[project @ 2003-01-07 14:31:19 by simonmar]

[ghc-hetmet.git] / ghc / compiler / codeGen / CgMonad.lhs

diff --git a/ghc/compiler/codeGen/CgMonad.lhs b/ghc/compiler/codeGen/CgMonad.lhs
index 2a7e3ea..a14b77a 100644 (file)
--- a/ghc/compiler/codeGen/CgMonad.lhs
+++ b/ghc/compiler/codeGen/CgMonad.lhs
@@ -1,7 +1,7 @@
 %
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-% $Id: CgMonad.lhs,v 1.36 2002/12/11 15:36:26 simonmar Exp $
+% $Id: CgMonad.lhs,v 1.37 2003/01/07 14:31:20 simonmar Exp $
 %
 \section[CgMonad]{The code generation monad}
 
@@ -206,6 +206,14 @@ type StackUsage =
         Int,              -- realSp:  Virtual offset of real stack pointer
         Int)              -- hwSp:    Highest value ever taken by virtSp
 
+-- ToDo (SDM, 7 Jan 2003): I'm not sure that the distinction between
+-- Free and NonPointer in the free list is needed any more.  It used
+-- to be needed because we constructed bitmaps from the free list, but
+-- now we construct bitmaps by finding all the live pointer bindings
+-- instead.  Non-pointer stack slots (i.e. saved cost centres) can
+-- just be removed from the free list instead of being recorded as a
+-- NonPointer.
+
 type HeapUsage =
        (HeapOffset,    -- virtHp: Virtual offset of highest-allocated word
         HeapOffset)    -- realHp: Virtual offset of real heap ptr