Update some comments that are related to formal access.

Author: atrick

lib/SILGen/FormalEvaluation.h

@@ -71,6 +71,10 @@ class FormalAccess {
   virtual void finishImpl(SILGenFunction &SGF) = 0;
 };
 
+// FIXME: Misnomer. This is not used for borrowing a formal memory location
+// (ExclusiveBorrowFormalAccess is always used for that). This is only used for
+// formal access from a +0 value, which requires producing a "borrowed"
+// SILValue.
 class SharedBorrowFormalAccess : public FormalAccess {
   SILValue originalValue;
   SILValue borrowedValue;

lib/SILGen/Initialization.h

@@ -235,7 +235,6 @@ class KnownAddressInitialization : public SingleBufferInitialization {
   void finishUninitialized(SILGenFunction &SGF) override {}
 };
 
-/// Abstract base class for single-buffer initializations.
 class TemporaryInitialization : public SingleBufferInitialization {
   SILValue Addr;
   CleanupHandle Cleanup;

lib/SILGen/LValue.h

@@ -500,6 +500,8 @@ class InOutConversionScope {
   ~InOutConversionScope();
 };
 
+// FIXME: Misnomer. This class is used for both shared (read) and exclusive
+// (modify) formal borrows.
 struct LLVM_LIBRARY_VISIBILITY ExclusiveBorrowFormalAccess : FormalAccess {
   std::unique_ptr<LogicalPathComponent> component;
   ManagedValue base;