[PATCH] D80437: [CodeGen] Let computeKnownBits do something sensible for scalable vectors

[David Sherwood via Phabricator via llvm-commits]

david-arm updated this revision to Diff 269426.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D80437/new/

https://reviews.llvm.org/D80437

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
@@ -2275,11 +2275,7 @@
 /// for bits that V cannot have.
 bool SelectionDAG::MaskedValueIsZero(SDValue V, const APInt &Mask,
                                      unsigned Depth) const {
-  EVT VT = V.getValueType();
-  APInt DemandedElts = VT.isVector()
-                           ? APInt::getAllOnesValue(VT.getVectorNumElements())
-                           : APInt(1, 1);
-  return MaskedValueIsZero(V, Mask, DemandedElts, Depth);
+  return Mask.isSubsetOf(computeKnownBits(V, Depth).Zero);
 }
 
 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero in
@@ -2548,6 +2544,14 @@
 /// every vector element.
 KnownBits SelectionDAG::computeKnownBits(SDValue Op, unsigned Depth) const {
   EVT VT = Op.getValueType();
+
+  // TOOD: Until we have a plan for how to represent demanded elements for
+  // scalable vectors, we can just bail out for now.
+  if (Op.getValueType().isScalableVector()) {
+    unsigned BitWidth = Op.getScalarValueSizeInBits();
+    return KnownBits(BitWidth);
+  }
+
   APInt DemandedElts = VT.isVector()
                            ? APInt::getAllOnesValue(VT.getVectorNumElements())
                            : APInt(1, 1);
@@ -2563,6 +2567,11 @@
 
   KnownBits Known(BitWidth);   // Don't know anything.
 
+  // TOOD: Until we have a plan for how to represent demanded elements for
+  // scalable vectors, we can just bail out for now.
+  if (Op.getValueType().isScalableVector())
+    return Known;
+
   if (auto *C = dyn_cast<ConstantSDNode>(Op)) {
     // We know all of the bits for a constant!
     Known.One = C->getAPIntValue();


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