2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[CodeGen]{@CodeGen@: main module of the code generator}
6 This module says how things get going at the top level.
8 @codeGen@ is the interface to the outside world. The \tr{cgTop*}
9 functions drive the mangling of top-level bindings.
11 %************************************************************************
13 \subsection[codeGen-outside-interface]{The code generator's offering to the world}
15 %************************************************************************
18 module CodeGen ( codeGen ) where
20 #include "HsVersions.h"
22 -- Kludge (??) so that CgExpr is reached via at least one non-SOURCE
23 -- import. Before, that wasn't the case, and CM therefore didn't
24 -- bother to compile it.
25 import CgExpr ( {-NOTHING!-} ) -- DO NOT DELETE THIS IMPORT
28 import CgBindery ( CgIdInfo, addBindC, addBindsC, getCgIdInfo,
30 import CgClosure ( cgTopRhsClosure )
31 import CgCon ( cgTopRhsCon, cgTyCon )
32 import CgUtils ( cmmRegOffW, emitRODataLits, cmmNeWord, emitRtsCall )
36 import CmmUtils ( zeroCLit, mkIntCLit, mkLblExpr )
37 import PprCmm ( pprCmms )
38 import MachOp ( wordRep, MachHint(..) )
41 import PrelNames ( gHC_PRIM, rOOT_MAIN, mAIN, pREL_TOP_HANDLER )
42 import DynFlags ( DynFlags(..), DynFlag(..), dopt )
43 import StaticFlags ( opt_SccProfilingOn )
45 import HscTypes ( ForeignStubs(..), TypeEnv, typeEnvTyCons )
46 import CostCentre ( CollectedCCs )
47 import Id ( Id, idName, setIdName )
48 import Name ( nameSrcLoc, nameOccName, nameUnique, isInternalName, mkExternalName )
49 import OccName ( mkLocalOcc )
50 import TyCon ( TyCon )
51 import Module ( Module, mkModule )
52 import ErrUtils ( dumpIfSet_dyn, showPass )
53 import Panic ( assertPanic )
65 -> [Module] -- directly-imported modules
66 -> CollectedCCs -- (Local/global) cost-centres needing declaring/registering.
67 -> [(StgBinding,[(Id,[Id])])] -- Bindings to convert, with SRTs
70 codeGen dflags this_mod data_tycons foreign_stubs imported_mods
71 cost_centre_info stg_binds
73 { showPass dflags "CodeGen"
74 ; let way = buildTag dflags
75 mb_main_mod = mainModIs dflags
78 -- ; mapM_ (\x -> seq x (return ())) data_tycons
80 ; code_stuff <- initC dflags this_mod $ do
81 { cmm_binds <- mapM (getCmm . cgTopBinding dflags) stg_binds
82 ; cmm_tycons <- mapM cgTyCon data_tycons
83 ; cmm_init <- getCmm (mkModuleInit dflags way cost_centre_info
85 foreign_stubs imported_mods)
86 ; return (cmm_binds ++ concat cmm_tycons ++ [cmm_init])
88 -- Put datatype_stuff after code_stuff, because the
89 -- datatype closure table (for enumeration types) to
90 -- (say) PrelBase_True_closure, which is defined in
93 ; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff)
98 %************************************************************************
100 \subsection[codegen-init]{Module initialisation code}
102 %************************************************************************
104 /* -----------------------------------------------------------------------------
105 Module initialisation
107 The module initialisation code looks like this, roughly:
110 JMP_(__stginit_Foo_1_p)
113 FN(__stginit_Foo_1_p) {
117 We have one version of the init code with a module version and the
118 'way' attached to it. The version number helps to catch cases
119 where modules are not compiled in dependency order before being
120 linked: if a module has been compiled since any modules which depend on
121 it, then the latter modules will refer to a different version in their
122 init blocks and a link error will ensue.
124 The 'way' suffix helps to catch cases where modules compiled in different
125 ways are linked together (eg. profiled and non-profiled).
127 We provide a plain, unadorned, version of the module init code
128 which just jumps to the version with the label and way attached. The
129 reason for this is that when using foreign exports, the caller of
130 startupHaskell() must supply the name of the init function for the "top"
131 module in the program, and we don't want to require that this name
132 has the version and way info appended to it.
133 -------------------------------------------------------------------------- */
135 We initialise the module tree by keeping a work-stack,
137 * that grows downward
138 * Sp points to the last occupied slot
144 -> String -- the "way"
145 -> CollectedCCs -- cost centre info
147 -> Maybe String -- Just m ==> we have flag: -main-is Foo.baz
151 mkModuleInit dflags way cost_centre_info this_mod mb_main_mod foreign_stubs imported_mods
153 if opt_SccProfilingOn
154 then do { -- Allocate the static boolean that records if this
155 -- module has been registered already
156 emitData Data [CmmDataLabel moduleRegdLabel,
157 CmmStaticLit zeroCLit]
159 ; emitSimpleProc real_init_lbl $ do
160 { ret_blk <- forkLabelledCode ret_code
162 ; init_blk <- forkLabelledCode $ do
163 { mod_init_code; stmtC (CmmBranch ret_blk) }
165 ; stmtC (CmmCondBranch (cmmNeWord (CmmLit zeroCLit) mod_reg_val)
167 ; stmtC (CmmBranch init_blk)
170 else emitSimpleProc real_init_lbl ret_code
172 -- Make the "plain" procedure jump to the "real" init procedure
173 ; emitSimpleProc plain_init_lbl jump_to_init
175 -- When compiling the module in which the 'main' function lives,
176 -- (that is, this_mod == main_mod)
177 -- we inject an extra stg_init procedure for stg_init_ZCMain, for the
178 -- RTS to invoke. We must consult the -main-is flag in case the
179 -- user specified a different function to Main.main
180 ; whenC (this_mod == main_mod)
181 (emitSimpleProc plain_main_init_lbl jump_to_init)
184 plain_init_lbl = mkPlainModuleInitLabel dflags this_mod
185 real_init_lbl = mkModuleInitLabel dflags this_mod way
186 plain_main_init_lbl = mkPlainModuleInitLabel dflags rOOT_MAIN
188 jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) [])
190 mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep
192 main_mod = case mb_main_mod of
193 Just mod_name -> mkModule mod_name
196 -- Main refers to GHC.TopHandler.runIO, so make sure we call the
197 -- init function for GHC.TopHandler.
199 | this_mod == main_mod = [pREL_TOP_HANDLER]
203 { -- Set mod_reg to 1 to record that we've been here
204 stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1)))
206 -- Now do local stuff
207 ; initCostCentres cost_centre_info
208 ; mapCs (registerModuleImport dflags way)
209 (imported_mods++extra_imported_mods)
212 -- The return-code pops the work stack by
213 -- incrementing Sp, and then jumpd to the popped item
214 ret_code = stmtsC [ CmmAssign spReg (cmmRegOffW spReg 1)
215 , CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ]
217 -----------------------
218 registerModuleImport :: DynFlags -> String -> Module -> Code
219 registerModuleImport dflags way mod
222 | otherwise -- Push the init procedure onto the work stack
223 = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
224 , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel dflags mod way)) ]
229 Cost-centre profiling: Besides the usual stuff, we must produce
230 declarations for the cost-centres defined in this module;
232 (The local cost-centres involved in this are passed into the
236 initCostCentres :: CollectedCCs -> Code
237 -- Emit the declarations, and return code to register them
238 initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
239 | not opt_SccProfilingOn = nopC
241 = do { mapM_ emitCostCentreDecl local_CCs
242 ; mapM_ emitCostCentreStackDecl singleton_CCSs
243 ; mapM_ emitRegisterCC local_CCs
244 ; mapM_ emitRegisterCCS singleton_CCSs
248 %************************************************************************
250 \subsection[codegen-top-bindings]{Converting top-level STG bindings}
252 %************************************************************************
254 @cgTopBinding@ is only used for top-level bindings, since they need
255 to be allocated statically (not in the heap) and need to be labelled.
256 No unboxed bindings can happen at top level.
258 In the code below, the static bindings are accumulated in the
259 @MkCgState@, and transferred into the ``statics'' slot by @forkStatics@.
260 This is so that we can write the top level processing in a compositional
261 style, with the increasing static environment being plumbed as a state
265 cgTopBinding :: DynFlags -> (StgBinding,[(Id,[Id])]) -> Code
266 cgTopBinding dflags (StgNonRec id rhs, srts)
267 = do { id' <- maybeExternaliseId dflags id
268 ; mapM_ (mkSRT dflags [id']) srts
269 ; (id,info) <- cgTopRhs id' rhs
270 ; addBindC id info -- Add the *un-externalised* Id to the envt,
271 -- so we find it when we look up occurrences
274 cgTopBinding dflags (StgRec pairs, srts)
275 = do { let (bndrs, rhss) = unzip pairs
276 ; bndrs' <- mapFCs (maybeExternaliseId dflags) bndrs
277 ; let pairs' = zip bndrs' rhss
278 ; mapM_ (mkSRT dflags bndrs') srts
279 ; _new_binds <- fixC (\ new_binds -> do
280 { addBindsC new_binds
281 ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
284 mkSRT :: DynFlags -> [Id] -> (Id,[Id]) -> Code
285 mkSRT dflags these (id,[]) = nopC
286 mkSRT dflags these (id,ids)
287 = do { ids <- mapFCs remap ids
289 ; emitRODataLits (mkSRTLabel (idName id))
290 (map (CmmLabel . mkClosureLabel dflags . idName) ids)
293 -- Sigh, better map all the ids against the environment in
294 -- case they've been externalised (see maybeExternaliseId below).
295 remap id = case filter (==id) these of
296 (id':_) -> returnFC id'
297 [] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) }
299 -- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs
300 -- to enclose the listFCs in cgTopBinding, but that tickled the
301 -- statics "error" call in initC. I DON'T UNDERSTAND WHY!
303 cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo)
304 -- The Id is passed along for setting up a binding...
305 -- It's already been externalised if necessary
307 cgTopRhs bndr (StgRhsCon cc con args)
308 = forkStatics (cgTopRhsCon bndr con args)
310 cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body)
311 = ASSERT(null fvs) -- There should be no free variables
312 setSRTLabel (mkSRTLabel (idName bndr)) $
313 forkStatics (cgTopRhsClosure bndr cc bi srt upd_flag args body)
317 %************************************************************************
319 \subsection{Stuff to support splitting}
321 %************************************************************************
323 If we're splitting the object, we need to externalise all the top-level names
324 (and then make sure we only use the externalised one in any C label we use
325 which refers to this name).
328 maybeExternaliseId :: DynFlags -> Id -> FCode Id
329 maybeExternaliseId dflags id
330 | dopt Opt_SplitObjs dflags, -- Externalise the name for -split-objs
331 isInternalName name = do { mod <- moduleName
332 ; returnFC (setIdName id (externalise mod)) }
333 | otherwise = returnFC id
335 externalise mod = mkExternalName uniq mod new_occ Nothing loc
337 uniq = nameUnique name
338 new_occ = mkLocalOcc uniq (nameOccName name)
339 loc = nameSrcLoc name
340 -- We want to conjure up a name that can't clash with any
341 -- existing name. So we generate
343 -- where 243 is the unique.