[PATCH] D81093: [CodeGen] Fix ComputeNumSignBits for scalable vectors

[David Sherwood via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG9e811b0d932c: [CodeGen] Fix ComputeNumSignBits for scalable vectors (authored by david-arm).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D81093/new/

https://reviews.llvm.org/D81093

Files:
  llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  llvm/unittests/CodeGen/AArch64SelectionDAGTest.cpp


Index: llvm/unittests/CodeGen/AArch64SelectionDAGTest.cpp
===================================================================
--- llvm/unittests/CodeGen/AArch64SelectionDAGTest.cpp
+++ llvm/unittests/CodeGen/AArch64SelectionDAGTest.cpp
@@ -146,6 +146,20 @@
   EXPECT_EQ(DAG->ComputeNumSignBits(Op, DemandedElts), 15u);
 }
 
+TEST_F(AArch64SelectionDAGTest, ComputeNumSignBitsSVE_SIGN_EXTEND_VECTOR_INREG) {
+  if (!TM)
+    return;
+  SDLoc Loc;
+  auto Int8VT = EVT::getIntegerVT(Context, 8);
+  auto Int16VT = EVT::getIntegerVT(Context, 16);
+  auto InVecVT = EVT::getVectorVT(Context, Int8VT, 4, /*IsScalable=*/true);
+  auto OutVecVT = EVT::getVectorVT(Context, Int16VT, 2, /*IsScalable=*/true);
+  auto InVec = DAG->getConstant(1, Loc, InVecVT);
+  auto Op = DAG->getNode(ISD::SIGN_EXTEND_VECTOR_INREG, Loc, OutVecVT, InVec);
+  auto DemandedElts = APInt(2, 3);
+  EXPECT_EQ(DAG->ComputeNumSignBits(Op, DemandedElts), 1u);
+}
+
 TEST_F(AArch64SelectionDAGTest, ComputeNumSignBits_EXTRACT_SUBVECTOR) {
   if (!TM)
     return;
Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3539,6 +3539,11 @@
 
 unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, unsigned Depth) const {
   EVT VT = Op.getValueType();
+
+  // TODO: Assume we don't know anything for now.
+  if (VT.isScalableVector())
+    return 1;
+
   APInt DemandedElts = VT.isVector()
                            ? APInt::getAllOnesValue(VT.getVectorNumElements())
                            : APInt(1, 1);
@@ -3562,7 +3567,7 @@
   if (Depth >= MaxRecursionDepth)
     return 1;  // Limit search depth.
 
-  if (!DemandedElts)
+  if (!DemandedElts || VT.isScalableVector())
     return 1;  // No demanded elts, better to assume we don't know anything.
 
   unsigned Opcode = Op.getOpcode();


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