%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
+%
+% $Id: CgExpr.lhs,v 1.34 2000/04/13 20:41:30 panne Exp $
%
%********************************************************
%* *
%********************************************************
\begin{code}
-#include "HsVersions.h"
+module CgExpr ( cgExpr ) where
-module CgExpr ( cgExpr, getPrimOpArgAmodes ) where
-
-IMP_Ubiq(){-uitous-}
-IMPORT_DELOOPER(CgLoop2) -- here for paranoia-checking
+#include "HsVersions.h"
+import Constants ( mAX_SPEC_SELECTEE_SIZE, mAX_SPEC_AP_SIZE )
import StgSyn
import CgMonad
import AbsCSyn
-
-import AbsCUtils ( mkAbsCStmts, mkAbstractCs )
-import CgBindery ( getArgAmodes )
-import CgCase ( cgCase, saveVolatileVarsAndRegs )
-import CgClosure ( cgRhsClosure )
+import AbsCUtils ( mkAbstractCs )
+import CLabel ( mkClosureTblLabel )
+
+import SMRep ( fixedHdrSize )
+import CgBindery ( getArgAmodes, getArgAmode, CgIdInfo,
+ nukeDeadBindings, addBindC, addBindsC )
+import CgCase ( cgCase, saveVolatileVarsAndRegs,
+ restoreCurrentCostCentre )
+import CgClosure ( cgRhsClosure, cgStdRhsClosure )
import CgCon ( buildDynCon, cgReturnDataCon )
-import CgHeapery ( allocHeap )
import CgLetNoEscape ( cgLetNoEscapeClosure )
-import CgRetConv ( dataReturnConvAlg, ctrlReturnConvAlg,
- DataReturnConvention(..), CtrlReturnConvention(..),
- assignPrimOpResultRegs, makePrimOpArgsRobust
- )
-import CgTailCall ( cgTailCall, performReturn,
- mkDynamicAlgReturnCode, mkPrimReturnCode
+import CgRetConv ( dataReturnConvPrim )
+import CgTailCall ( cgTailCall, performReturn, performPrimReturn,
+ mkDynamicAlgReturnCode, mkPrimReturnCode,
+ tailCallPrimOp, returnUnboxedTuple
)
-import CLabel ( mkPhantomInfoTableLabel, mkInfoTableVecTblLabel )
-import ClosureInfo ( mkClosureLFInfo )
-import CostCentre ( sccAbleCostCentre, isDictCC, isSccCountCostCentre )
-import HeapOffs ( SYN_IE(VirtualSpBOffset) )
-import Id ( mkIdSet, unionIdSets, GenId{-instance Outputable-} )
-import PprStyle ( PprStyle(..) )
-import PrimOp ( primOpCanTriggerGC, primOpHeapReq, HeapRequirement(..),
+import ClosureInfo ( mkClosureLFInfo, mkSelectorLFInfo,
+ mkApLFInfo, layOutDynCon )
+import CostCentre ( sccAbleCostCentre, isSccCountCostCentre )
+import Id ( idPrimRep, idType, Id )
+import VarSet
+import DataCon ( DataCon, dataConTyCon )
+import IdInfo ( ArityInfo(..) )
+import PrimOp ( primOpOutOfLine, ccallMayGC,
getPrimOpResultInfo, PrimOp(..), PrimOpResultInfo(..)
)
-import PrimRep ( getPrimRepSize, PrimRep(..) )
-import TyCon ( tyConDataCons )
-import Util ( panic, pprPanic, assertPanic )
+import PrimRep ( getPrimRepSize, PrimRep(..), isFollowableRep )
+import TyCon ( maybeTyConSingleCon,
+ isUnboxedTupleTyCon, isEnumerationTyCon )
+import Type ( Type, typePrimRep, splitTyConApp_maybe, repType )
+import PprType ( {- instance Outputable Type -} )
+import Maybes ( assocMaybe, maybeToBool )
+import Unique ( mkBuiltinUnique )
+import BasicTypes ( TopLevelFlag(..), RecFlag(..) )
+import Outputable
\end{code}
This module provides the support code for @StgToAbstractC@ to deal
@(STGApp (StgLitArg 42) [])@.
\begin{code}
-cgExpr (StgApp fun args live_vars) = cgTailCall fun args live_vars
+cgExpr (StgApp fun args) = cgTailCall fun args
\end{code}
%********************************************************
%********************************************************
\begin{code}
-cgExpr (StgCon con args live_vars)
+cgExpr (StgConApp con args)
= getArgAmodes args `thenFC` \ amodes ->
- cgReturnDataCon con amodes (all zero_size args) live_vars
- where
- zero_size atom = getPrimRepSize (getArgPrimRep atom) == 0
+ cgReturnDataCon con amodes
\end{code}
+Literals are similar to constructors; they return by putting
+themselves in an appropriate register and returning to the address on
+top of the stack.
+
+\begin{code}
+cgExpr (StgLit lit)
+ = performPrimReturn (text "literal" <+> ppr lit) (CLit lit)
+\end{code}
+
+
%********************************************************
%* *
%* STG PrimApps (unboxed primitive ops) *
Here is where we insert real live machine instructions.
+NOTE about _ccall_GC_:
+
+A _ccall_GC_ is treated as an out-of-line primop (returns True
+for primOpOutOfLine) so that when we see the call in case context
+ case (ccall ...) of { ... }
+we get a proper stack frame on the stack when we perform it. When we
+get in a tail-call position, however, we need to actually perform the
+call, so we treat it as an inline primop.
+
\begin{code}
-cgExpr x@(StgPrim op args live_vars)
+cgExpr (StgPrimApp op@(CCallOp ccall) args res_ty)
+ = primRetUnboxedTuple op args res_ty
+
+-- tagToEnum# is special: we need to pull the constructor out of the table,
+-- and perform an appropriate return.
+
+cgExpr (StgPrimApp TagToEnumOp [arg] res_ty)
+ = ASSERT(isEnumerationTyCon tycon)
+ getArgAmode arg `thenFC` \amode ->
+ -- save the tag in a temporary in case amode overlaps
+ -- with node.
+ absC (CAssign dyn_tag amode) `thenC`
+ performReturn (
+ CAssign (CReg node)
+ (CVal (CIndex
+ (CLbl (mkClosureTblLabel tycon) PtrRep)
+ dyn_tag PtrRep) PtrRep))
+ (\ sequel -> mkDynamicAlgReturnCode tycon dyn_tag sequel)
+ where
+ dyn_tag = CTemp (mkBuiltinUnique 0) IntRep
+ --
+ -- if you're reading this code in the attempt to figure
+ -- out why the compiler panic'ed here, it is probably because
+ -- you used tagToEnum# in a non-monomorphic setting, e.g.,
+ -- intToTg :: Enum a => Int -> a ; intToTg (I# x#) = tagToEnum# x#
+ --
+ -- That won't work.
+ --
+ (Just (tycon,_)) = splitTyConApp_maybe res_ty
+
+
+cgExpr x@(StgPrimApp op args res_ty)
+ | primOpOutOfLine op = tailCallPrimOp op args
+ | otherwise
= ASSERT(op /= SeqOp) -- can't handle SeqOp
- getPrimOpArgAmodes op args `thenFC` \ arg_amodes ->
- let
- result_regs = assignPrimOpResultRegs op
- result_amodes = map CReg result_regs
- may_gc = primOpCanTriggerGC op
- dyn_tag = head result_amodes
- -- The tag from a primitive op returning an algebraic data type
- -- is returned in the first result_reg_amode
- in
- (if may_gc then
- -- Use registers for args, and assign args to the regs
- -- (Can-trigger-gc primops guarantee to have their args in regs)
- let
- (arg_robust_amodes, liveness_mask, arg_assts)
- = makePrimOpArgsRobust op arg_amodes
-
- liveness_arg = mkIntCLit liveness_mask
- in
- returnFC (
- arg_assts,
- COpStmt result_amodes op
- (pin_liveness op liveness_arg arg_robust_amodes)
- liveness_mask
- [{-no vol_regs-}]
- )
- else
- -- Use args from their current amodes.
- let
- liveness_mask = panic "cgExpr: liveness of non-GC-ing primop touched\n"
- in
- returnFC (
- COpStmt result_amodes op arg_amodes liveness_mask [{-no vol_regs-}],
- AbsCNop
- )
- ) `thenFC` \ (do_before_stack_cleanup,
- do_just_before_jump) ->
+
+ getArgAmodes args `thenFC` \ arg_amodes ->
case (getPrimOpResultInfo op) of
ReturnsPrim kind ->
- performReturn do_before_stack_cleanup
- (\ sequel -> robustifySequel may_gc sequel
- `thenFC` \ (ret_asst, sequel') ->
- absC (ret_asst `mkAbsCStmts` do_just_before_jump)
- `thenC`
- mkPrimReturnCode sequel')
- live_vars
-
- ReturnsAlg tycon ->
- profCtrC SLIT("RET_NEW_IN_REGS") [num_of_fields] `thenC`
-
- performReturn do_before_stack_cleanup
- (\ sequel -> robustifySequel may_gc sequel
- `thenFC` \ (ret_asst, sequel') ->
- absC (mkAbstractCs [ret_asst,
- do_just_before_jump,
- info_ptr_assign])
- -- Must load info ptr here, not in do_just_before_stack_cleanup,
- -- because the info-ptr reg clashes with argument registers
- -- for the primop
- `thenC`
- mkDynamicAlgReturnCode tycon dyn_tag sequel')
- live_vars
- where
-
- -- Here, the destination _can_ be an update frame, so we need to make sure that
- -- infoptr (R2) is loaded with the constructor's info ptr.
-
- info_ptr_assign = CAssign (CReg infoptr) info_lbl
-
- info_lbl
- = case (ctrlReturnConvAlg tycon) of
- VectoredReturn _ -> vec_lbl
- UnvectoredReturn _ -> dir_lbl
-
- vec_lbl = CTableEntry (CLbl (mkInfoTableVecTblLabel tycon) DataPtrRep)
- dyn_tag DataPtrRep
-
- data_con = head (tyConDataCons tycon)
-
- (dir_lbl, num_of_fields)
- = case (dataReturnConvAlg data_con) of
- ReturnInRegs rs
- -> (CLbl (mkPhantomInfoTableLabel data_con) DataPtrRep,
- mkIntCLit (length rs)) -- for ticky-ticky only
-
- ReturnInHeap
- -> pprPanic "CgExpr: can't return prim in heap:" (ppr PprDebug data_con)
- -- Never used, and no point in generating
- -- the code for it!
- where
- -- for all PrimOps except ccalls, we pin the liveness info
- -- on as the first "argument"
- -- ToDo: un-duplicate?
-
- pin_liveness (CCallOp _ _ _ _ _) _ args = args
- pin_liveness other_op liveness_arg args
- = liveness_arg :args
-
- -- We only need to worry about the sequel when we may GC and the
- -- sequel is OnStack. If that's the case, arrange to pull the
- -- sequel out into RetReg before performing the primOp.
-
- robustifySequel True sequel@(OnStack _) =
- sequelToAmode sequel `thenFC` \ amode ->
- returnFC (CAssign (CReg RetReg) amode, InRetReg)
- robustifySequel _ sequel = returnFC (AbsCNop, sequel)
+ let result_amode = CReg (dataReturnConvPrim kind) in
+ performReturn
+ (COpStmt [result_amode] op arg_amodes [{-no vol_regs-}])
+ (mkPrimReturnCode (text "primapp)" <+> ppr x))
+
+ -- otherwise, must be returning an enumerated type (eg. Bool).
+ -- we've only got the tag in R2, so we have to load the constructor
+ -- itself into R1.
+
+ ReturnsAlg tycon
+ | isUnboxedTupleTyCon tycon -> primRetUnboxedTuple op args res_ty
+
+ | isEnumerationTyCon tycon ->
+ performReturn
+ (COpStmt [dyn_tag] op arg_amodes [{-no vol_regs-}])
+ (\ sequel ->
+ absC (CAssign (CReg node) closure_lbl) `thenC`
+ mkDynamicAlgReturnCode tycon dyn_tag sequel)
+
+ where
+ -- Pull a unique out of thin air to put the tag in.
+ -- It shouldn't matter if this overlaps with anything - we're
+ -- about to return anyway.
+ dyn_tag = CTemp (mkBuiltinUnique 0) IntRep
+
+ closure_lbl = CVal (CIndex
+ (CLbl (mkClosureTblLabel tycon) PtrRep)
+ dyn_tag PtrRep) PtrRep
+
\end{code}
%********************************************************
module, @CgCase@.
\begin{code}
-cgExpr (StgCase expr live_vars save_vars uniq alts)
- = cgCase expr live_vars save_vars uniq alts
+cgExpr (StgCase expr live_vars save_vars bndr srt alts)
+ = cgCase expr live_vars save_vars bndr srt alts
\end{code}
nukeDeadBindings live_in_whole_let `thenC`
saveVolatileVarsAndRegs live_in_rhss
`thenFC` \ (save_assts, rhs_eob_info, maybe_cc_slot) ->
-
- -- ToDo: cost centre???
+ -- ToDo: cost centre???
+ restoreCurrentCostCentre maybe_cc_slot `thenFC` \ restore_cc ->
-- Save those variables right now!
absC save_assts `thenC`
%* SCC Expressions *
%* *
%********************************************************
-\subsection[scc-codegen]{Converting StgSCC}
SCC expressions are treated specially. They set the current cost
centre.
\begin{code}
-cgExpr (StgSCC ty cc expr)
+cgExpr (StgSCC cc expr)
= ASSERT(sccAbleCostCentre cc)
costCentresC
- (if isDictCC cc then SLIT("SET_DICT_CCC") else SLIT("SET_CCC"))
+ SLIT("SET_CCC")
[mkCCostCentre cc, mkIntCLit (if isSccCountCostCentre cc then 1 else 0)]
`thenC`
cgExpr expr
%********************************************************
\subsection[non-top-level-bindings]{Converting non-top-level bindings}
-@cgBinding@ is only used for let/letrec, not for unboxed bindings.
-So the kind should always be @PtrRep@.
-
We rely on the support code in @CgCon@ (to do constructors) and
in @CgClosure@ (to do closures).
-- the Id is passed along so a binding can be set up
cgRhs name (StgRhsCon maybe_cc con args)
- = getArgAmodes args `thenFC` \ amodes ->
- buildDynCon name maybe_cc con amodes (all zero_size args)
- `thenFC` \ idinfo ->
+ = getArgAmodes args `thenFC` \ amodes ->
+ buildDynCon name maybe_cc con amodes `thenFC` \ idinfo ->
returnFC (name, idinfo)
- where
- zero_size atom = getPrimRepSize (getArgPrimRep atom) == 0
-cgRhs name (StgRhsClosure cc bi fvs upd_flag args body)
- = cgRhsClosure name cc bi fvs args body lf_info
+cgRhs name (StgRhsClosure cc bi srt@(NoSRT) fvs upd_flag args body)
+ = mkRhsClosure name cc bi srt fvs upd_flag args body
+cgRhs name (StgRhsClosure cc bi srt@(SRT _ _) fvs upd_flag args body)
+ = mkRhsClosure name cc bi srt fvs upd_flag args body
+\end{code}
+
+mkRhsClosure looks for two special forms of the right-hand side:
+ a) selector thunks.
+ b) AP thunks
+
+If neither happens, it just calls mkClosureLFInfo. You might think
+that mkClosureLFInfo should do all this, but it seems wrong for the
+latter to look at the structure of an expression
+
+Selectors
+~~~~~~~~~
+We look at the body of the closure to see if it's a selector---turgid,
+but nothing deep. We are looking for a closure of {\em exactly} the
+form:
+
+... = [the_fv] \ u [] ->
+ case the_fv of
+ con a_1 ... a_n -> a_i
+
+
+\begin{code}
+mkRhsClosure bndr cc bi srt
+ [the_fv] -- Just one free var
+ upd_flag -- Updatable thunk
+ [] -- A thunk
+ body@(StgCase (StgApp scrutinee [{-no args-}])
+ _ _ _ _ -- ignore uniq, etc.
+ (StgAlgAlts case_ty
+ [(con, params, use_mask,
+ (StgApp selectee [{-no args-}]))]
+ StgNoDefault))
+ | the_fv == scrutinee -- Scrutinee is the only free variable
+ && maybeToBool maybe_offset -- Selectee is a component of the tuple
+ && offset_into_int <= mAX_SPEC_SELECTEE_SIZE -- Offset is small enough
+ = ASSERT(is_single_constructor)
+ cgStdRhsClosure bndr cc bi [the_fv] [] body lf_info [StgVarArg the_fv]
where
- lf_info = mkClosureLFInfo False{-not top level-} fvs upd_flag args body
+ lf_info = mkSelectorLFInfo (idType bndr) offset_into_int
+ (isUpdatable upd_flag)
+ (_, params_w_offsets) = layOutDynCon con idPrimRep params
+ maybe_offset = assocMaybe params_w_offsets selectee
+ Just the_offset = maybe_offset
+ offset_into_int = the_offset - fixedHdrSize
+ is_single_constructor = maybeToBool (maybeTyConSingleCon tycon)
+ tycon = dataConTyCon con
+\end{code}
+
+
+Ap thunks
+~~~~~~~~~
+
+A more generic AP thunk of the form
+
+ x = [ x_1...x_n ] \.. [] -> x_1 ... x_n
+
+A set of these is compiled statically into the RTS, so we just use
+those. We could extend the idea to thunks where some of the x_i are
+global ids (and hence not free variables), but this would entail
+generating a larger thunk. It might be an option for non-optimising
+compilation, though.
+
+We only generate an Ap thunk if all the free variables are pointers,
+for semi-obvious reasons.
+
+\begin{code}
+mkRhsClosure bndr cc bi srt
+ fvs
+ upd_flag
+ [] -- No args; a thunk
+ body@(StgApp fun_id args)
+
+ | length args + 1 == arity
+ && all isFollowableRep (map idPrimRep fvs)
+ && isUpdatable upd_flag
+ && arity <= mAX_SPEC_AP_SIZE
+
+ -- Ha! an Ap thunk
+ = cgStdRhsClosure bndr cc bi fvs [] body lf_info payload
+
+ where
+ lf_info = mkApLFInfo (idType bndr) upd_flag arity
+ -- the payload has to be in the correct order, hence we can't
+ -- just use the fvs.
+ payload = StgVarArg fun_id : args
+ arity = length fvs
+\end{code}
+
+The default case
+~~~~~~~~~~~~~~~~
+\begin{code}
+mkRhsClosure bndr cc bi srt fvs upd_flag args body
+ = getSRTLabel `thenFC` \ srt_label ->
+ let lf_info =
+ mkClosureLFInfo bndr NotTopLevel fvs upd_flag args srt_label srt
+ in
+ cgRhsClosure bndr cc bi fvs args body lf_info
\end{code}
+
+%********************************************************
+%* *
+%* Let-no-escape bindings
+%* *
+%********************************************************
\begin{code}
cgLetNoEscapeBindings live_in_rhss rhs_eob_info maybe_cc_slot (StgNonRec binder rhs)
- = cgLetNoEscapeRhs live_in_rhss rhs_eob_info maybe_cc_slot binder rhs
+ = cgLetNoEscapeRhs live_in_rhss rhs_eob_info maybe_cc_slot
+ NonRecursive binder rhs
`thenFC` \ (binder, info) ->
addBindC binder info
cgLetNoEscapeBindings live_in_rhss rhs_eob_info maybe_cc_slot (StgRec pairs)
= fixC (\ new_bindings ->
addBindsC new_bindings `thenC`
- listFCs [ cgLetNoEscapeRhs full_live_in_rhss rhs_eob_info
- maybe_cc_slot b e | (b,e) <- pairs ]
+ listFCs [ cgLetNoEscapeRhs full_live_in_rhss
+ rhs_eob_info maybe_cc_slot Recursive b e
+ | (b,e) <- pairs ]
) `thenFC` \ new_bindings ->
addBindsC new_bindings
where
-- We add the binders to the live-in-rhss set so that we don't
-- delete the bindings for the binder from the environment!
- full_live_in_rhss = live_in_rhss `unionIdSets` (mkIdSet [b | (b,r) <- pairs])
+ full_live_in_rhss = live_in_rhss `unionVarSet` (mkVarSet [b | (b,r) <- pairs])
cgLetNoEscapeRhs
:: StgLiveVars -- Live in rhss
-> EndOfBlockInfo
- -> Maybe VirtualSpBOffset
+ -> Maybe VirtualSpOffset
+ -> RecFlag
-> Id
-> StgRhs
-> FCode (Id, CgIdInfo)
-cgLetNoEscapeRhs full_live_in_rhss rhs_eob_info maybe_cc_slot binder
- (StgRhsClosure cc bi _ upd_flag args body)
+cgLetNoEscapeRhs full_live_in_rhss rhs_eob_info maybe_cc_slot rec binder
+ (StgRhsClosure cc bi srt _ upd_flag args body)
= -- We could check the update flag, but currently we don't switch it off
-- for let-no-escaped things, so we omit the check too!
-- case upd_flag of
-- Updatable -> panic "cgLetNoEscapeRhs" -- Nothing to update!
-- other -> cgLetNoEscapeClosure binder cc bi live_in_whole_let live_in_rhss args body
- cgLetNoEscapeClosure binder cc bi full_live_in_rhss rhs_eob_info maybe_cc_slot args body
+ cgLetNoEscapeClosure binder cc bi srt full_live_in_rhss rhs_eob_info maybe_cc_slot rec args body
-- For a constructor RHS we want to generate a single chunk of code which
-- can be jumped to from many places, which will return the constructor.
-- It's easy; just behave as if it was an StgRhsClosure with a ConApp inside!
-cgLetNoEscapeRhs full_live_in_rhss rhs_eob_info maybe_cc_slot binder
+cgLetNoEscapeRhs full_live_in_rhss rhs_eob_info maybe_cc_slot rec binder
(StgRhsCon cc con args)
- = cgLetNoEscapeClosure binder cc stgArgOcc{-safe-} full_live_in_rhss rhs_eob_info maybe_cc_slot
+ = cgLetNoEscapeClosure binder cc stgArgOcc{-safe-} NoSRT full_live_in_rhss rhs_eob_info maybe_cc_slot rec
[] --No args; the binder is data structure, not a function
- (StgCon con args full_live_in_rhss)
+ (StgConApp con args)
\end{code}
-Some PrimOps require a {\em fixed} amount of heap allocation. Rather
-than tidy away ready for GC and do a full heap check, we simply
-allocate a completely uninitialised block in-line, just like any other
-thunk/constructor allocation, and pass it to the PrimOp as its first
-argument. Remember! The PrimOp is entirely responsible for
-initialising the object. In particular, the PrimOp had better not
-trigger GC before it has filled it in, and even then it had better
-make sure that the GC can find the object somehow.
+Little helper for primitives that return unboxed tuples.
-Main current use: allocating SynchVars.
\begin{code}
-getPrimOpArgAmodes op args
- = getArgAmodes args `thenFC` \ arg_amodes ->
-
- case primOpHeapReq op of
- FixedHeapRequired size -> allocHeap size `thenFC` \ amode ->
- returnFC (amode : arg_amodes)
-
- _ -> returnFC arg_amodes
+primRetUnboxedTuple :: PrimOp -> [StgArg] -> Type -> Code
+primRetUnboxedTuple op args res_ty
+ = getArgAmodes args `thenFC` \ arg_amodes ->
+ {-
+ put all the arguments in temporaries so they don't get stomped when
+ we push the return address.
+ -}
+ let
+ n_args = length args
+ arg_uniqs = map mkBuiltinUnique [0 .. n_args-1]
+ arg_reps = map getArgPrimRep args
+ arg_temps = zipWith CTemp arg_uniqs arg_reps
+ in
+ absC (mkAbstractCs (zipWith CAssign arg_temps arg_amodes)) `thenC`
+ {-
+ allocate some temporaries for the return values.
+ -}
+ let
+ (tc,ty_args) = case splitTyConApp_maybe (repType res_ty) of
+ Nothing -> pprPanic "primRetUnboxedTuple" (ppr res_ty)
+ Just pr -> pr
+ prim_reps = map typePrimRep ty_args
+ temp_uniqs = map mkBuiltinUnique [ n_args .. n_args + length ty_args - 1]
+ temp_amodes = zipWith CTemp temp_uniqs prim_reps
+ in
+ returnUnboxedTuple temp_amodes (absC (COpStmt temp_amodes op arg_temps []))
\end{code}
-
-