flow.c (count_basic_blocks, [...]): A rethrow can occur outside of an EH region.

        * flow.c (count_basic_blocks, find_basic_blocks_1): A rethrow
        can occur outside of an EH region.
        * except.c: Correct comments about rethrow behavior.
        (rethrow_symbol_map): Do nothing if !flag_new_exceptions.

        * flow.c (make_edges): Always call make_eh_edge for calls.

From-SVN: r32432

3 files changed, 54 insertions, 29 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index be50eae..17ab03e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2000-03-08  Jason Merrill  <jason@casey.cygnus.com>
+
+	* flow.c (count_basic_blocks, find_basic_blocks_1): A rethrow
+	can occur outside of an EH region.
+	* except.c: Correct comments about rethrow behavior.
+	(rethrow_symbol_map): Do nothing if !flag_new_exceptions.
+
+2000-03-08  Andrew MacLeod  <amacleod@cygnus.com>
+
+	* flow.c (make_edges): Always call make_eh_edge for calls.
+
 2000-03-08  Zack Weinberg  <zack@wolery.cumb.org>
 
 	* cpplib.h (parse_underflow_t, CPP_NULL_BUFFER): Delete.
diff --git a/gcc/except.c b/gcc/except.c
index 405a53f..7ecfaf8 100644
--- a/gcc/except.c
+++ b/gcc/except.c
@@ -495,6 +495,7 @@ static int eh_region_from_symbol PARAMS ((rtx));
 extern struct obstack permanent_obstack;
 
 /* Generate a SYMBOL_REF for rethrow to use */
+
 static rtx
 create_rethrow_ref (region_num)
      int region_num;
@@ -566,7 +567,7 @@ top_label_entry (stack)
   return (*stack)->u.tlabel;
 }
 
-/* get an exception label. These must be on the permanent obstack */
+/* Get an exception label.  */
 
 rtx
 gen_exception_label ()
@@ -602,7 +603,8 @@ push_eh_entry (stack)
   stack->top = node;
 }
 
-/* push an existing entry onto a stack. */
+/* Push an existing entry onto a stack.  */
+
 static void
 push_entry (stack, entry)
      struct eh_stack *stack;
@@ -695,7 +697,7 @@ struct func_eh_entry
 {
   int range_number;   /* EH region number from EH NOTE insn's.  */
   rtx rethrow_label;  /* Label for rethrow.  */
-  int rethrow_ref;    /* Is rethrow referenced?  */
+  int rethrow_ref;    /* Is rethrow_label referenced?  */
   struct handler_info *handlers;
 };
 
@@ -969,6 +971,7 @@ duplicate_eh_handlers (old_note_eh_region, new_note_eh_region, map)
 
 
 /* Given a rethrow symbol, find the EH region number this is for. */
+
 static int 
 eh_region_from_symbol (sym)
      rtx sym;
@@ -984,6 +987,7 @@ eh_region_from_symbol (sym)
 
 /* Like find_func_region, but using the rethrow symbol for the region
    rather than the region number itself.  */
+
 static int
 find_func_region_from_symbol (sym)
      rtx sym;
@@ -995,12 +999,17 @@ find_func_region_from_symbol (sym)
    __rethrow as well. This performs the remap. If a symbol isn't foiund,
    the original one is returned. This is not an efficient routine,
    so don't call it on everything!! */
+
 rtx 
 rethrow_symbol_map (sym, map)
      rtx sym;
      rtx (*map) PARAMS ((rtx));
 {
   int x, y;
+
+  if (! flag_new_exceptions)
+    return sym;
+
   for (x = 0; x < current_func_eh_entry; x++)
     if (function_eh_regions[x].rethrow_label == sym)
       {
@@ -1021,6 +1030,10 @@ rethrow_symbol_map (sym, map)
   return sym;
 }
 
+/* Returns nonzero if the rethrow label for REGION is referenced
+   somewhere (i.e. we rethrow out of REGION or some other region
+   masquerading as REGION).  */
+
 int 
 rethrow_used (region)
      int region;
@@ -2011,7 +2024,7 @@ expand_rethrow (label)
 	  label = last_rethrow_symbol;
 	emit_library_call (rethrow_libfunc, 0, VOIDmode, 1, label, Pmode);
 	region = find_func_region (eh_region_from_symbol (label));
-	/* If the region is -1, it doesn't exist yet.  We should be
+	/* If the region is -1, it doesn't exist yet.  We shouldn't be
 	   trying to rethrow there yet.  */
 	if (region == -1)
 	  abort ();
@@ -2194,14 +2207,12 @@ output_exception_table_entry (file, n)
   int index = find_func_region (n);
   rtx rethrow;
   
- /* form and emit the rethrow label, if needed  */
-  rethrow = function_eh_regions[index].rethrow_label;
-  if (rethrow != NULL_RTX && !flag_new_exceptions)
-      rethrow = NULL_RTX;
-  if (rethrow != NULL_RTX && handler == NULL)
-    if (! function_eh_regions[index].rethrow_ref)
-      rethrow = NULL_RTX;
-
+  /* Form and emit the rethrow label, if needed  */
+  if (flag_new_exceptions
+      && (handler || function_eh_regions[index].rethrow_ref))
+    rethrow = function_eh_regions[index].rethrow_label;
+  else
+    rethrow = NULL_RTX;
 
   for ( ; handler != NULL || rethrow != NULL_RTX; handler = handler->next)
     {
@@ -2301,7 +2312,7 @@ output_exception_table ()
       if (i != 0)
         assemble_integer (const0_rtx, i , 1);
 
-      /* Generate the label for offset calculations on rethrows */
+      /* Generate the label for offset calculations on rethrows.  */
       ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", 0);
       assemble_label(buf);
     }
@@ -2318,7 +2329,7 @@ output_exception_table ()
   assemble_label(buf);
   assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
 
-  /* for binary compatability, the old __throw checked the second
+  /* For binary compatibility, the old __throw checked the second
      position for a -1, so we should output at least 2 -1's */
   if (! flag_new_exceptions)
     assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
@@ -2666,7 +2677,7 @@ scan_region (insn, n, delete_outer)
   /* Assume we can delete the region.  */
   int delete = 1;
 
-  /* Can't delete something which is rethrown to. */
+  /* Can't delete something which is rethrown from. */
   if (rethrow_used (n))
     delete = 0;
 
@@ -2783,9 +2794,10 @@ exception_optimize ()
     }
 }
 
-/* This function determines whether any of the exception regions in the
-   current function are targets of a rethrow or not, and set the 
-   reference flag according.  */
+/* This function determines whether the rethrow labels for any of the
+   exception regions in the current function are used or not, and set
+   the reference flag according.  */
+
 void
 update_rethrow_references ()
 {
@@ -2800,7 +2812,7 @@ update_rethrow_references ()
   saw_rethrow = (int *) xcalloc (current_func_eh_entry, sizeof (int));
 
   /* Determine what regions exist, and whether there are any rethrows
-     to those regions or not.  */
+     from those regions or not.  */
   for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
     if (GET_CODE (insn) == CALL_INSN)
       {
@@ -3336,7 +3348,7 @@ reachable_handlers (block, info, insn, handlers)
   if (insn && GET_CODE (insn) == CALL_INSN)
     {
       /* RETHROWs specify a region number from which we are going to rethrow.
-	 This means we wont pass control to handlers in the specified
+	 This means we won't pass control to handlers in the specified
 	 region, but rather any region OUTSIDE the specified region.
 	 We accomplish this by setting block to the outer_index of the
 	 specified region.  */
diff --git a/gcc/flow.c b/gcc/flow.c
index e134794..5704835 100644
--- a/gcc/flow.c
+++ b/gcc/flow.c
@@ -469,8 +469,9 @@ count_basic_blocks (f)
 	  prev_call = insn;
 	  call_had_abnormal_edge = 0;
 
-	  /* If there is a specified EH region, we have an edge.  */
-	  if (eh_region && region > 0)
+	  /* If there is an EH region or rethrow, we have an edge.  */
+	  if ((eh_region && region > 0)
+	      || find_reg_note (insn, REG_EH_RETHROW, NULL_RTX))
 	    call_had_abnormal_edge = 1;
 	  else
 	    {
@@ -541,8 +542,9 @@ find_basic_blocks_1 (f)
 	  int region = (note ? XWINT (XEXP (note, 0), 0) : 1);
 	  call_has_abnormal_edge = 0;
 
-	  /* If there is an EH region, we have an edge.  */
-	  if (eh_list && region > 0)
+	  /* If there is an EH region or rethrow, we have an edge.  */
+	  if ((eh_list && region > 0)
+	      || find_reg_note (insn, REG_EH_RETHROW, NULL_RTX))
 	    call_has_abnormal_edge = 1;
 	  else
 	    {
@@ -983,10 +985,10 @@ make_edges (label_value_list)
 
       if (code == CALL_INSN || asynchronous_exceptions)
 	{
-	  /* If there's an EH region active at the end of a block,
-	     add the appropriate edges.  */
-	  if (bb->eh_end >= 0)
-	    make_eh_edge (edge_cache, eh_nest_info, bb, insn, bb->eh_end);
+	  /* Add any appropriate EH edges.  We do this unconditionally
+	     since there may be a REG_EH_REGION or REG_EH_RETHROW note
+	     on the call, and this needn't be within an EH region.  */
+	  make_eh_edge (edge_cache, eh_nest_info, bb, insn, bb->eh_end);
 
 	  /* If we have asynchronous exceptions, do the same for *all*
 	     exception regions active in the block.  */
@@ -1778,7 +1780,7 @@ delete_eh_regions ()
 	  {
 	    int num = NOTE_EH_HANDLER (insn);
 	    /* A NULL handler indicates a region is no longer needed,
-	       as long as it isn't the target of a rethrow.  */
+	       as long as its rethrow label isn't used.  */
 	    if (get_first_handler (num) == NULL && ! rethrow_used (num))
 	      {
 		NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;