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
67 -> [Module] -- directly-imported modules
68 -> CollectedCCs -- (Local/global) cost-centres needing declaring/registering.
69 -> [(StgBinding,[(Id,[Id])])] -- Bindings to convert, with SRTs
73 -- N.B. returning '[Cmm]' and not 'Cmm' here makes it
74 -- possible for object splitting to split up the
77 codeGen dflags this_mod data_tycons imported_mods
78 cost_centre_info stg_binds hpc_info
80 { showPass dflags "CodeGen"
81 ; let way = buildTag dflags
82 main_mod = mainModIs dflags
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 way cost_centre_info
92 imported_mods hpc_info)
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
150 :: String -- the "way"
151 -> CollectedCCs -- cost centre info
153 -> Module -- name of the Main module
157 mkModuleInit way cost_centre_info this_mod main_mod imported_mods hpc_info
158 = do { -- Allocate the static boolean that records if this
159 -- module has been registered already
160 emitData Data [CmmDataLabel moduleRegdLabel,
161 CmmStaticLit zeroCLit]
164 hpcTable this_mod hpc_info
166 -- we emit a recursive descent module search for all modules
167 -- and *choose* to chase it in :Main, below.
168 -- In this way, Hpc enabled modules can interact seamlessly with
169 -- not Hpc enabled moduled, provided Main is compiled with Hpc.
171 ; emitSimpleProc real_init_lbl $ do
172 { ret_blk <- forkLabelledCode ret_code
174 ; init_blk <- forkLabelledCode $ do
175 { mod_init_code; stmtC (CmmBranch ret_blk) }
177 ; stmtC (CmmCondBranch (cmmNeWord (CmmLit zeroCLit) mod_reg_val)
179 ; 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
191 -- Notice that the recursive descent is optional, depending on what options
194 ; whenC (this_mod == main_mod)
195 (emitSimpleProc plain_main_init_lbl rec_descent_init)
198 plain_init_lbl = mkPlainModuleInitLabel this_mod
199 real_init_lbl = mkModuleInitLabel this_mod way
200 plain_main_init_lbl = mkPlainModuleInitLabel rOOT_MAIN
202 jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) [])
204 mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep
206 -- Main refers to GHC.TopHandler.runIO, so make sure we call the
207 -- init function for GHC.TopHandler.
209 | this_mod == main_mod = [gHC_TOP_HANDLER]
213 { -- Set mod_reg to 1 to record that we've been here
214 stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1)))
216 ; whenC (opt_SccProfilingOn) $ do
217 initCostCentres cost_centre_info
220 initHpc this_mod hpc_info
222 ; mapCs (registerModuleImport way)
223 (imported_mods++extra_imported_mods)
227 -- The return-code pops the work stack by
228 -- incrementing Sp, and then jumpd to the popped item
229 ret_code = stmtsC [ CmmAssign spReg (cmmRegOffW spReg 1)
230 , CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ]
233 rec_descent_init = if opt_SccProfilingOn || isHpcUsed hpc_info
237 -----------------------
238 registerModuleImport :: String -> Module -> Code
239 registerModuleImport way mod
242 | otherwise -- Push the init procedure onto the work stack
243 = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
244 , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel mod way)) ]
249 Cost-centre profiling: Besides the usual stuff, we must produce
250 declarations for the cost-centres defined in this module;
252 (The local cost-centres involved in this are passed into the
256 initCostCentres :: CollectedCCs -> Code
257 -- Emit the declarations, and return code to register them
258 initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
259 | not opt_SccProfilingOn = nopC
261 = do { mapM_ emitCostCentreDecl local_CCs
262 ; mapM_ emitCostCentreStackDecl singleton_CCSs
263 ; mapM_ emitRegisterCC local_CCs
264 ; mapM_ emitRegisterCCS singleton_CCSs
268 %************************************************************************
270 \subsection[codegen-top-bindings]{Converting top-level STG bindings}
272 %************************************************************************
274 @cgTopBinding@ is only used for top-level bindings, since they need
275 to be allocated statically (not in the heap) and need to be labelled.
276 No unboxed bindings can happen at top level.
278 In the code below, the static bindings are accumulated in the
279 @MkCgState@, and transferred into the ``statics'' slot by @forkStatics@.
280 This is so that we can write the top level processing in a compositional
281 style, with the increasing static environment being plumbed as a state
285 cgTopBinding :: DynFlags -> (StgBinding,[(Id,[Id])]) -> Code
286 cgTopBinding dflags (StgNonRec id rhs, srts)
287 = do { id' <- maybeExternaliseId dflags id
288 ; mapM_ (mkSRT [id']) srts
289 ; (id,info) <- cgTopRhs id' rhs
290 ; addBindC id info -- Add the *un-externalised* Id to the envt,
291 -- so we find it when we look up occurrences
294 cgTopBinding dflags (StgRec pairs, srts)
295 = do { let (bndrs, rhss) = unzip pairs
296 ; bndrs' <- mapFCs (maybeExternaliseId dflags) bndrs
297 ; let pairs' = zip bndrs' rhss
298 ; mapM_ (mkSRT bndrs') srts
299 ; _new_binds <- fixC (\ new_binds -> do
300 { addBindsC new_binds
301 ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
304 mkSRT :: [Id] -> (Id,[Id]) -> Code
305 mkSRT these (id,[]) = nopC
307 = do { ids <- mapFCs remap ids
309 ; emitRODataLits (mkSRTLabel (idName id))
310 (map (CmmLabel . mkClosureLabel . idName) ids)
313 -- Sigh, better map all the ids against the environment in
314 -- case they've been externalised (see maybeExternaliseId below).
315 remap id = case filter (==id) these of
316 (id':_) -> returnFC id'
317 [] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) }
319 -- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs
320 -- to enclose the listFCs in cgTopBinding, but that tickled the
321 -- statics "error" call in initC. I DON'T UNDERSTAND WHY!
323 cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo)
324 -- The Id is passed along for setting up a binding...
325 -- It's already been externalised if necessary
327 cgTopRhs bndr (StgRhsCon cc con args)
328 = forkStatics (cgTopRhsCon bndr con args)
330 cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body)
331 = ASSERT(null fvs) -- There should be no free variables
332 setSRTLabel (mkSRTLabel (idName bndr)) $
334 forkStatics (cgTopRhsClosure bndr cc bi upd_flag args body)
338 %************************************************************************
340 \subsection{Stuff to support splitting}
342 %************************************************************************
344 If we're splitting the object, we need to externalise all the top-level names
345 (and then make sure we only use the externalised one in any C label we use
346 which refers to this name).
349 maybeExternaliseId :: DynFlags -> Id -> FCode Id
350 maybeExternaliseId dflags id
351 | dopt Opt_SplitObjs dflags, -- Externalise the name for -split-objs
352 isInternalName name = do { mod <- getModuleName
353 ; returnFC (setIdName id (externalise mod)) }
354 | otherwise = returnFC id
356 externalise mod = mkExternalName uniq mod new_occ loc
358 uniq = nameUnique name
359 new_occ = mkLocalOcc uniq (nameOccName name)
360 loc = nameSrcSpan name
361 -- We want to conjure up a name that can't clash with any
362 -- existing name. So we generate
364 -- where 243 is the unique.