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.
15 -- The above warning supression flag is a temporary kludge.
16 -- While working on this module you are encouraged to remove it and fix
17 -- any warnings in the module. See
18 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
21 module CodeGen ( codeGen ) where
23 #include "HsVersions.h"
25 -- Kludge (??) so that CgExpr is reached via at least one non-SOURCE
26 -- import. Before, that wasn't the case, and CM therefore didn't
27 -- bother to compile it.
28 import CgExpr ( {-NOTHING!-} ) -- DO NOT DELETE THIS IMPORT
64 -> [Module] -- directly-imported modules
65 -> CollectedCCs -- (Local/global) cost-centres needing declaring/registering.
66 -> [(StgBinding,[(Id,[Id])])] -- Bindings to convert, with SRTs
70 -- N.B. returning '[Cmm]' and not 'Cmm' here makes it
71 -- possible for object splitting to split up the
74 codeGen dflags this_mod data_tycons imported_mods
75 cost_centre_info stg_binds hpc_info
77 { showPass dflags "CodeGen"
78 ; let way = buildTag dflags
79 main_mod = mainModIs dflags
82 -- ; mapM_ (\x -> seq x (return ())) data_tycons
84 ; code_stuff <- initC dflags this_mod $ do
85 { cmm_binds <- mapM (getCmm . cgTopBinding dflags) stg_binds
86 ; cmm_tycons <- mapM cgTyCon data_tycons
87 ; cmm_init <- getCmm (mkModuleInit way cost_centre_info
89 imported_mods hpc_info)
90 ; return (cmm_binds ++ concat cmm_tycons ++ [cmm_init])
92 -- Put datatype_stuff after code_stuff, because the
93 -- datatype closure table (for enumeration types) to
94 -- (say) PrelBase_True_closure, which is defined in
97 ; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff)
102 %************************************************************************
104 \subsection[codegen-init]{Module initialisation code}
106 %************************************************************************
108 /* -----------------------------------------------------------------------------
109 Module initialisation
111 The module initialisation code looks like this, roughly:
114 JMP_(__stginit_Foo_1_p)
117 FN(__stginit_Foo_1_p) {
121 We have one version of the init code with a module version and the
122 'way' attached to it. The version number helps to catch cases
123 where modules are not compiled in dependency order before being
124 linked: if a module has been compiled since any modules which depend on
125 it, then the latter modules will refer to a different version in their
126 init blocks and a link error will ensue.
128 The 'way' suffix helps to catch cases where modules compiled in different
129 ways are linked together (eg. profiled and non-profiled).
131 We provide a plain, unadorned, version of the module init code
132 which just jumps to the version with the label and way attached. The
133 reason for this is that when using foreign exports, the caller of
134 startupHaskell() must supply the name of the init function for the "top"
135 module in the program, and we don't want to require that this name
136 has the version and way info appended to it.
137 -------------------------------------------------------------------------- */
139 We initialise the module tree by keeping a work-stack,
141 * that grows downward
142 * Sp points to the last occupied slot
147 :: String -- the "way"
148 -> CollectedCCs -- cost centre info
150 -> Module -- name of the Main module
154 mkModuleInit way cost_centre_info this_mod main_mod imported_mods hpc_info
155 = do { -- Allocate the static boolean that records if this
156 -- module has been registered already
157 emitData Data [CmmDataLabel moduleRegdLabel,
158 CmmStaticLit zeroCLit]
161 hpcTable this_mod hpc_info
163 -- we emit a recursive descent module search for all modules
164 -- and *choose* to chase it in :Main, below.
165 -- In this way, Hpc enabled modules can interact seamlessly with
166 -- not Hpc enabled moduled, provided Main is compiled with Hpc.
168 ; emitSimpleProc real_init_lbl $ do
169 { ret_blk <- forkLabelledCode ret_code
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)
179 -- Make the "plain" procedure jump to the "real" init procedure
180 ; emitSimpleProc plain_init_lbl jump_to_init
182 -- When compiling the module in which the 'main' function lives,
183 -- (that is, this_mod == main_mod)
184 -- we inject an extra stg_init procedure for stg_init_ZCMain, for the
185 -- RTS to invoke. We must consult the -main-is flag in case the
186 -- user specified a different function to Main.main
188 -- Notice that the recursive descent is optional, depending on what options
191 ; whenC (this_mod == main_mod)
192 (emitSimpleProc plain_main_init_lbl rec_descent_init)
195 plain_init_lbl = mkPlainModuleInitLabel this_mod
196 real_init_lbl = mkModuleInitLabel this_mod way
197 plain_main_init_lbl = mkPlainModuleInitLabel rOOT_MAIN
199 jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) [])
201 mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep
203 -- Main refers to GHC.TopHandler.runIO, so make sure we call the
204 -- init function for GHC.TopHandler.
206 | this_mod == main_mod = [gHC_TOP_HANDLER]
210 { -- Set mod_reg to 1 to record that we've been here
211 stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1)))
213 ; whenC (opt_SccProfilingOn) $ do
214 initCostCentres cost_centre_info
217 initHpc this_mod hpc_info
219 ; mapCs (registerModuleImport way)
220 (imported_mods++extra_imported_mods)
224 -- The return-code pops the work stack by
225 -- incrementing Sp, and then jumpd to the popped item
226 ret_code = stmtsC [ CmmAssign spReg (cmmRegOffW spReg 1)
227 , CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ]
230 rec_descent_init = if opt_SccProfilingOn || isHpcUsed hpc_info
234 -----------------------
235 registerModuleImport :: String -> Module -> Code
236 registerModuleImport way mod
239 | otherwise -- Push the init procedure onto the work stack
240 = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
241 , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel mod way)) ]
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 dflags id
285 ; mapM_ (mkSRT [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 dflags) bndrs
294 ; let pairs' = zip bndrs' rhss
295 ; mapM_ (mkSRT bndrs') srts
296 ; _new_binds <- fixC (\ new_binds -> do
297 { addBindsC new_binds
298 ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
301 mkSRT :: [Id] -> (Id,[Id]) -> Code
302 mkSRT these (id,[]) = nopC
304 = do { ids <- mapFCs remap ids
306 ; emitRODataLits (mkSRTLabel (idName id))
307 (map (CmmLabel . mkClosureLabel . 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)) $
331 forkStatics (cgTopRhsClosure bndr cc bi upd_flag args body)
335 %************************************************************************
337 \subsection{Stuff to support splitting}
339 %************************************************************************
341 If we're splitting the object, we need to externalise all the top-level names
342 (and then make sure we only use the externalised one in any C label we use
343 which refers to this name).
346 maybeExternaliseId :: DynFlags -> Id -> FCode Id
347 maybeExternaliseId dflags id
348 | dopt Opt_SplitObjs dflags, -- Externalise the name for -split-objs
349 isInternalName name = do { mod <- getModuleName
350 ; returnFC (setIdName id (externalise mod)) }
351 | otherwise = returnFC id
353 externalise mod = mkExternalName uniq mod new_occ loc
355 uniq = nameUnique name
356 new_occ = mkLocalOcc uniq (nameOccName name)
357 loc = nameSrcSpan name
358 -- We want to conjure up a name that can't clash with any
359 -- existing name. So we generate
361 -- where 243 is the unique.