[project @ 2002-09-04 10:00:45 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 3b3c403..0d8e4d2 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 1.32 2002/08/29 15:44:13 simonmar Exp $
+% $Id: CgHeapery.lhs,v 1.33 2002/09/04 10:00:46 simonmar Exp $
 %
 \section[CgHeapery]{Heap management functions}
 
@@ -236,7 +236,8 @@ have to do something about saving and restoring the other registers.
 
 \begin{code}
 altHeapCheck 
-       :: Bool                         -- is an algebraic alternative
+       :: Bool                         -- is a polymorphic case alt
+       -> Bool                         -- is an primitive case alt
        -> [MagicId]                    -- live registers
        -> [(VirtualSpOffset,Int)]      -- stack slots to tag
        -> AbstractC
@@ -247,7 +248,7 @@ altHeapCheck
 -- unboxed tuple alternatives and let-no-escapes (the two most annoying
 -- constructs to generate code for!):
 
-altHeapCheck is_fun regs tags fail_code (Just ret_addr) code
+altHeapCheck is_poly is_prim regs tags fail_code (Just ret_addr) code
   = mkTagAssts tags `thenFC` \tag_assts1 ->
     let tag_assts = mkAbstractCs [fail_code, tag_assts1]
     in
@@ -308,7 +309,7 @@ altHeapCheck is_fun regs tags fail_code (Just ret_addr) code
 
 -- normal algebraic and primitive case alternatives:
 
-altHeapCheck is_fun regs [] AbsCNop Nothing code
+altHeapCheck is_poly is_prim regs [] AbsCNop Nothing code
   = initHeapUsage (\ hHw -> do_heap_chk hHw `thenC` code)
   where
     do_heap_chk :: HeapOffset -> Code
@@ -334,28 +335,21 @@ altHeapCheck is_fun regs [] AbsCNop Nothing code
            [] ->
               CCheck HP_CHK_NOREGS [mkIntCLit words_required] AbsCNop
 
-           -- The SEQ case (polymophic/function typed case branch)
-           -- We need this case because the closure in Node won't return
-           -- directly when we enter it (it could be a function), so the
-           -- heap check code needs to push a seq frame on top of the stack.
+           -- R1 is boxed, but unlifted: DO NOT enter R1 when we return.
+           --
+           -- We also lump the polymorphic case in here, because we don't
+           -- want to enter R1 if it is a function, and we're guarnateed
+           -- that the return point has a direct return.
            [VanillaReg rep 1#]
-               |  rep == PtrRep
-               && is_fun ->
-                 CCheck HP_CHK_SEQ_NP
-                       [mkIntCLit words_required, mkIntCLit 1{-regs live-}]
-                       AbsCNop
+               | isFollowableRep rep && (is_poly || is_prim) ->
+                 CCheck HP_CHK_UNPT_R1 [mkIntCLit words_required] AbsCNop
 
            -- R1 is lifted (the common case)
-           [VanillaReg rep 1#]
-               | rep == PtrRep ->
-                 CCheck HP_CHK_NP
+               | isFollowableRep rep ->
+                 CCheck HP_CHK_NP
                        [mkIntCLit words_required, mkIntCLit 1{-regs live-}]
                        AbsCNop
 
-           -- R1 is boxed, but unlifted
-               | isFollowableRep rep ->
-                 CCheck HP_CHK_UNPT_R1 [mkIntCLit words_required] AbsCNop
-
            -- R1 is unboxed
                | otherwise ->
                  CCheck HP_CHK_UNBX_R1 [mkIntCLit words_required] AbsCNop