%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
-% $Id: CgStackery.lhs,v 1.21 2002/08/29 15:44:13 simonmar Exp $
+% $Id: CgStackery.lhs,v 1.25 2004/08/13 13:06:12 simonmar Exp $
%
\section[CgStackery]{Stack management functions}
\begin{code}
module CgStackery (
- allocStack, allocPrimStack, allocStackTop, deAllocStackTop,
- adjustStackHW, getFinalStackHW,
- mkTaggedVirtStkOffsets, mkTaggedStkAmodes, mkTagAssts,
- freeStackSlots, dataStackSlots, addFreeSlots,
- updateFrameSize, seqFrameSize
+ spRel, getVirtSp, getRealSp, setRealSp,
+ setRealAndVirtualSp, getSpRelOffset,
+
+ allocPrimStack, allocStackTop, deAllocStackTop,
+ adjustStackHW, getFinalStackHW,
+ setStackFrame, getStackFrame,
+ mkVirtStkOffsets, mkStkAmodes,
+ freeStackSlots,
+ pushUpdateFrame, emitPushUpdateFrame,
) where
#include "HsVersions.h"
import CgMonad
-import AbsCSyn
-
-import CgUsages ( getRealSp )
-import AbsCUtils ( mkAbstractCs, getAmodeRep )
-import PrimRep ( getPrimRepSize, PrimRep(..), isFollowableRep )
-import CmdLineOpts ( opt_SccProfilingOn, opt_GranMacros )
-import Panic ( panic )
+import CgUtils ( cmmOffsetB, cmmRegOffW )
+import CgProf ( initUpdFrameProf )
+import SMRep
+import Cmm
+import CmmUtils ( CmmStmts, mkLblExpr )
+import CLabel ( mkUpdInfoLabel )
import Constants
import Util ( sortLt )
+import FastString ( LitString )
+import OrdList ( toOL )
+import Outputable
+\end{code}
+
+%************************************************************************
+%* *
+\subsection[CgUsages-stackery]{Monad things for fiddling with stack usage}
+%* *
+%************************************************************************
+
+spRel is a little function that abstracts the stack direction. Note that most
+of the code generator is dependent on the stack direction anyway, so
+changing this on its own spells certain doom. ToDo: remove?
+
+ THIS IS DIRECTION SENSITIVE!
-import TRACE ( trace )
+Stack grows down, positive virtual offsets correspond to negative
+additions to the stack pointer.
+
+\begin{code}
+spRel :: VirtualSpOffset -- virtual offset of Sp
+ -> VirtualSpOffset -- virtual offset of The Thing
+ -> WordOff -- integer offset
+spRel sp off = sp - off
+\end{code}
+
+@setRealAndVirtualSp@ sets into the environment the offsets of the
+current position of the real and virtual stack pointers in the current
+stack frame. The high-water mark is set too. It generates no code.
+It is used to initialise things at the beginning of a closure body.
+
+\begin{code}
+setRealAndVirtualSp :: VirtualSpOffset -- New real Sp
+ -> Code
+
+setRealAndVirtualSp new_sp
+ = do { stk_usg <- getStkUsage
+ ; setStkUsage (stk_usg {virtSp = new_sp,
+ realSp = new_sp,
+ hwSp = new_sp}) }
+
+getVirtSp :: FCode VirtualSpOffset
+getVirtSp
+ = do { stk_usg <- getStkUsage
+ ; return (virtSp stk_usg) }
+
+getRealSp :: FCode VirtualSpOffset
+getRealSp
+ = do { stk_usg <- getStkUsage
+ ; return (realSp stk_usg) }
+
+setRealSp :: VirtualSpOffset -> Code
+setRealSp new_real_sp
+ = do { stk_usg <- getStkUsage
+ ; setStkUsage (stk_usg {realSp = new_real_sp}) }
+
+getSpRelOffset :: VirtualSpOffset -> FCode CmmExpr
+getSpRelOffset virtual_offset
+ = do { real_sp <- getRealSp
+ ; return (cmmRegOffW spReg (spRel real_sp virtual_offset)) }
\end{code}
+
%************************************************************************
%* *
\subsection[CgStackery-layout]{Laying out a stack frame}
%* *
%************************************************************************
-@mkTaggedVirtStkOffsets@ is given a list of arguments. The first
-argument gets the {\em largest} virtual stack offset (remember,
-virtual offsets increase towards the top of stack). This function
-also computes the correct tagging arrangement for standard function
-entry points. Each non-pointer on the stack is preceded by a tag word
-indicating the number of non-pointer words above it on the stack.
-
- offset --> | | <---- last allocated stack word
- --------- <
- | | .
- --------- .
- | | total_nptrs (words)
- --------- .
- | | .
- --------- <
-offset + tot_nptrs + 1 --> | tag |
- ---------
+'mkVirtStkOffsets' is given a list of arguments. The first argument
+gets the /largest/ virtual stack offset (remember, virtual offsets
+increase towards the top of stack).
\begin{code}
-mkTaggedVirtStkOffsets
+mkVirtStkOffsets
:: VirtualSpOffset -- Offset of the last allocated thing
- -> (a -> PrimRep) -- to be able to grab kinds
- -> [a] -- things to make offsets for
+ -> [(CgRep,a)] -- things to make offsets for
-> (VirtualSpOffset, -- OUTPUTS: Topmost allocated word
- [(a, VirtualSpOffset)], -- things with offsets
- [(VirtualSpOffset,Int)]) -- offsets for tags
+ [(a, VirtualSpOffset)]) -- things with offsets (voids filtered out)
-mkTaggedVirtStkOffsets init_Sp_offset kind_fun things
- = loop init_Sp_offset [] [] (reverse things)
+mkVirtStkOffsets init_Sp_offset things
+ = loop init_Sp_offset [] (reverse things)
where
- loop offset tags offs [] = (offset,offs,tags)
- loop offset tags offs (t:things)
- | isFollowableRep (kind_fun t) =
- loop (offset+1) tags ((t,offset+1):offs) things
- | otherwise =
- let
- size = getPrimRepSize (kind_fun t)
- tag_slot = offset+size+1
- in
- loop tag_slot ((tag_slot,size):tags) ((t,offset+size):offs) things
- -- offset of thing is offset+size, because we're growing the stack
- -- *downwards* as the offsets increase.
-\end{code}
-
-@mkTaggedStkAmodes@ is a higher-level version of
-@mkTaggedVirtStkOffsets@. It starts from the tail-call locations. It
-returns a single list of addressing modes for the stack locations, and
-therefore is in the monad.
+ loop offset offs [] = (offset,offs)
+ loop offset offs ((VoidArg,t):things) = loop offset offs things
+ -- ignore Void arguments
+ loop offset offs ((rep,t):things)
+ = loop thing_slot ((t,thing_slot):offs) things
+ where
+ thing_slot = offset + cgRepSizeW rep
+ -- offset of thing is offset+size, because we're
+ -- growing the stack *downwards* as the offsets increase.
-It *doesn't* adjust the high water mark.
+-- | 'mkStkAmodes' is a higher-level version of
+-- 'mkVirtStkOffsets'. It starts from the tail-call locations.
+-- It returns a single list of addressing modes for the stack
+-- locations, and therefore is in the monad. It /doesn't/ adjust the
+-- high water mark.
-\begin{code}
-mkTaggedStkAmodes
+mkStkAmodes
:: VirtualSpOffset -- Tail call positions
- -> [CAddrMode] -- things to make offsets for
+ -> [(CgRep,CmmExpr)] -- things to make offsets for
-> FCode (VirtualSpOffset, -- OUTPUTS: Topmost allocated word
- AbstractC, -- Assignments to appropriate stk slots
- AbstractC) -- Assignments for tagging
-
-mkTaggedStkAmodes tail_Sp things
- = getRealSp `thenFC` \ realSp ->
- let
- (last_Sp_offset, offsets, tags)
- = mkTaggedVirtStkOffsets tail_Sp getAmodeRep things
-
- abs_cs =
- [ CAssign (CVal (spRel realSp offset) (getAmodeRep thing)) thing
- | (thing, offset) <- offsets
- ]
-
- tag_cs =
- [ CAssign (CVal (spRel realSp offset) WordRep)
- (CMacroExpr WordRep ARG_TAG [mkIntCLit size])
- | (offset,size) <- tags
- ]
- in
- returnFC (last_Sp_offset, mkAbstractCs abs_cs, mkAbstractCs tag_cs)
-
-mkTagAssts :: [(VirtualSpOffset,Int)] -> FCode AbstractC
-mkTagAssts tags =
- getRealSp `thenFC` \realSp ->
- returnFC (mkAbstractCs
- [ CAssign (CVal (spRel realSp offset) WordRep)
- (CMacroExpr WordRep ARG_TAG [mkIntCLit size])
- | (offset,size) <- tags
- ])
-
+ CmmStmts) -- Assignments to appropriate stk slots
+
+mkStkAmodes tail_Sp things
+ = do { rSp <- getRealSp
+ ; let (last_Sp_offset, offsets) = mkVirtStkOffsets tail_Sp things
+ abs_cs = [ CmmStore (cmmRegOffW spReg (spRel rSp offset)) amode
+ | (amode, offset) <- offsets
+ ]
+ ; returnFC (last_Sp_offset, toOL abs_cs) }
\end{code}
%************************************************************************
Allocate a virtual offset for something.
\begin{code}
-allocStack :: FCode VirtualSpOffset
-allocStack = allocPrimStack 1
-
-allocPrimStack :: Int -> FCode VirtualSpOffset
-allocPrimStack size = do
- ((virt_sp, free_stk, real_sp, hw_sp),h_usage) <- getUsage
- let push_virt_sp = virt_sp + size
- let (chosen_slot, new_stk_usage) =
- case find_block free_stk of
- Nothing -> (push_virt_sp, (push_virt_sp, free_stk, real_sp,
- hw_sp `max` push_virt_sp))
+allocPrimStack :: CgRep -> FCode VirtualSpOffset
+allocPrimStack rep
+ = do { stk_usg <- getStkUsage
+ ; let free_stk = freeStk stk_usg
+ ; case find_block free_stk of
+ Nothing -> do
+ { let push_virt_sp = virtSp stk_usg + size
+ ; setStkUsage (stk_usg { virtSp = push_virt_sp,
+ hwSp = hwSp stk_usg `max` push_virt_sp })
-- Adjust high water mark
- Just slot -> (slot, (virt_sp,
- delete_block free_stk slot, real_sp, hw_sp))
- setUsage (new_stk_usage, h_usage)
- return chosen_slot
-
- where
- -- find_block looks for a contiguous chunk of free slots
- find_block :: [(VirtualSpOffset,Slot)] -> Maybe VirtualSpOffset
- find_block [] = Nothing
- find_block ((off,free):slots)
- | take size ((off,free):slots) ==
- zip [off..top_slot] (repeat Free) = Just top_slot
- | otherwise = find_block slots
- -- The stack grows downwards, with increasing virtual offsets.
- -- Therefore, the address of a multi-word object is the *highest*
- -- virtual offset it occupies (top_slot below).
- where top_slot = off+size-1
-
- delete_block free_stk slot = [ (s,f) | (s,f) <- free_stk,
- (s<=slot-size) || (s>slot) ]
- -- Retain slots which are not in the range
- -- slot-size+1..slot
+ ; return push_virt_sp }
+ Just slot -> do
+ { setStkUsage (stk_usg { freeStk = delete_block free_stk slot })
+ ; return slot }
+ }
+ where
+ size :: WordOff
+ size = cgRepSizeW rep
+
+ -- Find_block looks for a contiguous chunk of free slots
+ -- returning the offset of its topmost word
+ find_block :: [VirtualSpOffset] -> Maybe VirtualSpOffset
+ find_block [] = Nothing
+ find_block (slot:slots)
+ | take size (slot:slots) == [slot..top_slot]
+ = Just top_slot
+ | otherwise
+ = find_block slots
+ where -- The stack grows downwards, with increasing virtual offsets.
+ -- Therefore, the address of a multi-word object is the *highest*
+ -- virtual offset it occupies (top_slot below).
+ top_slot = slot+size-1
+
+ delete_block free_stk slot = [ s | s <- free_stk,
+ (s<=slot-size) || (s>slot) ]
+ -- Retain slots which are not in the range
+ -- slot-size+1..slot
\end{code}
Allocate a chunk ON TOP OF the stack.
-ToDo: should really register this memory as NonPointer stuff in the
-free list.
-
\begin{code}
-allocStackTop :: Int -> FCode VirtualSpOffset
-allocStackTop size = do
- ((virt_sp, free_stk, real_sp, hw_sp), h_usage) <- getUsage
- let push_virt_sp = virt_sp + size
- let new_stk_usage = (push_virt_sp, free_stk, real_sp, hw_sp `max` push_virt_sp)
- setUsage (new_stk_usage, h_usage)
- return push_virt_sp
+allocStackTop :: WordOff -> FCode VirtualSpOffset
+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 }
\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 :: Int -> FCode VirtualSpOffset
-deAllocStackTop size = do
- ((virt_sp, free_stk, real_sp, hw_sp), h_usage) <- getUsage
- let pop_virt_sp = virt_sp - size
- let new_stk_usage = (pop_virt_sp, free_stk, real_sp, hw_sp)
- setUsage (new_stk_usage, h_usage)
- return pop_virt_sp
+deAllocStackTop :: WordOff -> FCode VirtualSpOffset
+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 }
\end{code}
\begin{code}
adjustStackHW :: VirtualSpOffset -> Code
-adjustStackHW offset = do
- ((vSp,fSp,realSp,hwSp), h_usage) <- getUsage
- setUsage ((vSp, fSp, realSp, max offset hwSp), h_usage)
+adjustStackHW offset
+ = do { stk_usg <- getStkUsage
+ ; setStkUsage (stk_usg { hwSp = hwSp stk_usg `max` offset }) }
\end{code}
A knot-tying beast.
\begin{code}
getFinalStackHW :: (VirtualSpOffset -> Code) -> Code
-getFinalStackHW fcode = do
- fixC (\hwSp -> do
- fcode hwSp
- ((_,_,_, hwSp),_) <- getUsage
- return hwSp)
- return ()
+getFinalStackHW fcode
+ = do { fixC (\hw_sp -> do
+ { fcode hw_sp
+ ; stk_usg <- getStkUsage
+ ; return (hwSp stk_usg) })
+ ; return () }
\end{code}
\begin{code}
-updateFrameSize | opt_SccProfilingOn = pROF_UF_SIZE
- | opt_GranMacros = trace ("updateFrameSize = " ++ (show gRAN_UF_SIZE))gRAN_UF_SIZE
- | otherwise = uF_SIZE
+setStackFrame :: VirtualSpOffset -> Code
+setStackFrame offset
+ = do { stk_usg <- getStkUsage
+ ; setStkUsage (stk_usg { frameSp = offset }) }
+
+getStackFrame :: FCode VirtualSpOffset
+getStackFrame
+ = do { stk_usg <- getStkUsage
+ ; return (frameSp stk_usg) }
+\end{code}
+
-seqFrameSize | opt_SccProfilingOn = pROF_SEQ_FRAME_SIZE
- | opt_GranMacros = gRAN_SEQ_FRAME_SIZE
- | otherwise = sEQ_FRAME_SIZE
+%********************************************************
+%* *
+%* Setting up update frames *
+%* *
+%********************************************************
+
+@pushUpdateFrame@ $updatee$ pushes a general update frame which
+points to $updatee$ as the thing to be updated. It is only used
+when a thunk has just been entered, so the (real) stack pointers
+are guaranteed to be nicely aligned with the top of stack.
+@pushUpdateFrame@ adjusts the virtual and tail stack pointers
+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
+
+ allocStackTop (fixedHdrSize +
+ sIZEOF_StgUpdateFrame_NoHdr `quot` wORD_SIZE)
+ ; vsp <- getVirtSp
+ ; setStackFrame vsp
+ ; frame_addr <- getSpRelOffset vsp
+ -- The location of the lowest-address
+ -- word of the update frame itself
+
+ ; setEndOfBlockInfo (EndOfBlockInfo vsp UpdateCode) $
+ do { emitPushUpdateFrame frame_addr updatee
+ ; code }
+ }
+
+emitPushUpdateFrame :: CmmExpr -> CmmExpr -> Code
+emitPushUpdateFrame frame_addr updatee = do
+ stmtsC [ -- Set the info word
+ CmmStore frame_addr (mkLblExpr mkUpdInfoLabel)
+ , -- 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}
+
%************************************************************************
%* *
\subsection[CgStackery-free]{Free stack slots}
Explicitly free some stack space.
\begin{code}
-addFreeStackSlots :: [VirtualSpOffset] -> Slot -> Code
-addFreeStackSlots extra_free slot = do
- ((vsp, free, real, hw),heap_usage) <- getUsage
- let all_free = addFreeSlots free (zip (sortLt (<) extra_free) (repeat slot))
- let (new_vsp, new_free) = trim vsp all_free
- let new_usage = ((new_vsp, new_free, real, hw), heap_usage)
- setUsage new_usage
-
freeStackSlots :: [VirtualSpOffset] -> Code
-freeStackSlots slots = addFreeStackSlots slots Free
-
-dataStackSlots :: [VirtualSpOffset] -> Code
-dataStackSlots slots = addFreeStackSlots slots NonPointer
-
-addFreeSlots :: [(Int,Slot)] -> [(Int,Slot)] -> [(Int,Slot)]
+freeStackSlots extra_free
+ = do { stk_usg <- getStkUsage
+ ; let all_free = addFreeSlots (freeStk stk_usg) (sortLt (<) extra_free)
+ ; let (new_vsp, new_free) = trim (virtSp stk_usg) all_free
+ ; setStkUsage (stk_usg { virtSp = new_vsp, freeStk = new_free }) }
+
+addFreeSlots :: [VirtualSpOffset] -> [VirtualSpOffset] -> [VirtualSpOffset]
+-- Merge the two, assuming both are in increasing order
addFreeSlots cs [] = cs
addFreeSlots [] ns = ns
-addFreeSlots ((c,s):cs) ((n,s'):ns)
- = if c < n then
- (c,s) : addFreeSlots cs ((n,s'):ns)
- else if c > n then
- (n,s') : addFreeSlots ((c,s):cs) ns
- else if s /= s' then -- c == n
- (c,s') : addFreeSlots cs ns
- else
- panic ("addFreeSlots: equal slots: " ++ show (c:map fst cs)
- ++ show (n:map fst ns))
-
-trim :: Int{-offset-} -> [(Int,Slot)] -> (Int{-offset-}, [(Int,Slot)])
-trim current_sp free_slots
- = try current_sp free_slots
- where
- try csp [] = (csp,[])
-
- try csp (slot@(off,state):slots) =
- if state == Free && null slots' then
- if csp' < off then
- (csp', [])
- else if csp' == off then
- (csp'-1, [])
- else
- (csp',[slot])
- else
- (csp', slot:slots')
- where
- (csp',slots') = try csp slots
+addFreeSlots (c:cs) (n:ns)
+ | c < n = c : addFreeSlots cs (n:ns)
+ | otherwise = n : addFreeSlots (c:cs) ns
+
+trim :: VirtualSpOffset -> [VirtualSpOffset] -> (VirtualSpOffset, [VirtualSpOffset])
+-- Try to trim back the virtual stack pointer, where there is a
+-- continuous bunch of free slots at the end of the free list
+trim vsp [] = (vsp, [])
+trim vsp (slot:slots)
+ = case trim vsp slots of
+ (vsp', [])
+ | vsp' < slot -> pprTrace "trim: strange" (ppr vsp <+> ppr (slot:slots))
+ (vsp', [])
+ | vsp' == slot -> (vsp'-1, [])
+ | otherwise -> (vsp', [slot])
+ (vsp', slots') -> (vsp', slot:slots')
\end{code}
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