fix -funwind-tables

[Richard Henderson <rth at twiddle dot net>]

I noticed that -funwind-tables wasn't emitting anything.  It's clear
that it's more useful (in C anyway) to use -fexceptions instead, since
that allows us to elide some amount of the data.  But I thought this
worth fixing anyway.


r~


        * dwarf2out.c (output_call_frame_info): Ignore fde->nothrow as an
        optimization when flag_exceptions not enabled.

Index: dwarf2out.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/dwarf2out.c,v
retrieving revision 1.390.2.4
diff -c -p -d -u -r1.390.2.4 dwarf2out.c
--- dwarf2out.c	28 Mar 2003 07:54:09 -0000	1.390.2.4
+++ dwarf2out.c	2 Apr 2003 17:12:08 -0000
@@ -1812,7 +1812,7 @@ output_call_frame_info (for_eh)
   dw_fde_ref fde;
   dw_cfi_ref cfi;
   char l1[20], l2[20], section_start_label[20];
-  int any_lsda_needed = 0;
+  bool any_lsda_needed = false;
   char augmentation[6];
   int augmentation_size;
   int fde_encoding = DW_EH_PE_absptr;
@@ -1823,17 +1823,19 @@ output_call_frame_info (for_eh)
   if (fde_table_in_use == 0)
     return;
 
-  /* If we don't have any functions we'll want to unwind out of, don't emit any
-     EH unwind information.  */
+  /* If we don't have any functions we'll want to unwind out of, don't
+     emit any EH unwind information.  Note that if exceptions aren't
+     enabled, we won't have collected nothrow information, and if we
+     asked for asynchronous tables, we always want this info.  */
   if (for_eh)
     {
-      int any_eh_needed = flag_asynchronous_unwind_tables;
+      bool any_eh_needed = !flag_exceptions || flag_asynchronous_unwind_tables;
 
       for (i = 0; i < fde_table_in_use; i++)
 	if (fde_table[i].uses_eh_lsda)
-	  any_eh_needed = any_lsda_needed = 1;
+	  any_eh_needed = any_lsda_needed = true;
 	else if (! fde_table[i].nothrow)
-	  any_eh_needed = 1;
+	  any_eh_needed = true;
 
       if (! any_eh_needed)
 	return;
@@ -1971,7 +1973,7 @@ output_call_frame_info (for_eh)
       fde = &fde_table[i];
 
       /* Don't emit EH unwind info for leaf functions that don't need it.  */
-      if (!flag_asynchronous_unwind_tables && for_eh
+      if (for_eh && !flag_asynchronous_unwind_tables && flag_exceptions
 	  && (fde->nothrow || fde->all_throwers_are_sibcalls)
 	  && !fde->uses_eh_lsda)
 	continue;