Various comment and whitespace cleanups.

llvm-svn: 79533

llvm/include/llvm/Analysis/ScalarEvolutionExpander.h

@@ -126,4 +126,3 @@ namespace llvm {
 }
 
 #endif
-

llvm/lib/Analysis/ConstantFolding.cpp

@@ -208,7 +208,7 @@ static Constant *SymbolicallyEvaluateGEP(Constant* const* Ops, unsigned NumOps,
          "Computed GetElementPtr has unexpected type!");
 
   // If we ended up indexing a member with a type that doesn't match
-  // type type of what the original indices indexed, add a cast.
+  // the type of what the original indices indexed, add a cast.
   if (Ty != cast<PointerType>(ResultTy)->getElementType())
     C = ConstantExpr::getBitCast(C, ResultTy);
 

llvm/lib/Analysis/ScalarEvolution.cpp

@@ -3533,8 +3533,8 @@ ScalarEvolution::ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
     if (!isa<SCEVCouldNotCompute>(TC)) return TC;
     break;
   }
-  case ICmpInst::ICMP_EQ: {
+  case ICmpInst::ICMP_EQ: {                     // while (X == Y)
-    // Convert to: while (X-Y == 0)           // while (X == Y)
+    // Convert to: while (X-Y == 0)
     const SCEV *TC = HowFarToNonZero(getMinusSCEV(LHS, RHS), L);
     if (!isa<SCEVCouldNotCompute>(TC)) return TC;
     break;

llvm/lib/Analysis/ScalarEvolutionExpander.cpp

@@ -53,7 +53,6 @@ Value *SCEVExpander::InsertNoopCastOfTo(Value *V, const Type *Ty) {
         return CE->getOperand(0);
   }
 
-  // FIXME: keep track of the cast instruction.
   if (Constant *C = dyn_cast<Constant>(V))
     return ConstantExpr::getCast(Op, C, Ty);
 
@@ -317,13 +316,17 @@ static void SplitAddRecs(SmallVectorImpl<const SCEV *> &Ops,
   }
 }
 
-/// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
+/// expandAddToGEP - Expand an addition expression with a pointer type into
-/// instead of using ptrtoint+arithmetic+inttoptr. This helps
+/// a GEP instead of using ptrtoint+arithmetic+inttoptr. This helps
-/// BasicAliasAnalysis and other passes analyze the result.
+/// BasicAliasAnalysis and other passes analyze the result. See the rules
+/// for getelementptr vs. inttoptr in
+/// http://llvm.org/docs/LangRef.html#pointeraliasing
+/// for details.
 ///
-/// Design note: This depends on ScalarEvolution not recognizing inttoptr
+/// Design note: The correctness of using getelmeentptr here depends on
-/// and ptrtoint operators, as they may introduce pointer arithmetic
+/// ScalarEvolution not recognizing inttoptr and ptrtoint operators, as
-/// which may not be safely converted into getelementptr.
+/// they may introduce pointer arithmetic which may not be safely converted
+/// into getelementptr.
 ///
 /// Design note: It might seem desirable for this function to be more
 /// loop-aware. If some of the indices are loop-invariant while others