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%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[CodeGen]{@CodeGen@: main module of the code generator}
This module says how things get going at the top level.
@codeGen@ is the interface to the outside world. The \tr{cgTop*}
functions drive the mangling of top-level bindings.
%************************************************************************
%* *
\subsection[codeGen-outside-interface]{The code generator's offering to the world}
%* *
%************************************************************************
\begin{code}
module CodeGen ( codeGen ) where
#include "HsVersions.h"
import DriverState ( v_Build_tag, v_MainModIs )
-- Kludge (??) so that CgExpr is reached via at least one non-SOURCE
-- import. Before, that wasn't the case, and CM therefore didn't
-- bother to compile it.
import CgExpr ( {-NOTHING!-} ) -- DO NOT DELETE THIS IMPORT
import CgProf
import CgMonad
import CgBindery ( CgIdInfo, addBindC, addBindsC, getCgIdInfo,
cgIdInfoId )
import CgClosure ( cgTopRhsClosure )
import CgCon ( cgTopRhsCon, cgTyCon )
import CgUtils ( cmmRegOffW, emitRODataLits, cmmNeWord, emitRtsCall )
import CLabel ( mkSRTLabel, mkClosureLabel, moduleRegdLabel,
mkPlainModuleInitLabel, mkModuleInitLabel )
import Cmm
import CmmUtils ( zeroCLit, mkIntCLit, mkLblExpr )
import PprCmm ( pprCmms )
import MachOp ( wordRep, MachHint(..) )
import StgSyn
import PrelNames ( gHC_PRIM, rOOT_MAIN, mAIN_Name, pREL_TOP_HANDLER )
import CmdLineOpts ( DynFlags, DynFlag(..), opt_EnsureSplittableC,
opt_SccProfilingOn )
import HscTypes ( ForeignStubs(..), TypeEnv, typeEnvTyCons )
import CostCentre ( CollectedCCs )
import Id ( Id, idName, setIdName )
import Name ( nameSrcLoc, nameOccName, nameUnique, isInternalName, mkExternalName )
import OccName ( mkLocalOcc )
import TyCon ( isDataTyCon )
import Module ( Module, mkModuleName )
import ErrUtils ( dumpIfSet_dyn, showPass )
import Panic ( assertPanic )
import qualified Module ( moduleName )
#ifdef DEBUG
import Outputable
#endif
import DATA_IOREF ( readIORef )
\end{code}
\begin{code}
codeGen :: DynFlags
-> Module
-> TypeEnv
-> ForeignStubs
-> [Module] -- directly-imported modules
-> CollectedCCs -- (Local/global) cost-centres needing declaring/registering.
-> [(StgBinding,[(Id,[Id])])] -- Bindings to convert, with SRTs
-> IO [Cmm] -- Output
codeGen dflags this_mod type_env foreign_stubs imported_mods
cost_centre_info stg_binds
= do
{ showPass dflags "CodeGen"
; way <- readIORef v_Build_tag
; mb_main_mod <- readIORef v_MainModIs
; let tycons = typeEnvTyCons type_env
data_tycons = filter isDataTyCon tycons
-- Why?
-- ; mapM_ (\x -> seq x (return ())) data_tycons
; code_stuff <- initC this_mod $ do
{ cmm_binds <- mapM (getCmm . cgTopBinding) stg_binds
; cmm_tycons <- mapM cgTyCon data_tycons
; cmm_init <- getCmm (mkModuleInit way cost_centre_info
this_mod mb_main_mod
foreign_stubs imported_mods)
; return (cmm_binds ++ concat cmm_tycons ++ [cmm_init])
}
-- Put datatype_stuff after code_stuff, because the
-- datatype closure table (for enumeration types) to
-- (say) PrelBase_True_closure, which is defined in
-- code_stuff
; dumpIfSet_dyn dflags Opt_D_dump_cmm "Cmm" (pprCmms code_stuff)
; return code_stuff }
\end{code}
%************************************************************************
%* *
\subsection[codegen-init]{Module initialisation code}
%* *
%************************************************************************
/* -----------------------------------------------------------------------------
Module initialisation
The module initialisation code looks like this, roughly:
FN(__stginit_Foo) {
JMP_(__stginit_Foo_1_p)
}
FN(__stginit_Foo_1_p) {
...
}
We have one version of the init code with a module version and the
'way' attached to it. The version number helps to catch cases
where modules are not compiled in dependency order before being
linked: if a module has been compiled since any modules which depend on
it, then the latter modules will refer to a different version in their
init blocks and a link error will ensue.
The 'way' suffix helps to catch cases where modules compiled in different
ways are linked together (eg. profiled and non-profiled).
We provide a plain, unadorned, version of the module init code
which just jumps to the version with the label and way attached. The
reason for this is that when using foreign exports, the caller of
startupHaskell() must supply the name of the init function for the "top"
module in the program, and we don't want to require that this name
has the version and way info appended to it.
-------------------------------------------------------------------------- */
We initialise the module tree by keeping a work-stack,
* pointed to by Sp
* that grows downward
* Sp points to the last occupied slot
\begin{code}
mkModuleInit
:: String -- the "way"
-> CollectedCCs -- cost centre info
-> Module
-> Maybe String -- Just m ==> we have flag: -main-is Foo.baz
-> ForeignStubs
-> [Module]
-> Code
mkModuleInit way cost_centre_info this_mod mb_main_mod foreign_stubs imported_mods
= do {
-- Allocate the static boolean that records if this
-- module has been registered already
; emitData Data [CmmDataLabel moduleRegdLabel,
CmmStaticLit zeroCLit]
; emitSimpleProc real_init_lbl $ do
{ -- The return-code pops the work stack by
-- incrementing Sp, and then jumpd to the popped item
ret_blk <- forkLabelledCode $ stmtsC
[ CmmAssign spReg (cmmRegOffW spReg 1)
, CmmJump (CmmLoad (cmmRegOffW spReg (-1)) wordRep) [] ]
; init_blk <- forkLabelledCode $ do
{ mod_init_code; stmtC (CmmBranch ret_blk) }
; stmtC (CmmCondBranch (cmmNeWord (CmmLit zeroCLit) mod_reg_val)
ret_blk)
; stmtC (CmmBranch init_blk)
}
-- Make the "plain" procedure jump to the "real" init procedure
; emitSimpleProc plain_init_lbl jump_to_init
-- When compiling the module in which the 'main' function lives,
-- (that is, Module.moduleName this_mod == main_mod_name)
-- we inject an extra stg_init procedure for stg_init_ZCMain, for the
-- RTS to invoke. We must consult the -main-is flag in case the
-- user specified a different function to Main.main
; whenC (Module.moduleName this_mod == main_mod_name)
(emitSimpleProc plain_main_init_lbl jump_to_init)
}
where
plain_init_lbl = mkPlainModuleInitLabel this_mod
real_init_lbl = mkModuleInitLabel this_mod way
plain_main_init_lbl = mkPlainModuleInitLabel rOOT_MAIN
jump_to_init = stmtC (CmmJump (mkLblExpr real_init_lbl) [])
mod_reg_val = CmmLoad (mkLblExpr moduleRegdLabel) wordRep
main_mod_name = case mb_main_mod of
Just mod_name -> mkModuleName mod_name
Nothing -> mAIN_Name
-- Main refers to GHC.TopHandler.runIO, so make sure we call the
-- init function for GHC.TopHandler.
extra_imported_mods
| Module.moduleName this_mod == main_mod_name = [pREL_TOP_HANDLER]
| otherwise = []
mod_init_code = do
{ -- Set mod_reg to 1 to record that we've been here
stmtC (CmmStore (mkLblExpr moduleRegdLabel) (CmmLit (mkIntCLit 1)))
-- Now do local stuff
; registerForeignExports foreign_stubs
; initCostCentres cost_centre_info
; mapCs (registerModuleImport way) (imported_mods++extra_imported_mods)
}
-----------------------
registerModuleImport :: String -> Module -> Code
registerModuleImport way mod
| mod == gHC_PRIM
= nopC
| otherwise -- Push the init procedure onto the work stack
= stmtsC [ CmmAssign spReg (cmmRegOffW spReg (-1))
, CmmStore (CmmReg spReg) (mkLblExpr (mkModuleInitLabel mod way)) ]
-----------------------
registerForeignExports :: ForeignStubs -> Code
registerForeignExports NoStubs
= nopC
registerForeignExports (ForeignStubs _ _ _ fe_bndrs)
= mapM_ mk_export_register fe_bndrs
where
mk_export_register bndr
= emitRtsCall SLIT("getStablePtr")
[ (CmmLit (CmmLabel (mkClosureLabel (idName bndr))), PtrHint) ]
\end{code}
Cost-centre profiling: Besides the usual stuff, we must produce
declarations for the cost-centres defined in this module;
(The local cost-centres involved in this are passed into the
code-generator.)
\begin{code}
initCostCentres :: CollectedCCs -> Code
-- Emit the declarations, and return code to register them
initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
| not opt_SccProfilingOn = nopC
| otherwise
= do { mapM_ emitCostCentreDecl local_CCs
; mapM_ emitCostCentreStackDecl singleton_CCSs
; mapM_ emitRegisterCC local_CCs
; mapM_ emitRegisterCCS singleton_CCSs
}
\end{code}
%************************************************************************
%* *
\subsection[codegen-top-bindings]{Converting top-level STG bindings}
%* *
%************************************************************************
@cgTopBinding@ is only used for top-level bindings, since they need
to be allocated statically (not in the heap) and need to be labelled.
No unboxed bindings can happen at top level.
In the code below, the static bindings are accumulated in the
@MkCgState@, and transferred into the ``statics'' slot by @forkStatics@.
This is so that we can write the top level processing in a compositional
style, with the increasing static environment being plumbed as a state
variable.
\begin{code}
cgTopBinding :: (StgBinding,[(Id,[Id])]) -> Code
cgTopBinding (StgNonRec id rhs, srts)
= do { id' <- maybeExternaliseId id
; mapM_ (mkSRT [id']) srts
; (id,info) <- cgTopRhs id' rhs
; addBindC id info -- Add the *un-externalised* Id to the envt,
-- so we find it when we look up occurrences
}
cgTopBinding (StgRec pairs, srts)
= do { let (bndrs, rhss) = unzip pairs
; bndrs' <- mapFCs maybeExternaliseId bndrs
; let pairs' = zip bndrs' rhss
; mapM_ (mkSRT bndrs') srts
; new_binds <- fixC (\ new_binds -> do
{ addBindsC new_binds
; mapFCs ( \ (b,e) -> cgTopRhs b e ) pairs' })
; nopC }
mkSRT :: [Id] -> (Id,[Id]) -> Code
mkSRT these (id,[]) = nopC
mkSRT these (id,ids)
= do { ids <- mapFCs remap ids
; id <- remap id
; emitRODataLits (mkSRTLabel (idName id))
(map (CmmLabel . mkClosureLabel . idName) ids)
}
where
-- Sigh, better map all the ids against the environment in
-- case they've been externalised (see maybeExternaliseId below).
remap id = case filter (==id) these of
(id':_) -> returnFC id'
[] -> do { info <- getCgIdInfo id; return (cgIdInfoId info) }
-- Urgh! I tried moving the forkStatics call from the rhss of cgTopRhs
-- to enclose the listFCs in cgTopBinding, but that tickled the
-- statics "error" call in initC. I DON'T UNDERSTAND WHY!
cgTopRhs :: Id -> StgRhs -> FCode (Id, CgIdInfo)
-- The Id is passed along for setting up a binding...
-- It's already been externalised if necessary
cgTopRhs bndr (StgRhsCon cc con args)
= forkStatics (cgTopRhsCon bndr con args)
cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag srt args body)
= ASSERT(null fvs) -- There should be no free variables
setSRTLabel (mkSRTLabel (idName bndr)) $
forkStatics (cgTopRhsClosure bndr cc bi srt upd_flag args body)
\end{code}
%************************************************************************
%* *
\subsection{Stuff to support splitting}
%* *
%************************************************************************
If we're splitting the object, we need to externalise all the top-level names
(and then make sure we only use the externalised one in any C label we use
which refers to this name).
\begin{code}
maybeExternaliseId :: Id -> FCode Id
maybeExternaliseId id
| opt_EnsureSplittableC, -- Externalise the name for -split-objs
isInternalName name = do { mod <- moduleName
; returnFC (setIdName id (externalise mod)) }
| otherwise = returnFC id
where
externalise mod = mkExternalName uniq mod new_occ Nothing loc
name = idName id
uniq = nameUnique name
new_occ = mkLocalOcc uniq (nameOccName name)
loc = nameSrcLoc name
-- We want to conjure up a name that can't clash with any
-- existing name. So we generate
-- Mod_$L243foo
-- where 243 is the unique.
\end{code}
|