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, 1 insertions, 48 deletions

diff --git a/compiler/codeGen/CgHpc.hs b/compiler/codeGen/CgHpc.hs
index 8da2715ac2..48756505c3 100644
--- a/compiler/codeGen/CgHpc.hs
+++ b/compiler/codeGen/CgHpc.hs
@@ -6,24 +6,14 @@
 --
 -----------------------------------------------------------------------------
 
-module CgHpc (cgTickBox, initHpc, hpcTable) where
+module CgHpc (cgTickBox, hpcTable) where
 
 import OldCmm
 import CLabel
 import Module
 import OldCmmUtils
-import CgUtils
 import CgMonad
-import CgForeignCall
-import ForeignCall
-import ClosureInfo
-import FastString
 import HscTypes
-import Panic
-import BasicTypes
-
-import Data.Char
-import Data.Word
 
 cgTickBox :: Module -> Int -> Code
 cgTickBox mod n = do
@@ -40,47 +30,10 @@ cgTickBox mod n = do
 
 hpcTable :: Module -> HpcInfo -> Code
 hpcTable this_mod (HpcInfo hpc_tickCount _) = do
-                        emitData ReadOnlyData
-                                        [ CmmDataLabel mkHpcModuleNameLabel
-                                        , CmmString $ map (fromIntegral . ord)
-                                                         (full_name_str)
-                                                      ++ [0]
-                                        ]
                         emitData Data $ [ CmmDataLabel (mkHpcTicksLabel this_mod)
                                         ] ++
                                         [ CmmStaticLit (CmmInt 0 W64)
                                         | _ <- take hpc_tickCount [0::Int ..]
                                         ]
-  where
-    module_name_str = moduleNameString (Module.moduleName this_mod)
-    full_name_str   = if modulePackageId this_mod == mainPackageId 
-		      then module_name_str
-		      else packageIdString (modulePackageId this_mod) ++ "/" ++
-			   module_name_str
 
 hpcTable _ (NoHpcInfo {}) = error "TODO: impossible"
-
-initHpc :: Module -> HpcInfo -> Code
-initHpc this_mod (HpcInfo tickCount hashNo)
-  = do { id <- newTemp bWord
-       ; emitForeignCall'
-               PlayRisky
-               [CmmHinted id NoHint]
-               (CmmCallee
-                 (CmmLit $ CmmLabel $ mkForeignLabel mod_alloc Nothing ForeignLabelInThisPackage IsFunction)
-                  CCallConv
-               )
-               [ CmmHinted (mkLblExpr mkHpcModuleNameLabel) AddrHint
-               , CmmHinted (word32 tickCount) NoHint
-               , CmmHinted (word32 hashNo)    NoHint
-               , CmmHinted (CmmLit $ CmmLabel $ mkHpcTicksLabel $ this_mod) AddrHint
-               ]
-               (Just [])
-               NoC_SRT -- No SRT b/c we PlayRisky
-               CmmMayReturn
-       }
-  where
-       word32 i = CmmLit (CmmInt (fromIntegral (fromIntegral i :: Word32)) W32)
-       mod_alloc = mkFastString "hs_hpc_module"
-initHpc _ (NoHpcInfo {}) = panic "initHpc: NoHpcInfo"
-