except.c (can_throw): See through a SEQUENCE.

        * except.c (can_throw): See through a SEQUENCE.
        (nothrow_function_p): New fn.
        * except.h: Declare it.
        * function.c (current_function_nothrow): New var.
        (prepare_function_start): Initialize it.
        * output.h: Declare it.
        * toplev.c (rest_of_compilation): Set it.
        * dwarf2out.c (dwarf2out_begin_prologue): Use it.

From-SVN: r32449

7 files changed, 59 insertions, 17 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a362174..cc420c7 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2000-03-09  Jason Merrill  <jason@casey.cygnus.com>
+
+	* except.c (can_throw): See through a SEQUENCE.
+	(nothrow_function_p): New fn.
+	* except.h: Declare it.
+	* function.c (current_function_nothrow): New var.
+	(prepare_function_start): Initialize it.
+	* output.h: Declare it.
+	* toplev.c (rest_of_compilation): Set it.
+	* dwarf2out.c (dwarf2out_begin_prologue): Use it.
+
 2000-03-09  Zack Weinberg  <zack@wolery.cumb.org>
 
 	* cpphash.c (collect_formal_parameters): strncmp returns 0 for
@@ -409,7 +420,7 @@ Mon Mar  6 15:22:29 2000  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>
 	(struct tree_int_cst): int_cst_low is now unsigned HOST_WIDE_INT.
 	(attribute_hash_list, type_hash_canon): hashcode is now unsigned.
 	(type_hash_lookup, type_hash_add, type_hash_list): Likewise.
-	(min_precision): Result is unsignd.
+	(min_precision): Result is unsigned.
 	(add_double, neg_double, mul_double): Low word is unsigned.
 	(lshift_double, rshift_double, lrotate_double): Likewise.
 	(rrotate_double, div_and_round_double): Likewise.
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 20e8a1b..0f18779 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -1889,9 +1889,7 @@ dwarf2out_begin_prologue ()
   fde->dw_fde_current_label = NULL;
   fde->dw_fde_end = NULL;
   fde->dw_fde_cfi = NULL;
-
-  /* Normally, only calls can throw, so a leaf function will never throw.  */
-  fde->nothrow = (current_function_is_leaf && !asynchronous_exceptions);
+  fde->nothrow = current_function_nothrow;
 
   args_size = old_args_size = 0;
 }
@@ -7394,7 +7392,10 @@ add_abstract_origin_attribute (die, origin)
 
          Doing this for nested functions is wrong, however; functions are
 	 distinct units, and our context might not even be inline.  */
-      tree fn = decl_function_context (origin);
+      tree fn = origin;
+      if (TYPE_P (fn))
+	fn = TYPE_STUB_DECL (fn);
+      fn = decl_function_context (fn);
       if (fn)
 	gen_abstract_function (fn);
     }
diff --git a/gcc/except.c b/gcc/except.c
index 7ecfaf8..987305a 100644
--- a/gcc/except.c
+++ b/gcc/except.c
@@ -1646,16 +1646,7 @@ expand_fixup_region_end (cleanup)
 }
 
 /* If we are using the setjmp/longjmp EH codegen method, we emit a
-   call to __sjthrow.
-
-   Otherwise, we emit a call to __throw and note that we threw
-   something, so we know we need to generate the necessary code for
-   __throw.
-
-   Before invoking throw, the __eh_pc variable must have been set up
-   to contain the PC being thrown from. This address is used by
-   __throw to determine which exception region (if any) is
-   responsible for handling the exception.  */
+   call to __sjthrow.  Otherwise, we emit a call to __throw.  */
 
 void
 emit_throw ()
@@ -2629,6 +2620,10 @@ static int
 can_throw (insn)
      rtx insn;
 {
+  if (GET_CODE (insn) == INSN
+      && GET_CODE (PATTERN (insn)) == SEQUENCE)
+    insn = XVECEXP (PATTERN (insn), 0, 0);
+
   /* Calls can always potentially throw exceptions, unless they have
      a REG_EH_REGION note with a value of 0 or less.  */
   if (GET_CODE (insn) == CALL_INSN)
@@ -2649,6 +2644,24 @@ can_throw (insn)
   return 0;
 }
 
+/* Return nonzero if nothing in this function can throw.  */
+
+int
+nothrow_function_p ()
+{
+  rtx insn;
+
+  for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
+    if (can_throw (insn))
+      return 0;
+  for (insn = current_function_epilogue_delay_list; insn;
+       insn = XEXP (insn, 1))
+    if (can_throw (insn))
+      return 0;
+
+  return 1;
+}
+
 /* Scan a exception region looking for the matching end and then
    remove it if possible. INSN is the start of the region, N is the
    region number, and DELETE_OUTER is to note if anything in this
diff --git a/gcc/except.h b/gcc/except.h
index a1408c3..1087bc1 100644
--- a/gcc/except.h
+++ b/gcc/except.h
@@ -427,6 +427,10 @@ extern struct label_node *outer_context_label_stack;
 
 extern rtx exception_handler_labels;
 
+/* Return nonzero if nothing in this function can throw.  */
+
+extern int nothrow_function_p			PARAMS ((void));
+
 /* Performs optimizations for exception handling, such as removing
    unnecessary exception regions. Invoked from jump_optimize ().  */
 
diff --git a/gcc/function.c b/gcc/function.c
index 093a0d8..1ffb821 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -107,6 +107,11 @@ Boston, MA 02111-1307, USA.  */
    compiler passes. */
 int current_function_is_leaf;
 
+/* Nonzero if function being compiled doesn't contain any instructions
+   that can throw an exception.  This is set prior to final.  */
+
+int current_function_nothrow;
+
 /* Nonzero if function being compiled doesn't modify the stack pointer
    (ignoring the prologue and epilogue).  This is only valid after
    life_analysis has run. */
@@ -5760,6 +5765,7 @@ prepare_function_start ()
   current_function_calls_alloca = 0;
   current_function_contains_functions = 0;
   current_function_is_leaf = 0;
+  current_function_nothrow = 0;
   current_function_sp_is_unchanging = 0;
   current_function_uses_only_leaf_regs = 0;
   current_function_has_computed_jump = 0;
diff --git a/gcc/output.h b/gcc/output.h
index 160f124..97c6f2e 100644
--- a/gcc/output.h
+++ b/gcc/output.h
@@ -412,6 +412,11 @@ extern FILE *asm_out_file;
 
 extern int current_function_is_leaf;
 
+/* Nonzero if function being compiled doesn't contain any instructions
+   that can throw an exception.  This is set prior to final.  */
+
+extern int current_function_nothrow;
+
 /* Nonzero if function being compiled doesn't modify the stack pointer
    (ignoring the prologue and epilogue).  This is only valid after
    life_analysis has run. */
diff --git a/gcc/toplev.c b/gcc/toplev.c
index f10e1e2..8e1d5f7 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -3674,10 +3674,12 @@ rest_of_compilation (decl)
 	print_rtl_graph_with_bb (dump_base_name, ".20.stack", insns);
     }
 
-   if (ggc_p)
-     ggc_collect ();
+  if (ggc_p)
+    ggc_collect ();
 #endif
 
+  current_function_nothrow = nothrow_function_p ();
+
   /* Now turn the rtl into assembler code.  */
 
   TIMEVAR (final_time,