X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FcodeGen%2FCgStackery.lhs;h=532127a14773a966f4dd71c6eb501abe9d711830;hp=d6d9e5cfadb98fd50381050076cffbad7b5d1f1e;hb=5d52d9b64c21dcf77849866584744722f8121389;hpb=176fa33f17dd78355cc572e006d2ab26898e2c69

diff --git a/compiler/codeGen/CgStackery.lhs b/compiler/codeGen/CgStackery.lhs
index d6d9e5c..532127a 100644
--- a/compiler/codeGen/CgStackery.lhs
+++ b/compiler/codeGen/CgStackery.lhs
@@ -8,13 +8,6 @@ Stack-twiddling operations, which are pretty low-down and grimy.
 (This is the module that knows all about stack layouts, etc.)
 
 \begin{code}
-{-# OPTIONS -w #-}
--- The above warning supression flag is a temporary kludge.
--- While working on this module you are encouraged to remove it and fix
--- any warnings in the module. See
---     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
--- for details
-
 module CgStackery (
 	spRel, getVirtSp, getRealSp, setRealSp,
 	setRealAndVirtualSp, getSpRelOffset,
@@ -24,7 +17,7 @@ module CgStackery (
 	setStackFrame, getStackFrame,
 	mkVirtStkOffsets, mkStkAmodes,
 	freeStackSlots, 
-	pushUpdateFrame, emitPushUpdateFrame,
+	pushUpdateFrame, pushBHUpdateFrame, emitPushUpdateFrame,
     ) where
 
 #include "HsVersions.h"
@@ -38,7 +31,6 @@ import CmmUtils
 import CLabel
 import Constants
 import Util
-import FastString
 import OrdList
 import Outputable
 
@@ -125,7 +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
@@ -206,25 +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}
@@ -239,7 +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) })
@@ -275,6 +265,14 @@ to reflect the frame pushed.
 \begin{code}
 pushUpdateFrame :: CmmExpr -> Code -> Code
 pushUpdateFrame updatee code
+  = pushSpecUpdateFrame mkUpdInfoLabel updatee code
+
+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 ;
@@ -287,15 +285,25 @@ 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