[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
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 629f9be..82dc88f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -698,9 +698,8 @@
   }
 
   // This simplification is only valid if the upper range is not negative.
-  bool IsNegative, IsNotNegative;
-  ComputeSignBit(RangeEnd, IsNotNegative, IsNegative, /*Depth=*/0, Cmp1);
-  if (!IsNotNegative)
+  KnownBits Known = computeKnownBits(RangeEnd, /*Depth=*/0, Cmp1);
+  if (!Known.isNonNegative())
     return nullptr;
 
   if (Inverted)