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 )
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 Packages ( HomeModules )
43 import DynFlags ( DynFlags(..), DynFlag(..), dopt )
44 import StaticFlags ( opt_SccProfilingOn )
46 import HscTypes ( ForeignStubs(..), TypeEnv, typeEnvTyCons )
47 import CostCentre ( CollectedCCs )
48 import Id ( Id, idName, setIdName )
49 import Name ( nameSrcLoc, nameOccName, nameUnique, isInternalName, mkExternalName )
50 import OccName ( mkLocalOcc )
51 import TyCon ( TyCon )
52 import Module ( Module, mkModule )
53 import ErrUtils ( dumpIfSet_dyn, showPass )
54 import Panic ( assertPanic )
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 hmods this_mod data_tycons 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
80 -- ; mapM_ (\x -> seq x (return ())) data_tycons
82 ; code_stuff <- initC dflags hmods this_mod $ do
83 { cmm_binds <- mapM (getCmm . cgTopBinding dflags hmods) stg_binds
84 ; cmm_tycons <- mapM cgTyCon data_tycons
85 ; cmm_init <- getCmm (mkModuleInit dflags hmods way cost_centre_info
87 foreign_stubs imported_mods)
88 ; return (cmm_binds ++ concat cmm_tycons ++ [cmm_init])
90 -- Put datatype_stuff after code_stuff, because the
91 -- datatype closure table (for enumeration types) to
92 -- (say) PrelBase_True_closure, which is defined in
95 ; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff)
100 %************************************************************************
102 \subsection[codegen-init]{Module initialisation code}
104 %************************************************************************
106 /* -----------------------------------------------------------------------------
107 Module initialisation
109 The module initialisation code looks like this, roughly:
112 JMP_(__stginit_Foo_1_p)
115 FN(__stginit_Foo_1_p) {
119 We have one version of the init code with a module version and the
120 'way' attached to it. The version number helps to catch cases
121 where modules are not compiled in dependency order before being
122 linked: if a module has been compiled since any modules which depend on
123 it, then the latter modules will refer to a different version in their
124 init blocks and a link error will ensue.
126 The 'way' suffix helps to catch cases where modules compiled in different
127 ways are linked together (eg. profiled and non-profiled).
129 We provide a plain, unadorned, version of the module init code
130 which just jumps to the version with the label and way attached. The
131 reason for this is that when using foreign exports, the caller of
132 startupHaskell() must supply the name of the init function for the "top"
133 module in the program, and we don't want to require that this name
134 has the version and way info appended to it.
135 -------------------------------------------------------------------------- */
137 We initialise the module tree by keeping a work-stack,
139 * that grows downward
140 * Sp points to the last occupied slot
147 -> String -- the "way"
148 -> CollectedCCs -- cost centre info
150 -> Maybe String -- Just m ==> we have flag: -main-is Foo.baz
154 mkModuleInit dflags hmods way cost_centre_info this_mod mb_main_mod foreign_stubs imported_mods
156 if opt_SccProfilingOn
157 then do { -- Allocate the static boolean that records if this
158 -- module has been registered already
159 emitData Data [CmmDataLabel moduleRegdLabel,
160 CmmStaticLit zeroCLit]
162 ; emitSimpleProc real_init_lbl $ do
163 { ret_blk <- forkLabelledCode ret_code
165 ; init_blk <- forkLabelledCode $ do
166 { mod_init_code; stmtC (CmmBranch ret_blk) }
168 ; stmtC (CmmCondBranch (cmmNeWord (CmmLit zeroCLit) mod_reg_val)
170 ; stmtC (CmmBranch init_blk)
173 else emitSimpleProc real_init_lbl ret_code
175 -- Make the "plain" procedure jump to the "real" init procedure
176 ; emitSimpleProc plain_init_lbl jump_to_init
178 -- When compiling the module in which the 'main' function lives,
179 -- (that is, this_mod == main_mod)
180 -- we inject an extra stg_init procedure for stg_init_ZCMain, for the
181 -- RTS to invoke. We must consult the -main-is flag in case the
182 -- user specified a different function to Main.main
183 ; whenC (this_mod == main_mod)
184 (emitSimpleProc plain_main_init_lbl jump_to_init)
187 plain_init_lbl = mkPlainModuleInitLabel hmods this_mod
188 real_init_lbl = mkModuleInitLabel hmods this_mod way
189 plain_main_init_lbl = mkPlainModuleInitLabel hmods rOOT_MAIN
191 jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) [])
193 mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep
195 main_mod = case mb_main_mod of
196 Just mod_name -> mkModule mod_name
199 -- Main refers to GHC.TopHandler.runIO, so make sure we call the
200 -- init function for GHC.TopHandler.
202 | this_mod == main_mod = [pREL_TOP_HANDLER]
206 { -- Set mod_reg to 1 to record that we've been here
207 stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1)))
209 -- Now do local stuff
210 ; initCostCentres cost_centre_info
211 ; mapCs (registerModuleImport hmods way)
212 (imported_mods++extra_imported_mods)
215 -- The return-code pops the work stack by
216 -- incrementing Sp, and then jumpd to the popped item
217 ret_code = stmtsC [ CmmAssign spReg (cmmRegOffW spReg 1)
218 , CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ]
220 -----------------------
221 registerModuleImport :: HomeModules -> String -> Module -> Code
222 registerModuleImport hmods way mod
225 | otherwise -- Push the init procedure onto the work stack
226 = stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
227 , CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel hmods mod way)) ]
232 Cost-centre profiling: Besides the usual stuff, we must produce
233 declarations for the cost-centres defined in this module;
235 (The local cost-centres involved in this are passed into the
239 initCostCentres :: CollectedCCs -> Code
240 -- Emit the declarations, and return code to register them
241 initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
242 | not opt_SccProfilingOn = nopC
244 = do { mapM_ emitCostCentreDecl local_CCs
245 ; mapM_ emitCostCentreStackDecl singleton_CCSs
246 ; mapM_ emitRegisterCC local_CCs
247 ; mapM_ emitRegisterCCS singleton_CCSs
251 %************************************************************************
253 \subsection[codegen-top-bindings]{Converting top-level STG bindings}
255 %************************************************************************
257 @cgTopBinding@ is only used for top-level bindings, since they need
258 to be allocated statically (not in the heap) and need to be labelled.
259 No unboxed bindings can happen at top level.
261 In the code below, the static bindings are accumulated in the
262 @MkCgState@, and transferred into the ``statics'' slot by @forkStatics@.
263 This is so that we can write the top level processing in a compositional
264 style, with the increasing static environment being plumbed as a state
268 cgTopBinding :: DynFlags -> HomeModules -> (StgBinding,[(Id,[Id])]) -> Code
269 cgTopBinding dflags hmods (StgNonRec id rhs, srts)
270 = do { id' <- maybeExternaliseId dflags id
271 ; mapM_ (mkSRT hmods [id']) srts
272 ; (id,info) <- cgTopRhs id' rhs
273 ; addBindC id info -- Add the *un-externalised* Id to the envt,
274 -- so we find it when we look up occurrences
277 cgTopBinding dflags hmods (StgRec pairs, srts)
278 = do { let (bndrs, rhss) = unzip pairs
279 ; bndrs' <- mapFCs (maybeExternaliseId dflags) bndrs
280 ; let pairs' = zip bndrs' rhss
281 ; mapM_ (mkSRT hmods bndrs') srts
282 ; _new_binds <- fixC (\ new_binds -> do
283 { addBindsC new_binds
284 ; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
287 mkSRT :: HomeModules -> [Id] -> (Id,[Id]) -> Code
288 mkSRT hmods these (id,[]) = nopC
289 mkSRT hmods these (id,ids)
290 = do { ids <- mapFCs remap ids
292 ; emitRODataLits (mkSRTLabel (idName id))
293 (map (CmmLabel . mkClosureLabel hmods . idName) ids)
296 -- Sigh, better map all the ids against the environment in
297 -- case they've been externalised (see maybeExternaliseId below).
298 remap id = case filter (==id) these of
299 (id':_) -> returnFC id'
300 [] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) }
302 -- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs
303 -- to enclose the listFCs in cgTopBinding, but that tickled the
304 -- statics "error" call in initC. I DON'T UNDERSTAND WHY!
306 cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo)
307 -- The Id is passed along for setting up a binding...
308 -- It's already been externalised if necessary
310 cgTopRhs bndr (StgRhsCon cc con args)
311 = forkStatics (cgTopRhsCon bndr con args)
313 cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body)
314 = ASSERT(null fvs) -- There should be no free variables
315 setSRTLabel (mkSRTLabel (idName bndr)) $
316 forkStatics (cgTopRhsClosure bndr cc bi srt upd_flag args body)
320 %************************************************************************
322 \subsection{Stuff to support splitting}
324 %************************************************************************
326 If we're splitting the object, we need to externalise all the top-level names
327 (and then make sure we only use the externalised one in any C label we use
328 which refers to this name).
331 maybeExternaliseId :: DynFlags -> Id -> FCode Id
332 maybeExternaliseId dflags id
333 | dopt Opt_SplitObjs dflags, -- Externalise the name for -split-objs
334 isInternalName name = do { mod <- moduleName
335 ; returnFC (setIdName id (externalise mod)) }
336 | otherwise = returnFC id
338 externalise mod = mkExternalName uniq mod new_occ Nothing loc
340 uniq = nameUnique name
341 new_occ = mkLocalOcc uniq (nameOccName name)
342 loc = nameSrcLoc name
343 -- We want to conjure up a name that can't clash with any
344 -- existing name. So we generate
346 -- where 243 is the unique.