[TargetLowering] Add SimplifyDemandedBitsForTargetNode callback

Add a SimplifyDemandedBitsForTargetNode callback to handle target nodes.

Differential Revision: https://reviews.llvm.org/D53643

llvm-svn: 345179

2 files changed, 36 insertions, 1 deletions

diff --git a/llvm/include/llvm/CodeGen/TargetLowering.h b/llvm/include/llvm/CodeGen/TargetLowering.h
index 585d07cf044..4b1fae89be5 100644
--- a/llvm/include/llvm/CodeGen/TargetLowering.h
+++ b/llvm/include/llvm/CodeGen/TargetLowering.h
@@ -2916,11 +2916,22 @@ public:
   /// elements, returning true on success. Otherwise, analyze the expression and
   /// return a mask of KnownUndef and KnownZero elements for the expression
   /// (used to simplify the caller). The KnownUndef/Zero elements may only be
-  /// accurate for those bits in the DemandedMask
+  /// accurate for those bits in the DemandedMask.
   virtual bool SimplifyDemandedVectorEltsForTargetNode(
       SDValue Op, const APInt &DemandedElts, APInt &KnownUndef,
       APInt &KnownZero, TargetLoweringOpt &TLO, unsigned Depth = 0) const;
 
+  /// Attempt to simplify any target nodes based on the demanded bits,
+  /// returning true on success. Otherwise, analyze the
+  /// expression and return a mask of KnownOne and KnownZero bits for the
+  /// expression (used to simplify the caller).  The KnownZero/One bits may only
+  /// be accurate for those bits in the DemandedMask.
+  virtual bool SimplifyDemandedBitsForTargetNode(SDValue Op,
+                                                 const APInt &DemandedBits,
+                                                 KnownBits &Known,
+                                                 TargetLoweringOpt &TLO,
+                                                 unsigned Depth = 0) const;
+
   /// If \p SNaN is false, \returns true if \p Op is known to never be any
   /// NaN. If \p sNaN is true, returns if \p Op is known to never be a signaling
   /// NaN.
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 017db41fa9e..0189a11fa1d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1335,6 +1335,13 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
     LLVM_FALLTHROUGH;
   }
   default:
+    if (Op.getOpcode() >= ISD::BUILTIN_OP_END) {
+      if (SimplifyDemandedBitsForTargetNode(Op, DemandedBits, Known, TLO,
+                                            Depth))
+        return true;
+      break;
+    }
+
     // Just use computeKnownBits to compute output bits.
     TLO.DAG.computeKnownBits(Op, Known, Depth);
     break;
@@ -1803,6 +1810,23 @@ bool TargetLowering::SimplifyDemandedVectorEltsForTargetNode(
   return false;
 }
 
+bool TargetLowering::SimplifyDemandedBitsForTargetNode(
+    SDValue Op, const APInt &DemandedBits, KnownBits &Known,
+    TargetLoweringOpt &TLO, unsigned Depth) const {
+  assert((Op.getOpcode() >= ISD::BUILTIN_OP_END ||
+          Op.getOpcode() == ISD::INTRINSIC_WO_CHAIN ||
+          Op.getOpcode() == ISD::INTRINSIC_W_CHAIN ||
+          Op.getOpcode() == ISD::INTRINSIC_VOID) &&
+         "Should use SimplifyDemandedBits if you don't know whether Op"
+         " is a target node!");
+  EVT VT = Op.getValueType();
+  APInt DemandedElts = VT.isVector()
+                           ? APInt::getAllOnesValue(VT.getVectorNumElements())
+                           : APInt(1, 1);
+  computeKnownBitsForTargetNode(Op, Known, DemandedElts, TLO.DAG, Depth);
+  return false;
+}
+
 bool TargetLowering::isKnownNeverNaNForTargetNode(SDValue Op,
                                                   const SelectionDAG &DAG,
                                                   bool SNaN,