2002-08-24 Stuart Hastings <stuart@apple.com>

        * function.h (struct function): Add flag
        all_throwers_are_sibcalls.
        * except.c (set_nothrow_function_flags): Replaces
        nothrow_function_p. Set new flag.
        * except.h (set_nothrow_function_flags): Replaces
        nothrow_function_p.
        * dwarf2out.c (struct dw_fde_struct): Add flag
        all_throwers_are_sibcalls.
        (output_call_frame_info): Test it.
        (dwarf2out_begin_prologue) Propagate it from cfun to
        dw_fde_struct.
        * toplev.c (rest_of_compilation): Update calls to
        nothrow_function_p.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@56561 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 34 insertions, 9 deletions

diff --git a/gcc/except.c b/gcc/except.c
index a2818c3408f..17eeae1bd80 100644
--- a/gcc/except.c
+++ b/gcc/except.c
@@ -2893,25 +2893,50 @@ can_throw_external (insn)
   return true;
 }
 
-/* True if nothing in this function can throw outside this function.  */
+/* Set current_function_nothrow and cfun->all_throwers_are_sibcalls.  */
 
-bool
-nothrow_function_p ()
+void
+set_nothrow_function_flags ()
 {
   rtx insn;
+  
+  current_function_nothrow = 1;
 
-  if (! flag_exceptions)
-    return true;
+  /* Assume cfun->all_throwers_are_sibcalls until we encounter
+     something that can throw an exception.  We specifically exempt
+     CALL_INSNs that are SIBLING_CALL_P, as these are really jumps,
+     and can't throw.  Most CALL_INSNs are not SIBLING_CALL_P, so this
+     is optimistic.  */
 
+  cfun->all_throwers_are_sibcalls = 1;
+
+  if (! flag_exceptions)
+    return;
+  
   for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
     if (can_throw_external (insn))
-      return false;
+      {
+	current_function_nothrow = 0;
+
+	if (GET_CODE (insn) != CALL_INSN || !SIBLING_CALL_P (insn))
+	  {
+	    cfun->all_throwers_are_sibcalls = 0;
+	    return;
+	  }
+      }
+
   for (insn = current_function_epilogue_delay_list; insn;
        insn = XEXP (insn, 1))
-    if (can_throw_external (XEXP (insn, 0)))
-      return false;
+    if (can_throw_external (insn))
+      {
+	current_function_nothrow = 0;
 
-  return true;
+	if (GET_CODE (insn) != CALL_INSN || !SIBLING_CALL_P (insn))
+	  {
+	    cfun->all_throwers_are_sibcalls = 0;
+	    return;
+	  }
+      }
 }