From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gateway24.websitewelcome.com (gateway24.websitewelcome.com [192.185.51.61]) by sourceware.org (Postfix) with ESMTPS id 2E6A73857C71 for ; Thu, 4 Nov 2021 18:11:41 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 2E6A73857C71 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=tromey.com Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=tromey.com Received: from cm13.websitewelcome.com (cm13.websitewelcome.com [100.42.49.6]) by gateway24.websitewelcome.com (Postfix) with ESMTP id 30B6BA308 for ; Thu, 4 Nov 2021 13:11:13 -0500 (CDT) Received: from box5379.bluehost.com ([162.241.216.53]) by cmsmtp with SMTP id ihAmmB9FVG0jLihAmmElPJ; Thu, 04 Nov 2021 13:09:12 -0500 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tromey.com; s=default; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=NTojixV0J7thm//ZKeY9rfNMPoMIslZuFIF1uZoSnA0=; b=EuQMT26G9oiPE5o52H2cyKy0M2 Zq3+gXmwIBokQzRFWJqoLr88cIG+5ydqlcKo/r9Dz/FpE3SqZ5hjlh1tdTG19EK3iE6Yp4e6a1ClY TTmnNkFMJD7ckpIhxIsMdVIZO; Received: from 75-166-134-234.hlrn.qwest.net ([75.166.134.234]:51958 helo=localhost.localdomain) by box5379.bluehost.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mihAm-003Gzb-4D; Thu, 04 Nov 2021 12:09:12 -0600 From: Tom Tromey To: gdb-patches@sourceware.org Cc: Tom Tromey Subject: [PATCH v2 13/32] Introduce DWARF abbrev cache Date: Thu, 4 Nov 2021 12:08:48 -0600 Message-Id: <20211104180907.2360627-14-tom@tromey.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211104180907.2360627-1-tom@tromey.com> References: <20211104180907.2360627-1-tom@tromey.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - box5379.bluehost.com X-AntiAbuse: Original Domain - sourceware.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - tromey.com X-BWhitelist: no X-Source-IP: 75.166.134.234 X-Source-L: No X-Exim-ID: 1mihAm-003Gzb-4D X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: 75-166-134-234.hlrn.qwest.net (localhost.localdomain) [75.166.134.234]:51958 X-Source-Auth: tom+tromey.com X-Email-Count: 18 X-Source-Cap: ZWx5bnJvYmk7ZWx5bnJvYmk7Ym94NTM3OS5ibHVlaG9zdC5jb20= X-Local-Domain: yes X-Spam-Status: No, score=-3032.1 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, GIT_PATCH_0, JMQ_SPF_NEUTRAL, KAM_SHORT, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_PASS, SPF_NEUTRAL, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 04 Nov 2021 18:11:43 -0000 The replacement for the DWARF psymbol reader works in a somewhat different way. The current reader reads and stores all the DIEs that might be interesting. Then, if it is missing a DIE, it re-scans the CU and reads them all. This approach is used for both intra- and inter-CU references. I instrumented the partial DIE hash to see how frequently it was used: [ 0] -> 1538165 [ 1] -> 4912 [ 2] -> 96102 [ 3] -> 175 [ 4] -> 244 That is, most DIEs are never used, and some are looked up twice -- but this is just an artifact of the implementation of partial_die_info::fixup, which may do two lookups. Based on this, the new implementation doesn't try to store any DIEs, but instead just re-scans them on demand. In order to do this, though, it is convenient to have a cache of DWARF abbrevs. This way, if a second CU is needed to resolve an inter-CU reference, the abbrevs for that CU need only be computed a single time. --- gdb/Makefile.in | 1 + gdb/dwarf2/abbrev-cache.c | 65 +++++++++++++++++++++++++++++++++++++++ gdb/dwarf2/abbrev-cache.h | 58 ++++++++++++++++++++++++++++++++++ gdb/dwarf2/abbrev.c | 5 +-- gdb/dwarf2/abbrev.h | 4 ++- 5 files changed, 130 insertions(+), 3 deletions(-) create mode 100644 gdb/dwarf2/abbrev-cache.c create mode 100644 gdb/dwarf2/abbrev-cache.h diff --git a/gdb/Makefile.in b/gdb/Makefile.in index 73eaf12e339..7c0caff29f1 100644 --- a/gdb/Makefile.in +++ b/gdb/Makefile.in @@ -1035,6 +1035,7 @@ COMMON_SFILES = \ displaced-stepping.c \ dummy-frame.c \ dwarf2/abbrev.c \ + dwarf2/abbrev-cache.c \ dwarf2/attribute.c \ dwarf2/comp-unit-head.c \ dwarf2/cu.c \ diff --git a/gdb/dwarf2/abbrev-cache.c b/gdb/dwarf2/abbrev-cache.c new file mode 100644 index 00000000000..f0705065a3c --- /dev/null +++ b/gdb/dwarf2/abbrev-cache.c @@ -0,0 +1,65 @@ +/* DWARF 2 abbrev table cache + + Copyright (C) 2021 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include "defs.h" +#include "dwarf2/read.h" +#include "dwarf2/abbrev-cache.h" + +/* Hash function for an abbrev table. */ + +hashval_t +abbrev_cache::hash_table (const void *item) +{ + const struct abbrev_table *table = (const struct abbrev_table *) item; + return to_underlying (table->sect_off); +} + +/* Comparison function for abbrev table. */ + +int +abbrev_cache::eq_table (const void *lhs, const void *rhs) +{ + const struct abbrev_table *l_table = (const struct abbrev_table *) lhs; + const search_key *key = (const search_key *) rhs; + return (l_table->section == key->section + && l_table->sect_off == key->offset); +} + +abbrev_cache::abbrev_cache () + : m_tables (htab_create_alloc (20, hash_table, eq_table, + htab_delete_entry, + xcalloc, xfree)) +{ +} + +void +abbrev_cache::add (abbrev_table_up table) +{ + /* We allow this as a convenience to the caller. */ + if (table == nullptr) + return; + + search_key key = { table->section, table->sect_off }; + void **slot = htab_find_slot_with_hash (m_tables.get (), &key, + to_underlying (table->sect_off), + INSERT); + /* If this one already existed, then it should have been reused. */ + gdb_assert (*slot == nullptr); + *slot = (void *) table.release (); +} diff --git a/gdb/dwarf2/abbrev-cache.h b/gdb/dwarf2/abbrev-cache.h new file mode 100644 index 00000000000..a651fcc0ec0 --- /dev/null +++ b/gdb/dwarf2/abbrev-cache.h @@ -0,0 +1,58 @@ +/* DWARF abbrev table cache + + Copyright (C) 2020 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#ifndef GDB_DWARF2_ABBREV_CACHE_H +#define GDB_DWARF2_ABBREV_CACHE_H + +#include "dwarf2/abbrev.h" +#include +#include "gdbtypes.h" + +class abbrev_cache +{ +public: + abbrev_cache (); + DISABLE_COPY_AND_ASSIGN (abbrev_cache); + + abbrev_table *find (struct dwarf2_section_info *section, sect_offset offset) + { + search_key key = { section, offset }; + + return (abbrev_table *) htab_find_with_hash (m_tables.get (), &key, + to_underlying (offset)); + } + + void add (abbrev_table_up table); + +private: + + static hashval_t hash_table (const void *item); + static int eq_table (const void *lhs, const void *rhs); + + struct search_key + { + struct dwarf2_section_info *section; + sect_offset offset; + }; + + /* Hash table of abbrev tables. */ + htab_up m_tables; +}; + +#endif /* GDB_DWARF2_ABBREV_CACHE_H */ diff --git a/gdb/dwarf2/abbrev.c b/gdb/dwarf2/abbrev.c index a8bdf7182de..c84f21256fd 100644 --- a/gdb/dwarf2/abbrev.c +++ b/gdb/dwarf2/abbrev.c @@ -58,8 +58,9 @@ eq_abbrev (const void *lhs, const void *rhs) dies from a section we read in all abbreviations and install them in a hash table. */ -abbrev_table::abbrev_table (sect_offset off) +abbrev_table::abbrev_table (sect_offset off, struct dwarf2_section_info *sect) : sect_off (off), + section (sect), m_abbrevs (htab_create_alloc (20, hash_abbrev, eq_abbrev, nullptr, xcalloc, xfree)) { @@ -85,7 +86,7 @@ abbrev_table::read (struct dwarf2_section_info *section, const gdb_byte *abbrev_ptr; struct abbrev_info *cur_abbrev; - abbrev_table_up abbrev_table (new struct abbrev_table (sect_off)); + abbrev_table_up abbrev_table (new struct abbrev_table (sect_off, section)); struct obstack *obstack = &abbrev_table->m_abbrev_obstack; /* Caller must ensure this. */ diff --git a/gdb/dwarf2/abbrev.h b/gdb/dwarf2/abbrev.h index 50f2ed46083..0a1ca4d39b4 100644 --- a/gdb/dwarf2/abbrev.h +++ b/gdb/dwarf2/abbrev.h @@ -85,9 +85,11 @@ struct abbrev_table This is used as a sanity check when the table is used. */ const sect_offset sect_off; + struct dwarf2_section_info *section; + private: - explicit abbrev_table (sect_offset off); + abbrev_table (sect_offset off, struct dwarf2_section_info *sect); DISABLE_COPY_AND_ASSIGN (abbrev_table); -- 2.31.1