[SelectionDAG] MaskedValueIsZero - add demanded elements implementation

Will be used in an upcoming patch but I've updated the original implementation to call this to ensure test coverage.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@361738 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/SelectionDAG.h b/include/llvm/CodeGen/SelectionDAG.h
index 56dd1cc..9395fdb 100644 (file)
--- a/include/llvm/CodeGen/SelectionDAG.h
+++ b/include/llvm/CodeGen/SelectionDAG.h
@@ -1448,8 +1448,14 @@ public:
   /// Return true if 'Op & Mask' is known to be zero.  We
   /// use this predicate to simplify operations downstream.  Op and Mask are
   /// known to be the same type.
-  bool MaskedValueIsZero(SDValue Op, const APInt &Mask, unsigned Depth = 0)
-    const;
+  bool MaskedValueIsZero(SDValue Op, const APInt &Mask,
+                         unsigned Depth = 0) const;
+
+  /// Return true if 'Op & Mask' is known to be zero in DemandedElts.  We
+  /// use this predicate to simplify operations downstream.  Op and Mask are
+  /// known to be the same type.
+  bool MaskedValueIsZero(SDValue Op, const APInt &Mask,
+                         const APInt &DemandedElts, unsigned Depth = 0) const;
 
   /// Determine which bits of Op are known to be either zero or one and return
   /// them in Known. For vectors, the known bits are those that are shared by

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 553a46f..88cbfd1 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2207,9 +2207,22 @@ bool SelectionDAG::SignBitIsZero(SDValue Op, unsigned Depth) const {
 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero.  We use
 /// this predicate to simplify operations downstream.  Mask is known to be zero
 /// for bits that V cannot have.
-bool SelectionDAG::MaskedValueIsZero(SDValue Op, const APInt &Mask,
+bool SelectionDAG::MaskedValueIsZero(SDValue V, const APInt &Mask,
                                      unsigned Depth) const {
-  return Mask.isSubsetOf(computeKnownBits(Op, Depth).Zero);
+  EVT VT = V.getValueType();
+  APInt DemandedElts = VT.isVector()
+                           ? APInt::getAllOnesValue(VT.getVectorNumElements())
+                           : APInt(1, 1);
+  return MaskedValueIsZero(V, Mask, DemandedElts, Depth);
+}
+
+/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero in
+/// DemandedElts.  We use this predicate to simplify operations downstream.
+/// Mask is known to be zero for bits that V cannot have.
+bool SelectionDAG::MaskedValueIsZero(SDValue V, const APInt &Mask,
+                                     const APInt &DemandedElts,
+                                     unsigned Depth) const {
+  return Mask.isSubsetOf(computeKnownBits(V, DemandedElts, Depth).Zero);
 }
 
 /// isSplatValue - Return true if the vector V has the same value