[project @ 2003-01-07 13:25:07 by simonmar]

Expand bitmaps to cover the full size of the stack frame.  Previously
the bitmap would stop at the last non-zero bit, which might shorten
the bitmap by one or more words.  The behaviour used to be correct,
but with the eval/apply changes bitmaps must now cover the entire
stack frame rather than everything up to the last non-pointer word.

diff --git a/ghc/compiler/codeGen/CgBindery.lhs b/ghc/compiler/codeGen/CgBindery.lhs
index f2c32dc..634b406 100644 (file)
--- a/ghc/compiler/codeGen/CgBindery.lhs
+++ b/ghc/compiler/codeGen/CgBindery.lhs
@@ -514,11 +514,19 @@ buildContLivenessMask name = do
 
         let lbl = mkBitmapLabel name
 
-       -- realSp points to the frame-header for the current stack frame,
-       -- and the end of this frame is frame_sp.  The size is therefore
-       -- realSp - frame_sp - 1 (subtract one for the frame-header).
        frame_sp <- getStackFrame
-       let liveness = Liveness lbl (realSp-1-frame_sp) mask
+       let 
+            -- realSp points to the frame-header for the current stack frame,
+            -- and the end of this frame is frame_sp.  The size is therefore
+            -- realSp - frame_sp - 1 (subtract one for the frame-header).
+            frame_size = realSp - frame_sp - 1
+
+            -- make sure the bitmap covers the full frame, by adding
+            -- zero words at the end as necessary
+            expand n []     = take ((n+31) `quot` 32) (repeat emptyBS)
+            expand n (b:bs) = b : expand (n-32) bs
+
+            liveness = Liveness lbl frame_size (expand frame_size mask)
 
        absC (CBitmap liveness)
        return liveness