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(..) )
43 import StaticFlags ( opt_SplitObjs, 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 ( isDataTyCon )
51 import Module ( Module, mkModule )
52 import ErrUtils ( dumpIfSet_dyn, showPass )
53 import Panic ( assertPanic )
59 import DATA_IOREF ( readIORef )
67 -> [Module] -- directly-imported modules
68 -> CollectedCCs -- (Local/global) cost-centres needing declaring/registering.
69 -> [(StgBinding,[(Id,[Id])])] -- Bindings to convert, with SRTs
72 codeGen dflags this_mod type_env foreign_stubs imported_mods
73 cost_centre_info stg_binds
75 { showPass dflags "CodeGen"
76 ; let way = buildTag dflags
77 mb_main_mod = mainModIs dflags
79 ; let tycons = typeEnvTyCons type_env
80 data_tycons = filter isDataTyCon tycons
83 -- ; mapM_ (\x -> seq x (return ())) data_tycons
85 ; code_stuff <- initC dflags this_mod $ do
86 { cmm_binds <- mapM (getCmm . cgTopBinding dflags) stg_binds
87 ; cmm_tycons <- mapM cgTyCon data_tycons
88 ; cmm_init <- getCmm (mkModuleInit dflags way cost_centre_info
90 foreign_stubs imported_mods)
91 ; return (cmm_binds ++ concat cmm_tycons ++ [cmm_init])
93 -- Put datatype_stuff after code_stuff, because the
94 -- datatype closure table (for enumeration types) to
95 -- (say) PrelBase_True_closure, which is defined in
98 ; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff)
100 ; return code_stuff }
103 %************************************************************************
105 \subsection[codegen-init]{Module initialisation code}
107 %************************************************************************
109 /* -----------------------------------------------------------------------------
110 Module initialisation
112 The module initialisation code looks like this, roughly:
115 JMP_(__stginit_Foo_1_p)
118 FN(__stginit_Foo_1_p) {
122 We have one version of the init code with a module version and the
123 'way' attached to it. The version number helps to catch cases
124 where modules are not compiled in dependency order before being
125 linked: if a module has been compiled since any modules which depend on
126 it, then the latter modules will refer to a different version in their
127 init blocks and a link error will ensue.
129 The 'way' suffix helps to catch cases where modules compiled in different
130 ways are linked together (eg. profiled and non-profiled).
132 We provide a plain, unadorned, version of the module init code
133 which just jumps to the version with the label and way attached. The
134 reason for this is that when using foreign exports, the caller of
135 startupHaskell() must supply the name of the init function for the "top"
136 module in the program, and we don't want to require that this name
137 has the version and way info appended to it.
138 -------------------------------------------------------------------------- */
140 We initialise the module tree by keeping a work-stack,
142 * that grows downward
143 * Sp points to the last occupied slot
149 -> String -- the "way"
150 -> CollectedCCs -- cost centre info
152 -> Maybe String -- Just m ==> we have flag: -main-is Foo.baz
156 mkModuleInit dflags way cost_centre_info this_mod mb_main_mod foreign_stubs imported_mods
159 -- Allocate the static boolean that records if this
160 -- module has been registered already
161 ; emitData Data [CmmDataLabel moduleRegdLabel,
162 CmmStaticLit zeroCLit]
164 ; emitSimpleProc real_init_lbl $ do
165 { -- The return-code pops the work stack by
166 -- incrementing Sp, and then jumpd to the popped item
167 ret_blk <- forkLabelledCode $ stmtsC
168 [ CmmAssign spReg (cmmRegOffW spReg 1)
169 , CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ]
171 ; init_blk <- forkLabelledCode $ do
172 { mod_init_code; stmtC (CmmBranch ret_blk) }
174 ; stmtC (CmmCondBranch (cmmNeWord (CmmLit zeroCLit) mod_reg_val)
176 ; stmtC (CmmBranch init_blk)
180 -- Make the "plain" procedure jump to the "real" init procedure
181 ; emitSimpleProc plain_init_lbl jump_to_init
183 -- When compiling the module in which the 'main' function lives,
184 -- (that is, this_mod == main_mod)
185 -- we inject an extra stg_init procedure for stg_init_ZCMain, for the
186 -- RTS to invoke. We must consult the -main-is flag in case the
187 -- user specified a different function to Main.main
188 ; whenC (this_mod == main_mod)
189 (emitSimpleProc plain_main_init_lbl jump_to_init)
192 plain_init_lbl = mkPlainModuleInitLabel dflags this_mod
193 real_init_lbl = mkModuleInitLabel dflags this_mod way
194 plain_main_init_lbl = mkPlainModuleInitLabel dflags rOOT_MAIN
196 jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) [])
198 mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep
200 main_mod = case mb_main_mod of
201 Just mod_name -> mkModule mod_name
204 -- Main refers to GHC.TopHandler.runIO, so make sure we call the
205 -- init function for GHC.TopHandler.
207 | this_mod == main_mod = [pREL_TOP_HANDLER]
211 { -- Set mod_reg to 1 to record that we've been here
212 stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1)))
214 -- Now do local stuff
215 ; registerForeignExports foreign_stubs
216 ; initCostCentres cost_centre_info
217 ; mapCs (registerModuleImport dflags way)
218 (imported_mods++extra_imported_mods)
222 -----------------------
223 registerModuleImport :: DynFlags -> String -> Module -> Code
224 registerModuleImport dflags way mod
227 | otherwise -- Push the init procedure onto the work stack
228 = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
229 , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel dflags mod way)) ]
231 -----------------------
232 registerForeignExports :: ForeignStubs -> Code
233 registerForeignExports NoStubs
235 registerForeignExports (ForeignStubs _ _ _ fe_bndrs)
236 = mapM_ mk_export_register fe_bndrs
238 mk_export_register bndr
239 = emitRtsCall SLIT("getStablePtr")
240 [ (CmmLit (CmmLabel (mkLocalClosureLabel (idName bndr))),
246 Cost-centre profiling: Besides the usual stuff, we must produce
247 declarations for the cost-centres defined in this module;
249 (The local cost-centres involved in this are passed into the
253 initCostCentres :: CollectedCCs -> Code
254 -- Emit the declarations, and return code to register them
255 initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
256 | not opt_SccProfilingOn = nopC
258 = do { mapM_ emitCostCentreDecl local_CCs
259 ; mapM_ emitCostCentreStackDecl singleton_CCSs
260 ; mapM_ emitRegisterCC local_CCs
261 ; mapM_ emitRegisterCCS singleton_CCSs
265 %************************************************************************
267 \subsection[codegen-top-bindings]{Converting top-level STG bindings}
269 %************************************************************************
271 @cgTopBinding@ is only used for top-level bindings, since they need
272 to be allocated statically (not in the heap) and need to be labelled.
273 No unboxed bindings can happen at top level.
275 In the code below, the static bindings are accumulated in the
276 @MkCgState@, and transferred into the ``statics'' slot by @forkStatics@.
277 This is so that we can write the top level processing in a compositional
278 style, with the increasing static environment being plumbed as a state
282 cgTopBinding :: DynFlags -> (StgBinding,[(Id,[Id])]) -> Code
283 cgTopBinding dflags (StgNonRec id rhs, srts)
284 = do { id' <- maybeExternaliseId id
285 ; mapM_ (mkSRT dflags [id']) srts
286 ; (id,info) <- cgTopRhs id' rhs
287 ; addBindC id info -- Add the *un-externalised* Id to the envt,
288 -- so we find it when we look up occurrences
291 cgTopBinding dflags (StgRec pairs, srts)
292 = do { let (bndrs, rhss) = unzip pairs
293 ; bndrs' <- mapFCs maybeExternaliseId bndrs
294 ; let pairs' = zip bndrs' rhss
295 ; mapM_ (mkSRT dflags bndrs') srts
296 ; _new_binds <- fixC (\ new_binds -> do
297 { addBindsC new_binds
298 ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
301 mkSRT :: DynFlags -> [Id] -> (Id,[Id]) -> Code
302 mkSRT dflags these (id,[]) = nopC
303 mkSRT dflags these (id,ids)
304 = do { ids <- mapFCs remap ids
306 ; emitRODataLits (mkSRTLabel (idName id))
307 (map (CmmLabel . mkClosureLabel dflags . idName) ids)
310 -- Sigh, better map all the ids against the environment in
311 -- case they've been externalised (see maybeExternaliseId below).
312 remap id = case filter (==id) these of
313 (id':_) -> returnFC id'
314 [] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) }
316 -- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs
317 -- to enclose the listFCs in cgTopBinding, but that tickled the
318 -- statics "error" call in initC. I DON'T UNDERSTAND WHY!
320 cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo)
321 -- The Id is passed along for setting up a binding...
322 -- It's already been externalised if necessary
324 cgTopRhs bndr (StgRhsCon cc con args)
325 = forkStatics (cgTopRhsCon bndr con args)
327 cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body)
328 = ASSERT(null fvs) -- There should be no free variables
329 setSRTLabel (mkSRTLabel (idName bndr)) $
330 forkStatics (cgTopRhsClosure bndr cc bi srt upd_flag args body)
334 %************************************************************************
336 \subsection{Stuff to support splitting}
338 %************************************************************************
340 If we're splitting the object, we need to externalise all the top-level names
341 (and then make sure we only use the externalised one in any C label we use
342 which refers to this name).
345 maybeExternaliseId :: Id -> FCode Id
346 maybeExternaliseId id
347 | opt_SplitObjs, -- Externalise the name for -split-objs
348 isInternalName name = do { mod <- moduleName
349 ; returnFC (setIdName id (externalise mod)) }
350 | otherwise = returnFC id
352 externalise mod = mkExternalName uniq mod new_occ Nothing loc
354 uniq = nameUnique name
355 new_occ = mkLocalOcc uniq (nameOccName name)
356 loc = nameSrcLoc name
357 -- We want to conjure up a name that can't clash with any
358 -- existing name. So we generate
360 -- where 243 is the unique.