mrs/manson:

Update documentation.

From-SVN: r12715

gcc/except.h

@@ -26,6 +26,8 @@ Boston, MA 02111-1307, USA.  */
 
 #ifdef TREE_CODE
 
+/* A stack of labels. CHAIN points to the next entry in the stack.  */
+
 struct label_node {
   union {
     rtx rlabel;
@@ -34,8 +36,19 @@ struct label_node {
   struct label_node *chain;
 };
 
-/* A entry for the exception handling stack EHSTACK or the exception
-   handling queue EHQUEUE.  */
+/* An eh_entry is used to describe one exception handling region.
+
+   START_LABEL is the label corresponding to the start of the region.
+
+   END_LABEL is the label corresponding to the end of the region.
+
+   EXCEPTION_HANDLER_LABEL is the label corresponding to the handler
+   for this region.
+
+   FINALIZATION is the tree codes for the handler, or is NULL_TREE if
+   one hasn't been generated yet, or is integer_zero_node to mark the
+   end of a group of try blocks.  */
+
 struct eh_entry {
   rtx start_label;
   rtx end_label;
@@ -44,55 +57,179 @@ struct eh_entry {
   tree finalization;
 };
 
+/* A list of EH_ENTRYs. ENTRY is the entry; CHAIN points to the next
+   entry in the list, or is NULL if this is the last entry.  */
+
 struct eh_node {
   struct eh_entry *entry;
   struct eh_node *chain;
 };
 
+/* A stack of EH_ENTRYs. TOP is the topmost entry on the stack. TOP is
+   NULL if the stack is empty.  */
+
 struct eh_stack {
   struct eh_node *top;
 };
 
+/* A queue of EH_ENTRYs. HEAD is the front of the queue; TAIL is the
+   end (the latest entry). HEAD and TAIL are NULL if the queue is
+   empty.  */
+
 struct eh_queue {
   struct eh_node *head;
   struct eh_node *tail;
 };
 
 
+extern void expand_eh_region_start		PROTO((void));
+
+extern void expand_eh_region_end		PROTO((tree));
+
+/* Push RLABEL or TLABEL onto LABELSTACK. Only one of RLABEL or TLABEL
+   should be set; the other must be NULL.  */
+
 extern void push_label_entry			PROTO((struct label_node **labelstack, rtx rlabel, tree tlabel));
+
+/* Pop the topmost entry from LABELSTACK and return its value as an
+   rtx node. If LABELSTACK is empty, return NULL.  */
+
 extern rtx pop_label_entry			PROTO((struct label_node **labelstack));
+
+/* Return the topmost entry of LABELSTACK as a tree node, or return
+   NULL_TREE if LABELSTACK is empty.  */
+
 extern tree top_label_entry			PROTO((struct label_node **labelstack));
 
+/* The stack used to keep track of the exception region corresponding to
+   the current instruction.  */
+
 extern struct eh_stack ehstack;
+
+/* A queue used to track closed exception regions whose handlers have
+   not been emitted yet.  */
+
 extern struct eh_queue ehqueue;
+
+/* A set of insns for the catch clauses in the current function. They
+   will be emitted at the end of the current function.  */
+
 extern rtx catch_clauses;
-extern tree protect_list;
 
 #endif
 
 struct function;
 
+/* Toplevel initialization for EH.  */
+
 extern void init_eh				PROTO((void));
+
+/* Initialization for the per-function EH data.  */
+
 extern void init_eh_for_function		PROTO((void));
+
+/* Saves the current per-function EH data into P.  */
+
 extern void save_eh_status			PROTO((struct function *p));
+
+/* Restores the per-function EH data from P.  */
+
 extern void restore_eh_status			PROTO((struct function *p));
-extern void add_eh_table_entry			PROTO((int));
+
+/* Adds an EH table entry for EH entry number N. Called from
+   final_scan_insn for NOTE_INSN_EH_REGION_BEG.  */
+
+extern void add_eh_table_entry			PROTO((int n));
+
+/* Returns a non-zero value if we need to output an exception table.  */
+
 extern int exception_table_p			PROTO((void));
+
+/* Outputs the exception table if we have one.  */
+
 extern void output_exception_table		PROTO((void));
-extern rtx eh_outer_context			PROTO((rtx));
+
+/* Given a return address in ADDR, determine the address we should use
+   to find the corresponding EH region.  */
+
+extern rtx eh_outer_context			PROTO((rtx addr));
+
+/* Called at the start of a block of try statements for which there is
+   a supplied catch handler.  */
+
+extern void expand_start_try_stmts 		PROTO((void));
+
+/* Called at the start of a block of catch statements. It terminates the
+   previous set of try statements.  */
+
+extern void expand_start_all_catch		PROTO((void));
+
+/* Called at the end of a block of catch statements.  */
+
+extern void expand_end_all_catch		PROTO((void));
+
+#ifdef TREE_CODE
+/* Create a new exception region and add the handler for the region
+   onto a list. These regions will be ended (and their handlers
+   emitted) when end_protect_partials is invoked.  */
+
+extern void add_partial_entry			PROTO((tree handler));
+#endif
+
+/* End all of the pending exception regions that have handlers added with
+   push_protect_entry ().  */
+
+extern void end_protect_partials		PROTO((void));
+
+/* An internal throw with a direct CONTEXT we want to throw
+   from. CONTEXT must be a label.  */
+
+extern void expand_internal_throw		PROTO((rtx context));
+
+/* Called from expand_exception_blocks and expand_end_catch_block to
+   expand and pending handlers.  */
+
+extern void expand_leftover_cleanups		PROTO((void));
+
+/* If necessary, emit insns for the start of per-function unwinder for
+   the current function.  */
+
 extern void emit_unwinder			PROTO((void));
+
+/* If necessary, emit insns for the end of the per-function unwinder
+   for the current function.  */
+
 extern void end_eh_unwinder			PROTO((void));
-extern void find_handler_labels			PROTO((void));
-extern void check_handler_labels		PROTO((void));
 
+/* Builds a list of handler labels and puts them in the global
+   variable exception_handler_labels.  */
+
+extern void find_exception_handler_labels	PROTO((void));
+
+/* Performs sanity checking on the check_exception_handler_labels
+   list.  */
+
+extern void check_exception_handler_labels	PROTO((void));
+
+/* A stack used to keep track of the label used to resume normal program
+   flow out of the current exception handler region.  */
 
 extern struct label_node *caught_return_label_stack;
+
+/* A random area used for purposes elsewhere.  */
+
 extern struct label_node *false_label_stack;
 
+/* A list of labels used for exception handlers. It is created by
+   find_exception_handler_labels for the optimization passes.  */
+
 extern rtx exception_handler_labels;
 
 /* The rtx for the saved PC value.  */
 
 extern rtx eh_saved_pc_rtx;
 
+/* Performs optimizations for exception handling, such as removing
+   unnecessary exception regions. Invoked from jump_optimize ().  */
+
 extern void exception_optimize			PROTO((void));