3.4 patch for PR 13956

[Zack Weinberg <zack at codesourcery dot com>]

And here's the patch for 3.4.  Exact same concept, some hunks moved up
or down a little.  Now with extra special bonus correct PR number!

zw


        PR 13956
        * dbxout.c (dbx_output_lbrac, dbx_output_rbrac): New
        functions, broken out of dbxout_block.
        (dbxout_block): The block at depth 0 should get LBRAC/RBRAC
        stabs too, if it contains symbols.  Use the begin_label and
        the Lscope label (emitted by dbxout_function_end) for the
        range of this block.
        (dbxout_function_decl): Always call dbxout_function_end.
        (dbxout_function_end): Return after emitting the "Lscope" symbol
        under the same conditions that this function formerly wasn't called.
        Add explanatory comments.

===================================================================
Index: dbxout.c
--- dbxout.c	22 Apr 2004 21:33:22 -0000	1.172.2.1
+++ dbxout.c	4 Aug 2004 07:25:46 -0000
@@ -434,6 +434,9 @@ static void
 dbxout_function_end (void)
 {
   char lscope_label_name[100];
+
+  /* The Lscope label must be emitted even if we aren't doing anything
+     else; dbxout_block needs it.  */
   /* Convert Ltext into the appropriate format for local labels in case
      the system doesn't insert underscores in front of user generated
      labels.  */
@@ -441,6 +444,16 @@ dbxout_function_end (void)
   (*targetm.asm_out.internal_label) (asmfile, "Lscope", scope_labelno);
   scope_labelno++;
 
+  /* The N_FUN tag at the end of the function is a GNU extension,
+     which may be undesirable, and is unnecessary if we do not have
+     named sections.  */
+  if (!use_gnu_debug_info_extensions
+#if defined(NO_DBX_FUNCTION_END)
+      || NO_DBX_FUNCTION_END
+#endif
+      || !targetm.have_named_sections)
+    return;
+
   /* By convention, GCC will mark the end of a function with an N_FUN
      symbol and an empty string.  */
 #ifdef DBX_OUTPUT_NFUN
@@ -774,12 +787,7 @@ dbxout_function_decl (tree decl)
 #ifdef DBX_OUTPUT_FUNCTION_END
   DBX_OUTPUT_FUNCTION_END (asmfile, decl);
 #endif
-  if (use_gnu_debug_info_extensions
-#if defined(NO_DBX_FUNCTION_END)
-      && ! NO_DBX_FUNCTION_END
-#endif
-      && targetm.have_named_sections)
-    dbxout_function_end ();
+  dbxout_function_end ();
 }
 
 #endif /* DBX_DEBUGGING_INFO  */
@@ -3037,6 +3045,46 @@ dbxout_args (tree args)
     }
 }
 
+/* Subroutine of dbxout_block.  Emit an N_LBRAC stab referencing LABEL.
+   BEGIN_LABEL is the name of the beginning of the function, which may
+   be required.  */
+static void
+dbx_output_lbrac (const char *label,
+		  const char *begin_label ATTRIBUTE_UNUSED)
+{
+#ifdef DBX_OUTPUT_LBRAC
+  DBX_OUTPUT_LBRAC (asmfile, label);
+#else
+  fprintf (asmfile, "%s%d,0,0,", ASM_STABN_OP, N_LBRAC);
+  assemble_name (asmfile, label);
+#if DBX_BLOCKS_FUNCTION_RELATIVE
+  putc ('-', asmfile);
+  assemble_name (asmfile, begin_label);
+#endif
+  fprintf (asmfile, "\n");
+#endif
+}
+
+/* Subroutine of dbxout_block.  Emit an N_RBRAC stab referencing LABEL.
+   BEGIN_LABEL is the name of the beginning of the function, which may
+   be required.  */
+static void
+dbx_output_rbrac (const char *label,
+		  const char *begin_label ATTRIBUTE_UNUSED)
+{
+#ifdef DBX_OUTPUT_RBRAC
+  DBX_OUTPUT_RBRAC (asmfile, label);
+#else
+  fprintf (asmfile, "%s%d,0,0,", ASM_STABN_OP, N_RBRAC);
+  assemble_name (asmfile, label);
+#if DBX_BLOCKS_FUNCTION_RELATIVE
+  putc ('-', asmfile);
+  assemble_name (asmfile, begin_label);
+#endif
+  fprintf (asmfile, "\n");
+#endif
+}
+
 /* Output everything about a symbol block (a BLOCK node
    that represents a scope level),
    including recursive output of contained blocks.
@@ -3057,15 +3105,11 @@ dbxout_args (tree args)
 static void
 dbxout_block (tree block, int depth, tree args)
 {
-  int blocknum = -1;
-
-#if DBX_BLOCKS_FUNCTION_RELATIVE
   const char *begin_label;
   if (current_function_func_begin_label != NULL_TREE)
     begin_label = IDENTIFIER_POINTER (current_function_func_begin_label);
   else
     begin_label = XSTR (XEXP (DECL_RTL (current_function_decl), 0), 0);
-#endif
 
   while (block)
     {
@@ -3073,6 +3117,7 @@ dbxout_block (tree block, int depth, tre
       if (TREE_USED (block) && TREE_ASM_WRITTEN (block))
 	{
 	  int did_output;
+	  int blocknum = BLOCK_NUMBER (block);
 
 	  /* In dbx format, the syms of a block come before the N_LBRAC.
 	     If nothing is output, we don't need the N_LBRAC, either.  */
@@ -3086,11 +3131,20 @@ dbxout_block (tree block, int depth, tre
 	     the block.  Use the block's tree-walk order to generate
 	     the assembler symbols LBBn and LBEn
 	     that final will define around the code in this block.  */
-	  if (depth > 0 && did_output)
+	  if (did_output)
 	    {
 	      char buf[20];
-	      blocknum = BLOCK_NUMBER (block);
-	      ASM_GENERATE_INTERNAL_LABEL (buf, "LBB", blocknum);
+	      const char *scope_start;
+
+	      if (depth == 0)
+		/* The outermost block doesn't get LBB labels; use
+		   the function symbol.  */
+		scope_start = begin_label;
+	      else
+		{
+		  ASM_GENERATE_INTERNAL_LABEL (buf, "LBB", blocknum);
+		  scope_start = buf;
+		}
 
 	      if (BLOCK_HANDLER_BLOCK (block))
 		{
@@ -3100,44 +3154,30 @@ dbxout_block (tree block, int depth, tre
 		    {
 		      fprintf (asmfile, "%s\"%s:C1\",%d,0,0,", ASM_STABS_OP,
 			       IDENTIFIER_POINTER (DECL_NAME (decl)), N_CATCH);
-		      assemble_name (asmfile, buf);
+		      assemble_name (asmfile, scope_start);
 		      fprintf (asmfile, "\n");
 		      decl = TREE_CHAIN (decl);
 		    }
 		}
-
-#ifdef DBX_OUTPUT_LBRAC
-	      DBX_OUTPUT_LBRAC (asmfile, buf);
-#else
-	      fprintf (asmfile, "%s%d,0,0,", ASM_STABN_OP, N_LBRAC);
-	      assemble_name (asmfile, buf);
-#if DBX_BLOCKS_FUNCTION_RELATIVE
-	      putc ('-', asmfile);
-	      assemble_name (asmfile, begin_label);
-#endif
-	      fprintf (asmfile, "\n");
-#endif
+	      dbx_output_lbrac (scope_start, begin_label);
 	    }
 
 	  /* Output the subblocks.  */
 	  dbxout_block (BLOCK_SUBBLOCKS (block), depth + 1, NULL_TREE);
 
 	  /* Refer to the marker for the end of the block.  */
-	  if (depth > 0 && did_output)
+	  if (did_output)
 	    {
-	      char buf[20];
-	      ASM_GENERATE_INTERNAL_LABEL (buf, "LBE", blocknum);
-#ifdef DBX_OUTPUT_RBRAC
-	      DBX_OUTPUT_RBRAC (asmfile, buf);
-#else
-	      fprintf (asmfile, "%s%d,0,0,", ASM_STABN_OP, N_RBRAC);
-	      assemble_name (asmfile, buf);
-#if DBX_BLOCKS_FUNCTION_RELATIVE
-	      putc ('-', asmfile);
-	      assemble_name (asmfile, begin_label);
-#endif
-	      fprintf (asmfile, "\n");
-#endif
+	      char buf[100];
+	      if (depth == 0)
+		/* The outermost block doesn't get LBE labels;
+		   use the "scope" label which will be emitted
+		   by dbxout_function_end.  */
+		ASM_GENERATE_INTERNAL_LABEL (buf, "Lscope", scope_labelno);
+	      else
+		ASM_GENERATE_INTERNAL_LABEL (buf, "LBE", blocknum);
+
+	      dbx_output_rbrac (buf, begin_label);
 	    }
 	}
       block = BLOCK_CHAIN (block);