% % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[CodeGen]{@CodeGen@: main module of the code generator} This module says how things get going at the top level. @codeGen@ is the interface to the outside world. The \tr{cgTop*} functions drive the mangling of top-level bindings. %************************************************************************ %* * \subsection[codeGen-outside-interface]{The code generator's offering to the world} %* * %************************************************************************ \begin{code} module CodeGen ( codeGen ) where #include "HsVersions.h" -- Kludge (??) so that CgExpr is reached via at least one non-SOURCE -- import. Before, that wasn't the case, and CM therefore didn't -- bother to compile it. import CgExpr ( {-NOTHING!-} ) -- DO NOT DELETE THIS IMPORT import CgProf import CgMonad import CgBindery ( CgIdInfo, addBindC, addBindsC, getCgIdInfo, cgIdInfoId ) import CgClosure ( cgTopRhsClosure ) import CgCon ( cgTopRhsCon, cgTyCon ) import CgUtils ( cmmRegOffW, emitRODataLits, cmmNeWord ) import CLabel import Cmm import CmmUtils ( zeroCLit, mkIntCLit, mkLblExpr ) import PprCmm ( pprCmms ) import MachOp ( wordRep, MachHint(..) ) import StgSyn import PrelNames ( gHC_PRIM, rOOT_MAIN, mAIN, pREL_TOP_HANDLER ) import Packages ( HomeModules ) import DynFlags ( DynFlags(..), DynFlag(..), dopt ) import StaticFlags ( opt_SccProfilingOn ) import HscTypes ( ForeignStubs(..), TypeEnv, typeEnvTyCons ) import CostCentre ( CollectedCCs ) import Id ( Id, idName, setIdName ) import Name ( nameSrcLoc, nameOccName, nameUnique, isInternalName, mkExternalName ) import OccName ( mkLocalOcc ) import TyCon ( TyCon ) import Module ( Module, mkModule ) import ErrUtils ( dumpIfSet_dyn, showPass ) import Panic ( assertPanic ) #ifdef DEBUG import Outputable #endif \end{code} \begin{code} codeGen :: DynFlags -> HomeModules -> Module -> [TyCon] -> ForeignStubs -> [Module] -- directly-imported modules -> CollectedCCs -- (Local/global) cost-centres needing declaring/registering. -> [(StgBinding,[(Id,[Id])])] -- Bindings to convert, with SRTs -> IO [Cmm] -- Output codeGen dflags hmods this_mod data_tycons foreign_stubs imported_mods cost_centre_info stg_binds = do { showPass dflags "CodeGen" ; let way = buildTag dflags main_mod = mainModIs dflags -- Why? -- ; mapM_ (\x -> seq x (return ())) data_tycons ; code_stuff <- initC dflags hmods this_mod $ do { cmm_binds <- mapM (getCmm . cgTopBinding dflags hmods) stg_binds ; cmm_tycons <- mapM cgTyCon data_tycons ; cmm_init <- getCmm (mkModuleInit dflags hmods way cost_centre_info this_mod main_mod foreign_stubs imported_mods) ; return (cmm_binds ++ concat cmm_tycons ++ [cmm_init]) } -- Put datatype_stuff after code_stuff, because the -- datatype closure table (for enumeration types) to -- (say) PrelBase_True_closure, which is defined in -- code_stuff ; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff) ; return code_stuff } \end{code} %************************************************************************ %* * \subsection[codegen-init]{Module initialisation code} %* * %************************************************************************ /* ----------------------------------------------------------------------------- Module initialisation The module initialisation code looks like this, roughly: FN(__stginit_Foo) { JMP_(__stginit_Foo_1_p) } FN(__stginit_Foo_1_p) { ... } We have one version of the init code with a module version and the 'way' attached to it. The version number helps to catch cases where modules are not compiled in dependency order before being linked: if a module has been compiled since any modules which depend on it, then the latter modules will refer to a different version in their init blocks and a link error will ensue. The 'way' suffix helps to catch cases where modules compiled in different ways are linked together (eg. profiled and non-profiled). We provide a plain, unadorned, version of the module init code which just jumps to the version with the label and way attached. The reason for this is that when using foreign exports, the caller of startupHaskell() must supply the name of the init function for the "top" module in the program, and we don't want to require that this name has the version and way info appended to it. -------------------------------------------------------------------------- */ We initialise the module tree by keeping a work-stack, * pointed to by Sp * that grows downward * Sp points to the last occupied slot \begin{code} mkModuleInit :: DynFlags -> HomeModules -> String -- the "way" -> CollectedCCs -- cost centre info -> Module -> Module -- name of the Main module -> ForeignStubs -> [Module] -> Code mkModuleInit dflags hmods way cost_centre_info this_mod main_mod foreign_stubs imported_mods = do { if opt_SccProfilingOn then do { -- Allocate the static boolean that records if this -- module has been registered already emitData Data [CmmDataLabel moduleRegdLabel, CmmStaticLit zeroCLit] ; emitSimpleProc real_init_lbl $ do { ret_blk <- forkLabelledCode ret_code ; init_blk <- forkLabelledCode $ do { mod_init_code; stmtC (CmmBranch ret_blk) } ; stmtC (CmmCondBranch (cmmNeWord (CmmLit zeroCLit) mod_reg_val) ret_blk) ; stmtC (CmmBranch init_blk) } } else emitSimpleProc real_init_lbl ret_code -- Make the "plain" procedure jump to the "real" init procedure ; emitSimpleProc plain_init_lbl jump_to_init -- When compiling the module in which the 'main' function lives, -- (that is, this_mod == main_mod) -- we inject an extra stg_init procedure for stg_init_ZCMain, for the -- RTS to invoke. We must consult the -main-is flag in case the -- user specified a different function to Main.main ; whenC (this_mod == main_mod) (emitSimpleProc plain_main_init_lbl jump_to_init) } where plain_init_lbl = mkPlainModuleInitLabel hmods this_mod real_init_lbl = mkModuleInitLabel hmods this_mod way plain_main_init_lbl = mkPlainModuleInitLabel hmods rOOT_MAIN jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) []) mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep -- Main refers to GHC.TopHandler.runIO, so make sure we call the -- init function for GHC.TopHandler. extra_imported_mods | this_mod == main_mod = [pREL_TOP_HANDLER] | otherwise = [] mod_init_code = do { -- Set mod_reg to 1 to record that we've been here stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1))) -- Now do local stuff ; initCostCentres cost_centre_info ; mapCs (registerModuleImport hmods way) (imported_mods++extra_imported_mods) } -- The return-code pops the work stack by -- incrementing Sp, and then jumpd to the popped item ret_code = stmtsC [ CmmAssign spReg (cmmRegOffW spReg 1) , CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ] ----------------------- registerModuleImport :: HomeModules -> String -> Module -> Code registerModuleImport hmods way mod | mod == gHC_PRIM = nopC | otherwise -- Push the init procedure onto the work stack = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1)) , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel hmods mod way)) ] \end{code} Cost-centre profiling: Besides the usual stuff, we must produce declarations for the cost-centres defined in this module; (The local cost-centres involved in this are passed into the code-generator.) \begin{code} initCostCentres :: CollectedCCs -> Code -- Emit the declarations, and return code to register them initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs) | not opt_SccProfilingOn = nopC | otherwise = do { mapM_ emitCostCentreDecl local_CCs ; mapM_ emitCostCentreStackDecl singleton_CCSs ; mapM_ emitRegisterCC local_CCs ; mapM_ emitRegisterCCS singleton_CCSs } \end{code} %************************************************************************ %* * \subsection[codegen-top-bindings]{Converting top-level STG bindings} %* * %************************************************************************ @cgTopBinding@ is only used for top-level bindings, since they need to be allocated statically (not in the heap) and need to be labelled. No unboxed bindings can happen at top level. In the code below, the static bindings are accumulated in the @MkCgState@, and transferred into the ``statics'' slot by @forkStatics@. This is so that we can write the top level processing in a compositional style, with the increasing static environment being plumbed as a state variable. \begin{code} cgTopBinding :: DynFlags -> HomeModules -> (StgBinding,[(Id,[Id])]) -> Code cgTopBinding dflags hmods (StgNonRec id rhs, srts) = do { id' <- maybeExternaliseId dflags id ; mapM_ (mkSRT hmods [id']) srts ; (id,info) <- cgTopRhs id' rhs ; addBindC id info -- Add the *un-externalised* Id to the envt, -- so we find it when we look up occurrences } cgTopBinding dflags hmods (StgRec pairs, srts) = do { let (bndrs, rhss) = unzip pairs ; bndrs' <- mapFCs (maybeExternaliseId dflags) bndrs ; let pairs' = zip bndrs' rhss ; mapM_ (mkSRT hmods bndrs') srts ; _new_binds <- fixC (\ new_binds -> do { addBindsC new_binds ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' }) ; nopC } mkSRT :: HomeModules -> [Id] -> (Id,[Id]) -> Code mkSRT hmods these (id,[]) = nopC mkSRT hmods these (id,ids) = do { ids <- mapFCs remap ids ; id <- remap id ; emitRODataLits (mkSRTLabel (idName id)) (map (CmmLabel . mkClosureLabel hmods . idName) ids) } where -- Sigh, better map all the ids against the environment in -- case they've been externalised (see maybeExternaliseId below). remap id = case filter (==id) these of (id':_) -> returnFC id' [] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) } -- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs -- to enclose the listFCs in cgTopBinding, but that tickled the -- statics "error" call in initC. I DON'T UNDERSTAND WHY! cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo) -- The Id is passed along for setting up a binding... -- It's already been externalised if necessary cgTopRhs bndr (StgRhsCon cc con args) = forkStatics (cgTopRhsCon bndr con args) cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body) = ASSERT(null fvs) -- There should be no free variables setSRTLabel (mkSRTLabel (idName bndr)) $ forkStatics (cgTopRhsClosure bndr cc bi srt upd_flag args body) \end{code} %************************************************************************ %* * \subsection{Stuff to support splitting} %* * %************************************************************************ If we're splitting the object, we need to externalise all the top-level names (and then make sure we only use the externalised one in any C label we use which refers to this name). \begin{code} maybeExternaliseId :: DynFlags -> Id -> FCode Id maybeExternaliseId dflags id | dopt Opt_SplitObjs dflags, -- Externalise the name for -split-objs isInternalName name = do { mod <- moduleName ; returnFC (setIdName id (externalise mod)) } | otherwise = returnFC id where externalise mod = mkExternalName uniq mod new_occ Nothing loc name = idName id uniq = nameUnique name new_occ = mkLocalOcc uniq (nameOccName name) loc = nameSrcLoc name -- We want to conjure up a name that can't clash with any -- existing name. So we generate -- Mod_$L243foo -- where 243 is the unique. \end{code}