[llvm] e82d49b - [DAG] SimplifyMultipleUseDemandedBits - early-out for any scalable vector types

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2022-07-24T12:59:43+01:00
New Revision: e82d49bfed3879fcf3d79a9978135fe5fabc9843

URL: https://github.com/llvm/llvm-project/commit/e82d49bfed3879fcf3d79a9978135fe5fabc9843
DIFF: https://github.com/llvm/llvm-project/commit/e82d49bfed3879fcf3d79a9978135fe5fabc9843.diff

LOG: [DAG] SimplifyMultipleUseDemandedBits - early-out for any scalable vector types

Noticed while working to remove SelectionDAG::GetDemandedBits - we were relying on the callers to have already bailed for scalable vectors

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index cd4f0ae42bcd..6205e74837c0 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -654,6 +654,14 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
 SDValue TargetLowering::SimplifyMultipleUseDemandedBits(
     SDValue Op, const APInt &DemandedBits, const APInt &DemandedElts,
     SelectionDAG &DAG, unsigned Depth) const {
+  EVT VT = Op.getValueType();
+
+  // Pretend we don't know anything about scalable vectors for now.
+  // TODO: We can probably do more work on simplifying the operations for
+  // scalable vectors, but for now we just bail out.
+  if (VT.isScalableVector())
+    return SDValue();
+
   // Limit search depth.
   if (Depth >= SelectionDAG::MaxRecursionDepth)
     return SDValue();
@@ -664,7 +672,7 @@ SDValue TargetLowering::SimplifyMultipleUseDemandedBits(
 
   // Not demanding any bits/elts from Op.
   if (DemandedBits == 0 || DemandedElts == 0)
-    return DAG.getUNDEF(Op.getValueType());
+    return DAG.getUNDEF(VT);
 
   bool IsLE = DAG.getDataLayout().isLittleEndian();
   unsigned NumElts = DemandedElts.getBitWidth();
@@ -894,6 +902,13 @@ SDValue TargetLowering::SimplifyMultipleUseDemandedBits(
     SDValue Op, const APInt &DemandedBits, SelectionDAG &DAG,
     unsigned Depth) const {
   EVT VT = Op.getValueType();
+
+  // Pretend we don't know anything about scalable vectors for now.
+  // TODO: We can probably do more work on simplifying the operations for
+  // scalable vectors, but for now we just bail out.
+  if (VT.isScalableVector())
+    return SDValue();
+
   APInt DemandedElts = VT.isVector()
                            ? APInt::getAllOnes(VT.getVectorNumElements())
                            : APInt(1, 1);