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From: Simon Marchi <simark@simark.ca>
To: Christian Biesinger <cbiesinger@google.com>
Cc: Tom de Vries <tdevries@suse.de>,
	Simon Marchi <simon.marchi@efficios.com>,
	gdb-patches <gdb-patches@sourceware.org>
Subject: Re: [PATCH v2 28/42] Remove dwarf2_per_cu_data::objfile ()
Date: Thu, 28 May 2020 12:52:54 -0400	[thread overview]
Message-ID: <1d6d971e-6699-2510-14da-8c5b79c1172d@simark.ca> (raw)
In-Reply-To: <CAPTJ0XFTtM=fouUppX3xQBd1fQdPMPbfpoTRfS=meyQ56ABKdA@mail.gmail.com>

On 2020-05-28 12:24 p.m., Christian Biesinger wrote:
> On Thu, May 28, 2020 at 10:33 AM Simon Marchi <simark@simark.ca> wrote:
>>
>> On 2020-05-28 9:05 a.m., Tom de Vries wrote:
>>> Hi,
>>>
>>> thanks for looking into this.
>>>
>>> I tried out the patch, and it fixes all regressions for me.
>>>
>>> Thanks,
>>> - Tom
>>
>> Thanks, I pushed it with the following commit message.
> 
> Maybe add a comment describing this case, so that future developers
> looking at the code know why the two objfiles can be different?

I am the first one to ask others to comment their code and not assume that everybody
is a domain expert, so yes :)

I would add this:

From 54c8c8f45b2196538a6c87c4cc7d498a8a5ade36 Mon Sep 17 00:00:00 2001
From: Simon Marchi <simon.marchi@polymtl.ca>
Date: Thu, 28 May 2020 12:38:03 -0400
Subject: [PATCH] gdb: add comment in
 dwarf_evaluate_loc_desc::push_dwarf_reg_entry_value

Add a comment to clarify why we temporarily override some of the
context's fields, and especially the per_objfile field.  A longer
explanation can be found in this previous commit

    44486dcf19b ("gdb: use caller objfile in dwarf_evaluate_loc_desc::push_dwarf_reg_entry_value")

gdb/ChangeLog:

	* dwarf2/loc.c (class dwarf_evaluate_loc_desc)
	<push_dwarf_reg_entry_value>: Add comment.

Change-Id: I60c6e1062799f729b30a9db78bcb6448783324b4
---
 gdb/dwarf2/loc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/gdb/dwarf2/loc.c b/gdb/dwarf2/loc.c
index 1aab1a4f51bc..400bb4d16fc7 100644
--- a/gdb/dwarf2/loc.c
+++ b/gdb/dwarf2/loc.c
@@ -731,6 +731,12 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context
       throw_error (NO_ENTRY_VALUE_ERROR,
 		   _("Cannot resolve DW_AT_call_data_value"));

+    /* We are about to evaluate an expression in the context of the caller
+       of the current frame.  This evaluation context may be different from
+       the current (callee's) context), so temporarily set the caller's context.
+
+       It is possible for the caller to be from a different objfile from the
+       callee if the call is made through a function pointer.  */
     scoped_restore save_frame = make_scoped_restore (&this->frame,
 						     caller_frame);
     scoped_restore save_per_cu = make_scoped_restore (&this->per_cu,
-- 
2.26.2


  reply	other threads:[~2020-05-28 16:52 UTC|newest]

Thread overview: 92+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-12 21:08 [PATCH v2 00/42] Share DWARF partial symtabs between objfiles Simon Marchi
2020-05-12 21:08 ` [PATCH v2 01/42] Introduce dwarf2_per_objfile::obstack Simon Marchi
2020-05-12 21:08 ` [PATCH v2 02/42] Add "objfile" parameter to two partial_symtab methods Simon Marchi
2020-05-12 21:08 ` [PATCH v2 03/42] Add dwarf2_per_cu_data::index Simon Marchi
2020-05-12 21:08 ` [PATCH v2 04/42] Add dwarf2_per_objfile member to DWARF batons Simon Marchi
2020-05-12 21:08 ` [PATCH v2 05/42] Split dwarf2_per_objfile into dwarf2_per_objfile and dwarf2_per_bfd Simon Marchi
2020-05-12 21:08 ` [PATCH v2 06/42] Remove symtab links from dwarf2_psymtab and dwarf2_per_cu_quick_data Simon Marchi
2020-05-12 21:08 ` [PATCH v2 07/42] Move die_type_hash to dwarf2_per_objfile Simon Marchi
2020-05-12 21:08 ` [PATCH v2 08/42] Add dwarf2_per_objfile field to dwarf2_cu Simon Marchi
2020-05-12 21:08 ` [PATCH v2 09/42] Remove reference to dwarf2_per_cu_data::dwarf2_per_objfile in dw2_do_instantiate_symtab Simon Marchi
2020-05-12 21:11 ` [PATCH v2 10/42] Remove dwarf2_cu->per_cu->dwarf2_per_objfile references Simon Marchi
2020-05-12 21:11 ` [PATCH v2 11/42] Add dwarf2_per_bfd field to dwarf2_per_cu_data Simon Marchi
2020-05-12 21:11 ` [PATCH v2 12/42] Make dwarf2_get_dwz_file take a dwarf2_per_bfd Simon Marchi
2020-05-12 21:11 ` [PATCH v2 13/42] Use bfd_get_filename instead of objfile_name in lookup_dwo_unit Simon Marchi
2020-05-12 21:11 ` [PATCH v2 14/42] Add dwarf2_per_objfile parameter to cutu_reader's constructors Simon Marchi
2020-05-12 21:11 ` [PATCH v2 15/42] Make queue_and_load_dwo_tu receive a dwarf2_cu Simon Marchi
2020-05-22 20:45   ` Tom Tromey
2020-05-25 19:10     ` Simon Marchi
2020-05-12 21:11 ` [PATCH v2 16/42] Remove dwarf2_per_cu_data::dwarf2_per_objfile reference in cutu_reader::keep Simon Marchi
2020-05-12 21:11 ` [PATCH v2 17/42] Add dwarf2_per_objfile parameter to create_partial_symtab Simon Marchi
2020-05-12 21:11 ` [PATCH v2 18/42] Add dwarf2_per_objfile parameter to recursively_compute_inclusions Simon Marchi
2020-05-12 21:11 ` [PATCH v2 19/42] Add dwarf2_per_objfile parameter to process_full_{comp, type}_unit Simon Marchi
2020-05-12 21:12 ` [PATCH v2 20/42] Pass dwarf2_cu objects to dwo-related functions, instead of dwarf2_per_cu_data Simon Marchi
2020-05-12 21:12 ` [PATCH v2 21/42] Remove reference to dwarf2_per_cu_data::dwarf2_per_objfile in queue_and_load_all_dwo_tus Simon Marchi
2020-05-12 21:12 ` [PATCH v2 22/42] Move int type methods out of dwarf2_per_cu_data Simon Marchi
2020-05-12 21:12 ` [PATCH v2 23/42] Add dwarf2_per_objfile to dwarf_expr_context and dwarf2_frame_cache Simon Marchi
2020-05-22 21:04   ` Tom Tromey
2020-05-25 19:50     ` Simon Marchi
2020-05-28  1:44       ` Simon Marchi
2020-05-12 21:12 ` [PATCH v2 24/42] Remove dwarf2_per_cu_data::text_offset Simon Marchi
2020-05-12 21:12 ` [PATCH v2 25/42] Add dwarf2_per_objfile parameter to dwarf2_read_addr_index Simon Marchi
2020-05-12 21:12 ` [PATCH v2 26/42] Add dwarf2_per_objfile parameter to allocate_piece_closure Simon Marchi
2020-05-12 21:12 ` [PATCH v2 27/42] Add dwarf2_per_objfile parameters to dwarf2_fetch_* functions Simon Marchi
2020-05-12 21:12 ` [PATCH v2 28/42] Remove dwarf2_per_cu_data::objfile () Simon Marchi
2020-05-27 16:27   ` Tom de Vries
2020-05-27 16:52     ` Tom de Vries
2020-05-27 20:03     ` Simon Marchi
2020-05-27 21:08       ` Tom de Vries
2020-05-27 21:55         ` Simon Marchi
2020-05-27 22:16           ` Simon Marchi
2020-05-28  2:00             ` Simon Marchi
2020-05-28 13:05               ` Tom de Vries
2020-05-28 15:33                 ` Simon Marchi
2020-05-28 16:24                   ` Christian Biesinger
2020-05-28 16:52                     ` Simon Marchi [this message]
2020-05-28 19:49                       ` Simon Marchi
2020-05-12 21:12 ` [PATCH v2 29/42] Add dwarf2_per_objfile parameter to free_one_cached_comp_unit Simon Marchi
2020-05-12 21:17 ` [PATCH v2 30/42] Add dwarf2_per_objfile parameter to get_die_type_at_offset Simon Marchi
2020-05-12 21:17 ` [PATCH v2 31/42] Remove leftover references to dwarf2_per_cu_data::dwarf2_per_objfile Simon Marchi
2020-05-12 21:17 ` [PATCH v2 32/42] Remove dwarf2_per_cu_data::dwarf2_per_objfile Simon Marchi
2020-05-12 21:17 ` [PATCH v2 33/42] Split type_unit_group Simon Marchi
2020-05-13  9:54   ` Tom de Vries
2020-05-13 15:06     ` Simon Marchi
2020-05-12 21:17 ` [PATCH v2 34/42] Move signatured_type::type to unshareable object Simon Marchi
2020-05-12 21:17 ` [PATCH v2 35/42] Pass dwarf2_per_bfd instead of dwarf2_per_objfile to some index-related functions Simon Marchi
2020-05-12 21:17 ` [PATCH v2 36/42] Pass dwarf2_cu to process_full_{comp,type}_unit Simon Marchi
2020-05-12 21:17 ` [PATCH v2 37/42] Make load_cu return the loaded dwarf2_cu Simon Marchi
2020-05-12 21:17 ` [PATCH v2 38/42] Add comp_unit_head to dwarf2_per_cu_data Simon Marchi
2020-05-12 21:17 ` [PATCH v2 39/42] Pass existing_cu object to cutu_reader Simon Marchi
2020-05-22 20:57   ` Tom Tromey
2020-05-25 19:10     ` Simon Marchi
2020-05-12 21:18 ` [PATCH v2 40/42] Replace dwarf2_per_cu_data::cu backlink with per-objfile map Simon Marchi
2020-05-12 21:18 ` [PATCH v2 41/42] Make mapped_debug_names independent of objfile Simon Marchi
2020-05-22 21:01   ` Tom Tromey
2020-05-25 19:53     ` Simon Marchi
2020-05-12 21:18 ` [PATCH v2 42/42] Share DWARF partial symtabs Simon Marchi
2020-05-13 10:17 ` [PATCH v2 00/42] Share DWARF partial symtabs between objfiles Tom de Vries
2020-05-13 15:46   ` Simon Marchi
2020-05-22 21:02     ` Tom Tromey
2020-05-25 19:53       ` Simon Marchi
2020-05-13 14:52 ` Simon Marchi
2020-05-22 21:07 ` Tom Tromey
2020-05-23 12:24   ` Pedro Alves
2020-05-25 19:56     ` Simon Marchi
2020-05-26 11:17       ` Pedro Alves
2020-05-26 15:35         ` Simon Marchi
2020-05-26 21:34           ` Simon Marchi
2020-05-27  5:08             ` Simon Marchi
2020-05-27 14:53               ` Simon Marchi
2020-05-27 15:51                 ` Simon Marchi
2020-05-29 10:23                   ` Tom de Vries
2020-05-29 12:55                     ` Tom de Vries
2020-05-31  4:16                     ` Simon Marchi
2020-05-31 14:22                       ` Tom de Vries
2020-06-02 21:27                         ` Simon Marchi
2020-06-04 17:55                           ` Tom de Vries
2020-06-04 18:04                             ` Simon Marchi
2020-06-10  3:43                               ` Simon Marchi
2020-06-12  3:25                                 ` Tom Tromey
2020-05-27 14:50 ` [PATCH v2 41.5/42] Move line_header_hash to dwarf2_per_objfile Simon Marchi
2020-05-27 15:07   ` Tom Tromey
2020-05-27 15:10     ` Simon Marchi

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