From 18c038b9ca6f4e60c625636506cfe5a3290475a9 Mon Sep 17 00:00:00 2001
From: Mark Mitchell <mark@codesourcery.com>
Date: Mon, 28 Feb 2000 09:51:42 +0000
Subject: emit-rtl.c (remove_unncessary_notes): Remove notes for empty blocks.

	* emit-rtl.c (remove_unncessary_notes): Remove notes for empty
	blocks.
	* final.c (next_block_index): Remove.
	(max_block_depth): Likewise.
	(pending_blocks): Likewise.
	(init_final): Don't initialize them.
	(final_start_function): Don't set next_block_index.  Set up
	BLOCK_NUMBER.
	(final_scan_insn): Use BLOCK_NUMBER, not next_block_index.
	* function.h (number_blocks): New function.
	* function.c (get_block_vector): New function.
	(identify_blocks): Use it.
	(reorder_blocks): Set NOTE_BLOCK.
	(number_blocks): New function.
	* tree.def (BLOCK): Add documentation for TREE_ASM_WRITTEN flag.
	* tree.h (BLOCK_NUMBER): New macro.
	(tree_block): Add block_num field.
	* dbxout.c (next_block_number): Remove.
	(dbxout_init): Don't set it.
	(dbxout_block): Only output blocks that have TREE_ASM_WRITTEN
	set.  Use BLOCK_NUMBER, rather than next_block_num, to determine
	block numbers.
	* toplev.c (rest_of_compilation): Always call
	find_loop_tree_blocks.  Fix indentation.
	* dwarf2out.c (next_block_number): Remove.
	(gen_lexical_block_die): Use BLOCK_NUMBER, not next_block_number,
	to determine block numbers.
	(gen_inlined_subroutine_die): Likewise.
	(gen_block_die): Only output blocks that have TREE_ASM_WRITTEN set.
	(decls_for_scope): Don't increment next_block_number.
	* dwarfout.c (next_block_number): Remove.
	(output_lexical_block_die): Use BLOCK_NUMBER, not next_block_number,
	to determine block numbers.
	(output_inlined_subroutine_die): Likewise.
	(output_block): Only output blocks that have TREE_ASM_WRITTEN set.
	(output_decls_for_scope): Don't increment next_block_number.
	* sdbout.c (next_block_number): Remove.
	(sdbout_block): Use BLOCK_NUMBER.
	(sdbout_begin_block): Simplify.
	* xcoffout.c (next_block_number): Remove.
	(xcoffout_block): Use BLOCK_NUMBER, not next_block_number.
	(xcoffout_begin_block): Don't set next_block_number.
	(xcoffout_begin_function): Likewise. Use BLOCK_NUMBER, not
	next_block_number.

From-SVN: r32228
---
 gcc/emit-rtl.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

(limited to 'gcc/emit-rtl.c')

diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index d6f736e..c6e5cb1 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -2681,6 +2681,48 @@ remove_unncessary_notes ()
 
       if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED)
 	remove_insn (insn);
+      else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
+	{
+	  /* Scan back to see if there are any non-note instructions
+	     between INSN and the beginning of this block.  If not,
+	     then there is no PC range in the generated code that will
+	     actually be in this block, so there's no point in
+	     remembering the existence of the block.  */
+	  rtx prev;
+
+	  for (prev = PREV_INSN (insn); prev; prev = PREV_INSN (prev))
+	    {
+	      /* This block contains a real instruction.  Note that we
+		 don't include labels; if the only thing in the block
+		 is a label, then there are still no PC values that
+		 lie within the block.  */
+	      if (GET_RTX_CLASS (GET_CODE (prev)) == 'i')
+		break;
+
+	      /* We're only interested in NOTEs.  */
+	      if (GET_CODE (prev) != NOTE)
+		continue;
+
+	      if (NOTE_LINE_NUMBER (prev) == NOTE_INSN_BLOCK_BEG)
+		{
+		  /* If the BLOCKs referred to by these notes don't
+		     match, then something is wrong with our BLOCK
+		     nesting structure.  */
+		  if (NOTE_BLOCK (prev) != NOTE_BLOCK (insn))
+		    abort ();
+		  
+		  remove_insn (prev);
+		  remove_insn (insn);
+		  break;
+		}
+	      else if (NOTE_LINE_NUMBER (prev) == NOTE_INSN_BLOCK_END)
+		/* There's a nested block.  We need to leave the
+		   current block in place since otherwise the debugger
+		   wouldn't be able to show symbols from our block in
+		   the nested block.  */
+		break;
+	    }
+	}
     }
 }
 
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