except.h (eh_nesting_info): Add new structure defintion.

Tue Aug 10 10:47:42 EDT 1999  Andrew MacLeod  <amacleod@cygnus.com>

	* except.h (eh_nesting_info): Add new structure defintion.
	(init_eh_nesting_info, free_eh_nesting_info): Add function prototypes.
	(reachable_handlers, update_rethrow_references): Add function
	prototypes.
	* rtl.h (struct rtvec_def): Update comments.  REG_EH_RETHROW takes
	a rethrow symbol instead of an integer exception region number.
	* flow.c (Make_edges): Use new exception nesting routines to determine
	which handlers are reachable from a CALL or asynchronous insn.
	Dont add an edge for calls with a REG_EH_REGION of -1 to non-local
	goto receivers.
	(delete_eh_regions): Update rethrow labels, and don't delete
	regions which are the target of a rethrow.
	* except.c (struct func_eh_entry): Add rethrow_ref field, now we can
	avoid overloading the SYMBOL_REF_USED flag.
	(rethrow_symbol_map): Use new rethrow_ref field.
	(rethrow_used): Use new rethrow_ref field.
	(expand_rethrow): REG_EH_RETHROW now has a SYMBOL_REF instead
	of an integer.  Fix formatting.
	(output_exception_table_entry): Use new rethrow_ref field.
	(can_throw): Check for EH_REGION_NOTE before deciding
	whether a CALL can throw or not.
	(scan_region): Call rethrow_used() instead of accessing data structure.
	(update_rethrow_references): New function to make sure only regions
	which are still targets of a rethrow are flagged as such.
	(process_nestinfo): New static function to initialize a handler
	list for a specific region.
	(init_eh_nesting_info): New function to allocate and initialize
	the list of all EH handlers reachable from all regions.
	(reachable_handlers): New function to retrieve the list of handlers
	reachable from a specific region and insn.
	(free_eh_nesting_info): New function to dispose of a list of
	reachable handlers.

From-SVN: r28647

1 files changed, 45 insertions, 0 deletions

diff --git a/gcc/except.h b/gcc/except.h
index 2e3e794f7f3..73bbe4dc8d7 100644
--- a/gcc/except.h
+++ b/gcc/except.h
@@ -266,6 +266,11 @@ rtx rethrow_symbol_map                          PROTO((rtx, rtx (*)(rtx)));
 
 int rethrow_used                                PROTO((int));
 
+/* Update the rethrow references to reflect rethrows which have been
+   optimized away.  */
+
+void update_rethrow_references			PROTO((void));
+
 /* Return the region number a this is the rethrow label for. */
 
 int eh_region_from_symbol                       PROTO((rtx));
@@ -278,6 +283,46 @@ struct handler_info *get_first_handler          PROTO((int));
 
 int find_all_handler_type_matches               PROTO((void ***));
 
+/* The eh_nesting_info structure is used to find a list of valid handlers
+   for any arbitrary exception region.  When init_eh_nesting_info is called,
+   the information is all pre-calculated and entered in this structure.
+   REGION_INDEX is a vector over all possible region numbers.  Since the
+   number of regions is typically much smaller than the range of block
+   numbers, this is a sparse vector and the other data structures are 
+   represented as dense vectors.  Indexed with an exception region number, this
+   returns the index to use in the other data structures to retreive the
+   correct information.
+   HANDLERS is an array of vectors which point to handler_info structures.
+   when indexed, it gives the list of all possible handlers which can 
+   be reached by a throw from this exception region.
+   NUM_HANDLERS is the equivilent array indicating how many handler
+   pointers there are in the HANDLERS vector.
+   OUTER_INDEX indicates which index represents the information for the
+   outer block.  0 indicates there is no outer context.
+   REGION_COUNT is the number of regions.  */
+
+typedef struct eh_nesting 
+{
+  int *region_index;
+  handler_info ***handlers;
+  int *num_handlers;
+  int *outer_index;
+  int region_count;
+} eh_nesting_info;
+
+/* Initialize the eh_nesting_info structure.  */
+
+eh_nesting_info *init_eh_nesting_info 		PROTO((void));
+
+/* Get a list of handlers reachable from a an exception region/insn.  */
+
+int reachable_handlers 			PROTO((int, eh_nesting_info *, rtx, 
+					       handler_info ***handlers));
+
+/* Free the eh_nesting_info structure.  */
+
+void free_eh_nesting_info 			PROTO((eh_nesting_info *));
+
 extern void init_eh				PROTO((void));
 
 /* Initialization for the per-function EH data.  */