Add setjmp/longjmp exception handling.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@13968 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 166 insertions, 0 deletions

diff --git a/gcc/libgcc2.c b/gcc/libgcc2.c
index 338707029ce..725161865dd 100644
--- a/gcc/libgcc2.c
+++ b/gcc/libgcc2.c
@@ -3102,6 +3102,172 @@ EH_TABLE_LOOKUP
 
 #else
 
+void
+__default_terminate ()
+{
+  abort ();
+}
+
+void (*__terminate_func)() = __default_terminate;
+
+void
+__terminate ()
+{
+  (*__terminate_func)();
+}
+
+/* Calls to __sjthrow are generated by the compiler when an exception
+   is raised when using the setjmp/longjmp exception handling codegen
+   method.  */
+
+extern longjmp (void *, int);
+
+extern void *__eh_type;
+
+static void *top_elt[2];
+void **__dynamic_handler_chain = top_elt;
+
+/* Routine to get the head of the current thread's dynamic handler chain
+   use for exception handling.
+
+   TODO: make thread safe.  */
+
+void ***
+__get_dynamic_handler_chain ()
+{
+  return &__dynamic_handler_chain;
+}
+
+/* This is used to throw an exception when the setjmp/longjmp codegen
+   method is used for exception handling.
+
+   We call __terminate if there are no handlers left (we know this
+   when the dynamic handler chain is top_elt).  Otherwise we run the
+   cleanup actions off the dynamic cleanup stack, and pop the top of
+   the dynamic handler chain, and use longjmp to transfer back to the
+   associated handler.  */
+
+void
+__sjthrow ()
+{
+  void ***dhc = __get_dynamic_handler_chain ();
+  void *jmpbuf;
+  void (*func)(void *, int);
+  void *arg;
+  void ***cleanup;
+
+  /* The cleanup chain is one word into the buffer.  Get the cleanup
+     chain.  */
+  cleanup = (void***)&(*dhc)[1];
+
+  /* If there are any cleanups in the chain, run them now.  */
+  if (cleanup[0])
+    {
+      double store[200];
+      void **buf = (void**)store;
+      buf[1] = 0;
+      buf[0] = (*dhc);
+
+      /* try { */
+      if (! setjmp (&buf[2]))
+	{
+	  *dhc = buf;
+	  while (cleanup[0])
+	    {
+	      func = (void(*)(void*, int))cleanup[0][1];
+	      arg = (void*)cleanup[0][2];
+
+	      /* Update this before running the cleanup.  */
+	      cleanup[0] = (void **)cleanup[0][0];
+
+	      (*func)(arg, 2);
+	    }
+	  *dhc = buf[0];
+	}
+      /* catch (...) */
+      else
+	{
+	  __terminate ();
+	}
+    }
+  
+  /* We must call terminate if we try and rethrow an exception, when
+     there is no exception currently active and when there are no
+     handlers left.  */
+  if (! __eh_type || (*dhc) == top_elt)
+    __terminate ();
+    
+  /* Find the jmpbuf associated with the top element of the dynamic
+     handler chain.  The jumpbuf starts two words into the buffer.  */
+  jmpbuf = &(*dhc)[2];
+
+  /* Then we pop the top element off the dynamic handler chain.  */
+  *dhc = (void**)(*dhc)[0];
+
+  /* And then we jump to the handler.  */
+
+#ifdef USE_BUILTIN_SETJMP
+  __builtin_longjmp (jmpbuf, 1);
+#else
+  longjmp (jmpbuf, 1);
+#endif
+}
+
+/* Run cleanups on the dynamic cleanup stack for the current dynamic
+   handler, then pop the handler off the dynamic handler stack, and
+   then throw.  This is used to skip the first handler, and transfer
+   control to the next handler in the dynamic handler stack.  */
+
+void
+__sjpopnthrow ()
+{
+  void ***dhc = __get_dynamic_handler_chain ();
+  void *jmpbuf;
+  void (*func)(void *, int);
+  void *arg;
+  void ***cleanup;
+
+  /* The cleanup chain is one word into the buffer.  Get the cleanup
+     chain.  */
+  cleanup = (void***)&(*dhc)[1];
+
+  /* If there are any cleanups in the chain, run them now.  */
+  if (cleanup[0])
+    {
+      double store[200];
+      void **buf = (void**)store;
+      buf[1] = 0;
+      buf[0] = (*dhc);
+
+      /* try { */
+      if (! setjmp (&buf[2]))
+	{
+	  *dhc = buf;
+	  while (cleanup[0])
+	    {
+	      func = (void(*)(void*, int))cleanup[0][1];
+	      arg = (void*)cleanup[0][2];
+
+	      /* Update this before running the cleanup.  */
+	      cleanup[0] = (void **)cleanup[0][0];
+
+	      (*func)(arg, 2);
+	    }
+	  *dhc = buf[0];
+	}
+      /* catch (...) */
+      else
+	{
+	  __terminate ();
+	}
+    }
+
+  /* Then we pop the top element off the dynamic handler chain.  */
+  *dhc = (void**)(*dhc)[0];
+
+  __sjthrow ();
+}
+
 typedef struct {
   void *start;
   void *end;