re PR debug/51902 (lexical_blocks inside inlined_subroutines generate duplicate debug_ranges)

	PR debug/51902
	* tree.h (BLOCK_SAME_RANGE): Define.
	* function.c (block_fragments_nreverse): Clear BLOCK_SAME_RANGE
	if BLOCK_FRAGMENT_CHAIN is non-NULL, but has it cleared.
	Also clear BLOCK_SAME_RANGE if fragment chain's supercontext fragment
	isn't equal to supercontext fragment's fragment chain.
	Adjust BLOCK_SUPERCONTEXT to point to supercontext fragment's
	fragment origin.
	(blocks_nreverse_all): Likewise.
	(reorder_blocks_1): Compute BLOCK_SAME_RANGE bits.  Set
	BLOCK_SUPERCONTEXT to supercontext fragment instead of
	supercontext fragment's fragment origin.
	* dwarf2out.c (add_high_low_attributes): If stmt has the same
	range as its parent (or parents thereof etc.), use the parent's
	DW_AT_ranges value instead of creating a new .debug_ranges range.

From-SVN: r184958

1 files changed, 53 insertions, 1 deletions

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 63c46c0..b5f921a 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -18134,7 +18134,9 @@ add_high_low_attributes (tree stmt, dw_die_ref die)
   if (BLOCK_FRAGMENT_CHAIN (stmt)
       && (dwarf_version >= 3 || !dwarf_strict))
     {
-      tree chain;
+      tree chain, superblock = NULL_TREE;
+      dw_die_ref pdie;
+      dw_attr_ref attr = NULL;
 
       if (inlined_function_outer_scope_p (stmt))
 	{
@@ -18143,6 +18145,56 @@ add_high_low_attributes (tree stmt, dw_die_ref die)
 	  add_AT_lbl_id (die, DW_AT_entry_pc, label);
 	}
 
+      /* Optimize duplicate .debug_ranges lists or even tails of
+	 lists.  If this BLOCK has same ranges as its supercontext,
+	 lookup DW_AT_ranges attribute in the supercontext (and
+	 recursively so), verify that the ranges_table contains the
+	 right values and use it instead of adding a new .debug_range.  */
+      for (chain = stmt, pdie = die;
+	   BLOCK_SAME_RANGE (chain);
+	   chain = BLOCK_SUPERCONTEXT (chain))
+	{
+	  dw_attr_ref new_attr;
+
+	  pdie = pdie->die_parent;
+	  if (pdie == NULL)
+	    break;
+	  if (BLOCK_SUPERCONTEXT (chain) == NULL_TREE)
+	    break;
+	  new_attr = get_AT (pdie, DW_AT_ranges);
+	  if (new_attr == NULL
+	      || new_attr->dw_attr_val.val_class != dw_val_class_range_list)
+	    break;
+	  attr = new_attr;
+	  superblock = BLOCK_SUPERCONTEXT (chain);
+	}
+      if (attr != NULL
+	  && (ranges_table[attr->dw_attr_val.v.val_offset
+			   / 2 / DWARF2_ADDR_SIZE].num
+	      == BLOCK_NUMBER (superblock))
+	  && BLOCK_FRAGMENT_CHAIN (superblock))
+	{
+	  unsigned long off = attr->dw_attr_val.v.val_offset
+			      / 2 / DWARF2_ADDR_SIZE;
+	  unsigned long supercnt = 0, thiscnt = 0;
+	  for (chain = BLOCK_FRAGMENT_CHAIN (superblock);
+	       chain; chain = BLOCK_FRAGMENT_CHAIN (chain))
+	    {
+	      ++supercnt;
+	      gcc_checking_assert (ranges_table[off + supercnt].num
+				   == BLOCK_NUMBER (chain));
+	    }
+	  gcc_checking_assert (ranges_table[off + supercnt + 1].num == 0);
+	  for (chain = BLOCK_FRAGMENT_CHAIN (stmt);
+	       chain; chain = BLOCK_FRAGMENT_CHAIN (chain))
+	    ++thiscnt;
+	  gcc_assert (supercnt >= thiscnt);
+	  add_AT_range_list (die, DW_AT_ranges,
+			     (off + supercnt - thiscnt)
+			     * 2 * DWARF2_ADDR_SIZE);
+	  return;
+	}
+
       add_AT_range_list (die, DW_AT_ranges, add_ranges (stmt));
 
       chain = BLOCK_FRAGMENT_CHAIN (stmt);