[project @ 2003-10-01 10:57:39 by wolfgang]

[ghc-hetmet.git] / ghc / includes / StgMacros.h

diff --git a/ghc/includes/StgMacros.h b/ghc/includes/StgMacros.h
index faa8e07..4a5a985 100644 (file)
--- a/ghc/includes/StgMacros.h
+++ b/ghc/includes/StgMacros.h
@@ -1,5 +1,5 @@
 /* -----------------------------------------------------------------------------
- * $Id: StgMacros.h,v 1.51 2003/04/22 16:25:08 simonmar Exp $
+ * $Id: StgMacros.h,v 1.56 2003/08/05 14:01:34 simonpj Exp $
  *
  * (c) The GHC Team, 1998-1999
  *
@@ -246,15 +246,26 @@ typedef StgWord StgWordArray[];
    we assume that the size of a double is always 2 pointers (wasting a
    word when it is only one pointer, but avoiding lots of #ifdefs).
 
+   NOTE: if you change the layout of RET_DYN stack frames, then you
+   might also need to adjust the value of RESERVED_STACK_WORDS in
+   Constants.h.
    -------------------------------------------------------------------------- */
 
 // VERY MAGIC CONSTANTS! 
-// must agree with code in HeapStackCheck.c, stg_gen_chk
+// must agree with code in HeapStackCheck.c, stg_gen_chk, and
+// RESERVED_STACK_WORDS in Constants.h.
 //
 #define RET_DYN_BITMAP_SIZE 8
 #define RET_DYN_NONPTR_REGS_SIZE 10
 #define ALL_NON_PTRS 0xff
 
+// Sanity check that RESERVED_STACK_WORDS is reasonable.  We can't
+// just derive RESERVED_STACK_WORDS because it's used in Haskell code
+// too.
+#if RESERVED_STACK_WORDS != (3 + RET_DYN_BITMAP_SIZE + RET_DYN_NONPTR_REGS_SIZE)
+#error RESERVED_STACK_WORDS may be wrong!
+#endif
+
 #define LIVENESS_MASK(ptr_regs)  (ALL_NON_PTRS ^ (ptr_regs))
 
 // We can have up to 255 pointers and 255 nonpointers in the stack
@@ -434,6 +445,14 @@ EXTFUN_RTS(stg_gen_block);
 #   else
 // An object is replaced by a blackhole, so we fill the slop with zeros.
 // 
+// This looks like it can't work - we're overwriting the contents of
+// the THUNK with slop!  Perhaps this never worked??? --SDM
+// The problem is that with eager-black-holing we currently perform
+// the black-holing operation at the *beginning* of the basic block,
+// when we still need the contents of the thunk.
+// Perhaps the thing to do is to overwrite it at the *end* of the
+// basic block, when we've already sucked out the thunk's contents? -- SLPJ
+//
 // Todo: maybe use SET_HDR() and remove LDV_recordCreate()?
 // 
 #    define UPD_BH_UPDATABLE(info)             \
@@ -453,8 +472,6 @@ EXTFUN_RTS(stg_gen_block);
 #  define UPD_BH_SINGLE_ENTRY(thunk) /* nothing */
 #endif /* EAGER_BLACKHOLING */
 
-#define UPD_FRAME_UPDATEE(p)  ((P_)(((StgUpdateFrame *)(p))->updatee))
-
 /* -----------------------------------------------------------------------------
    Moving Floats and Doubles