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 import DriverState ( v_Build_tag, v_MainModIs )
24 -- Kludge (??) so that CgExpr is reached via at least one non-SOURCE
25 -- import. Before, that wasn't the case, and CM therefore didn't
26 -- bother to compile it.
27 import CgExpr ( {-NOTHING!-} ) -- DO NOT DELETE THIS IMPORT
30 import CgBindery ( CgIdInfo, addBindC, addBindsC, getCgIdInfo,
32 import CgClosure ( cgTopRhsClosure )
33 import CgCon ( cgTopRhsCon, cgTyCon )
34 import CgUtils ( cmmRegOffW, emitRODataLits, cmmNeWord, emitRtsCall )
38 import CmmUtils ( zeroCLit, mkIntCLit, mkLblExpr )
39 import PprCmm ( pprCmms )
40 import MachOp ( wordRep, MachHint(..) )
43 import PrelNames ( gHC_PRIM, rOOT_MAIN, mAIN, pREL_TOP_HANDLER )
44 import CmdLineOpts ( DynFlags, DynFlag(..), opt_EnsureSplittableC,
47 import HscTypes ( ForeignStubs(..), TypeEnv, typeEnvTyCons )
48 import CostCentre ( CollectedCCs )
49 import Id ( Id, idName, setIdName )
50 import Name ( nameSrcLoc, nameOccName, nameUnique, isInternalName, mkExternalName )
51 import OccName ( mkLocalOcc )
52 import TyCon ( isDataTyCon )
53 import Module ( Module, mkModule )
54 import ErrUtils ( dumpIfSet_dyn, showPass )
55 import Panic ( assertPanic )
61 import DATA_IOREF ( readIORef )
69 -> [Module] -- directly-imported modules
70 -> CollectedCCs -- (Local/global) cost-centres needing declaring/registering.
71 -> [(StgBinding,[(Id,[Id])])] -- Bindings to convert, with SRTs
74 codeGen dflags this_mod type_env foreign_stubs imported_mods
75 cost_centre_info stg_binds
77 { showPass dflags "CodeGen"
78 ; way <- readIORef v_Build_tag
79 ; mb_main_mod <- readIORef v_MainModIs
81 ; let tycons = typeEnvTyCons type_env
82 data_tycons = filter isDataTyCon tycons
85 -- ; mapM_ (\x -> seq x (return ())) data_tycons
87 ; code_stuff <- initC dflags this_mod $ do
88 { cmm_binds <- mapM (getCmm . cgTopBinding dflags) stg_binds
89 ; cmm_tycons <- mapM cgTyCon data_tycons
90 ; cmm_init <- getCmm (mkModuleInit dflags way cost_centre_info
92 foreign_stubs imported_mods)
93 ; return (cmm_binds ++ concat cmm_tycons ++ [cmm_init])
95 -- Put datatype_stuff after code_stuff, because the
96 -- datatype closure table (for enumeration types) to
97 -- (say) PrelBase_True_closure, which is defined in
100 ; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff)
102 ; return code_stuff }
105 %************************************************************************
107 \subsection[codegen-init]{Module initialisation code}
109 %************************************************************************
111 /* -----------------------------------------------------------------------------
112 Module initialisation
114 The module initialisation code looks like this, roughly:
117 JMP_(__stginit_Foo_1_p)
120 FN(__stginit_Foo_1_p) {
124 We have one version of the init code with a module version and the
125 'way' attached to it. The version number helps to catch cases
126 where modules are not compiled in dependency order before being
127 linked: if a module has been compiled since any modules which depend on
128 it, then the latter modules will refer to a different version in their
129 init blocks and a link error will ensue.
131 The 'way' suffix helps to catch cases where modules compiled in different
132 ways are linked together (eg. profiled and non-profiled).
134 We provide a plain, unadorned, version of the module init code
135 which just jumps to the version with the label and way attached. The
136 reason for this is that when using foreign exports, the caller of
137 startupHaskell() must supply the name of the init function for the "top"
138 module in the program, and we don't want to require that this name
139 has the version and way info appended to it.
140 -------------------------------------------------------------------------- */
142 We initialise the module tree by keeping a work-stack,
144 * that grows downward
145 * Sp points to the last occupied slot
151 -> String -- the "way"
152 -> CollectedCCs -- cost centre info
154 -> Maybe String -- Just m ==> we have flag: -main-is Foo.baz
158 mkModuleInit dflags way cost_centre_info this_mod mb_main_mod foreign_stubs imported_mods
161 -- Allocate the static boolean that records if this
162 -- module has been registered already
163 ; emitData Data [CmmDataLabel moduleRegdLabel,
164 CmmStaticLit zeroCLit]
166 ; emitSimpleProc real_init_lbl $ do
167 { -- The return-code pops the work stack by
168 -- incrementing Sp, and then jumpd to the popped item
169 ret_blk <- forkLabelledCode $ stmtsC
170 [ CmmAssign spReg (cmmRegOffW spReg 1)
171 , CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ]
173 ; init_blk <- forkLabelledCode $ do
174 { mod_init_code; stmtC (CmmBranch ret_blk) }
176 ; stmtC (CmmCondBranch (cmmNeWord (CmmLit zeroCLit) mod_reg_val)
178 ; stmtC (CmmBranch init_blk)
182 -- Make the "plain" procedure jump to the "real" init procedure
183 ; emitSimpleProc plain_init_lbl jump_to_init
185 -- When compiling the module in which the 'main' function lives,
186 -- (that is, this_mod == main_mod)
187 -- we inject an extra stg_init procedure for stg_init_ZCMain, for the
188 -- RTS to invoke. We must consult the -main-is flag in case the
189 -- user specified a different function to Main.main
190 ; whenC (this_mod == main_mod)
191 (emitSimpleProc plain_main_init_lbl jump_to_init)
194 plain_init_lbl = mkPlainModuleInitLabel dflags this_mod
195 real_init_lbl = mkModuleInitLabel dflags this_mod way
196 plain_main_init_lbl = mkPlainModuleInitLabel dflags rOOT_MAIN
198 jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) [])
200 mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep
202 main_mod = case mb_main_mod of
203 Just mod_name -> mkModule mod_name
206 -- Main refers to GHC.TopHandler.runIO, so make sure we call the
207 -- init function for GHC.TopHandler.
209 | this_mod == main_mod = [pREL_TOP_HANDLER]
213 { -- Set mod_reg to 1 to record that we've been here
214 stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1)))
216 -- Now do local stuff
217 ; registerForeignExports foreign_stubs
218 ; initCostCentres cost_centre_info
219 ; mapCs (registerModuleImport dflags way)
220 (imported_mods++extra_imported_mods)
224 -----------------------
225 registerModuleImport :: DynFlags -> String -> Module -> Code
226 registerModuleImport dflags way mod
229 | otherwise -- Push the init procedure onto the work stack
230 = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
231 , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel dflags mod way)) ]
233 -----------------------
234 registerForeignExports :: ForeignStubs -> Code
235 registerForeignExports NoStubs
237 registerForeignExports (ForeignStubs _ _ _ fe_bndrs)
238 = mapM_ mk_export_register fe_bndrs
240 mk_export_register bndr
241 = emitRtsCall SLIT("getStablePtr")
242 [ (CmmLit (CmmLabel (mkLocalClosureLabel (idName bndr))),
248 Cost-centre profiling: Besides the usual stuff, we must produce
249 declarations for the cost-centres defined in this module;
251 (The local cost-centres involved in this are passed into the
255 initCostCentres :: CollectedCCs -> Code
256 -- Emit the declarations, and return code to register them
257 initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
258 | not opt_SccProfilingOn = nopC
260 = do { mapM_ emitCostCentreDecl local_CCs
261 ; mapM_ emitCostCentreStackDecl singleton_CCSs
262 ; mapM_ emitRegisterCC local_CCs
263 ; mapM_ emitRegisterCCS singleton_CCSs
267 %************************************************************************
269 \subsection[codegen-top-bindings]{Converting top-level STG bindings}
271 %************************************************************************
273 @cgTopBinding@ is only used for top-level bindings, since they need
274 to be allocated statically (not in the heap) and need to be labelled.
275 No unboxed bindings can happen at top level.
277 In the code below, the static bindings are accumulated in the
278 @MkCgState@, and transferred into the ``statics'' slot by @forkStatics@.
279 This is so that we can write the top level processing in a compositional
280 style, with the increasing static environment being plumbed as a state
284 cgTopBinding :: DynFlags -> (StgBinding,[(Id,[Id])]) -> Code
285 cgTopBinding dflags (StgNonRec id rhs, srts)
286 = do { id' <- maybeExternaliseId id
287 ; mapM_ (mkSRT dflags [id']) srts
288 ; (id,info) <- cgTopRhs id' rhs
289 ; addBindC id info -- Add the *un-externalised* Id to the envt,
290 -- so we find it when we look up occurrences
293 cgTopBinding dflags (StgRec pairs, srts)
294 = do { let (bndrs, rhss) = unzip pairs
295 ; bndrs' <- mapFCs maybeExternaliseId bndrs
296 ; let pairs' = zip bndrs' rhss
297 ; mapM_ (mkSRT dflags bndrs') srts
298 ; _new_binds <- fixC (\ new_binds -> do
299 { addBindsC new_binds
300 ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
303 mkSRT :: DynFlags -> [Id] -> (Id,[Id]) -> Code
304 mkSRT dflags these (id,[]) = nopC
305 mkSRT dflags these (id,ids)
306 = do { ids <- mapFCs remap ids
308 ; emitRODataLits (mkSRTLabel (idName id))
309 (map (CmmLabel . mkClosureLabel dflags . idName) ids)
312 -- Sigh, better map all the ids against the environment in
313 -- case they've been externalised (see maybeExternaliseId below).
314 remap id = case filter (==id) these of
315 (id':_) -> returnFC id'
316 [] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) }
318 -- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs
319 -- to enclose the listFCs in cgTopBinding, but that tickled the
320 -- statics "error" call in initC. I DON'T UNDERSTAND WHY!
322 cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo)
323 -- The Id is passed along for setting up a binding...
324 -- It's already been externalised if necessary
326 cgTopRhs bndr (StgRhsCon cc con args)
327 = forkStatics (cgTopRhsCon bndr con args)
329 cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body)
330 = ASSERT(null fvs) -- There should be no free variables
331 setSRTLabel (mkSRTLabel (idName bndr)) $
332 forkStatics (cgTopRhsClosure bndr cc bi srt upd_flag args body)
336 %************************************************************************
338 \subsection{Stuff to support splitting}
340 %************************************************************************
342 If we're splitting the object, we need to externalise all the top-level names
343 (and then make sure we only use the externalised one in any C label we use
344 which refers to this name).
347 maybeExternaliseId :: Id -> FCode Id
348 maybeExternaliseId id
349 | opt_EnsureSplittableC, -- Externalise the name for -split-objs
350 isInternalName name = do { mod <- moduleName
351 ; returnFC (setIdName id (externalise mod)) }
352 | otherwise = returnFC id
354 externalise mod = mkExternalName uniq mod new_occ Nothing loc
356 uniq = nameUnique name
357 new_occ = mkLocalOcc uniq (nameOccName name)
358 loc = nameSrcLoc name
359 -- We want to conjure up a name that can't clash with any
360 -- existing name. So we generate
362 -- where 243 is the unique.