[PATCH] D81936: [CodeGen] Fix warnings in foldCONCAT_VECTORS

[David Sherwood via Phabricator via llvm-commits]

david-arm created this revision.
david-arm added reviewers: sdesmalen, kmclaughlin, efriedma.
Herald added subscribers: llvm-commits, hiraditya, kristof.beyls.
Herald added a reviewer: rengolin.
Herald added a project: LLVM.

Instead of asserting the number of elements is the same, we should be
comparing the element counts instead. In addition, when looking at
concats of extract_subvectors it's fine to use getVectorMinNumElements()
for scalable vectors.

I discovered these warnings when compiling the structured loads tests in
this file:

  test/CodeGen/AArch64/sve-intrinsics-loads.ll


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D81936

Files:
  llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp


Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4315,8 +4315,8 @@
                         return Ops[0].getValueType() == Op.getValueType();
                       }) &&
          "Concatenation of vectors with inconsistent value types!");
-  assert((Ops.size() * Ops[0].getValueType().getVectorNumElements()) ==
-             VT.getVectorNumElements() &&
+  assert((Ops[0].getValueType().getVectorElementCount() * Ops.size()) ==
+             VT.getVectorElementCount() &&
          "Incorrect element count in vector concatenation!");
 
   if (Ops.size() == 1)
@@ -4333,7 +4333,7 @@
   bool IsIdentity = true;
   for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
     SDValue Op = Ops[i];
-    unsigned IdentityIndex = i * Op.getValueType().getVectorNumElements();
+    unsigned IdentityIndex = i * Op.getValueType().getVectorMinNumElements();
     if (Op.getOpcode() != ISD::EXTRACT_SUBVECTOR ||
         Op.getOperand(0).getValueType() != VT ||
         (IdentitySrc && Op.getOperand(0) != IdentitySrc) ||
@@ -4350,6 +4350,11 @@
     return IdentitySrc;
   }
 
+  // The code below this point is only designed to work for fixed width
+  // vectors, so we bail out for now.
+  if (VT.isScalableVector())
+    return SDValue();
+
   // A CONCAT_VECTOR with all UNDEF/BUILD_VECTOR operands can be
   // simplified to one big BUILD_VECTOR.
   // FIXME: Add support for SCALAR_TO_VECTOR as well.


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