re PR tree-optimization/37709 (inlining causes explosion in debug info)

	PR tree-optimization/37709                                              
	* tree.c (block_ultimate_origin): Move here from dwarf2out.             
	* tree.h (block_ultimate_origin): Declare.                              
	* dwarf2out.c (block_ultimate_origin): Move to tree.c                   
	* tree-ssa-live.c (remove_unused_scope_block_p):
	Eliminate blocks containig no instructions nor live variables nor
	nested blocks.
	(dump_scope_block): New function.
	(remove_unused_locals): Enable removal of dead blocks by default;
	enable dumping at TDF_DETAILS.

From-SVN: r144381

6 files changed, 117 insertions, 60 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1961e74..01968ba 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+2009-02-23  Jan Hubicka  <jh@suse.cz>
+
+	PR tree-optimization/37709                                              
+	* tree.c (block_ultimate_origin): Move here from dwarf2out.             
+	* tree.h (block_ultimate_origin): Declare.                              
+	* dwarf2out.c (block_ultimate_origin): Move to tree.c                   
+	* tree-ssa-live.c (remove_unused_scope_block_p):
+	Eliminate blocks containig no instructions nor live variables nor
+	nested blocks.
+	(dump_scope_block): New function.
+	(remove_unused_locals): Enable removal of dead blocks by default;
+	enable dumping at TDF_DETAILS.                                          
+
 2008-02-21  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* config/i386/i386.c (classify_argument): Don't allow COImode
diff --git a/gcc/dbxout.c b/gcc/dbxout.c
index f4a2792..6cfa55f 100644
--- a/gcc/dbxout.c
+++ b/gcc/dbxout.c
@@ -3593,7 +3593,7 @@ dbxout_block (tree block, int depth, tree args)
   while (block)
     {
       /* Ignore blocks never expanded or otherwise marked as real.  */
-      if (TREE_USED (block) && TREE_ASM_WRITTEN (block))
+      if (TREE_ASM_WRITTEN (block))
 	{
 	  int did_output;
 	  int blocknum = BLOCK_NUMBER (block);
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index d3de6e6..2e5f032 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -4947,7 +4947,6 @@ static const char *dwarf_tag_name (unsigned);
 static const char *dwarf_attr_name (unsigned);
 static const char *dwarf_form_name (unsigned);
 static tree decl_ultimate_origin (const_tree);
-static tree block_ultimate_origin (const_tree);
 static tree decl_class_context (tree);
 static void add_dwarf_attr (dw_die_ref, dw_attr_ref);
 static inline enum dw_val_class AT_class (dw_attr_ref);
@@ -5772,51 +5771,6 @@ decl_ultimate_origin (const_tree decl)
   return DECL_ABSTRACT_ORIGIN (decl);
 }
 
-/* Determine the "ultimate origin" of a block.  The block may be an inlined
-   instance of an inlined instance of a block which is local to an inline
-   function, so we have to trace all of the way back through the origin chain
-   to find out what sort of node actually served as the original seed for the
-   given block.  */
-
-static tree
-block_ultimate_origin (const_tree block)
-{
-  tree immediate_origin = BLOCK_ABSTRACT_ORIGIN (block);
-
-  /* output_inline_function sets BLOCK_ABSTRACT_ORIGIN for all the
-     nodes in the function to point to themselves; ignore that if
-     we're trying to output the abstract instance of this function.  */
-  if (BLOCK_ABSTRACT (block) && immediate_origin == block)
-    return NULL_TREE;
-
-  if (immediate_origin == NULL_TREE)
-    return NULL_TREE;
-  else
-    {
-      tree ret_val;
-      tree lookahead = immediate_origin;
-
-      do
-	{
-	  ret_val = lookahead;
-	  lookahead = (TREE_CODE (ret_val) == BLOCK
-		       ? BLOCK_ABSTRACT_ORIGIN (ret_val) : NULL);
-	}
-      while (lookahead != NULL && lookahead != ret_val);
-
-      /* The block's abstract origin chain may not be the *ultimate* origin of
-	 the block. It could lead to a DECL that has an abstract origin set.
-	 If so, we want that DECL's abstract origin (which is what DECL_ORIGIN
-	 will give us if it has one).  Note that DECL's abstract origins are
-	 supposed to be the most distant ancestor (or so decl_ultimate_origin
-	 claims), so we don't need to loop following the DECL origins.  */
-      if (DECL_P (ret_val))
-	return DECL_ORIGIN (ret_val);
-
-      return ret_val;
-    }
-}
-
 /* Get the class to which DECL belongs, if any.  In g++, the DECL_CONTEXT
    of a virtual function may refer to a base class, so we check the 'this'
    parameter.  */
diff --git a/gcc/tree-ssa-live.c b/gcc/tree-ssa-live.c
index 8ebf30e..81e65f7 100644
--- a/gcc/tree-ssa-live.c
+++ b/gcc/tree-ssa-live.c
@@ -485,10 +485,13 @@ remove_unused_scope_block_p (tree scope)
       next = &TREE_CHAIN (*t);
 
       /* Debug info of nested function refers to the block of the
-	 function.  */
+	 function.  We might stil call it even if all statements
+	 of function it was nested into was elliminated.
+	 
+	 TODO: We can actually look into cgraph to see if function
+	 will be output to file.  */
       if (TREE_CODE (*t) == FUNCTION_DECL)
 	unused = false;
-
       /* Remove everything we don't generate debug info for.  */
       else if (DECL_IGNORED_P (*t))
 	{
@@ -506,15 +509,24 @@ remove_unused_scope_block_p (tree scope)
 
       /* When we are not doing full debug info, we however can keep around
 	 only the used variables for cfgexpand's memory packing saving quite
-	 a lot of memory.  */
+	 a lot of memory.  
+
+	 For sake of -g3, we keep around those vars but we don't count this as
+	 use of block, so innermost block with no used vars and no instructions
+	 can be considered dead.  We only want to keep around blocks user can
+	 breakpoint into and ask about value of optimized out variables. 
+
+	 Similarly we need to keep around types at least until all variables of
+	 all nested blocks are gone.  We track no information on whether given
+	 type is used or not.  */
+
       else if (debug_info_level == DINFO_LEVEL_NORMAL
 	       || debug_info_level == DINFO_LEVEL_VERBOSE
 	       /* Removing declarations before inlining is going to affect
 		  DECL_UID that in turn is going to affect hashtables and
 		  code generation.  */
 	       || !cfun->after_inlining)
-	unused = false;
-
+	;
       else
 	{
 	  *t = TREE_CHAIN (*t);
@@ -537,10 +549,7 @@ remove_unused_scope_block_p (tree scope)
 	    nsubblocks ++;
 	  }
 	else
-	  {
-	    gcc_assert (!BLOCK_VARS (*t));
-	    *t = BLOCK_CHAIN (*t);
-	  }
+	  *t = BLOCK_CHAIN (*t);
       }
     else
       {
@@ -576,6 +585,38 @@ mark_all_vars_used (tree *expr_p, void *data)
   walk_tree (expr_p, mark_all_vars_used_1, data, NULL);
 }
 
+/* Dump scope blocks.  */
+
+static void
+dump_scope_block (FILE *file, int indent, tree scope, int flags)
+{
+  tree var, t;
+
+  fprintf (file, "\n%*sScope block #%i %s\n",indent, "" , BLOCK_NUMBER (scope),
+  	   TREE_USED (scope) ? "" : "(unused)");
+  if (BLOCK_ABSTRACT_ORIGIN (scope) && DECL_P (block_ultimate_origin (scope)))
+    {
+      fprintf (file, "\n%*sOriginating from ",indent + 1, "");
+      print_generic_decl (file, block_ultimate_origin (scope), flags);
+      fprintf (file, "\n");
+    }
+  for (var = BLOCK_VARS (scope); var; var = TREE_CHAIN (var))
+    {
+      bool used = false;
+      var_ann_t ann;
+
+      if ((ann = var_ann (var))
+	  && ann->used)
+	used = true;
+
+      fprintf (file, "%*s",indent, "");
+      print_generic_decl (file, var, flags);
+      fprintf (file, "%s\n", used ? "" : " (unused)");
+    }
+  for (t = BLOCK_SUBBLOCKS (scope); t ; t = BLOCK_CHAIN (t))
+    dump_scope_block (file, indent + 2, t, flags);
+}
+
 
 /* Remove local variables that are not referenced in the IL.  */
 
@@ -588,8 +629,7 @@ remove_unused_locals (void)
   var_ann_t ann;
   bitmap global_unused_vars = NULL;
 
-  if (optimize)
-    mark_scope_block_unused (DECL_INITIAL (current_function_decl));
+  mark_scope_block_unused (DECL_INITIAL (current_function_decl));
 
   /* Assume all locals are unused.  */
   FOR_EACH_REFERENCED_VAR (t, rvi)
@@ -716,8 +756,12 @@ remove_unused_locals (void)
 	&& !TREE_ADDRESSABLE (t)
 	&& (optimize || DECL_ARTIFICIAL (t)))
       remove_referenced_var (t);
-  if (optimize)
-    remove_unused_scope_block_p (DECL_INITIAL (current_function_decl));
+  remove_unused_scope_block_p (DECL_INITIAL (current_function_decl));
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    {
+      fprintf (dump_file, "Scope blocks after cleanups:\n");
+      dump_scope_block (dump_file, 0, DECL_INITIAL (current_function_decl), false);
+    }
 }
 
 
diff --git a/gcc/tree.c b/gcc/tree.c
index 03c54cc..423c868 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -9199,4 +9199,49 @@ build_target_option_node (void)
   return t;
 }
 
+/* Determine the "ultimate origin" of a block.  The block may be an inlined
+   instance of an inlined instance of a block which is local to an inline
+   function, so we have to trace all of the way back through the origin chain
+   to find out what sort of node actually served as the original seed for the
+   given block.  */
+
+tree
+block_ultimate_origin (const_tree block)
+{
+  tree immediate_origin = BLOCK_ABSTRACT_ORIGIN (block);
+
+  /* output_inline_function sets BLOCK_ABSTRACT_ORIGIN for all the
+     nodes in the function to point to themselves; ignore that if
+     we're trying to output the abstract instance of this function.  */
+  if (BLOCK_ABSTRACT (block) && immediate_origin == block)
+    return NULL_TREE;
+
+  if (immediate_origin == NULL_TREE)
+    return NULL_TREE;
+  else
+    {
+      tree ret_val;
+      tree lookahead = immediate_origin;
+
+      do
+	{
+	  ret_val = lookahead;
+	  lookahead = (TREE_CODE (ret_val) == BLOCK
+		       ? BLOCK_ABSTRACT_ORIGIN (ret_val) : NULL);
+	}
+      while (lookahead != NULL && lookahead != ret_val);
+
+      /* The block's abstract origin chain may not be the *ultimate* origin of
+	 the block. It could lead to a DECL that has an abstract origin set.
+	 If so, we want that DECL's abstract origin (which is what DECL_ORIGIN
+	 will give us if it has one).  Note that DECL's abstract origins are
+	 supposed to be the most distant ancestor (or so decl_ultimate_origin
+	 claims), so we don't need to loop following the DECL origins.  */
+      if (DECL_P (ret_val))
+	return DECL_ORIGIN (ret_val);
+
+      return ret_val;
+    }
+}
+
 #include "gt-tree.h"
diff --git a/gcc/tree.h b/gcc/tree.h
index 5a7e765..ae42913 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -5022,6 +5022,7 @@ extern bool gimple_alloca_call_p (const_gimple);
 extern bool alloca_call_p (const_tree);
 extern bool must_pass_in_stack_var_size (enum machine_mode, const_tree);
 extern bool must_pass_in_stack_var_size_or_pad (enum machine_mode, const_tree);
+extern tree block_ultimate_origin (const_tree);
 
 /* In attribs.c.  */