[PATCH] Two DW_OP_GNU_variable_value fixes / tweaks

[PATCH] Two DW_OP_GNU_variable_value fixes / tweaks

[Richard Biener]

While bringing early LTO debug up-to-speed I noticed the following two
issues.  The first patch avoids useless work in 
note_variable_value_in_expr and actually makes use of the DIE we
eventually create in resolve_variable_value_in_expr.

The second avoids generating a DW_OP_GNU_variable_value for a decl
we'll never have a DIE for -- this might be less obvious than the
other patch but I think we'll also never have any other debug info
we can resolve the decl with(?)

Bootstrapped and tested the first patch sofar
on x86_64-unknown-linux-gnu, 2nd is pending.

Ok?

Thanks,
Richard.

2017-05-15  Richard Biener  <rguenther@suse.de>

	* dwarf2out.c (resolve_variable_value_in_expr): Lookup DIE
	just generated.
	(note_variable_value_in_expr): If we resolved the decl ref
	do not push to the stack.

Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c	(revision 248055)
+++ gcc/dwarf2out.c	(working copy)
@@ -30109,8 +30109,9 @@ resolve_variable_value_in_expr (dw_attr_
 	      break;
 	    }
 	  /* Create DW_TAG_variable that we can refer to.  */
-	  ref = gen_decl_die (decl, NULL_TREE, NULL,
-			      lookup_decl_die (current_function_decl));
+	  gen_decl_die (decl, NULL_TREE, NULL,
+			lookup_decl_die (current_function_decl));
+	  ref = lookup_decl_die (decl);
 	  if (ref)
 	    {
 	      loc->dw_loc_oprnd1.val_class = dw_val_class_die_ref;
@@ -30203,6 +30204,7 @@ note_variable_value_in_expr (dw_die_ref
 	    loc->dw_loc_oprnd1.val_class = dw_val_class_die_ref;
 	    loc->dw_loc_oprnd1.v.val_die_ref.die = ref;
 	    loc->dw_loc_oprnd1.v.val_die_ref.external = 0;
+	    continue;
 	  }
 	if (VAR_P (decl)
 	    && DECL_CONTEXT (decl)


2017-05-15  Richard Biener  <rguenther@suse.de>

	* dwarf2out.c (loc_list_from_tree_1): Do not create
	DW_OP_GNU_variable_value for DECL_IGNORED_P decls.

Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c	(revision 248054)
+++ gcc/dwarf2out.c	(working copy)
@@ -17373,6 +17685,7 @@ loc_list_from_tree_1 (tree loc, int want
 		&& early_dwarf
 		&& current_function_decl
 		&& want_address != 1
+		&& ! DECL_IGNORED_P (loc)
 		&& (INTEGRAL_TYPE_P (TREE_TYPE (loc))
 		    || POINTER_TYPE_P (TREE_TYPE (loc)))
 		&& DECL_CONTEXT (loc) == current_function_decl

Re: [PATCH] Two DW_OP_GNU_variable_value fixes / tweaks

[Jakub Jelinek]

On Mon, May 15, 2017 at 02:43:43PM +0200, Richard Biener wrote:
> 
> While bringing early LTO debug up-to-speed I noticed the following two
> issues.  The first patch avoids useless work in 
> note_variable_value_in_expr and actually makes use of the DIE we
> eventually create in resolve_variable_value_in_expr.
> 
> The second avoids generating a DW_OP_GNU_variable_value for a decl
> we'll never have a DIE for -- this might be less obvious than the
> other patch but I think we'll also never have any other debug info
> we can resolve the decl with(?)
> 
> Bootstrapped and tested the first patch sofar
> on x86_64-unknown-linux-gnu, 2nd is pending.
> 
> Ok?
> 
> Thanks,
> Richard.
> 
> 2017-05-15  Richard Biener  <rguenther@suse.de>
> 
> 	* dwarf2out.c (resolve_variable_value_in_expr): Lookup DIE
> 	just generated.
> 	(note_variable_value_in_expr): If we resolved the decl ref
> 	do not push to the stack.

LGTM.

> 2017-05-15  Richard Biener  <rguenther@suse.de>
> 
> 	* dwarf2out.c (loc_list_from_tree_1): Do not create
> 	DW_OP_GNU_variable_value for DECL_IGNORED_P decls.

Can you verify it e.g. in a bootstrapped cc1plus doesn't change the debug info
(except for dwarf2out.o itself)?
It looks reasonable and it would surprise me if did, just want to be sure.

	Jakub

Re: [PATCH] Two DW_OP_GNU_variable_value fixes / tweaks

[Richard Biener]

On Mon, May 15, 2017 at 3:19 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Mon, May 15, 2017 at 02:43:43PM +0200, Richard Biener wrote:
>>
>> While bringing early LTO debug up-to-speed I noticed the following two
>> issues.  The first patch avoids useless work in
>> note_variable_value_in_expr and actually makes use of the DIE we
>> eventually create in resolve_variable_value_in_expr.
>>
>> The second avoids generating a DW_OP_GNU_variable_value for a decl
>> we'll never have a DIE for -- this might be less obvious than the
>> other patch but I think we'll also never have any other debug info
>> we can resolve the decl with(?)
>>
>> Bootstrapped and tested the first patch sofar
>> on x86_64-unknown-linux-gnu, 2nd is pending.
>>
>> Ok?
>>
>> Thanks,
>> Richard.
>>
>> 2017-05-15  Richard Biener  <rguenther@suse.de>
>>
>>       * dwarf2out.c (resolve_variable_value_in_expr): Lookup DIE
>>       just generated.
>>       (note_variable_value_in_expr): If we resolved the decl ref
>>       do not push to the stack.
>
> LGTM.
>
>> 2017-05-15  Richard Biener  <rguenther@suse.de>
>>
>>       * dwarf2out.c (loc_list_from_tree_1): Do not create
>>       DW_OP_GNU_variable_value for DECL_IGNORED_P decls.
>
> Can you verify it e.g. in a bootstrapped cc1plus doesn't change the debug info
> (except for dwarf2out.o itself)?
> It looks reasonable and it would surprise me if did, just want to be sure.

Done.  Note it only happened for Ada.

Richard.

>         Jakub