[SelectionDAG] computeKnownBits - early-out if any BUILD_VECTOR element has no known...

No need to check the remaining elements - no common known bits are available.

llvm-svn: 285399

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index e6b8d2f..db6accf 100644 (file)
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2042,6 +2042,10 @@ void SelectionDAG::computeKnownBits(SDValue Op, APInt &KnownZero,
       // TODO: support per-element known bits.
       KnownOne &= KnownOne2;
       KnownZero &= KnownZero2;
+
+      // If we don't know any bits, early out.
+      if (!KnownOne && !KnownZero)
+        break;
     }
     break;
   case ISD::AND: