[KnownBits] Add wrapper methods for setting and clear all bits in the underlying APInts in KnownBits.

This adds routines for reseting KnownBits to unknown, making the value all zeros or all ones. It also adds methods for querying if the value is zero, all ones or unknown.

Differential Revision: https://reviews.llvm.org/D32637

llvm-svn: 302262

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 932ab9d00e4..f248a829b8e 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -12640,7 +12640,7 @@ void ARMTargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
                                                       const SelectionDAG &DAG,
                                                       unsigned Depth) const {
   unsigned BitWidth = Known.getBitWidth();
-  Known.Zero.clearAllBits(); Known.One.clearAllBits();
+  Known.resetAll();
   switch (Op.getOpcode()) {
   default: break;
   case ARMISD::ADDC:
@@ -12655,7 +12655,8 @@ void ARMTargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
   case ARMISD::CMOV: {
     // Bits are known zero/one if known on the LHS and RHS.
     DAG.computeKnownBits(Op.getOperand(0), Known, Depth+1);
-    if (Known.Zero == 0 && Known.One == 0) return;
+    if (Known.isUnknown())
+      return;
 
     KnownBits KnownRHS;
     DAG.computeKnownBits(Op.getOperand(1), KnownRHS, Depth+1);