[commit: ghc] ghc-7.2: Fix Windows breakage (#5322). When I modified StgRun to use the pure (6145813)

[Ian Lynagh]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : ghc-7.2

http://hackage.haskell.org/trac/ghc/changeset/61458136b878afaa0f8eaf00ba0feeb945fcacbf

>---------------------------------------------------------------

commit 61458136b878afaa0f8eaf00ba0feeb945fcacbf
Author: Simon Marlow <marlowsd at gmail.com>
Date:   Mon Jul 18 13:48:53 2011 +0100

    Fix Windows breakage (#5322).  When I modified StgRun to use the pure
    assembly version as part of the fix for #5250, we inadvertently lost
    the Windows magic for extending the stack.  Win32 requires that the
    stack is extended a page at a time, otherwise you get a segfault.  The
    C compiler knows how to do this, so we now call a C stub to ensure
    there's enough stack space at each invocation of the scheduler.

>---------------------------------------------------------------

 rts/Schedule.c |    4 ++++
 rts/StgCRun.c  |   12 ++++++++++++
 rts/StgRun.h   |    4 ++++
 3 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/rts/Schedule.c b/rts/Schedule.c
index 45959a9..50e0663 100644
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -581,6 +581,10 @@ static void
 schedulePreLoop(void)
 {
   // initialisation for scheduler - what cannot go into initScheduler()  
+
+#if defined(mingw32_HOST_OS)
+    win32AllocStack();
+#endif
 }
 
 /* -----------------------------------------------------------------------------
diff --git a/rts/StgCRun.c b/rts/StgCRun.c
index 54ac041..69d9549 100644
--- a/rts/StgCRun.c
+++ b/rts/StgCRun.c
@@ -192,6 +192,18 @@ StgRunIsImplementedInAssembler(void)
     );
 }
 
+#if defined(mingw32_HOST_OS)
+// On windows the stack has to be allocated 4k at a time, otherwise
+// we get a segfault.  The C compiler knows how to do this (it calls
+// _alloca()), so we make sure that we can allocate as much stack as
+// we need:
+StgWord8 *win32AllocStack(void)
+{
+    StgWord8 stack[RESERVED_C_STACK_BYTES + 16 + 12];
+    return stack;
+}
+#endif
+
 #endif
 
 /* ----------------------------------------------------------------------------
diff --git a/rts/StgRun.h b/rts/StgRun.h
index f277097..71b92e2 100644
--- a/rts/StgRun.h
+++ b/rts/StgRun.h
@@ -11,4 +11,8 @@
 
 RTS_PRIVATE StgRegTable * StgRun (StgFunPtr f, StgRegTable *basereg);
 
+#if defined(mingw32_HOST_OS)
+StgWord8 *win32AllocStack(void);
+#endif
+
 #endif /* STGRUN_H */