AddressPool::HasBeenUsed: Add comment explaining the use-case for this flag.

Based on code review by Eric Christopher on r207323

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207460 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/AsmPrinter/AddressPool.h b/lib/CodeGen/AsmPrinter/AddressPool.h
index 3058fed33fd08941212327c916d2298345def1a9..42757d732fd5247587939089f888f051b61a0176 100644 (file)
--- a/lib/CodeGen/AsmPrinter/AddressPool.h
+++ b/lib/CodeGen/AsmPrinter/AddressPool.h
@@ -26,6 +26,11 @@ class AddressPool {
     AddressPoolEntry(unsigned Number, bool TLS) : Number(Number), TLS(TLS) {}
   };
   DenseMap<const MCSymbol *, AddressPoolEntry> Pool;
+
+  /// Record whether the AddressPool has been queried for an address index since
+  /// the last "resetUsedFlag" call. Used to implement type unit fallback - a
+  /// type that references addresses cannot be placed in a type unit when using
+  /// fission.
   bool HasBeenUsed;
 
 public: