%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
+%
+% $Id: CgTailCall.lhs,v 1.37 2003/05/14 09:13:56 simonmar Exp $
%
%********************************************************
%* *
%********************************************************
\begin{code}
-#include "HsVersions.h"
-
module CgTailCall (
- cgTailCall,
- performReturn,
+ cgTailCall, performTailCall,
+ performReturn, performPrimReturn,
mkStaticAlgReturnCode, mkDynamicAlgReturnCode,
+ returnUnboxedTuple, ccallReturnUnboxedTuple,
mkPrimReturnCode,
+ tailCallPrimOp,
- tailCallBusiness
-
- -- and to make the interface self-sufficient...
+ pushReturnAddress
) where
-IMPORT_Trace
-import Pretty -- Pretty/Outputable: rm (debugging only) ToDo
-import Outputable
+#include "HsVersions.h"
-import StgSyn
import CgMonad
-import AbsCSyn
+import CgBindery ( getArgAmodes, getCAddrMode, getCAddrModeAndInfo )
+import CgRetConv
+import CgStackery
+import CgUsages ( getSpRelOffset, adjustSpAndHp )
+import ClosureInfo
-import Type ( isPrimType, Type )
-import CgBindery ( getAtomAmodes, getCAddrMode, getCAddrModeAndInfo )
-import CgCompInfo ( oTHER_TAG, iND_TAG )
-import CgRetConv ( dataReturnConvPrim, ctrlReturnConvAlg, dataReturnConvAlg,
- mkLiveRegsBitMask,
- CtrlReturnConvention(..), DataReturnConvention(..)
- )
-import CgStackery ( adjustRealSps, mkStkAmodes )
-import CgUsages ( getSpARelOffset, getSpBRelOffset )
-import CLabel ( CLabel, mkStdUpdCodePtrVecLabel, mkConUpdCodePtrVecLabel )
-import ClosureInfo ( nodeMustPointToIt, getEntryConvention, EntryConvention(..) )
-import CmdLineOpts ( GlobalSwitch(..) )
-import Id ( getDataConTyCon, getDataConTag,
- idType, getIdPrimRep, fIRST_TAG, Id,
- ConTag(..)
- )
-import Maybes ( assocMaybe, maybeToBool, Maybe(..) )
-import PrimRep ( retPrimRepSize )
-import Util
-\end{code}
+import AbsCUtils ( mkAbstractCs, getAmodeRep )
+import AbsCSyn
+import CLabel ( mkUpdInfoLabel, mkRtsPrimOpLabel, mkSeqInfoLabel )
+
+import Id ( Id, idType, idName )
+import DataCon ( DataCon, dataConTyCon, dataConTag, fIRST_TAG )
+import PrimRep ( PrimRep(..) )
+import StgSyn ( StgArg )
+import Type ( isUnLiftedType )
+import Name ( Name )
+import TyCon ( TyCon )
+import PrimOp ( PrimOp )
+import Util ( zipWithEqual, splitAtList )
+import ListSetOps ( assocMaybe )
+import PrimRep ( isFollowableRep )
+import Outputable
+import Panic ( panic, assertPanic )
+
+import List ( partition )
+
+-----------------------------------------------------------------------------
+-- Tail Calls
+
+cgTailCall :: Id -> [StgArg] -> Code
+
+-- Here's the code we generate for a tail call. (NB there may be no
+-- arguments, in which case this boils down to just entering a variable.)
+--
+-- * Put args in the top locations of the stack.
+-- * Adjust the stack ptr
+-- * Make R1 point to the function closure if necessary.
+-- * Perform the call.
+--
+-- Things to be careful about:
+--
+-- * Don't overwrite stack locations before you have finished with
+-- them (remember you need the function and the as-yet-unmoved
+-- arguments).
+-- * Preferably, generate no code to replace x by x on the stack (a
+-- common situation in tail-recursion).
+-- * Adjust the stack high water mark appropriately.
+--
+-- Treat unboxed locals exactly like literals (above) except use the addr
+-- mode for the local instead of (CLit lit) in the assignment.
+
+-- Case for unboxed returns first:
+cgTailCall fun []
+ | isUnLiftedType (idType fun)
+ = getCAddrMode fun `thenFC` \ amode ->
+ performPrimReturn (ppr fun) amode
+
+-- The general case (@fun@ is boxed):
+cgTailCall fun args
+ = getCAddrModeAndInfo fun `thenFC` \ (fun', fun_amode, lf_info) ->
+ getArgAmodes args `thenFC` \ arg_amodes ->
+ performTailCall fun' fun_amode lf_info arg_amodes AbsCNop
+
+
+-- -----------------------------------------------------------------------------
+-- The guts of a tail-call
+
+performTailCall
+ :: Id -- function
+ -> CAddrMode -- function amode
+ -> LambdaFormInfo
+ -> [CAddrMode]
+ -> AbstractC -- Pending simultaneous assignments
+ -- *** GUARANTEED to contain only stack assignments.
+ -> Code
+
+performTailCall fun fun_amode lf_info arg_amodes pending_assts =
+ nodeMustPointToIt lf_info `thenFC` \ node_points ->
+ let
+ -- assign to node if necessary
+ node_asst
+ | node_points = CAssign (CReg node) fun_amode
+ | otherwise = AbsCNop
+ in
+
+ getEndOfBlockInfo `thenFC` \ eob@(EndOfBlockInfo args_sp sequel) ->
-%************************************************************************
-%* *
-\subsection[tailcall-doc]{Documentation}
-%* *
-%************************************************************************
+ let
+ -- set up for a let-no-escape if necessary
+ join_sp = case fun_amode of
+ CJoinPoint sp -> sp
+ other -> args_sp
+ in
-\begin{code}
-cgTailCall :: StgArg -> [StgArg] -> StgLiveVars -> Code
-\end{code}
+ -- decide how to code the tail-call: which registers assignments to make,
+ -- what args to push on the stack, and how to make the jump
+ constructTailCall (idName fun) lf_info arg_amodes join_sp
+ node_points fun_amode sequel
+ `thenFC` \ (final_sp, arg_assts, jump_code) ->
-Here's the code we generate for a tail call. (NB there may be no
-arguments, in which case this boils down to just entering a variable.)
-
-\begin{itemize}
-\item Adjust the stack ptr to \tr{tailSp + #args}.
-\item Put args in the top locations of the resulting stack.
-\item Make Node point to the function closure.
-\item Enter the function closure.
-\end{itemize}
-
-Things to be careful about:
-\begin{itemize}
-\item Don't overwrite stack locations before you have finished with
- them (remember you need the function and the as-yet-unmoved
- arguments).
-\item Preferably, generate no code to replace x by x on the stack (a
- common situation in tail-recursion).
-\item Adjust the stack high water mark appropriately.
-\end{itemize}
-
-Literals are similar to constructors; they return by putting
-themselves in an appropriate register and returning to the address on
-top of the B stack.
+ let sim_assts = mkAbstractCs [node_asst,
+ pending_assts,
+ arg_assts]
-\begin{code}
-cgTailCall (StgLitArg lit) [] live_vars
- = performPrimReturn (CLit lit) live_vars
-\end{code}
-
-Treat unboxed locals exactly like literals (above) except use the addr
-mode for the local instead of (CLit lit) in the assignment.
+ is_lne = case fun_amode of { CJoinPoint _ -> True; _ -> False }
+ in
-Case for unboxed @Ids@ first:
-\begin{code}
-cgTailCall atom@(StgVarArg fun) [] live_vars
- | isPrimType (idType fun)
- = getCAddrMode fun `thenFC` \ amode ->
- performPrimReturn amode live_vars
-\end{code}
+ doFinalJump final_sp sim_assts is_lne (const jump_code)
+
+
+-- Figure out how to do a particular tail-call.
+
+constructTailCall
+ :: Name
+ -> LambdaFormInfo
+ -> [CAddrMode]
+ -> VirtualSpOffset -- Sp at which to make the call
+ -> Bool -- node points to the fun closure?
+ -> CAddrMode -- addressing mode of the function
+ -> Sequel -- the sequel, in case we need it
+ -> FCode (
+ VirtualSpOffset, -- Sp after pushing the args
+ AbstractC, -- assignments
+ Code -- code to do the jump
+ )
+
+constructTailCall name lf_info arg_amodes sp node_points fun_amode sequel =
+
+ getEntryConvention name lf_info (map getAmodeRep arg_amodes)
+ `thenFC` \ entry_conv ->
+
+ case entry_conv of
+ EnterIt -> returnFC (sp, AbsCNop, code)
+ where code = profCtrC FSLIT("TICK_ENT_VIA_NODE") [] `thenC`
+ absC (CJump (CMacroExpr CodePtrRep ENTRY_CODE
+ [CVal (nodeRel 0) DataPtrRep]))
+
+ -- A function, but we have zero arguments. It is already in WHNF,
+ -- so we can just return it.
+ ReturnIt -> returnFC (sp, asst, code)
+ where -- if node doesn't already point to the closure, we have to
+ -- load it up.
+ asst | node_points = AbsCNop
+ | otherwise = CAssign (CReg node) fun_amode
+
+ code = sequelToAmode sequel `thenFC` \ dest_amode ->
+ absC (CReturn dest_amode DirectReturn)
+
+ JumpToIt lbl -> returnFC (sp, AbsCNop, code)
+ where code = absC (CJump (CLbl lbl CodePtrRep))
+
+ -- a slow function call via the RTS apply routines
+ SlowCall ->
+ let (apply_fn, new_amodes) = constructSlowCall arg_amodes
+
+ -- if node doesn't already point to the closure,
+ -- we have to load it up.
+ node_asst | node_points = AbsCNop
+ | otherwise = CAssign (CReg node) fun_amode
+ in
-The general case (@fun@ is boxed):
-\begin{code}
-cgTailCall (StgVarArg fun) args live_vars = performTailCall fun args live_vars
-\end{code}
+ -- Fill in all the arguments on the stack
+ mkStkAmodes sp new_amodes `thenFC`
+ \ (final_sp, stk_assts) ->
+
+ returnFC
+ (final_sp + 1, -- add one, because the stg_ap functions
+ -- expect there to be a free slot on the stk
+ mkAbstractCs [node_asst, stk_assts],
+ absC (CJump apply_fn)
+ )
+
+ -- A direct function call (possibly with some left-over arguments)
+ DirectEntry lbl arity regs
+
+ -- A let-no-escape is slightly different, because we
+ -- arrange the stack arguments into pointers and non-pointers
+ -- to make the heap check easier. The tail-call sequence
+ -- is very similar to returning an unboxed tuple, so we
+ -- share some code.
+ | is_let_no_escape ->
+ pushUnboxedTuple sp arg_amodes `thenFC` \ (final_sp, assts) ->
+ returnFC (final_sp, assts, absC (CJump (CLbl lbl CodePtrRep)))
+
+
+ -- A normal fast call
+ | otherwise ->
+ let
+ -- first chunk of args go in registers
+ (reg_arg_amodes, stk_arg_amodes) =
+ splitAtList regs arg_amodes
+
+ -- the rest of this function's args go straight on the stack
+ (stk_args, extra_stk_args) =
+ splitAt (arity - length regs) stk_arg_amodes
+
+ -- any "extra" arguments are placed in frames on the
+ -- stack after the other arguments.
+ slow_stk_args = slowArgs extra_stk_args
+
+ reg_assts
+ = mkAbstractCs (zipWithEqual "assign_to_reg2"
+ assign_to_reg regs reg_arg_amodes)
+
+ in
+ mkStkAmodes sp (stk_args ++ slow_stk_args) `thenFC`
+ \ (final_sp, stk_assts) ->
+
+ returnFC
+ (final_sp,
+ mkAbstractCs [reg_assts, stk_assts],
+ absC (CJump (CLbl lbl CodePtrRep))
+ )
+
+ where is_let_no_escape = case fun_amode of
+ CJoinPoint _ -> True
+ _ -> False
+
+-- -----------------------------------------------------------------------------
+-- The final clean-up before we do a jump at the end of a basic block.
+-- This code is shared by tail-calls and returns.
+
+doFinalJump :: VirtualSpOffset -> AbstractC -> Bool -> (Sequel -> Code) -> Code
+doFinalJump final_sp sim_assts is_let_no_escape jump_code =
+
+ -- adjust the high-water mark if necessary
+ adjustStackHW final_sp `thenC`
+
+ -- Do the simultaneous assignments,
+ absC (CSimultaneous sim_assts) `thenC`
+
+ -- push a return address if necessary (after the assignments
+ -- above, in case we clobber a live stack location)
+ --
+ -- DONT push the return address when we're about to jump to a
+ -- let-no-escape: the final tail call in the let-no-escape
+ -- will do this.
+ getEndOfBlockInfo `thenFC` \ eob@(EndOfBlockInfo args_sp sequel) ->
+ (if is_let_no_escape then nopC
+ else pushReturnAddress eob) `thenC`
-%************************************************************************
-%* *
-\subsection[return-and-tail-call]{Return and tail call}
-%* *
-%************************************************************************
+ -- Final adjustment of Sp/Hp
+ adjustSpAndHp final_sp `thenC`
-ADR-HACK
+ -- and do the jump
+ jump_code sequel
- A quick bit of hacking to try to solve my void#-leaking blues...
+-- -----------------------------------------------------------------------------
+-- A general return (just a special case of doFinalJump, above)
- I think I'm getting bitten by this stuff because code like
+performReturn :: AbstractC -- Simultaneous assignments to perform
+ -> (Sequel -> Code) -- The code to execute to actually do
+ -- the return, given an addressing mode
+ -- for the return address
+ -> Code
- \begin{pseudocode}
- case ds.s12 :: IoWorld of {
- -- lvs: [ds.s12]; rhs lvs: []; uniq: c0
- IoWorld ds.s13# -> ds.s13#;
- } :: Universe#
- \end{pseudocode}
+performReturn sim_assts finish_code
+ = getEndOfBlockInfo `thenFC` \ eob@(EndOfBlockInfo args_sp sequel) ->
+ doFinalJump args_sp sim_assts False{-not a LNE-} finish_code
- causes me to try to allocate a register to return the result in. The
- hope is that the following will avoid such problems (and that Will
- will do this in a cleaner way when he hits the same problem).
+-- -----------------------------------------------------------------------------
+-- Primitive Returns
-KCAH-RDA
+-- Just load the return value into the right register, and return.
-\begin{code}
-performPrimReturn :: CAddrMode -- The thing to return
- -> StgLiveVars
+performPrimReturn :: SDoc -- Just for debugging (sigh)
+ -> CAddrMode -- The thing to return
-> Code
-performPrimReturn amode live_vars
+performPrimReturn doc amode
= let
kind = getAmodeRep amode
ret_reg = dataReturnConvPrim kind
assign_possibly = case kind of
- VoidRep -> AbsCNop
- kind -> (CAssign (CReg ret_reg) amode)
+ VoidRep -> AbsCNop
+ kind -> (CAssign (CReg ret_reg) amode)
in
- performReturn assign_possibly mkPrimReturnCode live_vars
+ performReturn assign_possibly (mkPrimReturnCode doc)
-mkPrimReturnCode :: Sequel -> Code
-mkPrimReturnCode (UpdateCode _) = panic "mkPrimReturnCode: Upd"
-mkPrimReturnCode sequel = sequelToAmode sequel `thenFC` \ dest_amode ->
+mkPrimReturnCode :: SDoc -- Debugging only
+ -> Sequel
+ -> Code
+mkPrimReturnCode doc UpdateCode = pprPanic "mkPrimReturnCode: Upd" doc
+mkPrimReturnCode doc sequel = sequelToAmode sequel `thenFC` \ dest_amode ->
absC (CReturn dest_amode DirectReturn)
-- Direct, no vectoring
--- All constructor arguments in registers; Node and InfoPtr are set.
+-- -----------------------------------------------------------------------------
+-- Algebraic constructor returns
+
+-- Constructor is built on the heap; Node is set.
-- All that remains is
-- (a) to set TagReg, if necessary
--- (b) to set InfoPtr to the info ptr, if necessary
-- (c) to do the right sort of jump.
-mkStaticAlgReturnCode :: Id -- The constructor
- -> Maybe CLabel -- The info ptr, if it isn't already set
+mkStaticAlgReturnCode :: DataCon -- The constructor
-> Sequel -- where to return to
-> Code
-mkStaticAlgReturnCode con maybe_info_lbl sequel
+mkStaticAlgReturnCode con sequel
= -- Generate profiling code if necessary
(case return_convention of
- VectoredReturn sz -> profCtrC SLIT("VEC_RETURN") [mkIntCLit sz]
+ VectoredReturn sz -> profCtrC FSLIT("TICK_VEC_RETURN") [mkIntCLit sz]
other -> nopC
) `thenC`
-- Generate the right jump or return
(case sequel of
- UpdateCode _ -> -- Ha! We know the constructor,
- -- so we can go direct to the correct
- -- update code for that constructor
-
- -- Set the info pointer, and jump
- set_info_ptr `thenC`
- getIntSwitchChkrC `thenFC` \ isw_chkr ->
- absC (CJump (CLbl (update_label isw_chkr) CodePtrRep))
-
- CaseAlts _ (Just (alts, _)) -> -- Ho! We know the constructor so
+ CaseAlts _ (Just (alts, _)) False -> -- Ho! We know the constructor so
-- we can go right to the alternative
- -- No need to set info ptr when returning to a
- -- known join point. After all, the code at
- -- the destination knows what constructor it
- -- is going to handle.
+ case assocMaybe alts tag of
+ Just (alt_absC, join_lbl) ->
+ absC (CJump (CLbl join_lbl CodePtrRep))
+ Nothing -> panic "mkStaticAlgReturnCode: default"
+ -- The Nothing case should never happen;
+ -- it's the subject of a wad of special-case
+ -- code in cgReturnCon
- case assocMaybe alts tag of
- Just (alt_absC, join_lbl) -> absC (CJump (CLbl join_lbl CodePtrRep))
- Nothing -> panic "mkStaticAlgReturnCode: default"
- -- The Nothing case should never happen; it's the subject
- -- of a wad of special-case code in cgReturnCon
-
- other -> -- OnStack, or (CaseAlts) ret_amode Nothing)
- -- Set the info pointer, and jump
- set_info_ptr `thenC`
+ other -> -- OnStack, or (CaseAlts ret_amode Nothing),
+ -- or UpdateCode.
sequelToAmode sequel `thenFC` \ ret_amode ->
absC (CReturn ret_amode return_info)
)
where
- tag = getDataConTag con
- tycon = getDataConTyCon con
+ tag = dataConTag con
+ tycon = dataConTyCon con
return_convention = ctrlReturnConvAlg tycon
zero_indexed_tag = tag - fIRST_TAG -- Adjust tag to be zero-indexed
-- cf AbsCUtils.mkAlgAltsCSwitch
- update_label isw_chkr
- = case (dataReturnConvAlg isw_chkr con) of
- ReturnInHeap -> mkStdUpdCodePtrVecLabel tycon tag
- ReturnInRegs _ -> mkConUpdCodePtrVecLabel tycon tag
+ return_info =
+ case return_convention of
+ UnvectoredReturn _ -> DirectReturn
+ VectoredReturn _ -> StaticVectoredReturn zero_indexed_tag
- return_info = case return_convention of
- UnvectoredReturn _ -> DirectReturn
- VectoredReturn _ -> StaticVectoredReturn zero_indexed_tag
- set_info_ptr = case maybe_info_lbl of
- Nothing -> nopC
- Just info_lbl -> absC (CAssign (CReg infoptr) (CLbl info_lbl DataPtrRep))
+-- -----------------------------------------------------------------------------
+-- Returning an enumerated type from a PrimOp
+-- This function is used by PrimOps that return enumerated types (i.e.
+-- all the comparison operators).
mkDynamicAlgReturnCode :: TyCon -> CAddrMode -> Sequel -> Code
= case ctrlReturnConvAlg tycon of
VectoredReturn sz ->
- profCtrC SLIT("VEC_RETURN") [mkIntCLit sz] `thenC`
+ profCtrC FSLIT("TICK_VEC_RETURN") [mkIntCLit sz] `thenC`
sequelToAmode sequel `thenFC` \ ret_addr ->
absC (CReturn ret_addr (DynamicVectoredReturn dyn_tag))
sequelToAmode sequel `thenFC` \ ret_addr ->
-- Generate the right jump or return
absC (CReturn ret_addr DirectReturn)
-\end{code}
-\begin{code}
-performReturn :: AbstractC -- Simultaneous assignments to perform
- -> (Sequel -> Code) -- The code to execute to actually do
- -- the return, given an addressing mode
- -- for the return address
- -> StgLiveVars
- -> Code
-performReturn sim_assts finish_code live_vars
- = getEndOfBlockInfo `thenFC` \ (EndOfBlockInfo args_spa args_spb sequel) ->
+-- ---------------------------------------------------------------------------
+-- Unboxed tuple returns
- -- Do the simultaneous assignments,
- doSimAssts args_spa live_vars sim_assts `thenC`
+-- These are a bit like a normal tail call, except that:
+--
+-- - The tail-call target is an info table on the stack
+--
+-- - We separate stack arguments into pointers and non-pointers,
+-- to make it easier to leave things in a sane state for a heap check.
+-- This is OK because we can never partially-apply an unboxed tuple,
+-- unlike a function. The same technique is used when calling
+-- let-no-escape functions, because they also can't be partially
+-- applied.
- -- Adjust stack pointers
- adjustRealSps args_spa args_spb `thenC`
+returnUnboxedTuple :: [CAddrMode] -> Code
+returnUnboxedTuple amodes =
+ getEndOfBlockInfo `thenFC` \ eob@(EndOfBlockInfo args_sp sequel) ->
- -- Do the return
- finish_code sequel -- "sequel" is `robust' in that it doesn't
- -- depend on stk-ptr values
-\end{code}
+ profCtrC FSLIT("TICK_RET_UNBOXED_TUP") [mkIntCLit (length amodes)] `thenC`
-\begin{code}
-performTailCall :: Id -- Function
- -> [StgArg] -- Args
- -> StgLiveVars
- -> Code
+ pushUnboxedTuple args_sp amodes `thenFC` \ (final_sp, assts) ->
+ doFinalJump final_sp assts False{-not a LNE-} mkUnboxedTupleReturnCode
-performTailCall fun args live_vars
- = -- Get all the info we have about the function and args and go on to
- -- the business end
- getCAddrModeAndInfo fun `thenFC` \ (fun_amode, lf_info) ->
- getAtomAmodes args `thenFC` \ arg_amodes ->
- tailCallBusiness
- fun fun_amode lf_info arg_amodes
- live_vars AbsCNop {- No pending assignments -}
-
-
-tailCallBusiness :: Id -> CAddrMode -- Function and its amode
- -> LambdaFormInfo -- Info about the function
- -> [CAddrMode] -- Arguments
- -> StgLiveVars -- Live in continuation
-
- -> AbstractC -- Pending simultaneous assignments
- -- *** GUARANTEED to contain only stack assignments.
- -- In ptic, we don't need to look in here to
- -- discover all live regs
-
- -> Code
-
-tailCallBusiness fun fun_amode lf_info arg_amodes live_vars pending_assts
- = isSwitchSetC EmitArityChecks `thenFC` \ do_arity_chks ->
-
- nodeMustPointToIt lf_info `thenFC` \ node_points ->
- getEntryConvention fun lf_info
- (map getAmodeRep arg_amodes) `thenFC` \ entry_conv ->
-
- getEndOfBlockInfo `thenFC` \ (EndOfBlockInfo args_spa args_spb sequel) ->
+pushUnboxedTuple
+ :: VirtualSpOffset -- Sp at which to start pushing
+ -> [CAddrMode] -- amodes of the components
+ -> FCode (VirtualSpOffset, -- final Sp
+ AbstractC) -- assignments (regs+stack)
+pushUnboxedTuple sp amodes =
let
- node_asst
- = if node_points then
- CAssign (CReg node) fun_amode
- else
- AbsCNop
-
- (arg_regs, finish_code)
- = case entry_conv of
- ViaNode ->
- ([],
- mkAbstractCs [
- CCallProfCtrMacro SLIT("ENT_VIA_NODE") [],
- CAssign (CReg infoptr)
-
- (CMacroExpr DataPtrRep INFO_PTR [CReg node]),
- CJump (CMacroExpr CodePtrRep ENTRY_CODE [CReg infoptr])
- ])
- StdEntry lbl Nothing -> ([], CJump (CLbl lbl CodePtrRep))
- StdEntry lbl (Just itbl) -> ([], CAssign (CReg infoptr) (CLbl itbl DataPtrRep)
- `mkAbsCStmts`
- CJump (CLbl lbl CodePtrRep))
- DirectEntry lbl arity regs ->
- (regs, (if do_arity_chks
- then CMacroStmt SET_ARITY [mkIntCLit arity]
- else AbsCNop)
- `mkAbsCStmts` CJump (CLbl lbl CodePtrRep))
-
- no_of_args = length arg_amodes
-
- (reg_arg_assts, stk_arg_amodes)
- = (mkAbstractCs (zipWithEqual assign_to_reg arg_regs arg_amodes),
- drop (length arg_regs) arg_amodes) -- No regs, or
- -- args beyond arity
-
- assign_to_reg reg_id amode = CAssign (CReg reg_id) amode
- in
- case fun_amode of
- CJoinPoint join_spa join_spb -> -- Ha! A let-no-escape thingy
-
- ASSERT(not (args_spa > join_spa) || (args_spb > join_spb))
- -- If ASSERTion fails: Oops: the join point has *lower*
- -- stack ptrs than the continuation Note that we take
- -- the SpB point without the return address here. The
- -- return address is put on by the let-no-escapey thing
- -- when it finishes.
-
- mkStkAmodes join_spa join_spb stk_arg_amodes
- `thenFC` \ (final_spa, final_spb, stk_arg_assts) ->
+ (arg_regs, _leftovers) = assignRegs [] (map getAmodeRep amodes)
- -- Do the simultaneous assignments,
- doSimAssts join_spa live_vars
- (mkAbstractCs [pending_assts, reg_arg_assts, stk_arg_assts])
- `thenC`
+ (reg_arg_amodes, stk_arg_amodes) = splitAtList arg_regs amodes
- -- Adjust stack ptrs
- adjustRealSps final_spa final_spb `thenC`
+ -- separate the rest of the args into pointers and non-pointers
+ ( ptr_args, nptr_args ) =
+ partition (isFollowableRep . getAmodeRep) stk_arg_amodes
- -- Jump to join point
- absC finish_code
-
- _ -> -- else: not a let-no-escape (the common case)
+ reg_arg_assts
+ = mkAbstractCs (zipWithEqual "assign_to_reg2"
+ assign_to_reg arg_regs reg_arg_amodes)
+ in
- -- Make instruction to save return address
- loadRetAddrIntoRetReg sequel `thenFC` \ ret_asst ->
+ -- push ptrs, then nonptrs, on the stack
+ mkStkAmodes sp ptr_args `thenFC` \ (ptr_sp, ptr_assts) ->
+ mkStkAmodes ptr_sp nptr_args `thenFC` \ (final_sp, nptr_assts) ->
- mkStkAmodes args_spa args_spb stk_arg_amodes
- `thenFC`
- \ (final_spa, final_spb, stk_arg_assts) ->
+ returnFC (final_sp,
+ mkAbstractCs [reg_arg_assts, ptr_assts, nptr_assts])
+
+
- -- The B-stack space for the pushed return addess, with any args pushed
- -- on top, is recorded in final_spb.
+mkUnboxedTupleReturnCode :: Sequel -> Code
+mkUnboxedTupleReturnCode sequel
+ = case sequel of
+ -- can't update with an unboxed tuple!
+ UpdateCode -> panic "mkUnboxedTupleReturnCode"
- -- Do the simultaneous assignments,
- doSimAssts args_spa live_vars
- (mkAbstractCs [pending_assts, node_asst, ret_asst,
- reg_arg_assts, stk_arg_assts])
- `thenC`
+ CaseAlts _ (Just ([(_,(alt_absC,join_lbl))], _)) False ->
+ absC (CJump (CLbl join_lbl CodePtrRep))
- -- Final adjustment of stack pointers
- adjustRealSps final_spa final_spb `thenC`
+ other -> -- OnStack, or (CaseAlts ret_amode something)
+ sequelToAmode sequel `thenFC` \ ret_amode ->
+ absC (CReturn ret_amode DirectReturn)
+
+-- -----------------------------------------------------------------------------
+-- Returning unboxed tuples. This is mainly to support _ccall_GC_, where
+-- we want to do things in a slightly different order to normal:
+--
+-- - push return address
+-- - adjust stack pointer
+-- - r = call(args...)
+-- - assign regs for unboxed tuple (usually just R1 = r)
+-- - return to continuation
+--
+-- The return address (i.e. stack frame) must be on the stack before
+-- doing the call in case the call ends up in the garbage collector.
+--
+-- Sadly, the information about the continuation is lost after we push it
+-- (in order to avoid pushing it again), so we end up doing a needless
+-- indirect jump (ToDo).
+
+ccallReturnUnboxedTuple :: [CAddrMode] -> Code -> Code
+ccallReturnUnboxedTuple amodes before_jump
+ = getEndOfBlockInfo `thenFC` \ eob@(EndOfBlockInfo args_sp sequel) ->
+
+ -- push a return address if necessary
+ pushReturnAddress eob `thenC`
+ setEndOfBlockInfo (EndOfBlockInfo args_sp (OnStack args_sp)) (
+
+ -- Adjust Sp/Hp
+ adjustSpAndHp args_sp `thenC`
+
+ before_jump `thenC`
+
+ returnUnboxedTuple amodes
+ )
+
+-- -----------------------------------------------------------------------------
+-- Calling an out-of-line primop
+
+tailCallPrimOp :: PrimOp -> [StgArg] -> Code
+tailCallPrimOp op args =
+ -- we're going to perform a normal-looking tail call,
+ -- except that *all* the arguments will be in registers.
+ getArgAmodes args `thenFC` \ arg_amodes ->
+ let (arg_regs, leftovers) = assignAllRegs [] (map getAmodeRep arg_amodes)
+
+ reg_arg_assts
+ = mkAbstractCs (zipWithEqual "assign_to_reg2"
+ assign_to_reg arg_regs arg_amodes)
+
+ jump_to_primop =
+ absC (CJump (CLbl (mkRtsPrimOpLabel op) CodePtrRep))
+ in
- -- Now decide about semi-tagging
- isSwitchSetC DoSemiTagging `thenFC` \ semi_tagging_on ->
- case (semi_tagging_on, arg_amodes, node_points, sequel) of
+ ASSERT(null leftovers) -- no stack-resident args
- --
- -- *************** The semi-tagging case ***************
- --
- ( True, [], True, CaseAlts _ (Just (st_alts, maybe_deflt_join_details))) ->
-
- -- Whoppee! Semi-tagging rules OK!
- -- (a) semi-tagging is switched on
- -- (b) there are no arguments,
- -- (c) Node points to the closure
- -- (d) we have a case-alternative sequel with
- -- some visible alternatives
-
- -- Why is test (c) necessary?
- -- Usually Node will point to it at this point, because we're
- -- scrutinsing something which is either a thunk or a
- -- constructor.
- -- But not always! The example I came across is when we have
- -- a top-level Double:
- -- lit.3 = D# 3.000
- -- ... (case lit.3 of ...) ...
- -- Here, lit.3 is built as a re-entrant thing, which you must enter.
- -- (OK, the simplifier should have eliminated this, but it's
- -- easy to deal with the case anyway.)
- let
- join_details_to_code (load_regs_and_profiling_code, join_lbl)
- = load_regs_and_profiling_code `mkAbsCStmts`
- CJump (CLbl join_lbl CodePtrRep)
-
- semi_tagged_alts = [ (mkMachInt (toInteger (tag - fIRST_TAG)),
- join_details_to_code join_details)
- | (tag, join_details) <- st_alts
- ]
-
- enter_jump
- -- Enter Node (we know infoptr will have the info ptr in it)!
- = mkAbstractCs [
- CCallProfCtrMacro SLIT("RET_SEMI_FAILED")
- [CMacroExpr IntRep INFO_TAG [CReg infoptr]],
- CJump (CMacroExpr CodePtrRep ENTRY_CODE [CReg infoptr]) ]
- in
- -- Final switch
- absC (mkAbstractCs [
- CAssign (CReg infoptr)
- (CVal (NodeRel zeroOff) DataPtrRep),
-
- case maybe_deflt_join_details of
- Nothing ->
- CSwitch (CMacroExpr IntRep INFO_TAG [CReg infoptr])
- (semi_tagged_alts)
- (enter_jump)
- Just (_, details) ->
- CSwitch (CMacroExpr IntRep EVAL_TAG [CReg infoptr])
- [(mkMachInt 0, enter_jump)]
- (CSwitch
- (CMacroExpr IntRep INFO_TAG [CReg infoptr])
- (semi_tagged_alts)
- (join_details_to_code details))
- ])
+ getEndOfBlockInfo `thenFC` \ eob@(EndOfBlockInfo args_sp sequel) ->
+ doFinalJump args_sp reg_arg_assts False{-not a LNE-} (const jump_to_primop)
- --
- -- *************** The non-semi-tagging case ***************
- --
- other -> absC finish_code
-\end{code}
+-- -----------------------------------------------------------------------------
+-- Return Addresses
-\begin{code}
-loadRetAddrIntoRetReg :: Sequel -> FCode AbstractC
+-- | We always push the return address just before performing a tail call
+-- or return. The reason we leave it until then is because the stack
+-- slot that the return address is to go into might contain something
+-- useful.
+--
+-- If the end of block info is 'CaseAlts', then we're in the scrutinee of a
+-- case expression and the return address is still to be pushed.
+--
+-- There are cases where it doesn't look necessary to push the return
+-- address: for example, just before doing a return to a known
+-- continuation. However, the continuation will expect to find the
+-- return address on the stack in case it needs to do a heap check.
-loadRetAddrIntoRetReg InRetReg
- = returnFC AbsCNop -- Return address already there
+pushReturnAddress :: EndOfBlockInfo -> Code
-loadRetAddrIntoRetReg sequel
- = sequelToAmode sequel `thenFC` \ amode ->
- returnFC (CAssign (CReg RetReg) amode)
+pushReturnAddress (EndOfBlockInfo args_sp sequel@(CaseAlts amode _ False)) =
+ getSpRelOffset args_sp `thenFC` \ sp_rel ->
+ absC (CAssign (CVal sp_rel RetRep) amode)
-\end{code}
+-- For a polymorphic case, we have two return addresses to push: the case
+-- return, and stg_seq_frame_info which turns a possible vectored return
+-- into a direct one.
+pushReturnAddress (EndOfBlockInfo args_sp sequel@(CaseAlts amode _ True)) =
+ getSpRelOffset (args_sp-1) `thenFC` \ sp_rel ->
+ absC (CAssign (CVal sp_rel RetRep) amode) `thenC`
+ getSpRelOffset args_sp `thenFC` \ sp_rel ->
+ absC (CAssign (CVal sp_rel RetRep) (CLbl mkSeqInfoLabel RetRep))
+pushReturnAddress _ = nopC
-%************************************************************************
-%* *
-\subsection[doSimAssts]{@doSimAssts@}
-%* *
-%************************************************************************
+-- -----------------------------------------------------------------------------
+-- Misc.
-@doSimAssts@ happens at the end of every block of code.
-They are separate because we sometimes do some jiggery-pokery in between.
+assign_to_reg reg_id amode = CAssign (CReg reg_id) amode
-\begin{code}
-doSimAssts :: VirtualSpAOffset -- tail_spa: SpA as seen by continuation
- -> StgLiveVars -- Live in continuation
- -> AbstractC
- -> Code
-
-doSimAssts tail_spa live_vars sim_assts
- = -- Do the simultaneous assignments
- absC (CSimultaneous sim_assts) `thenC`
-
- -- Stub any unstubbed slots; the only live variables are indicated in
- -- the end-of-block info in the monad
- nukeDeadBindings live_vars `thenC`
- getUnstubbedAStackSlots tail_spa `thenFC` \ a_slots ->
- -- Passing in tail_spa here should actually be redundant, because
- -- the stack should be trimmed (by nukeDeadBindings) to
- -- exactly the tail_spa position anyhow.
-
- -- Emit code to stub dead regs; this only generates actual
- -- machine instructions in in the DEBUG version
- -- *** NOT DONE YET ***
-
- (if (null a_slots)
- then nopC
- else profCtrC SLIT("A_STK_STUB") [mkIntCLit (length a_slots)] `thenC`
- mapCs stub_A_slot a_slots
- )
- where
- stub_A_slot :: VirtualSpAOffset -> Code
- stub_A_slot offset = getSpARelOffset offset `thenFC` \ spa_rel ->
- absC (CAssign (CVal spa_rel PtrRep)
- (CReg StkStubReg))
\end{code}
projects / ghc-hetmet.git / blobdiff