[ValueTracking] Replace all uses of ComputeSignBit with computeKnownBits.

This patch finishes off the conversion of ComputeSignBit to computeKnownBits.

Differential Revision: https://reviews.llvm.org/D33166

llvm-svn: 303035

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -40,6 +40,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/GraphWriter.h"
+#include "llvm/Support/KnownBits.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Utils/LoopUtils.h"
 #include "llvm/Transforms/Vectorize.h"
@@ -3695,10 +3696,8 @@ void BoUpSLP::computeMinimumValueSizes() {
     // Determine if the sign bit of all the roots is known to be zero. If not,
     // IsKnownPositive is set to False.
     IsKnownPositive = all_of(TreeRoot, [&](Value *R) {
-      bool KnownZero = false;
-      bool KnownOne = false;
-      ComputeSignBit(R, KnownZero, KnownOne, *DL);
-      return KnownZero;
+      KnownBits Known = computeKnownBits(R, *DL);
+      return Known.isNonNegative();
     });
 
     // Determine the maximum number of bits required to store the scalar