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 {-# OPTIONS_GHC -w #-}
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/WorkingConventions#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 codeGen dflags this_mod data_tycons imported_mods
74 cost_centre_info stg_binds hpc_info
76 { showPass dflags "CodeGen"
77 ; let way = buildTag dflags
78 main_mod = mainModIs dflags
81 -- ; mapM_ (\x -> seq x (return ())) data_tycons
83 ; code_stuff <- initC dflags this_mod $ do
84 { cmm_binds <- mapM (getCmm . cgTopBinding dflags) stg_binds
85 ; cmm_tycons <- mapM cgTyCon data_tycons
86 ; cmm_init <- getCmm (mkModuleInit way cost_centre_info
88 imported_mods hpc_info)
89 ; return (cmm_binds ++ concat cmm_tycons ++ [cmm_init])
91 -- Put datatype_stuff after code_stuff, because the
92 -- datatype closure table (for enumeration types) to
93 -- (say) PrelBase_True_closure, which is defined in
96 ; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff)
101 %************************************************************************
103 \subsection[codegen-init]{Module initialisation code}
105 %************************************************************************
107 /* -----------------------------------------------------------------------------
108 Module initialisation
110 The module initialisation code looks like this, roughly:
113 JMP_(__stginit_Foo_1_p)
116 FN(__stginit_Foo_1_p) {
120 We have one version of the init code with a module version and the
121 'way' attached to it. The version number helps to catch cases
122 where modules are not compiled in dependency order before being
123 linked: if a module has been compiled since any modules which depend on
124 it, then the latter modules will refer to a different version in their
125 init blocks and a link error will ensue.
127 The 'way' suffix helps to catch cases where modules compiled in different
128 ways are linked together (eg. profiled and non-profiled).
130 We provide a plain, unadorned, version of the module init code
131 which just jumps to the version with the label and way attached. The
132 reason for this is that when using foreign exports, the caller of
133 startupHaskell() must supply the name of the init function for the "top"
134 module in the program, and we don't want to require that this name
135 has the version and way info appended to it.
136 -------------------------------------------------------------------------- */
138 We initialise the module tree by keeping a work-stack,
140 * that grows downward
141 * Sp points to the last occupied slot
146 :: String -- the "way"
147 -> CollectedCCs -- cost centre info
149 -> Module -- name of the Main module
153 mkModuleInit way cost_centre_info this_mod main_mod imported_mods hpc_info
154 = do { -- Allocate the static boolean that records if this
155 -- module has been registered already
156 emitData Data [CmmDataLabel moduleRegdLabel,
157 CmmStaticLit zeroCLit]
160 hpcTable this_mod hpc_info
162 -- we emit a recursive descent module search for all modules
163 -- and *choose* to chase it in :Main, below.
164 -- In this way, Hpc enabled modules can interact seamlessly with
165 -- not Hpc enabled moduled, provided Main is compiled with Hpc.
167 ; emitSimpleProc real_init_lbl $ do
168 { ret_blk <- forkLabelledCode ret_code
170 ; init_blk <- forkLabelledCode $ do
171 { mod_init_code; stmtC (CmmBranch ret_blk) }
173 ; stmtC (CmmCondBranch (cmmNeWord (CmmLit zeroCLit) mod_reg_val)
175 ; stmtC (CmmBranch init_blk)
178 -- Make the "plain" procedure jump to the "real" init procedure
179 ; emitSimpleProc plain_init_lbl jump_to_init
181 -- When compiling the module in which the 'main' function lives,
182 -- (that is, this_mod == main_mod)
183 -- we inject an extra stg_init procedure for stg_init_ZCMain, for the
184 -- RTS to invoke. We must consult the -main-is flag in case the
185 -- user specified a different function to Main.main
187 -- Notice that the recursive descent is optional, depending on what options
190 ; whenC (this_mod == main_mod)
191 (emitSimpleProc plain_main_init_lbl rec_descent_init)
194 plain_init_lbl = mkPlainModuleInitLabel this_mod
195 real_init_lbl = mkModuleInitLabel this_mod way
196 plain_main_init_lbl = mkPlainModuleInitLabel rOOT_MAIN
198 jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) [])
200 mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep
202 -- Main refers to GHC.TopHandler.runIO, so make sure we call the
203 -- init function for GHC.TopHandler.
205 | this_mod == main_mod = [gHC_TOP_HANDLER]
209 { -- Set mod_reg to 1 to record that we've been here
210 stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1)))
212 ; whenC (opt_SccProfilingOn) $ do
213 initCostCentres cost_centre_info
216 initHpc this_mod hpc_info
218 ; mapCs (registerModuleImport way)
219 (imported_mods++extra_imported_mods)
223 -- The return-code pops the work stack by
224 -- incrementing Sp, and then jumpd to the popped item
225 ret_code = stmtsC [ CmmAssign spReg (cmmRegOffW spReg 1)
226 , CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ]
229 rec_descent_init = if opt_SccProfilingOn || isHpcUsed hpc_info
233 -----------------------
234 registerModuleImport :: String -> Module -> Code
235 registerModuleImport way mod
238 | otherwise -- Push the init procedure onto the work stack
239 = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
240 , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel mod way)) ]
245 Cost-centre profiling: Besides the usual stuff, we must produce
246 declarations for the cost-centres defined in this module;
248 (The local cost-centres involved in this are passed into the
252 initCostCentres :: CollectedCCs -> Code
253 -- Emit the declarations, and return code to register them
254 initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
255 | not opt_SccProfilingOn = nopC
257 = do { mapM_ emitCostCentreDecl local_CCs
258 ; mapM_ emitCostCentreStackDecl singleton_CCSs
259 ; mapM_ emitRegisterCC local_CCs
260 ; mapM_ emitRegisterCCS singleton_CCSs
264 %************************************************************************
266 \subsection[codegen-top-bindings]{Converting top-level STG bindings}
268 %************************************************************************
270 @cgTopBinding@ is only used for top-level bindings, since they need
271 to be allocated statically (not in the heap) and need to be labelled.
272 No unboxed bindings can happen at top level.
274 In the code below, the static bindings are accumulated in the
275 @MkCgState@, and transferred into the ``statics'' slot by @forkStatics@.
276 This is so that we can write the top level processing in a compositional
277 style, with the increasing static environment being plumbed as a state
281 cgTopBinding :: DynFlags -> (StgBinding,[(Id,[Id])]) -> Code
282 cgTopBinding dflags (StgNonRec id rhs, srts)
283 = do { id' <- maybeExternaliseId dflags id
284 ; mapM_ (mkSRT [id']) srts
285 ; (id,info) <- cgTopRhs id' rhs
286 ; addBindC id info -- Add the *un-externalised* Id to the envt,
287 -- so we find it when we look up occurrences
290 cgTopBinding dflags (StgRec pairs, srts)
291 = do { let (bndrs, rhss) = unzip pairs
292 ; bndrs' <- mapFCs (maybeExternaliseId dflags) bndrs
293 ; let pairs' = zip bndrs' rhss
294 ; mapM_ (mkSRT bndrs') srts
295 ; _new_binds <- fixC (\ new_binds -> do
296 { addBindsC new_binds
297 ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
300 mkSRT :: [Id] -> (Id,[Id]) -> Code
301 mkSRT these (id,[]) = nopC
303 = do { ids <- mapFCs remap ids
305 ; emitRODataLits (mkSRTLabel (idName id))
306 (map (CmmLabel . mkClosureLabel . idName) ids)
309 -- Sigh, better map all the ids against the environment in
310 -- case they've been externalised (see maybeExternaliseId below).
311 remap id = case filter (==id) these of
312 (id':_) -> returnFC id'
313 [] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) }
315 -- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs
316 -- to enclose the listFCs in cgTopBinding, but that tickled the
317 -- statics "error" call in initC. I DON'T UNDERSTAND WHY!
319 cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo)
320 -- The Id is passed along for setting up a binding...
321 -- It's already been externalised if necessary
323 cgTopRhs bndr (StgRhsCon cc con args)
324 = forkStatics (cgTopRhsCon bndr con args)
326 cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body)
327 = ASSERT(null fvs) -- There should be no free variables
328 setSRTLabel (mkSRTLabel (idName bndr)) $
330 forkStatics (cgTopRhsClosure bndr cc bi upd_flag args body)
334 %************************************************************************
336 \subsection{Stuff to support splitting}
338 %************************************************************************
340 If we're splitting the object, we need to externalise all the top-level names
341 (and then make sure we only use the externalised one in any C label we use
342 which refers to this name).
345 maybeExternaliseId :: DynFlags -> Id -> FCode Id
346 maybeExternaliseId dflags id
347 | dopt Opt_SplitObjs dflags, -- Externalise the name for -split-objs
348 isInternalName name = do { mod <- getModuleName
349 ; returnFC (setIdName id (externalise mod)) }
350 | otherwise = returnFC id
352 externalise mod = mkExternalName uniq mod new_occ loc
354 uniq = nameUnique name
355 new_occ = mkLocalOcc uniq (nameOccName name)
356 loc = nameSrcSpan name
357 -- We want to conjure up a name that can't clash with any
358 -- existing name. So we generate
360 -- where 243 is the unique.