X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FcodeGen%2FCgStackery.lhs;fp=ghc%2Fcompiler%2FcodeGen%2FCgStackery.lhs;h=19d89b0d71efab558b5568f1a43109137e858013;hb=438596897ebbe25a07e1c82085cfbc5bdb00f09e;hp=cba5106b4fa7080d7e7967d96e511d75db03b629;hpb=967cc47f37cb93a5e2b6df7822c9a646f0428247;p=ghc-hetmet.git diff --git a/ghc/compiler/codeGen/CgStackery.lhs b/ghc/compiler/codeGen/CgStackery.lhs index cba5106..19d89b0 100644 --- a/ghc/compiler/codeGen/CgStackery.lhs +++ b/ghc/compiler/codeGen/CgStackery.lhs @@ -1,5 +1,7 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 +% +% $Id: CgStackery.lhs,v 1.9 1998/12/02 13:17:51 simonm Exp $ % \section[CgStackery]{Stack management functions} @@ -8,10 +10,11 @@ Stack-twiddling operations, which are pretty low-down and grimy. \begin{code} module CgStackery ( - allocAStack, allocBStack, allocAStackTop, allocBStackTop, + allocStack, allocPrimStack, allocStackTop, deAllocStackTop, allocUpdateFrame, - adjustRealSps, getFinalStackHW, - mkVirtStkOffsets, mkStkAmodes + adjustRealSp, adjustStackHW, getFinalStackHW, + mkTaggedVirtStkOffsets, mkTaggedStkAmodes, mkTagAssts, + freeStackSlots, addFreeSlots ) where #include "HsVersions.h" @@ -19,12 +22,10 @@ module CgStackery ( import CgMonad import AbsCSyn +import CgUsages ( getRealSp ) import AbsCUtils ( mkAbstractCs, mkAbsCStmts, getAmodeRep ) -import HeapOffs ( VirtualSpAOffset, VirtualSpBOffset ) -import PrimRep ( getPrimRepSize, separateByPtrFollowness, - PrimRep(..) - ) -import Util ( mapAccumR, panic ) +import PrimRep ( getPrimRepSize, PrimRep(..), isFollowableRep ) +import Util ( panic ) \end{code} %************************************************************************ @@ -33,88 +34,92 @@ import Util ( mapAccumR, panic ) %* * %************************************************************************ -@mkVirtStkOffsets@ 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). +@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 | + --------- \begin{code} -mkVirtStkOffsets :: VirtualSpAOffset -- Offset of the last allocated thing - -> VirtualSpBOffset -- ditto +mkTaggedVirtStkOffsets + :: VirtualSpOffset -- Offset of the last allocated thing -> (a -> PrimRep) -- to be able to grab kinds -> [a] -- things to make offsets for - -> (VirtualSpAOffset, -- OUTPUTS: Topmost allocated word - VirtualSpBOffset, -- ditto - [(a, VirtualSpAOffset)], -- boxed things with offsets - [(a, VirtualSpBOffset)]) -- unboxed things with offsets - -mkVirtStkOffsets init_SpA_offset init_SpB_offset kind_fun things - = let (boxeds, unboxeds) - = separateByPtrFollowness kind_fun things - (last_SpA_offset, boxd_w_offsets) - = mapAccumR computeOffset init_SpA_offset boxeds - (last_SpB_offset, ubxd_w_offsets) - = mapAccumR computeOffset init_SpB_offset unboxeds - in - (last_SpA_offset, last_SpB_offset, boxd_w_offsets, ubxd_w_offsets) + -> (VirtualSpOffset, -- OUTPUTS: Topmost allocated word + [(a, VirtualSpOffset)], -- things with offsets + [(VirtualSpOffset,Int)]) -- offsets for tags + +mkTaggedVirtStkOffsets init_Sp_offset kind_fun things + = loop init_Sp_offset [] [] (reverse things) where - computeOffset offset thing - = (offset + (max 1 . getPrimRepSize . kind_fun) thing, (thing, offset+(1::Int))) - -- The "max 1" bit is ULTRA important - -- Why? mkVirtStkOffsets is the unique function that lays out function - -- arguments on the stack. The "max 1" ensures that every argument takes - -- at least one stack slot, even if it's of kind VoidKind that actually - -- takes no space at all. - -- This is important to make sure that argument satisfaction checks work - -- properly. Consider - -- f a b s# = (a,b) - -- where s# is a VoidKind. f's argument satisfaction check will check - -- that s# is on the B stack above SuB; but if s# takes zero space, the - -- check will be ARGS_B_CHK(0), which always succeeds. As a result, even - -- if a,b aren't available either, the PAP update won't trigger and - -- we are throughly hosed. (SLPJ 96/05) + 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} -@mkStackAmodes@ is a higher-level version of @mkStackOffsets@. -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. +@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. -It also adjusts the high water mark if necessary. +It *doesn't* adjust the high water mark. \begin{code} -mkStkAmodes :: VirtualSpAOffset -- Tail call positions - -> VirtualSpBOffset - -> [CAddrMode] -- things to make offsets for - -> FCode (VirtualSpAOffset, -- OUTPUTS: Topmost allocated word - VirtualSpBOffset, -- ditto - AbstractC) -- Assignments to appropriate stk slots - -mkStkAmodes tail_spa tail_spb things - info_down (MkCgState absC binds usage) - = (result, MkCgState absC binds new_usage) - where - result = (last_SpA_offset, last_SpB_offset, mkAbstractCs abs_cs) - - (last_SpA_offset, last_SpB_offset, ptrs_w_offsets, non_ptrs_w_offsets) - = mkVirtStkOffsets tail_spa tail_spb getAmodeRep things - - abs_cs - = [ CAssign (CVal (SpARel realSpA offset) PtrRep) thing - | (thing, offset) <- ptrs_w_offsets +mkTaggedStkAmodes + :: VirtualSpOffset -- Tail call positions + -> [CAddrMode] -- 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 ] - ++ - [ CAssign (CVal (SpBRel realSpB offset) (getAmodeRep thing)) thing - | (thing, offset) <- non_ptrs_w_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) - ((vspA,fspA,realSpA,hwSpA), (vspB,fspB,realSpB,hwSpB), h_usage) = usage - - new_usage = ((vspA,fspA,realSpA,max last_SpA_offset hwSpA), - (vspB,fspB,realSpB,max last_SpB_offset hwSpB), - h_usage) - -- No need to fiddle with virtual SpA etc because this call is - -- only done just before the end of a block - +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 + ]) \end{code} @@ -125,123 +130,112 @@ mkStkAmodes tail_spa tail_spb things %************************************************************************ Allocate a virtual offset for something. + \begin{code} -allocAStack :: FCode VirtualSpAOffset +allocStack :: FCode VirtualSpOffset +allocStack = allocPrimStack 1 -allocAStack info_down (MkCgState absC binds - ((virt_a, free_a, real_a, hw_a), b_usage, h_usage)) - = (chosen_slot, MkCgState absC binds (new_a_usage, b_usage, h_usage)) - where - push_virt_a = virt_a + 1 - - (chosen_slot, new_a_usage) - = if null free_a then - -- No free slots, so push a new one - -- We need to adjust the high-water mark - (push_virt_a, (push_virt_a, [], real_a, hw_a `max` push_virt_a)) - else - -- Free slots available, so use one - (free_slot, (virt_a, new_free_a, real_a, hw_a)) - - (free_slot, _) = head ([f | f@(slot, st) <- free_a, not (isStubbed st)] ++ free_a) - -- Try to find an un-stubbed location; - -- if none, return the first in the free list - -- We'll only try this if free_a is known to be non-empty - - -- Free list with the free_slot deleted - new_free_a = [ f | f@(s,_) <- free_a, s /= free_slot ] - -allocBStack :: Int -> FCode VirtualSpBOffset -allocBStack size info_down (MkCgState absC binds - (a_usage, (virt_b, free_b, real_b, hw_b), h_usage)) - = (chosen_slot, MkCgState absC binds (a_usage, new_b_usage, h_usage)) +allocPrimStack :: Int -> FCode VirtualSpOffset +allocPrimStack size info_down (MkCgState absC binds + ((virt_sp, free_stk, real_sp, hw_sp), h_usage)) + = (chosen_slot, MkCgState absC binds (new_stk_usage, h_usage)) where - push_virt_b = virt_b + size + push_virt_sp = virt_sp + size - (chosen_slot, new_b_usage) - = case find_block free_b of - Nothing -> (virt_b+1, (push_virt_b, free_b, real_b, - hw_b `max` push_virt_b)) + (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)) -- Adjust high water mark - Just slot -> (slot, (virt_b, delete_block free_b slot, real_b, hw_b)) + Just slot -> (slot, (virt_sp, + delete_block free_stk slot, real_sp, hw_sp)) -- find_block looks for a contiguous chunk of free slots - find_block :: [VirtualSpBOffset] -> Maybe VirtualSpBOffset + find_block :: [VirtualSpOffset] -> Maybe VirtualSpOffset find_block [] = Nothing find_block (slot:slots) - | take size (slot:slots) == [slot..slot+size-1] - = Just slot - | otherwise - = find_block slots - - delete_block free_b slot = [s | s <- free_b, (s=slot+size)] + | take size (slot:slots) == [slot..top_slot] = 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 = 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..slot+size-1 + -- slot-size+1..slot -- Allocate a chunk ON TOP OF the stack -allocAStackTop :: Int -> FCode VirtualSpAOffset -allocAStackTop size info_down (MkCgState absC binds - ((virt_a, free_a, real_a, hw_a), b_usage, h_usage)) - = (chosen_slot, MkCgState absC binds (new_a_usage, b_usage, h_usage)) +allocStackTop :: Int -> FCode VirtualSpOffset +allocStackTop size info_down (MkCgState absC binds + ((virt_sp, free_stk, real_sp, hw_sp), h_usage)) + = (push_virt_sp, MkCgState absC binds (new_stk_usage, h_usage)) where - push_virt_a = virt_a + size - chosen_slot = virt_a + 1 - new_a_usage = (push_virt_a, free_a, real_a, hw_a `max` push_virt_a) + push_virt_sp = virt_sp + size + new_stk_usage = (push_virt_sp, free_stk, real_sp, hw_sp `max` push_virt_sp) -- Adjust high water mark +\end{code} --- Allocate a chunk ON TOP OF the stack -allocBStackTop :: Int -> FCode VirtualSpBOffset -allocBStackTop size info_down (MkCgState absC binds - (a_usage, (virt_b, free_b, real_b, hw_b), h_usage)) - = (chosen_slot, MkCgState absC binds (a_usage, new_b_usage, h_usage)) +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 info_down (MkCgState absC binds + ((virt_sp, free_stk, real_sp, hw_sp), h_usage)) + = (pop_virt_sp, MkCgState absC binds (new_stk_usage, h_usage)) where - push_virt_b = virt_b + size - chosen_slot = virt_b+1 - new_b_usage = (push_virt_b, free_b, real_b, hw_b `max` push_virt_b) - -- Adjust high water mark + pop_virt_sp = virt_sp - size + new_stk_usage = (pop_virt_sp, free_stk, real_sp, hw_sp) \end{code} -@allocUpdateFrame@ allocates enough space for an update frame -on the B stack, records the fact in the end-of-block info (in the ``args'' +@allocUpdateFrame@ allocates enough space for an update frame on the +stack, records the fact in the end-of-block info (in the ``args'' fields), and passes on the old ``args'' fields to the enclosed code. This is all a bit disgusting. \begin{code} allocUpdateFrame :: Int -- Size of frame - -> CAddrMode -- Return address which is to be the - -- top word of frame - -> ((VirtualSpAOffset, VirtualSpBOffset, VirtualSpBOffset) -> Code) - -- Scope of update + -> Code -- Scope of update -> Code -allocUpdateFrame size update_amode code - (MkCgInfoDown c_info statics (EndOfBlockInfo args_spa args_spb sequel)) - (MkCgState absc binds (a_usage, (vB,rr,qq,hwB),h_usage)) +allocUpdateFrame size code + (MkCgInfoDown c_info statics srt (EndOfBlockInfo args_Sp sequel)) + (MkCgState absc binds ((vSp,rr,qq,hwSp),h_usage)) = case sequel of - InRetReg -> code (args_spa, args_spb, vB) - (MkCgInfoDown c_info statics new_eob_info) - (MkCgState absc binds new_usage) + OnStack _ -> code (MkCgInfoDown c_info statics srt new_eob_info) + (MkCgState absc binds new_usage) - other -> panic "allocUpdateFrame" + other -> panic "allocUpdateFrame" where - new_vB = vB + size - new_eob_info = EndOfBlockInfo args_spa new_vB (UpdateCode update_amode) - new_usage = (a_usage, (new_vB,rr,qq,hwB `max` new_vB), h_usage) + new_vSp = vSp + size + new_eob_info = EndOfBlockInfo new_vSp UpdateCode + new_usage = ((new_vSp,rr,qq,hwSp `max` new_vSp), h_usage) \end{code} +\begin{code} +adjustStackHW :: VirtualSpOffset -> Code +adjustStackHW offset info_down (MkCgState absC binds usage) + = MkCgState absC binds new_usage + where + ((vSp,fSp,realSp,hwSp), h_usage) = usage + new_usage = ((vSp, fSp, realSp, max offset hwSp), h_usage) + -- No need to fiddle with virtual Sp etc because this call is + -- only done just before the end of a block +\end{code} A knot-tying beast. \begin{code} -getFinalStackHW :: (VirtualSpAOffset -> VirtualSpBOffset -> Code) -> Code +getFinalStackHW :: (VirtualSpOffset -> Code) -> Code getFinalStackHW fcode info_down (MkCgState absC binds usages) = state1 where - state1 = fcode hwSpA hwSpB info_down (MkCgState absC binds usages) - (MkCgState _ _ ((_,_,_, hwSpA), (_,_,_, hwSpB), _)) = state1 + state1 = fcode hwSp info_down (MkCgState absC binds usages) + (MkCgState _ _ ((_,_,_, hwSp), _)) = state1 \end{code} @@ -260,39 +254,59 @@ These functions {\em do not} deal with high-water-mark adjustment. That's done by functions which allocate stack space. \begin{code} -adjustRealSpA :: VirtualSpAOffset -- New offset for Arg stack ptr +adjustRealSp :: VirtualSpOffset -- New offset for Arg stack ptr -> Code -adjustRealSpA newRealSpA info_down (MkCgState absC binds - ((vspA,fA,realSpA,hwspA), - b_usage, h_usage)) - = MkCgState (mkAbsCStmts absC move_instrA) binds new_usage +adjustRealSp newRealSp info_down (MkCgState absC binds + ((vSp,fSp,realSp,hwSp), h_usage)) + = MkCgState (mkAbsCStmts absC move_instr) binds new_usage where - move_instrA = if (newRealSpA == realSpA) then AbsCNop + move_instr = if (newRealSp == realSp) then AbsCNop else (CAssign - (CReg SpA) - (CAddr (SpARel realSpA newRealSpA))) - new_usage = ((vspA, fA, newRealSpA, hwspA), - b_usage, h_usage) + (CReg Sp) + (CAddr (spRel realSp newRealSp))) + new_usage = ((vSp, fSp, newRealSp, hwSp), h_usage) +\end{code} -adjustRealSpB :: VirtualSpBOffset -- New offset for Basic/Control stack ptr - -> Code -adjustRealSpB newRealSpB info_down (MkCgState absC binds - (a_usage, - (vspB,fB,realSpB,hwspB), - h_usage)) - = MkCgState (mkAbsCStmts absC move_instrB) binds new_usage - where - move_instrB = if (newRealSpB == realSpB) then AbsCNop - else (CAssign {-PtrRep-} - (CReg SpB) - (CAddr (SpBRel realSpB newRealSpB))) - new_usage = (a_usage, - (vspB, fB, newRealSpB, hwspB), - h_usage) - -adjustRealSps :: VirtualSpAOffset -- New offset for Arg stack ptr - -> VirtualSpBOffset -- Ditto B stack - -> Code -adjustRealSps newRealSpA newRealSpB - = adjustRealSpA newRealSpA `thenC` adjustRealSpB newRealSpB +%************************************************************************ +%* * +\subsection[CgStackery-free]{Free stack slots} +%* * +%************************************************************************ + +Explicitly free some stack space. + +\begin{code} +freeStackSlots :: [VirtualSpOffset] -> Code +freeStackSlots extra_free info_down + state@(MkCgState abs_c binds ((vsp, free, real, hw), heap_usage)) + = MkCgState abs_c binds new_usage + where + new_usage = ((new_vsp, new_free, real, hw), heap_usage) + (new_vsp, new_free) = trim vsp (addFreeSlots free extra_free) + +addFreeSlots :: [Int] -> [Int] -> [Int] +addFreeSlots cs [] = cs +addFreeSlots [] ns = ns +addFreeSlots (c:cs) (n:ns) + = if c < n then + c : addFreeSlots cs (n:ns) + else if c > n then + n : addFreeSlots (c:cs) ns + else + panic ("addFreeSlots: equal slots: " ++ show (c:cs) ++ show (n:ns)) + +trim :: Int{-offset-} -> [Int] -> (Int{-offset-}, [Int]) +trim current_sp free_slots + = try current_sp (reverse free_slots) + where + try csp [] = (csp, []) + try csp (slot:slots) + = if csp < slot then + try csp slots -- Free slot off top of stk; ignore + + else if csp == slot then + try (csp-1) slots -- Free slot at top of stk; trim + + else + (csp, reverse (slot:slots)) -- Otherwise gap; give up \end{code}