1 files changed, 27 insertions, 21 deletions

diff --git a/include/llvm/Analysis/AliasSetTracker.h b/include/llvm/Analysis/AliasSetTracker.h
index ba2eae903da6..881699d09225 100644
--- a/include/llvm/Analysis/AliasSetTracker.h
+++ b/include/llvm/Analysis/AliasSetTracker.h
@@ -117,24 +117,30 @@ class AliasSet : public ilist_node<AliasSet> {
   // AliasSets forwarding to it.
   unsigned RefCount : 28;
 
-  /// AccessType - Keep track of whether this alias set merely refers to the
-  /// locations of memory, whether it modifies the memory, or whether it does
-  /// both.  The lattice goes from "NoModRef" to either Refs or Mods, then to
-  /// ModRef as necessary.
+  /// The kinds of access this alias set models.
   ///
-  enum AccessType {
-    NoModRef = 0, Refs = 1,         // Ref = bit 1
-    Mods     = 2, ModRef = 3        // Mod = bit 2
+  /// We keep track of whether this alias set merely refers to the locations of
+  /// memory (and not any particular access), whether it modifies or references
+  /// the memory, or whether it does both. The lattice goes from "NoAccess" to
+  /// either RefAccess or ModAccess, then to ModRefAccess as necessary.
+  enum AccessLattice {
+    NoAccess = 0,
+    RefAccess = 1,
+    ModAccess = 2,
+    ModRefAccess = RefAccess | ModAccess
   };
-  unsigned AccessTy : 2;
+  unsigned Access : 2;
 
-  /// AliasType - Keep track the relationships between the pointers in the set.
-  /// Lattice goes from MustAlias to MayAlias.
+  /// The kind of alias relationship between pointers of the set.
   ///
-  enum AliasType {
-    MustAlias = 0, MayAlias = 1
+  /// These represent conservatively correct alias results between any members
+  /// of the set. We represent these independently of the values of alias
+  /// results in order to pack it into a single bit. Lattice goes from
+  /// MustAlias to MayAlias.
+  enum AliasLattice {
+    SetMustAlias = 0, SetMayAlias = 1
   };
-  unsigned AliasTy : 1;
+  unsigned Alias : 1;
 
   // Volatile - True if this alias set contains volatile loads or stores.
   bool Volatile : 1;
@@ -153,10 +159,10 @@ class AliasSet : public ilist_node<AliasSet> {
   
 public:
   /// Accessors...
-  bool isRef() const { return AccessTy & Refs; }
-  bool isMod() const { return AccessTy & Mods; }
-  bool isMustAlias() const { return AliasTy == MustAlias; }
-  bool isMayAlias()  const { return AliasTy == MayAlias; }
+  bool isRef() const { return Access & RefAccess; }
+  bool isMod() const { return Access & ModAccess; }
+  bool isMustAlias() const { return Alias == SetMustAlias; }
+  bool isMayAlias()  const { return Alias == SetMayAlias; }
 
   // isVolatile - Return true if this alias set contains volatile loads or
   // stores.
@@ -218,7 +224,7 @@ private:
   friend struct ilist_sentinel_traits<AliasSet>;
   AliasSet()
     : PtrList(nullptr), PtrListEnd(&PtrList), Forward(nullptr), RefCount(0),
-      AccessTy(NoModRef), AliasTy(MustAlias), Volatile(false) {
+      Access(NoAccess), Alias(SetMustAlias), Volatile(false) {
   }
 
   AliasSet(const AliasSet &AS) = delete;
@@ -419,11 +425,11 @@ private:
   }
 
   AliasSet &addPointer(Value *P, uint64_t Size, const AAMDNodes &AAInfo,
-                       AliasSet::AccessType E,
+                       AliasSet::AccessLattice E,
                        bool &NewSet) {
     NewSet = false;
     AliasSet &AS = getAliasSetForPointer(P, Size, AAInfo, &NewSet);
-    AS.AccessTy |= E;
+    AS.Access |= E;
     return AS;
   }
   AliasSet *findAliasSetForPointer(const Value *Ptr, uint64_t Size,
@@ -437,6 +443,6 @@ inline raw_ostream& operator<<(raw_ostream &OS, const AliasSetTracker &AST) {
   return OS;
 }
 
-} // namespace llvm
+} // End llvm namespace
 
 #endif