[PATCH] D93416: [GlobalISel] Map extractelt to G_EXTRACT_VECTOR_ELT

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope created this revision.
bjope added reviewers: dsanders, arsenm, t.p.northover.
Herald added subscribers: hiraditya, kristof.beyls, rovka.
bjope requested review of this revision.
Herald added a subscriber: wdng.
Herald added a project: LLVM.

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).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D93416

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


Index: llvm/utils/TableGen/GlobalISelEmitter.cpp
===================================================================
--- llvm/utils/TableGen/GlobalISelEmitter.cpp
+++ llvm/utils/TableGen/GlobalISelEmitter.cpp
@@ -4690,6 +4690,8 @@
 
   // EXTRACT_SUBREG needs to use a subregister COPY.
   if (Name == "EXTRACT_SUBREG") {
+    if (!Dst->getChild(1)->isLeaf())
+      return failedImport("EXTRACT_SUBREG child #1 is not a leaf");
     DefInit *SubRegInit = dyn_cast<DefInit>(Dst->getChild(1)->getLeafValue());
     if (!SubRegInit)
       return failedImport("EXTRACT_SUBREG child #1 is not a subreg index");
Index: llvm/lib/Target/AArch64/AArch64InstrGISel.td
===================================================================
--- llvm/lib/Target/AArch64/AArch64InstrGISel.td
+++ llvm/lib/Target/AArch64/AArch64InstrGISel.td
@@ -164,7 +164,9 @@
 def : GINodeEquiv<G_VASHR, AArch64vashr>;
 def : GINodeEquiv<G_VLSHR, AArch64vlshr>;
 
+def : GINodeEquiv<G_EXTRACT_VECTOR_ELT, vector_extract>;
+
 // These are patterns that we only use for GlobalISel via the importer.
 def : Pat<(f32 (fadd (vector_extract (v2f32 FPR64:$Rn), (i64 0)),
                      (vector_extract (v2f32 FPR64:$Rn), (i64 1)))),
            (f32 (FADDPv2i32p (v2f32 FPR64:$Rn)))>;
\ No newline at end of file
Index: llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td
===================================================================
--- llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td
+++ llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td
@@ -116,7 +116,7 @@
 def : GINodeEquiv<G_CTLZ_ZERO_UNDEF, ctlz_zero_undef>;
 def : GINodeEquiv<G_CTTZ_ZERO_UNDEF, cttz_zero_undef>;
 def : GINodeEquiv<G_CTPOP, ctpop>;
-def : GINodeEquiv<G_EXTRACT_VECTOR_ELT, vector_extract>;
+def : GINodeEquiv<G_EXTRACT_VECTOR_ELT, extractelt>;
 def : GINodeEquiv<G_CONCAT_VECTORS, concat_vectors>;
 def : GINodeEquiv<G_BUILD_VECTOR, build_vector>;
 def : GINodeEquiv<G_FCEIL, fceil>;


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