Keep C main separate from rts lib and link it in for standalone progs

Previously the object code for the C main function lived in the rts
lib, however this is a problem when the rts is built as a shared lib.
With Windows DLLs it always causes problems while on ELF systems it's a
problem when the user decides to use their own C main function rather
than a Haskell Main.main. So instead we now put main in it's own tiny
little static lib libHSrtsmain.a which we install next to the rts libs.
Whenever ghc links a program (without -no-hs-main) then it also links
in -lHSrtsmain. For consistency we always do it this way now rather
than trying to do it differently for static vs shared libraries.

1 files changed, 179 insertions, 0 deletions

diff --git a/rts/RtsMain.c b/rts/RtsMain.c
new file mode 100644
index 0000000000..aa2fe0f6dc
--- /dev/null
+++ b/rts/RtsMain.c
@@ -0,0 +1,179 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team 1998-2000
+ *
+ * Main function for a standalone Haskell program.
+ *
+ * ---------------------------------------------------------------------------*/
+
+#define COMPILING_RTS_MAIN
+
+#include "PosixSource.h"
+#include "Rts.h"
+#include "RtsAPI.h"
+#include "SchedAPI.h"
+#include "RtsFlags.h"
+#include "RtsUtils.h"
+#include "RtsMain.h"
+#include "Prelude.h"
+#include "Task.h"
+#if defined(mingw32_HOST_OS)
+#include "win32/seh_excn.h"
+#endif
+#include <stdlib.h>
+
+#ifdef DEBUG
+# include "Printer.h"   /* for printing        */
+#endif
+
+#ifdef PAR
+# include "Parallel.h"
+# include "ParallelRts.h"
+# include "LLC.h"
+#endif
+
+#if defined(GRAN) || defined(PAR)
+# include "GranSimRts.h"
+#endif
+
+#ifdef HAVE_WINDOWS_H
+# include <windows.h>
+#endif
+
+extern void __stginit_ZCMain(void);
+
+/* Annoying global vars for passing parameters to real_main() below
+ * This is to get around problem with Windows SEH, see hs_main(). */
+static int progargc;
+static char **progargv;
+static void (*progmain_init)(void);   /* This will be __stginit_ZCMain */
+static StgClosure *progmain_closure;  /* This will be ZCMain_main_closure */
+
+/* Hack: we assume that we're building a batch-mode system unless 
+ * INTERPRETER is set
+ */
+#ifndef INTERPRETER /* Hack */
+static void real_main(void)
+{
+    int exit_status;
+    SchedulerStatus status;
+    /* all GranSim/GUM init is done in startupHaskell; sets IAmMainThread! */
+
+    startupHaskell(progargc,progargv,progmain_init);
+
+    /* kick off the computation by creating the main thread with a pointer
+       to mainIO_closure representing the computation of the overall program;
+       then enter the scheduler with this thread and off we go;
+      
+       the same for GranSim (we have only one instance of this code)
+
+       in a parallel setup, where we have many instances of this code
+       running on different PEs, we should do this only for the main PE
+       (IAmMainThread is set in startupHaskell) 
+    */
+
+#  if defined(PAR)
+
+#   if defined(DEBUG)
+    { /* a wait loop to allow attachment of gdb to UNIX threads */
+      nat i, j, s;
+
+      for (i=0, s=0; i<(nat)RtsFlags.ParFlags.wait; i++)
+	for (j=0; j<1000000; j++) 
+	  s += j % 65536;
+    }
+    IF_PAR_DEBUG(verbose,
+		 belch("Passed wait loop"));
+#   endif
+
+    if (IAmMainThread == rtsTrue) {
+      IF_PAR_DEBUG(verbose,
+		   debugBelch("==== [%x] Main Thread Started ...\n", mytid));
+
+      /* ToDo: Dump event for the main thread */
+      status = rts_mainLazyIO(progmain_closure, NULL);
+    } else {
+      /* Just to show we're alive */
+      IF_PAR_DEBUG(verbose,
+		   debugBelch("== [%x] Non-Main PE enters scheduler via taskStart() without work ...\n",
+			   mytid));
+     
+      /* all non-main threads enter the scheduler without work */
+      taskStart();       
+      status = Success;  // declare victory (see shutdownParallelSystem)
+    }
+
+#  elif defined(GRAN)
+
+    /* ToDo: Dump event for the main thread */
+    status = rts_mainLazyIO(progmain_closure, NULL);
+
+#  else /* !PAR && !GRAN */
+
+    /* ToDo: want to start with a larger stack size */
+    { 
+	Capability *cap = rts_lock();
+	cap = rts_evalLazyIO(cap,progmain_closure, NULL);
+	status = rts_getSchedStatus(cap);
+	taskTimeStamp(myTask());
+	rts_unlock(cap);
+    }
+
+#  endif /* !PAR && !GRAN */
+
+    /* check the status of the entire Haskell computation */
+    switch (status) {
+    case Killed:
+      errorBelch("main thread exited (uncaught exception)");
+      exit_status = EXIT_KILLED;
+      break;
+    case Interrupted:
+      errorBelch("interrupted");
+      exit_status = EXIT_INTERRUPTED;
+      break;
+    case HeapExhausted:
+      exit_status = EXIT_HEAPOVERFLOW;
+      break;
+    case Success:
+      exit_status = EXIT_SUCCESS;
+      break;
+#if defined(PAR)
+    case NoStatus:
+      errorBelch("main thread PE killed; probably due to failure of another PE; check /tmp/pvml...");
+      exit_status = EXIT_KILLED;
+      break;
+#endif 
+    default:
+      barf("main thread completed with invalid status");
+    }
+    shutdownHaskellAndExit(exit_status);
+}
+
+/* The rts entry point from a compiled program using a Haskell main function.
+ * This gets called from a tiny main function which gets linked into each
+ * compiled Haskell program that uses a Haskell main function.
+ *
+ * We expect the caller to pass __stginit_ZCMain for main_init and
+ * ZCMain_main_closure for main_closure. The reason we cannot refer to
+ * these symbols directly is because we're inside the rts and we do not know
+ * for sure that we'll be using a Haskell main function.
+ */
+int hs_main(int argc, char *argv[], void (*main_init)(void), StgClosure *main_closure)
+{
+    /* We do this dance with argc and argv as otherwise the SEH exception
+       stuff (the BEGIN/END CATCH below) on Windows gets confused */
+    progargc = argc;
+    progargv = argv;
+    progmain_init    = main_init;
+    progmain_closure = main_closure;
+
+#if defined(mingw32_HOST_OS)
+    BEGIN_CATCH
+#endif
+    real_main();
+#if defined(mingw32_HOST_OS)
+    END_CATCH
+#endif
+    return 0; /* not reached, but keeps gcc -Wall happy */
+}
+# endif /* BATCH_MODE */