[SelectionDAG] GetDemandedBits - add demanded elements wrapper implementation

The DemandedElts variable is pretty much inert at the moment - the original GetDemandedBits implementation calls it with an 'all ones' DemandedElts value so the function is active and behaves exactly as it used to.

llvm-svn: 361773

2 files changed, 29 insertions, 5 deletions

diff --git a/llvm/include/llvm/CodeGen/SelectionDAG.h b/llvm/include/llvm/CodeGen/SelectionDAG.h
index 08333870467..070c644e337 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAG.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -1434,13 +1434,23 @@ public:
   SDValue FoldSetCC(EVT VT, SDValue N1, SDValue N2, ISD::CondCode Cond,
                     const SDLoc &dl);
 
-  /// See if the specified operand can be simplified with the knowledge that only
-  /// the bits specified by Mask are used.  If so, return the simpler operand,
-  /// otherwise return a null SDValue.
+  /// See if the specified operand can be simplified with the knowledge that
+  /// only the bits specified by DemandedBits are used.  If so, return the
+  /// simpler operand, otherwise return a null SDValue.
   ///
   /// (This exists alongside SimplifyDemandedBits because GetDemandedBits can
   /// simplify nodes with multiple uses more aggressively.)
-  SDValue GetDemandedBits(SDValue V, const APInt &Mask);
+  SDValue GetDemandedBits(SDValue V, const APInt &DemandedBits);
+
+  /// See if the specified operand can be simplified with the knowledge that
+  /// only the bits specified by DemandedBits are used in the elements specified
+  /// by DemandedElts.  If so, return the simpler operand, otherwise return a
+  /// null SDValue.
+  ///
+  /// (This exists alongside SimplifyDemandedBits because GetDemandedBits can
+  /// simplify nodes with multiple uses more aggressively.)
+  SDValue GetDemandedBits(SDValue V, const APInt &DemandedBits,
+                          const APInt &DemandedElts);
 
   /// Return true if the sign bit of Op is known to be zero.
   /// We use this predicate to simplify operations downstream.
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index ad534ab497b..46474b97412 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2122,10 +2122,24 @@ SDValue SelectionDAG::FoldSetCC(EVT VT, SDValue N1, SDValue N2,
 }
 
 /// See if the specified operand can be simplified with the knowledge that only
-/// the bits specified by Mask are used.
+/// the bits specified by DemandedBits are used.
 /// TODO: really we should be making this into the DAG equivalent of
 /// SimplifyMultipleUseDemandedBits and not generate any new nodes.
 SDValue SelectionDAG::GetDemandedBits(SDValue V, const APInt &DemandedBits) {
+  EVT VT = V.getValueType();
+  APInt DemandedElts = VT.isVector()
+                           ? APInt::getAllOnesValue(VT.getVectorNumElements())
+                           : APInt(1, 1);
+  return GetDemandedBits(V, DemandedBits, DemandedElts);
+}
+
+/// See if the specified operand can be simplified with the knowledge that only
+/// the bits specified by DemandedBits are used in the elements specified by
+/// DemandedElts.
+/// TODO: really we should be making this into the DAG equivalent of
+/// SimplifyMultipleUseDemandedBits and not generate any new nodes.
+SDValue SelectionDAG::GetDemandedBits(SDValue V, const APInt &DemandedBits,
+                                      const APInt &DemandedElts) {
   switch (V.getOpcode()) {
   default:
     break;