legality checks. If
that happens we should not fall back to a vector type. This triggers
an assertion in the rotate handling when it finds a vector type
instead of an integer type.

In theory we could use a shufflevector in place of the rotate, but
right now I'd just like to fix the crash.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D108839