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, 6 insertions, 6 deletions

diff --git a/includes/rts/Hpc.h b/includes/rts/Hpc.h
index 26da35d4cd..bceb81c961 100644
--- a/includes/rts/Hpc.h
+++ b/includes/rts/Hpc.h
@@ -18,16 +18,16 @@
 typedef struct _HpcModuleInfo {
   char *modName;		// name of module
   StgWord32 tickCount;		// number of ticks
-  StgWord32 tickOffset;		// offset into a single large .tix Array
-  StgWord32 hashNo;		// Hash number for this module's mix info
+  StgWord32 hashNo;             // Hash number for this module's mix info
   StgWord64 *tixArr;		// tix Array; local for this module
+  rtsBool from_file;            // data was read from the .tix file
   struct _HpcModuleInfo *next;
 } HpcModuleInfo;
 
-int hs_hpc_module (char *modName, 
-                   StgWord32 modCount, 
-                   StgWord32 modHashNo,
-                   StgWord64 *tixArr);
+void hs_hpc_module (char *modName,
+                    StgWord32 modCount,
+                    StgWord32 modHashNo,
+                    StgWord64 *tixArr);
 
 HpcModuleInfo * hs_hpc_rootModule (void);