[project @ 2005-02-10 13:01:52 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 58fbe94..b0bdf46 100644 (file)
--- a/ghc/compiler/codeGen/CgHeapery.lhs
+++ b/ghc/compiler/codeGen/CgHeapery.lhs
@@ -1,7 +1,7 @@
 %
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-% $Id: CgHeapery.lhs,v 1.42 2004/11/26 16:20:09 simonmar Exp $
+% $Id: CgHeapery.lhs,v 1.43 2005/02/10 13:01:53 simonmar Exp $
 %
 \section[CgHeapery]{Heap management functions}
 
@@ -34,9 +34,8 @@ import CgTicky                ( staticTickyHdr, tickyDynAlloc, tickyAllocHeap )
 import CgParallel      ( staticGranHdr, staticParHdr, doGranAllocate )
 import CgStackery      ( getFinalStackHW, getRealSp )
 import CgCallConv      ( mkRegLiveness )
-import ClosureInfo     ( closureSize, closureUpdReqd,
-                         staticClosureNeedsLink, 
-                         mkConInfo, 
+import ClosureInfo     ( closureSize, staticClosureNeedsLink, 
+                         mkConInfo,  closureNeedsUpdSpace,
                          infoTableLabelFromCI, closureLabelFromCI,
                          nodeMustPointToIt, closureLFInfo,                     
                          ClosureInfo )
@@ -189,26 +188,37 @@ mkStaticClosureFields
        -> [CmmLit]             -- Payload
        -> [CmmLit]             -- The full closure
 mkStaticClosureFields cl_info ccs caf_refs payload
-  = mkStaticClosure info_lbl ccs payload padding_wds static_link_field
+  = mkStaticClosure info_lbl ccs payload padding_wds 
+       static_link_field saved_info_field
   where
     info_lbl = infoTableLabelFromCI cl_info
 
-    upd_reqd = closureUpdReqd cl_info
+    -- CAFs must have consistent layout, regardless of whether they
+    -- are actually updatable or not.  The layout of a CAF is:
+    --
+    --        3 saved_info
+    --        2 static_link
+    --        1 indirectee
+    --        0 info ptr
+    --
+    -- the static_link and saved_info fields must always be in the same
+    -- place.  So we use closureNeedsUpdSpace rather than
+    -- closureUpdReqd here:
+
+    is_caf = closureNeedsUpdSpace cl_info
 
-    -- for the purposes of laying out the static closure, we consider all
-    -- thunks to be "updatable", so that the static link field is always
-    -- in the same place.
     padding_wds
-       | not upd_reqd = []
-       | otherwise    = replicate n (mkIntCLit 0) -- a bunch of 0s
+       | not is_caf = []
+       | otherwise  = replicate n (mkIntCLit 0) -- a bunch of 0s
        where n = max 0 (mIN_UPD_SIZE - length payload)
 
-       -- We always have a static link field for a thunk, it's used to
-       -- save the closure's info pointer when we're reverting CAFs
-       -- (see comment in Storage.c)
     static_link_field
-       | upd_reqd || staticClosureNeedsLink cl_info = [static_link_value]
-       | otherwise                                  = []
+       | is_caf || staticClosureNeedsLink cl_info = [static_link_value]
+       | otherwise                                = []
+
+    saved_info_field
+       | is_caf     = [mkIntCLit 0]
+       | otherwise  = []
 
        -- for a static constructor which has NoCafRefs, we set the
        -- static link field to a non-zero value so the garbage
@@ -218,13 +228,14 @@ mkStaticClosureFields cl_info ccs caf_refs payload
        | otherwise     = mkIntCLit 1
 
 mkStaticClosure :: CLabel -> CostCentreStack -> [CmmLit]
-  -> [CmmLit] -> [CmmLit] -> [CmmLit]
-mkStaticClosure info_lbl ccs payload padding_wds static_link_field
+  -> [CmmLit] -> [CmmLit] -> [CmmLit] -> [CmmLit]
+mkStaticClosure info_lbl ccs payload padding_wds static_link_field saved_info_field
   =  [CmmLabel info_lbl]
   ++ variable_header_words
   ++ payload
   ++ padding_wds
   ++ static_link_field
+  ++ saved_info_field
   where
     variable_header_words
        =  staticGranHdr