[X86] Clear KnownBits instead of reconstructing it. NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301767 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 535be01abc5bc16d5944ffd912711eb4f09f7e2e..d767a7a7d2c7e7ae3ecf4d4de826450274227efa 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -26682,7 +26682,7 @@ void X86TargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
          "Should use MaskedValueIsZero if you don't know whether Op"
          " is a target node!");
 
-  Known = KnownBits(BitWidth);   // Don't know anything.
+  Known.Zero.clearAllBits(); Known.One.clearAllBits();
   switch (Opc) {
   default: break;
   case X86ISD::ADD: