Add clarifying comments

diff --git a/compiler/codeGen/SMRep.lhs b/compiler/codeGen/SMRep.lhs
index ed0a440..4bc1222 100644 (file)
--- a/compiler/codeGen/SMRep.lhs
+++ b/compiler/codeGen/SMRep.lhs
@@ -119,8 +119,10 @@ entry to the garbage collector.
 \begin{code}
 data CgRep 
   = VoidArg    -- Void
-  | PtrArg     -- Word-sized Ptr
+  | PtrArg     -- Word-sized heap pointer, followed
+               -- by the garbage collector
   | NonPtrArg  -- Word-sized non-pointer
+               -- (including addresses not followed by GC)
   | LongArg    -- 64-bit non-pointer
   | FloatArg   -- 32-bit float
   | DoubleArg  -- 64-bit float