2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
8 This module says how things get going at the top level.
10 @codeGen@ is the interface to the outside world. The \tr{cgTop*}
11 functions drive the mangling of top-level bindings.
14 module CodeGen ( codeGen ) where
16 #include "HsVersions.h"
18 -- Kludge (??) so that CgExpr is reached via at least one non-SOURCE
19 -- import. Before, that wasn't the case, and CM therefore didn't
20 -- bother to compile it.
21 import CgExpr ( {-NOTHING!-} ) -- DO NOT DELETE THIS IMPORT
60 -> [Module] -- directly-imported modules
61 -> CollectedCCs -- (Local/global) cost-centres needing declaring/registering.
62 -> [(StgBinding,[(Id,[Id])])] -- Bindings to convert, with SRTs
66 codeGen dflags this_mod data_tycons imported_mods
67 cost_centre_info stg_binds hpc_info
69 { showPass dflags "CodeGen"
70 ; let way = buildTag dflags
71 main_mod = mainModIs dflags
74 -- ; mapM_ (\x -> seq x (return ())) data_tycons
76 ; code_stuff <- initC dflags this_mod $ do
77 { cmm_binds <- mapM (getCmm . cgTopBinding dflags) stg_binds
78 ; cmm_tycons <- mapM cgTyCon data_tycons
79 ; cmm_init <- getCmm (mkModuleInit way cost_centre_info
81 imported_mods hpc_info)
82 ; return (cmm_binds ++ concat cmm_tycons ++ [cmm_init])
84 -- Put datatype_stuff after code_stuff, because the
85 -- datatype closure table (for enumeration types) to
86 -- (say) PrelBase_True_closure, which is defined in
89 ; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff)
94 %************************************************************************
96 \subsection[codegen-init]{Module initialisation code}
98 %************************************************************************
100 /* -----------------------------------------------------------------------------
101 Module initialisation
103 The module initialisation code looks like this, roughly:
106 JMP_(__stginit_Foo_1_p)
109 FN(__stginit_Foo_1_p) {
113 We have one version of the init code with a module version and the
114 'way' attached to it. The version number helps to catch cases
115 where modules are not compiled in dependency order before being
116 linked: if a module has been compiled since any modules which depend on
117 it, then the latter modules will refer to a different version in their
118 init blocks and a link error will ensue.
120 The 'way' suffix helps to catch cases where modules compiled in different
121 ways are linked together (eg. profiled and non-profiled).
123 We provide a plain, unadorned, version of the module init code
124 which just jumps to the version with the label and way attached. The
125 reason for this is that when using foreign exports, the caller of
126 startupHaskell() must supply the name of the init function for the "top"
127 module in the program, and we don't want to require that this name
128 has the version and way info appended to it.
129 -------------------------------------------------------------------------- */
131 We initialise the module tree by keeping a work-stack,
133 * that grows downward
134 * Sp points to the last occupied slot
139 :: String -- the "way"
140 -> CollectedCCs -- cost centre info
142 -> Module -- name of the Main module
146 mkModuleInit way cost_centre_info this_mod main_mod imported_mods hpc_info
147 = do { -- Allocate the static boolean that records if this
148 -- module has been registered already
149 emitData Data [CmmDataLabel moduleRegdLabel,
150 CmmStaticLit zeroCLit]
153 hpcTable this_mod hpc_info
155 -- we emit a recursive descent module search for all modules
156 -- and *choose* to chase it in :Main, below.
157 -- In this way, Hpc enabled modules can interact seamlessly with
158 -- not Hpc enabled moduled, provided Main is compiled with Hpc.
160 ; emitSimpleProc real_init_lbl $ do
161 { ret_blk <- forkLabelledCode ret_code
163 ; init_blk <- forkLabelledCode $ do
164 { mod_init_code; stmtC (CmmBranch ret_blk) }
166 ; stmtC (CmmCondBranch (cmmNeWord (CmmLit zeroCLit) mod_reg_val)
168 ; stmtC (CmmBranch init_blk)
171 -- Make the "plain" procedure jump to the "real" init procedure
172 ; emitSimpleProc plain_init_lbl jump_to_init
174 -- When compiling the module in which the 'main' function lives,
175 -- (that is, this_mod == main_mod)
176 -- we inject an extra stg_init procedure for stg_init_ZCMain, for the
177 -- RTS to invoke. We must consult the -main-is flag in case the
178 -- user specified a different function to Main.main
180 -- Notice that the recursive descent is optional, depending on what options
183 ; whenC (this_mod == main_mod)
184 (emitSimpleProc plain_main_init_lbl rec_descent_init)
187 plain_init_lbl = mkPlainModuleInitLabel this_mod
188 real_init_lbl = mkModuleInitLabel this_mod way
189 plain_main_init_lbl = mkPlainModuleInitLabel rOOT_MAIN
191 jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) [])
193 mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep
195 -- Main refers to GHC.TopHandler.runIO, so make sure we call the
196 -- init function for GHC.TopHandler.
198 | this_mod == main_mod = [gHC_TOP_HANDLER]
202 { -- Set mod_reg to 1 to record that we've been here
203 stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1)))
205 ; whenC (opt_SccProfilingOn) $ do
206 initCostCentres cost_centre_info
209 initHpc this_mod hpc_info
211 ; mapCs (registerModuleImport way)
212 (imported_mods++extra_imported_mods)
216 -- The return-code pops the work stack by
217 -- incrementing Sp, and then jumpd to the popped item
218 ret_code = stmtsC [ CmmAssign spReg (cmmRegOffW spReg 1)
219 , CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ]
222 rec_descent_init = if opt_SccProfilingOn || isHpcUsed hpc_info
226 -----------------------
227 registerModuleImport :: String -> Module -> Code
228 registerModuleImport way mod
231 | otherwise -- Push the init procedure onto the work stack
232 = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
233 , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel mod way)) ]
238 Cost-centre profiling: Besides the usual stuff, we must produce
239 declarations for the cost-centres defined in this module;
241 (The local cost-centres involved in this are passed into the
245 initCostCentres :: CollectedCCs -> Code
246 -- Emit the declarations, and return code to register them
247 initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
248 | not opt_SccProfilingOn = nopC
250 = do { mapM_ emitCostCentreDecl local_CCs
251 ; mapM_ emitCostCentreStackDecl singleton_CCSs
252 ; mapM_ emitRegisterCC local_CCs
253 ; mapM_ emitRegisterCCS singleton_CCSs
257 %************************************************************************
259 \subsection[codegen-top-bindings]{Converting top-level STG bindings}
261 %************************************************************************
263 @cgTopBinding@ is only used for top-level bindings, since they need
264 to be allocated statically (not in the heap) and need to be labelled.
265 No unboxed bindings can happen at top level.
267 In the code below, the static bindings are accumulated in the
268 @MkCgState@, and transferred into the ``statics'' slot by @forkStatics@.
269 This is so that we can write the top level processing in a compositional
270 style, with the increasing static environment being plumbed as a state
274 cgTopBinding :: DynFlags -> (StgBinding,[(Id,[Id])]) -> Code
275 cgTopBinding dflags (StgNonRec id rhs, srts)
276 = do { id' <- maybeExternaliseId dflags id
277 ; mapM_ (mkSRT [id']) srts
278 ; (id,info) <- cgTopRhs id' rhs
279 ; addBindC id info -- Add the *un-externalised* Id to the envt,
280 -- so we find it when we look up occurrences
283 cgTopBinding dflags (StgRec pairs, srts)
284 = do { let (bndrs, rhss) = unzip pairs
285 ; bndrs' <- mapFCs (maybeExternaliseId dflags) bndrs
286 ; let pairs' = zip bndrs' rhss
287 ; mapM_ (mkSRT bndrs') srts
288 ; _new_binds <- fixC (\ new_binds -> do
289 { addBindsC new_binds
290 ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
293 mkSRT :: [Id] -> (Id,[Id]) -> Code
294 mkSRT these (id,[]) = nopC
296 = do { ids <- mapFCs remap ids
298 ; emitRODataLits (mkSRTLabel (idName id))
299 (map (CmmLabel . mkClosureLabel . idName) ids)
302 -- Sigh, better map all the ids against the environment in
303 -- case they've been externalised (see maybeExternaliseId below).
304 remap id = case filter (==id) these of
305 (id':_) -> returnFC id'
306 [] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) }
308 -- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs
309 -- to enclose the listFCs in cgTopBinding, but that tickled the
310 -- statics "error" call in initC. I DON'T UNDERSTAND WHY!
312 cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo)
313 -- The Id is passed along for setting up a binding...
314 -- It's already been externalised if necessary
316 cgTopRhs bndr (StgRhsCon cc con args)
317 = forkStatics (cgTopRhsCon bndr con args)
319 cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body)
320 = ASSERT(null fvs) -- There should be no free variables
321 setSRTLabel (mkSRTLabel (idName bndr)) $
323 forkStatics (cgTopRhsClosure bndr cc bi upd_flag args body)
327 %************************************************************************
329 \subsection{Stuff to support splitting}
331 %************************************************************************
333 If we're splitting the object, we need to externalise all the top-level names
334 (and then make sure we only use the externalised one in any C label we use
335 which refers to this name).
338 maybeExternaliseId :: DynFlags -> Id -> FCode Id
339 maybeExternaliseId dflags id
340 | dopt Opt_SplitObjs dflags, -- Externalise the name for -split-objs
341 isInternalName name = do { mod <- getModuleName
342 ; returnFC (setIdName id (externalise mod)) }
343 | otherwise = returnFC id
345 externalise mod = mkExternalName uniq mod new_occ loc
347 uniq = nameUnique name
348 new_occ = mkLocalOcc uniq (nameOccName name)
349 loc = nameSrcSpan name
350 -- We want to conjure up a name that can't clash with any
351 -- existing name. So we generate
353 -- where 243 is the unique.