[all-commits] [llvm/llvm-project] 32c073: [GlobalISel] Map extractelt to G_EXTRACT_VECTOR_ELT

[Björn Pettersson via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 32c073acb320db3b22ca76b1e21dd688a70b50e8
      https://github.com/llvm/llvm-project/commit/32c073acb320db3b22ca76b1e21dd688a70b50e8
  Author: Bjorn Pettersson <bjorn.a.pettersson at ericsson.com>
  Date:   2021-01-11 (Mon, 11 Jan 2021)

  Changed paths:
    M llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td
    M llvm/lib/Target/AArch64/AArch64InstrGISel.td
    M llvm/utils/TableGen/GlobalISelEmitter.cpp

  Log Message:
  -----------
  [GlobalISel] Map extractelt to G_EXTRACT_VECTOR_ELT

Before this patch there was generic mapping from vector_extract
to G_EXTRACT_VECTOR_ELT added in SelectionDAGCompat.td. That
mapping is now replaced by a mapping from extractelt instead.

The reasoning is that vector_extract is marked as deprecated,
so it is assumed that a majority of targets will use extractelt
and not vector_extract (and that the long term solution for all
targets would be to use extractelt).

Targets like AArch64 that still use vector_extract can add an
additional mapping from the deprecated vector_extract as target
specific tablegen definitions. Such a mapping is added for AArch64
in this patch to avoid breaking tests.

When adding the extractelt => G_EXTRACT_VECTOR_ELT mapping we
triggered some new code paths in GlobalISelEmitter, ending up in
an assert when trying to import a pattern containing EXTRACT_SUBREG
for ARM. Therefore this patch also adds a "failedImport" warning
for that situation (instead of hitting the assert).

Differential Revision: https://reviews.llvm.org/D93416