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 ( 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
91 ; return (cmm_binds ++ concat cmm_tycons
92 ++ if opt_SccProfilingOn then [cmm_init] else [])
94 -- Put datatype_stuff after code_stuff, because the
95 -- datatype closure table (for enumeration types) to
96 -- (say) PrelBase_True_closure, which is defined in
99 ; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff)
101 ; return code_stuff }
104 %************************************************************************
106 \subsection[codegen-init]{Module initialisation code}
108 %************************************************************************
110 /* -----------------------------------------------------------------------------
111 Module initialisation
113 The module initialisation code looks like this, roughly:
116 JMP_(__stginit_Foo_1_p)
119 FN(__stginit_Foo_1_p) {
123 We have one version of the init code with a module version and the
124 'way' attached to it. The version number helps to catch cases
125 where modules are not compiled in dependency order before being
126 linked: if a module has been compiled since any modules which depend on
127 it, then the latter modules will refer to a different version in their
128 init blocks and a link error will ensue.
130 The 'way' suffix helps to catch cases where modules compiled in different
131 ways are linked together (eg. profiled and non-profiled).
133 We provide a plain, unadorned, version of the module init code
134 which just jumps to the version with the label and way attached. The
135 reason for this is that when using foreign exports, the caller of
136 startupHaskell() must supply the name of the init function for the "top"
137 module in the program, and we don't want to require that this name
138 has the version and way info appended to it.
139 -------------------------------------------------------------------------- */
141 We initialise the module tree by keeping a work-stack,
143 * that grows downward
144 * Sp points to the last occupied slot
150 -> String -- the "way"
151 -> CollectedCCs -- cost centre info
153 -> Maybe String -- Just m ==> we have flag: -main-is Foo.baz
156 mkModuleInit dflags way cost_centre_info this_mod mb_main_mod 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 ; initCostCentres cost_centre_info
216 ; mapCs (registerModuleImport dflags way)
217 (imported_mods++extra_imported_mods)
221 -----------------------
222 registerModuleImport :: DynFlags -> String -> Module -> Code
223 registerModuleImport dflags way mod
226 | otherwise -- Push the init procedure onto the work stack
227 = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
228 , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel dflags mod way)) ]
234 Cost-centre profiling: Besides the usual stuff, we must produce
235 declarations for the cost-centres defined in this module;
237 (The local cost-centres involved in this are passed into the
241 initCostCentres :: CollectedCCs -> Code
242 -- Emit the declarations, and return code to register them
243 initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
244 | not opt_SccProfilingOn = nopC
246 = do { mapM_ emitCostCentreDecl local_CCs
247 ; mapM_ emitCostCentreStackDecl singleton_CCSs
248 ; mapM_ emitRegisterCC local_CCs
249 ; mapM_ emitRegisterCCS singleton_CCSs
253 %************************************************************************
255 \subsection[codegen-top-bindings]{Converting top-level STG bindings}
257 %************************************************************************
259 @cgTopBinding@ is only used for top-level bindings, since they need
260 to be allocated statically (not in the heap) and need to be labelled.
261 No unboxed bindings can happen at top level.
263 In the code below, the static bindings are accumulated in the
264 @MkCgState@, and transferred into the ``statics'' slot by @forkStatics@.
265 This is so that we can write the top level processing in a compositional
266 style, with the increasing static environment being plumbed as a state
270 cgTopBinding :: DynFlags -> (StgBinding,[(Id,[Id])]) -> Code
271 cgTopBinding dflags (StgNonRec id rhs, srts)
272 = do { id' <- maybeExternaliseId dflags id
273 ; mapM_ (mkSRT dflags [id']) srts
274 ; (id,info) <- cgTopRhs id' rhs
275 ; addBindC id info -- Add the *un-externalised* Id to the envt,
276 -- so we find it when we look up occurrences
279 cgTopBinding dflags (StgRec pairs, srts)
280 = do { let (bndrs, rhss) = unzip pairs
281 ; bndrs' <- mapFCs (maybeExternaliseId dflags) bndrs
282 ; let pairs' = zip bndrs' rhss
283 ; mapM_ (mkSRT dflags bndrs') srts
284 ; _new_binds <- fixC (\ new_binds -> do
285 { addBindsC new_binds
286 ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
289 mkSRT :: DynFlags -> [Id] -> (Id,[Id]) -> Code
290 mkSRT dflags these (id,[]) = nopC
291 mkSRT dflags these (id,ids)
292 = do { ids <- mapFCs remap ids
294 ; emitRODataLits (mkSRTLabel (idName id))
295 (map (CmmLabel . mkClosureLabel dflags . idName) ids)
298 -- Sigh, better map all the ids against the environment in
299 -- case they've been externalised (see maybeExternaliseId below).
300 remap id = case filter (==id) these of
301 (id':_) -> returnFC id'
302 [] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) }
304 -- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs
305 -- to enclose the listFCs in cgTopBinding, but that tickled the
306 -- statics "error" call in initC. I DON'T UNDERSTAND WHY!
308 cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo)
309 -- The Id is passed along for setting up a binding...
310 -- It's already been externalised if necessary
312 cgTopRhs bndr (StgRhsCon cc con args)
313 = forkStatics (cgTopRhsCon bndr con args)
315 cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body)
316 = ASSERT(null fvs) -- There should be no free variables
317 setSRTLabel (mkSRTLabel (idName bndr)) $
318 forkStatics (cgTopRhsClosure bndr cc bi srt upd_flag args body)
322 %************************************************************************
324 \subsection{Stuff to support splitting}
326 %************************************************************************
328 If we're splitting the object, we need to externalise all the top-level names
329 (and then make sure we only use the externalised one in any C label we use
330 which refers to this name).
333 maybeExternaliseId :: DynFlags -> Id -> FCode Id
334 maybeExternaliseId dflags id
335 | dopt Opt_SplitObjs dflags, -- Externalise the name for -split-objs
336 isInternalName name = do { mod <- moduleName
337 ; returnFC (setIdName id (externalise mod)) }
338 | otherwise = returnFC id
340 externalise mod = mkExternalName uniq mod new_occ Nothing loc
342 uniq = nameUnique name
343 new_occ = mkLocalOcc uniq (nameOccName name)
344 loc = nameSrcLoc name
345 -- We want to conjure up a name that can't clash with any
346 -- existing name. So we generate
348 -- where 243 is the unique.