[ValueTracking] Extend range metadata to call/invoke

Summary:
With this patch, range metadata can be added to call/invoke including
IntrinsicInst. Previously, it could only be added to load.

Rename computeKnownBitsLoad to computeKnownBitsFromRangeMetadata because
range metadata is not only used by load.

Update the language reference to reflect this change.

Test Plan:
Add several tests in range-2.ll to confirm the verifier is happy with
having range metadata on call/invoke.

Add two tests in AddOverFlow.ll to confirm annotating range metadata to
call/invoke can benefit InstCombine.

Reviewers: meheff, nlewycky, reames, hfinkel, eliben

Reviewed By: eliben

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D4187

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211281 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/ValueTracking.h

@@ -37,7 +37,10 @@ namespace llvm {
   /// for all of the elements in the vector.
   void computeKnownBits(Value *V,  APInt &KnownZero, APInt &KnownOne,
                         const DataLayout *TD = nullptr, unsigned Depth = 0);
-  void computeKnownBitsLoad(const MDNode &Ranges, APInt &KnownZero);
+  /// Compute known bits from the range metadata.
+  /// \p KnownZero the set of bits that are known to be zero
+  void computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
+                                         APInt &KnownZero);
 
   /// ComputeSignBit - Determine whether the sign bit is known to be zero or
   /// one.  Convenience wrapper around computeKnownBits.