X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FcodeGen%2FCgStackery.lhs;h=532127a14773a966f4dd71c6eb501abe9d711830;hp=7cb310d521022f610b0ec644556d2119d6a61e3c;hb=5d52d9b64c21dcf77849866584744722f8121389;hpb=0065d5ab628975892cea1ec7303f968c3338cbe1

diff --git a/compiler/codeGen/CgStackery.lhs b/compiler/codeGen/CgStackery.lhs
index 7cb310d..532127a 100644
--- a/compiler/codeGen/CgStackery.lhs
+++ b/compiler/codeGen/CgStackery.lhs
@@ -1,8 +1,7 @@
 %
+% (c) The University of Glasgow 2006
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-% $Id: CgStackery.lhs,v 1.27 2004/09/30 10:35:49 simonpj Exp $
-%
 \section[CgStackery]{Stack management functions}
 
 Stack-twiddling operations, which are pretty low-down and grimy.
@@ -18,23 +17,24 @@ module CgStackery (
 	setStackFrame, getStackFrame,
 	mkVirtStkOffsets, mkStkAmodes,
 	freeStackSlots, 
-	pushUpdateFrame, emitPushUpdateFrame,
+	pushUpdateFrame, pushBHUpdateFrame, emitPushUpdateFrame,
     ) where
 
 #include "HsVersions.h"
 
 import CgMonad
-import CgUtils		( cmmOffsetB, cmmRegOffW )
-import CgProf		( initUpdFrameProf )
+import CgUtils
+import CgProf
 import SMRep
 import Cmm
-import CmmUtils		( CmmStmts, mkLblExpr )
-import CLabel		( mkUpdInfoLabel )
+import CmmUtils
+import CLabel
 import Constants
-import Util		( sortLe )
-import FastString	( LitString )
-import OrdList		( toOL )
+import Util
+import OrdList
 import Outputable
+
+import Control.Monad
 \end{code}
 
 %************************************************************************
@@ -117,7 +117,7 @@ mkVirtStkOffsets init_Sp_offset things
     = loop init_Sp_offset [] (reverse things)
   where
     loop offset offs [] = (offset,offs)
-    loop offset offs ((VoidArg,t):things) = loop offset offs things
+    loop offset offs ((VoidArg,_):things) = loop offset offs things
 	-- ignore Void arguments
     loop offset offs ((rep,t):things)
 	= loop thing_slot ((t,thing_slot):offs) things
@@ -198,25 +198,23 @@ allocPrimStack rep
 Allocate a chunk ON TOP OF the stack.  
 
 \begin{code}
-allocStackTop :: WordOff -> FCode VirtualSpOffset
+allocStackTop :: WordOff -> FCode ()
 allocStackTop size
   = do	{ stk_usg <- getStkUsage
 	; let push_virt_sp = virtSp stk_usg + size
 	; setStkUsage (stk_usg { virtSp = push_virt_sp,
-				 hwSp   = hwSp stk_usg `max` push_virt_sp })
-	; return push_virt_sp }
+				 hwSp   = hwSp stk_usg `max` push_virt_sp }) }
 \end{code}
 
 Pop some words from the current top of stack.  This is used for
 de-allocating the return address in a case alternative.
 
 \begin{code}
-deAllocStackTop :: WordOff -> FCode VirtualSpOffset
+deAllocStackTop :: WordOff -> FCode ()
 deAllocStackTop size
   = do	{ stk_usg <- getStkUsage
 	; let pop_virt_sp = virtSp stk_usg - size
-	; setStkUsage (stk_usg { virtSp = pop_virt_sp })
-	; return pop_virt_sp }
+	; setStkUsage (stk_usg { virtSp = pop_virt_sp }) }
 \end{code}
 
 \begin{code}
@@ -231,7 +229,7 @@ A knot-tying beast.
 \begin{code}
 getFinalStackHW :: (VirtualSpOffset -> Code) -> Code
 getFinalStackHW fcode
-  = do	{ fixC (\hw_sp -> do
+  = do	{ fixC_ (\hw_sp -> do
 		{ fcode hw_sp
 		; stk_usg <- getStkUsage
 		; return (hwSp stk_usg) })
@@ -266,15 +264,20 @@ to reflect the frame pushed.
 
 \begin{code}
 pushUpdateFrame :: CmmExpr -> Code -> Code
-
 pushUpdateFrame updatee code
-  = do	{
-#ifdef DEBUG
-	  EndOfBlockInfo _ sequel <- getEndOfBlockInfo ;
-	  ASSERT(case sequel of { OnStack -> True; _ -> False})
-#endif
+  = pushSpecUpdateFrame mkUpdInfoLabel updatee code
 
-	  allocStackTop (fixedHdrSize + 
+pushBHUpdateFrame :: CmmExpr -> Code -> Code
+pushBHUpdateFrame updatee code
+  = pushSpecUpdateFrame mkBHUpdInfoLabel updatee code
+
+pushSpecUpdateFrame :: CLabel -> CmmExpr -> Code -> Code
+pushSpecUpdateFrame lbl updatee code
+  = do	{
+      when debugIsOn $ do
+    	{ EndOfBlockInfo _ sequel <- getEndOfBlockInfo ;
+    	; MASSERT(case sequel of { OnStack -> True; _ -> False}) }
+	; allocStackTop (fixedHdrSize + 
 			   sIZEOF_StgUpdateFrame_NoHdr `quot` wORD_SIZE)
 	; vsp <- getVirtSp
 	; setStackFrame vsp
@@ -282,22 +285,32 @@ pushUpdateFrame updatee code
 		-- The location of the lowest-address
 		-- word of the update frame itself
 
-	; setEndOfBlockInfo (EndOfBlockInfo vsp UpdateCode) $
-	    do	{ emitPushUpdateFrame frame_addr updatee
+                -- NB. we used to set the Sequel to 'UpdateCode' so
+                -- that we could jump directly to the update code if
+                -- we know that the next frame on the stack is an
+                -- update frame.  However, the RTS can sometimes
+                -- change an update frame into something else (see
+                -- e.g. Note [upd-black-hole] in rts/sm/Scav.c), so we
+                -- no longer make this assumption.
+	; setEndOfBlockInfo (EndOfBlockInfo vsp OnStack) $
+	    do	{ emitSpecPushUpdateFrame lbl frame_addr updatee
 		; code }
 	}
 
 emitPushUpdateFrame :: CmmExpr -> CmmExpr -> Code
-emitPushUpdateFrame frame_addr updatee = do
+emitPushUpdateFrame = emitSpecPushUpdateFrame mkUpdInfoLabel
+
+emitSpecPushUpdateFrame :: CLabel -> CmmExpr -> CmmExpr -> Code
+emitSpecPushUpdateFrame lbl frame_addr updatee = do
 	stmtsC [  -- Set the info word
-		  CmmStore frame_addr (mkLblExpr mkUpdInfoLabel)
+		  CmmStore frame_addr (mkLblExpr lbl)
 		, -- And the updatee
 		  CmmStore (cmmOffsetB frame_addr off_updatee) updatee ]
 	initUpdFrameProf frame_addr
 
 off_updatee :: ByteOff
 off_updatee = fixedHdrSize*wORD_SIZE + oFFSET_StgUpdateFrame_updatee
-\end{code}			
+\end{code}
 
 
 %************************************************************************