Rework updateValueSet() and surrounding code.

a) Revise documentation strategy to avoid duplication.

 - Document what a method does in the header file.
 - Document (if not obvious) how it works in the cpp file.

  Idea from:
  https://softwareengineering.stackexchange.com/questions/84071/is-it-better-to-document-functions-in-the-header-file-or-the-source-file

b) Make updateValueSet() work by reference.

This means that we don't need to talk about pointers in the docstring.

Author: vext01

llvm/include/llvm/Transforms/Yk/LivenessAnalysis.h

@@ -22,9 +22,8 @@ class LivenessAnalysis {
   /// Find the successor instructions of the specified instruction.
   std::set<Instruction *> getSuccessorInstructions(Instruction *I);
 
-  /// Replaces the value set behind the pointer `S` with the value set `R` and
-  /// returns whether the set behind `S` changed.
-  bool updateValueSet(std::set<Value *> *S, const std::set<Value *> R);
+  /// Replaces the set `S` with the set `R`, returning if the set changed.
+  bool updateValueSet(std::set<Value *> &S, const std::set<Value *> &R);
 
 public:
   LivenessAnalysis(Function *Func);

llvm/lib/Transforms/Yk/LivenessAnalysis.cpp

@@ -40,7 +40,7 @@ void vset_union(const std::set<Value *> &S1, const std::set<Value *> &S2,
 }
 
 namespace llvm {
-/// Find the successor instructions of the specified instruction.
+
 std::set<Instruction *>
 LivenessAnalysis::getSuccessorInstructions(Instruction *I) {
   Instruction *Term = I->getParent()->getTerminator();
@@ -58,12 +58,10 @@ LivenessAnalysis::getSuccessorInstructions(Instruction *I) {
   return SuccInsts;
 }
 
-/// Replaces the value set behind the pointer `S` with the value set `R` and
-/// returns whether the set behind `S` changed.
-bool LivenessAnalysis::updateValueSet(std::set<Value *> *S,
-                                      const std::set<Value *> R) {
-  const bool Changed = (*S != R);
-  *S = R;
+bool LivenessAnalysis::updateValueSet(std::set<Value *> &S,
+                                      const std::set<Value *> &R) {
+  const bool Changed = (S != R);
+  S = R;
   return Changed;
 }
 
@@ -138,22 +136,20 @@ LivenessAnalysis::LivenessAnalysis(Function *Func) {
         for (Instruction *SI : SuccInsts) {
           NewOut.insert(In[SI].begin(), In[SI].end());
         }
-        Changed |= updateValueSet(&Out[I], std::move(NewOut));
+        Changed |= updateValueSet(Out[I], NewOut);
 
         // Update in[I].
         std::set<Value *> OutMinusDef;
         vset_difference(Out[I], Defs[I], OutMinusDef);
 
         std::set<Value *> NewIn;
         vset_union(Uses[I], OutMinusDef, NewIn);
-        Changed |= updateValueSet(&In[I], std::move(NewIn));
+        Changed |= updateValueSet(In[I], NewIn);
       }
     }
   } while (Changed); // Until a fixed-point.
 }
 
-/// Returns the set of live variables immediately before the specified
-/// instruction.
 std::set<Value *> LivenessAnalysis::getLiveVarsBefore(Instruction *I) {
   return In[I];
 }