{-# LANGUAGE CPP #-} ----------------------------------------------------------------------------- -- -- Stg to C--: code generation for constructors -- -- This module provides the support code for StgCmm to deal with with -- constructors on the RHSs of let(rec)s. -- -- (c) The University of Glasgow 2004-2006 -- ----------------------------------------------------------------------------- module StgCmmCon ( cgTopRhsCon, buildDynCon, bindConArgs ) where #include "HsVersions.h" import StgSyn import CoreSyn ( AltCon(..) ) import StgCmmMonad import StgCmmEnv import StgCmmHeap import StgCmmLayout import StgCmmUtils import StgCmmClosure import StgCmmProf ( curCCS ) import CmmExpr import CLabel import MkGraph import SMRep import CostCentre import Module import DataCon import DynFlags import FastString import Id import Literal import PrelInfo import Outputable import Platform import Util import Control.Monad import Data.Char --------------------------------------------------------------- -- Top-level constructors --------------------------------------------------------------- cgTopRhsCon :: DynFlags -> Id -- Name of thing bound to this RHS -> DataCon -- Id -> [StgArg] -- Args -> (CgIdInfo, FCode ()) cgTopRhsCon dflags id con args = let id_info = litIdInfo dflags id (mkConLFInfo con) (CmmLabel closure_label) in (id_info, gen_code) where name = idName id caffy = idCafInfo id -- any stgArgHasCafRefs args closure_label = mkClosureLabel name caffy gen_code = do { this_mod <- getModuleName ; when (platformOS (targetPlatform dflags) == OSMinGW32) $ -- Windows DLLs have a problem with static cross-DLL refs. ASSERT( not (isDllConApp dflags this_mod con args) ) return () ; ASSERT( args `lengthIs` dataConRepRepArity con ) return () -- LAY IT OUT ; let (tot_wds, -- #ptr_wds + #nonptr_wds ptr_wds, -- #ptr_wds nv_args_w_offsets) = mkVirtConstrOffsets dflags (addArgReps args) nonptr_wds = tot_wds - ptr_wds -- we're not really going to emit an info table, so having -- to make a CmmInfoTable is a bit overkill, but mkStaticClosureFields -- needs to poke around inside it. info_tbl = mkDataConInfoTable dflags con True ptr_wds nonptr_wds get_lit (arg, _offset) = do { CmmLit lit <- getArgAmode arg ; return lit } ; payload <- mapM get_lit nv_args_w_offsets -- NB1: nv_args_w_offsets is sorted into ptrs then non-ptrs -- NB2: all the amodes should be Lits! ; let closure_rep = mkStaticClosureFields dflags info_tbl dontCareCCS -- Because it's static data caffy -- Has CAF refs payload -- BUILD THE OBJECT ; emitDataLits closure_label closure_rep ; return () } --------------------------------------------------------------- -- Lay out and allocate non-top-level constructors --------------------------------------------------------------- buildDynCon :: Id -- Name of the thing to which this constr will -- be bound -> Bool -- is it genuinely bound to that name, or just for profiling? -> CostCentreStack -- Where to grab cost centre from; -- current CCS if currentOrSubsumedCCS -> DataCon -- The data constructor -> [StgArg] -- Its args -> FCode (CgIdInfo, FCode CmmAGraph) -- Return details about how to find it and initialization code buildDynCon binder actually_bound cc con args = do dflags <- getDynFlags buildDynCon' dflags (targetPlatform dflags) binder actually_bound cc con args buildDynCon' :: DynFlags -> Platform -> Id -> Bool -> CostCentreStack -> DataCon -> [StgArg] -> FCode (CgIdInfo, FCode CmmAGraph) {- We used to pass a boolean indicating whether all the args were of size zero, so we could use a static constructor; but I concluded that it just isn't worth it. Now I/O uses unboxed tuples there just aren't any constructors with all size-zero args. The reason for having a separate argument, rather than looking at the addr modes of the args is that we may be in a "knot", and premature looking at the args will cause the compiler to black-hole! -} -------- buildDynCon': Nullary constructors -------------- -- First we deal with the case of zero-arity constructors. They -- will probably be unfolded, so we don't expect to see this case much, -- if at all, but it does no harm, and sets the scene for characters. -- -- In the case of zero-arity constructors, or, more accurately, those -- which have exclusively size-zero (VoidRep) args, we generate no code -- at all. buildDynCon' dflags _ binder _ _cc con [] = return (litIdInfo dflags binder (mkConLFInfo con) (CmmLabel (mkClosureLabel (dataConName con) (idCafInfo binder))), return mkNop) -------- buildDynCon': Charlike and Intlike constructors ----------- {- The following three paragraphs about @Char@-like and @Int@-like closures are obsolete, but I don't understand the details well enough to properly word them, sorry. I've changed the treatment of @Char@s to be analogous to @Int@s: only a subset is preallocated, because @Char@ has now 31 bits. Only literals are handled here. -- Qrczak Now for @Char@-like closures. We generate an assignment of the address of the closure to a temporary. It would be possible simply to generate no code, and record the addressing mode in the environment, but we'd have to be careful if the argument wasn't a constant --- so for simplicity we just always asssign to a temporary. Last special case: @Int@-like closures. We only special-case the situation in which the argument is a literal in the range @mIN_INTLIKE@..@mAX_INTLILKE@. NB: for @Char@-like closures we can work with any old argument, but for @Int@-like ones the argument has to be a literal. Reason: @Char@ like closures have an argument type which is guaranteed in range. Because of this, we use can safely return an addressing mode. We don't support this optimisation when compiling into Windows DLLs yet because they don't support cross package data references well. -} buildDynCon' dflags platform binder _ _cc con [arg] | maybeIntLikeCon con , platformOS platform /= OSMinGW32 || not (gopt Opt_PIC dflags) , StgLitArg (MachInt val) <- arg , val <= fromIntegral (mAX_INTLIKE dflags) -- Comparisons at type Integer! , val >= fromIntegral (mIN_INTLIKE dflags) -- ...ditto... = do { let intlike_lbl = mkCmmClosureLabel rtsUnitId (fsLit "stg_INTLIKE") val_int = fromIntegral val :: Int offsetW = (val_int - mIN_INTLIKE dflags) * (fixedHdrSizeW dflags + 1) -- INTLIKE closures consist of a header and one word payload intlike_amode = cmmLabelOffW dflags intlike_lbl offsetW ; return ( litIdInfo dflags binder (mkConLFInfo con) intlike_amode , return mkNop) } buildDynCon' dflags platform binder _ _cc con [arg] | maybeCharLikeCon con , platformOS platform /= OSMinGW32 || not (gopt Opt_PIC dflags) , StgLitArg (MachChar val) <- arg , let val_int = ord val :: Int , val_int <= mAX_CHARLIKE dflags , val_int >= mIN_CHARLIKE dflags = do { let charlike_lbl = mkCmmClosureLabel rtsUnitId (fsLit "stg_CHARLIKE") offsetW = (val_int - mIN_CHARLIKE dflags) * (fixedHdrSizeW dflags + 1) -- CHARLIKE closures consist of a header and one word payload charlike_amode = cmmLabelOffW dflags charlike_lbl offsetW ; return ( litIdInfo dflags binder (mkConLFInfo con) charlike_amode , return mkNop) } -------- buildDynCon': the general case ----------- buildDynCon' dflags _ binder actually_bound ccs con args = do { (id_info, reg) <- rhsIdInfo binder lf_info ; return (id_info, gen_code reg) } where lf_info = mkConLFInfo con gen_code reg = do { let (tot_wds, ptr_wds, args_w_offsets) = mkVirtConstrOffsets dflags (addArgReps args) -- No void args in args_w_offsets nonptr_wds = tot_wds - ptr_wds info_tbl = mkDataConInfoTable dflags con False ptr_wds nonptr_wds ; let ticky_name | actually_bound = Just binder | otherwise = Nothing ; hp_plus_n <- allocDynClosure ticky_name info_tbl lf_info use_cc blame_cc args_w_offsets ; return (mkRhsInit dflags reg lf_info hp_plus_n) } where use_cc -- cost-centre to stick in the object | isCurrentCCS ccs = curCCS | otherwise = panic "buildDynCon: non-current CCS not implemented" blame_cc = use_cc -- cost-centre on which to blame the alloc (same) --------------------------------------------------------------- -- Binding constructor arguments --------------------------------------------------------------- bindConArgs :: AltCon -> LocalReg -> [Id] -> FCode [LocalReg] -- bindConArgs is called from cgAlt of a case -- (bindConArgs con args) augments the environment with bindings for the -- binders args, assuming that we have just returned from a 'case' which -- found a con bindConArgs (DataAlt con) base args = ASSERT(not (isUnboxedTupleCon con)) do dflags <- getDynFlags let (_, _, args_w_offsets) = mkVirtConstrOffsets dflags (addIdReps args) tag = tagForCon dflags con -- The binding below forces the masking out of the tag bits -- when accessing the constructor field. bind_arg :: (NonVoid Id, VirtualHpOffset) -> FCode LocalReg bind_arg (arg, offset) = do emit $ mkTaggedObjectLoad dflags (idToReg dflags arg) base offset tag bindArgToReg arg mapM bind_arg args_w_offsets bindConArgs _other_con _base args = ASSERT( null args ) return []