[PPC] Always use the version of computeKnownBits that returns a value. NFCI.

Continues the work started by @bogner in rL340594 to remove uses of the KnownBits output paramater version.

llvm-svn: 349903
diff --git a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 4f05f50..2036dbd 100644
--- a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -688,9 +688,8 @@
   SDValue Op1 = N->getOperand(1);
   SDLoc dl(N);
 
-  KnownBits LKnown, RKnown;
-  CurDAG->computeKnownBits(Op0, LKnown);
-  CurDAG->computeKnownBits(Op1, RKnown);
+  KnownBits LKnown = CurDAG->computeKnownBits(Op0);
+  KnownBits RKnown = CurDAG->computeKnownBits(Op1);
 
   unsigned TargetMask = LKnown.Zero.getZExtValue();
   unsigned InsertMask = RKnown.Zero.getZExtValue();
@@ -734,8 +733,7 @@
        // The AND mask might not be a constant, and we need to make sure that
        // if we're going to fold the masking with the insert, all bits not
        // know to be zero in the mask are known to be one.
-        KnownBits MKnown;
-        CurDAG->computeKnownBits(Op1.getOperand(1), MKnown);
+        KnownBits MKnown = CurDAG->computeKnownBits(Op1.getOperand(1));
         bool CanFoldMask = InsertMask == MKnown.One.getZExtValue();
 
         unsigned SHOpc = Op1.getOperand(0).getOpcode();
@@ -4613,8 +4611,7 @@
     int16_t Imm;
     if (N->getOperand(0)->getOpcode() == ISD::FrameIndex &&
         isIntS16Immediate(N->getOperand(1), Imm)) {
-      KnownBits LHSKnown;
-      CurDAG->computeKnownBits(N->getOperand(0), LHSKnown);
+      KnownBits LHSKnown = CurDAG->computeKnownBits(N->getOperand(0));
 
       // If this is equivalent to an add, then we can fold it with the
       // FrameIndex calculation.
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 92af82d..a1c2e2f 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -2216,11 +2216,10 @@
     // If this is an or of disjoint bitfields, we can codegen this as an add
     // (for better address arithmetic) if the LHS and RHS of the OR are provably
     // disjoint.
-    KnownBits LHSKnown, RHSKnown;
-    DAG.computeKnownBits(N.getOperand(0), LHSKnown);
+    KnownBits LHSKnown = DAG.computeKnownBits(N.getOperand(0));
 
     if (LHSKnown.Zero.getBoolValue()) {
-      DAG.computeKnownBits(N.getOperand(1), RHSKnown);
+      KnownBits RHSKnown = DAG.computeKnownBits(N.getOperand(1));
       // If all of the bits are known zero on the LHS or RHS, the add won't
       // carry.
       if (~(LHSKnown.Zero | RHSKnown.Zero) == 0) {
@@ -2319,8 +2318,7 @@
       // If this is an or of disjoint bitfields, we can codegen this as an add
       // (for better address arithmetic) if the LHS and RHS of the OR are
       // provably disjoint.
-      KnownBits LHSKnown;
-      DAG.computeKnownBits(N.getOperand(0), LHSKnown);
+      KnownBits LHSKnown = DAG.computeKnownBits(N.getOperand(0));
 
       if ((LHSKnown.Zero.getZExtValue()|~(uint64_t)imm) == ~0ULL) {
         // If all of the bits are known zero on the LHS or RHS, the add won't
@@ -11316,9 +11314,8 @@
     } else {
       // This is neither a signed nor an unsigned comparison, just make sure
       // that the high bits are equal.
-      KnownBits Op1Known, Op2Known;
-      DAG.computeKnownBits(N->getOperand(0), Op1Known);
-      DAG.computeKnownBits(N->getOperand(1), Op2Known);
+      KnownBits Op1Known = DAG.computeKnownBits(N->getOperand(0));
+      KnownBits Op2Known = DAG.computeKnownBits(N->getOperand(1));
 
       // We don't really care about what is known about the first bit (if
       // anything), so clear it in all masks prior to comparing them.