vendor/llvm/llvm-trunk-r300422

1 files changed, 24 insertions, 8 deletions

diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h
index aaf6f888e06f..e3c2f3bed227 100644
--- a/include/llvm/Analysis/ValueTracking.h
+++ b/include/llvm/Analysis/ValueTracking.h
@@ -31,6 +31,7 @@ template <typename T> class ArrayRef;
   class Instruction;
   class Loop;
   class LoopInfo;
+  class OptimizationRemarkEmitter;
   class MDNode;
   class StringRef;
   class TargetLibraryInfo;
@@ -52,7 +53,8 @@ template <typename T> class ArrayRef;
                         const DataLayout &DL, unsigned Depth = 0,
                         AssumptionCache *AC = nullptr,
                         const Instruction *CxtI = nullptr,
-                        const DominatorTree *DT = nullptr);
+                        const DominatorTree *DT = nullptr,
+                        OptimizationRemarkEmitter *ORE = nullptr);
   /// Compute known bits from the range metadata.
   /// \p KnownZero the set of bits that are known to be zero
   /// \p KnownOne the set of bits that are known to be one
@@ -86,8 +88,10 @@ template <typename T> class ArrayRef;
 
   /// Return true if the given value is known to be non-zero when defined. For
   /// vectors, return true if every element is known to be non-zero when
-  /// defined. Supports values with integer or pointer type and vectors of
-  /// integers.
+  /// defined. For pointers, if the context instruction and dominator tree are
+  /// specified, perform context-sensitive analysis and return true if the
+  /// pointer couldn't possibly be null at the specified instruction.
+  /// Supports values with integer or pointer type and vectors of integers.
   bool isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth = 0,
                       AssumptionCache *AC = nullptr,
                       const Instruction *CxtI = nullptr,
@@ -167,13 +171,25 @@ template <typename T> class ArrayRef;
   bool CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI,
                             unsigned Depth = 0);
 
-  /// Return true if we can prove that the specified FP value is either a NaN or
-  /// never less than 0.0.
-  /// If \p IncludeNeg0 is false, -0.0 is considered less than 0.0.
+  /// Return true if we can prove that the specified FP value is either NaN or
+  /// never less than -0.0.
+  ///
+  ///      NaN --> true
+  ///       +0 --> true
+  ///       -0 --> true
+  ///   x > +0 --> true
+  ///   x < -0 --> false
+  ///
   bool CannotBeOrderedLessThanZero(const Value *V, const TargetLibraryInfo *TLI);
 
-  /// \returns true if we can prove that the specified FP value has a 0 sign
-  /// bit.
+  /// Return true if we can prove that the specified FP value's sign bit is 0.
+  ///
+  ///      NaN --> true/false (depending on the NaN's sign bit)
+  ///       +0 --> true
+  ///       -0 --> false
+  ///   x > +0 --> true
+  ///   x < -0 --> false
+  ///
   bool SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI);
 
   /// If the specified value can be set by repeating the same byte in memory,