Change the way module initialisation is done (#3252, #4417)

Previously the code generator generated small code fragments labelled
with __stginit_M for each module M, and these performed whatever
initialisation was necessary for that module and recursively invoked
the initialisation functions for imported modules.  This appraoch had
drawbacks:

 - FFI users had to call hs_add_root() to ensure the correct
   initialisation routines were called.  This is a non-standard,
   and ugly, API.

 - unless we were using -split-objs, the __stginit dependencies would
   entail linking the whole transitive closure of modules imported,
   whether they were actually used or not.  In an extreme case (#4387,
   #4417), a module from GHC might be imported for use in Template
   Haskell or an annotation, and that would force the whole of GHC to
   be needlessly linked into the final executable.

So now instead we do our initialisation with C functions marked with
__attribute__((constructor)), which are automatically invoked at
program startup time (or DSO load-time).  The C initialisers are
emitted into the stub.c file.  This means that every time we compile
with -prof or -hpc, we now get a stub file, but thanks to #3687 that
is now invisible to the user.

There are some refactorings in the RTS (particularly for HPC) to
handle the fact that initialisers now get run earlier than they did
before.

The __stginit symbols are still generated, and the hs_add_root()
function still exists (but does nothing), for backwards compatibility.

1 files changed, 7 insertions, 66 deletions

diff --git a/compiler/cmm/CLabel.hs b/compiler/cmm/CLabel.hs
index 4d9596197e..c151a26391 100644
--- a/compiler/cmm/CLabel.hs
+++ b/compiler/cmm/CLabel.hs
@@ -51,9 +51,7 @@ module CLabel (
 
 	mkAsmTempLabel,
 
-	mkModuleInitLabel,
-	mkPlainModuleInitLabel,
-	mkModuleInitTableLabel,
+        mkPlainModuleInitLabel,
 
 	mkSplitMarkerLabel,
 	mkDirty_MUT_VAR_Label,
@@ -70,10 +68,7 @@ module CLabel (
 	mkRtsPrimOpLabel,
 	mkRtsSlowTickyCtrLabel,
 
-	moduleRegdLabel,
-	moduleRegTableLabel,
-
-	mkSelectorInfoLabel,
+        mkSelectorInfoLabel,
 	mkSelectorEntryLabel,
 
 	mkCmmInfoLabel,
@@ -102,7 +97,6 @@ module CLabel (
         mkDeadStripPreventer,
 
         mkHpcTicksLabel,
-        mkHpcModuleNameLabel,
 
         hasCAF,
 	infoLblToEntryLbl, entryLblToInfoLbl, cvtToClosureLbl, cvtToSRTLbl,
@@ -202,23 +196,9 @@ data CLabel
   | StringLitLabel
 	{-# UNPACK #-} !Unique
 
-  | ModuleInitLabel 
-	Module			-- the module name
-	String			-- its "way"
-	-- at some point we might want some kind of version number in
-	-- the module init label, to guard against compiling modules in
-	-- the wrong order.  We can't use the interface file version however,
-	-- because we don't always recompile modules which depend on a module
-	-- whose version has changed.
-
-  | PlainModuleInitLabel	-- without the version & way info
+  | PlainModuleInitLabel        -- without the version & way info
 	Module
 
-  | ModuleInitTableLabel	-- table of imported modules to init
-	Module
-
-  | ModuleRegdLabel
-
   | CC_Label  CostCentre
   | CCS_Label CostCentreStack
 
@@ -242,9 +222,6 @@ data CLabel
   -- | Per-module table of tick locations
   | HpcTicksLabel Module
 
-  -- | Per-module name of the module for Hpc
-  | HpcModuleNameLabel
-
   -- | Label of an StgLargeSRT
   | LargeSRTLabel
         {-# UNPACK #-} !Unique
@@ -490,7 +467,6 @@ mkRtsSlowTickyCtrLabel pat = RtsLabel (RtsSlowTickyCtr pat)
 
 -- Constructing Code Coverage Labels
 mkHpcTicksLabel                = HpcTicksLabel
-mkHpcModuleNameLabel           = HpcModuleNameLabel
 
 
 -- Constructing labels used for dynamic linking
@@ -515,19 +491,9 @@ mkStringLitLabel		= StringLitLabel
 mkAsmTempLabel :: Uniquable a => a -> CLabel
 mkAsmTempLabel a		= AsmTempLabel (getUnique a)
 
-mkModuleInitLabel :: Module -> String -> CLabel
-mkModuleInitLabel mod way	= ModuleInitLabel mod way
-
 mkPlainModuleInitLabel :: Module -> CLabel
 mkPlainModuleInitLabel mod	= PlainModuleInitLabel mod
 
-mkModuleInitTableLabel :: Module -> CLabel
-mkModuleInitTableLabel mod	= ModuleInitTableLabel mod
-
-moduleRegdLabel			= ModuleRegdLabel
-moduleRegTableLabel		= ModuleInitTableLabel	
-
-
 -- -----------------------------------------------------------------------------
 -- Converting between info labels and entry/ret labels.
 
@@ -591,10 +557,7 @@ needsCDecl (LargeSRTLabel _)		= False
 needsCDecl (LargeBitmapLabel _)		= False
 needsCDecl (IdLabel _ _ _)		= True
 needsCDecl (CaseLabel _ _)	        = True
-needsCDecl (ModuleInitLabel _ _)	= True
-needsCDecl (PlainModuleInitLabel _)	= True
-needsCDecl (ModuleInitTableLabel _)	= True
-needsCDecl ModuleRegdLabel		= False
+needsCDecl (PlainModuleInitLabel _)     = True
 
 needsCDecl (StringLitLabel _)		= False
 needsCDecl (AsmTempLabel _)		= False
@@ -612,7 +575,6 @@ needsCDecl l@(ForeignLabel{})		= not (isMathFun l)
 needsCDecl (CC_Label _)			= True
 needsCDecl (CCS_Label _)		= True
 needsCDecl (HpcTicksLabel _)            = True
-needsCDecl HpcModuleNameLabel           = False
 
 
 -- | Check whether a label is a local temporary for native code generation
@@ -725,11 +687,8 @@ externallyVisibleCLabel :: CLabel -> Bool -- not C "static"
 externallyVisibleCLabel (CaseLabel _ _)		= False
 externallyVisibleCLabel (StringLitLabel _)	= False
 externallyVisibleCLabel (AsmTempLabel _)	= False
-externallyVisibleCLabel (ModuleInitLabel _ _)	= True
 externallyVisibleCLabel (PlainModuleInitLabel _)= True
-externallyVisibleCLabel (ModuleInitTableLabel _)= False
-externallyVisibleCLabel ModuleRegdLabel		= False
-externallyVisibleCLabel (RtsLabel _)		= True
+externallyVisibleCLabel (RtsLabel _)            = True
 externallyVisibleCLabel (CmmLabel _ _ _)	= True
 externallyVisibleCLabel (ForeignLabel{})	= True
 externallyVisibleCLabel (IdLabel name _ _)	= isExternalName name
@@ -737,8 +696,7 @@ externallyVisibleCLabel (CC_Label _)		= True
 externallyVisibleCLabel (CCS_Label _)		= True
 externallyVisibleCLabel (DynamicLinkerLabel _ _)  = False
 externallyVisibleCLabel (HpcTicksLabel _)	= True
-externallyVisibleCLabel HpcModuleNameLabel	= False
-externallyVisibleCLabel (LargeBitmapLabel _)	= False
+externallyVisibleCLabel (LargeBitmapLabel _)    = False
 externallyVisibleCLabel (LargeSRTLabel _)	= False
 
 -- -----------------------------------------------------------------------------
@@ -777,9 +735,7 @@ labelType (RtsLabel (RtsApInfoTable _ _))       = DataLabel
 labelType (RtsLabel (RtsApFast _))              = CodeLabel
 labelType (CaseLabel _ CaseReturnInfo)          = DataLabel
 labelType (CaseLabel _ _)	                = CodeLabel
-labelType (ModuleInitLabel _ _)                 = CodeLabel
 labelType (PlainModuleInitLabel _)              = CodeLabel
-labelType (ModuleInitTableLabel _)              = DataLabel
 labelType (LargeSRTLabel _)                     = DataLabel
 labelType (LargeBitmapLabel _)                  = DataLabel
 labelType (ForeignLabel _ _ _ IsFunction)	= CodeLabel
@@ -837,10 +793,8 @@ labelDynamic this_pkg lbl =
    CmmLabel pkg _ _     -> True 
 
 #endif
-   ModuleInitLabel m _    -> not opt_Static && this_pkg /= (modulePackageId m)
    PlainModuleInitLabel m -> not opt_Static && this_pkg /= (modulePackageId m)
-   ModuleInitTableLabel m -> not opt_Static && this_pkg /= (modulePackageId m)
-   
+
    -- Note that DynamicLinkerLabels do NOT require dynamic linking themselves.
    _ 		     -> False
 
@@ -1008,9 +962,6 @@ pprCLbl (RtsLabel (RtsPrimOp primop))
 pprCLbl (RtsLabel (RtsSlowTickyCtr pat)) 
   = ptext (sLit "SLOW_CALL_") <> text pat <> ptext (sLit "_ctr")
 
-pprCLbl ModuleRegdLabel
-  = ptext (sLit "_module_registered")
-
 pprCLbl (ForeignLabel str _ _ _)
   = ftext str
 
@@ -1019,22 +970,12 @@ pprCLbl (IdLabel name cafs flavor) = ppr name <> ppIdFlavor flavor
 pprCLbl (CC_Label cc) 		= ppr cc
 pprCLbl (CCS_Label ccs) 	= ppr ccs
 
-pprCLbl (ModuleInitLabel mod way)
-   = ptext (sLit "__stginit_") <> ppr mod
-	<> char '_' <> text way
-
 pprCLbl (PlainModuleInitLabel mod)
    = ptext (sLit "__stginit_") <> ppr mod
 
-pprCLbl (ModuleInitTableLabel mod)
-   = ptext (sLit "__stginittable_") <> ppr mod
-
 pprCLbl (HpcTicksLabel mod)
   = ptext (sLit "_hpc_tickboxes_")  <> ppr mod <> ptext (sLit "_hpc")
 
-pprCLbl HpcModuleNameLabel
-  = ptext (sLit "_hpc_module_name_str")
-
 ppIdFlavor :: IdLabelInfo -> SDoc
 ppIdFlavor x = pp_cSEP <>
 	       (case x of