[project @ 1999-06-24 13:04:13 by simonmar]

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

diff --git a/ghc/compiler/codeGen/CgHeapery.lhs b/ghc/compiler/codeGen/CgHeapery.lhs
index 80d968f..1663846 100644 (file)
--- a/ghc/compiler/codeGen/CgHeapery.lhs
+++ b/ghc/compiler/codeGen/CgHeapery.lhs
@@ -1,14 +1,14 @@
 %
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-% $Id: CgHeapery.lhs,v 1.17 1999/05/26 14:12:13 simonmar Exp $
+% $Id: CgHeapery.lhs,v 1.18 1999/06/24 13:04:19 simonmar Exp $
 %
 \section[CgHeapery]{Heap management functions}
 
 \begin{code}
 module CgHeapery (
        fastEntryChecks, altHeapCheck, thunkChecks,
-       allocDynClosure
+       allocDynClosure, inPlaceAllocDynClosure
 
         -- new functions, basically inserting macro calls into Code -- HWL
         ,fetchAndReschedule, yield
@@ -468,11 +468,42 @@ allocDynClosure closure_info use_cc blame_cc amodes_with_offsets
   where
     closure_size = closureSize closure_info
     slop_size    = slopSize closure_info
+\end{code}
+
+Occasionally we can update a closure in place instead of allocating
+new space for it.  This is the function that does the business, assuming:
+
+       - node points to the closure to be overwritten
+
+       - the new closure doesn't contain any pointers if we're
+         using a generational collector.
+
+\begin{code}
+inPlaceAllocDynClosure
+       :: ClosureInfo
+       -> CAddrMode            -- Pointer to beginning of closure
+       -> CAddrMode            -- Cost Centre to stick in the object
+
+       -> [(CAddrMode, VirtualHeapOffset)]     -- Offsets from start of the object
+                                               -- ie Info ptr has offset zero.
+       -> Code
+
+inPlaceAllocDynClosure closure_info head use_cc amodes_with_offsets
+  = let        -- do_move IS THE ASSIGNMENT FUNCTION
+        do_move (amode, offset_from_start)
+          = CAssign (CVal (CIndex head (mkIntCLit offset_from_start) WordRep)
+                       (getAmodeRep amode))
+                    amode
+    in
+       -- GENERATE THE CODE
+    absC ( mkAbstractCs (
+          [ CInitHdr closure_info head use_cc ]
+          ++ (map do_move amodes_with_offsets)))
 
 -- Avoid hanging on to anything in the CC field when we're not profiling.
 
 cInitHdr closure_info amode cc 
-  | opt_SccProfilingOn = CInitHdr closure_info amode cc
-  | otherwise          = CInitHdr closure_info amode (panic "absent cc")
+  | opt_SccProfilingOn = CInitHdr closure_info (CAddr amode) cc
+  | otherwise          = CInitHdr closure_info (CAddr amode) (panic "absent cc")
        
 \end{code}