From patchwork Fri Nov 9 02:28:43 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Keith Seitz X-Patchwork-Id: 30089 Received: (qmail 86258 invoked by alias); 9 Nov 2018 02:28:55 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 86056 invoked by uid 89); 9 Nov 2018 02:28:53 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-25.4 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_STOCKGEN, SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=utilizing, aide, conclude, exhaustive X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 09 Nov 2018 02:28:50 +0000 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 67E383C2CC5 for ; Fri, 9 Nov 2018 02:28:49 +0000 (UTC) Received: from theo.uglyboxes.com.com (ovpn04.gateway.prod.ext.phx2.redhat.com [10.5.9.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1BF855D783 for ; Fri, 9 Nov 2018 02:28:49 +0000 (UTC) From: Keith Seitz To: gdb-patches@sourceware.org Subject: [PATCH 1/5] gdb/23712: Introduce multidictionary's Date: Thu, 8 Nov 2018 18:28:43 -0800 Message-Id: <20181109022847.32049-1-keiths@redhat.com> X-IsSubscribed: yes gdb/23712 is a new manifestation of the now-infamous (at least to me) symtab/23010 assertion failure (DICT_LANGUAGE == SYMBOL_LANGAUGE). An example of the problem (using test case from symtab/23010): Reading symbols from /home/rdiez/rdiez/arduino/JtagDue/BuildOutput/JtagDue-obj-release/firmware.elf...done. (gdb) p SysTick_Handler dwarf2read.c:9715: internal-error: void dw2_add_symbol_to_list(symbol*, pending**): Assertion `(*listhead) == NULL || (SYMBOL_LANGUAGE ((*listhead)->symbol[0]) == SYMBOL_LANGUAGE (symbol))' failed. A problem internal to GDB has been detected, further debugging may prove unreliable. Quit this debugging session? (y or n) This assertion was added specifically to catch this condition (of adding symbols of different languages to a single pending list). The problems we're now seeing on systems utilizing DWARF debugging seem to be caused by the use of LTO, which adds a CU with an artificial DIE of language C99 which references DIEs in other CUs of language C++. Thus, we create a dictionary containing symbols of C99 but end up stuffing C++ symbols into it, and the dw2_add_symbol_to_list triggers. The approach taken here to fix this is to introduce multi-language dictionaries to "replace" the standard, single-language dictionaries used today. Note to reviewers: This patch introduces some temporary functions to aide with review. This and other artifacts (such as "See dictionary.h" which appear incorrect) will all be valid at the end of the series. This first patch introduces the new multidictionary and its API (which is, by design, identical to the old dictionary interface). It also mutates dict_create_hashed and dict_create_linear so that they take a std::vector instead of the usual struct pending linked list. This will be needed later on. This patch does /not/ actually enable multidictionary's. That is left for a subsequent patch in the series. I've done exhaustive performance testing with this approach, and I've attempted to minimize the overhead for the (overwhelmingly) most common one-language scenario. On average, a -g3 -O0 GDB (the one we developers use) will see approximately a 4% slowdown when initially reading symbols. [I've tested only GDB and firefox with -readnow.] When using -O2, this difference shrinks to ~0.5%. Since a number of runs with these patches actually run /faster/ than unpatched GDB, I conclude that these tests have at least a 0.5% error margin. On our own gdb.perf test suite, again, results appear to be pretty negligible. Differences to unpatched GDB range from -7.8% (yes, patched version is again faster than unpatched) to 27%. All tests lying outside "negligible," such as the 27% slowdown, involve a total run time of 0.0007 (or less) with smaller numbers of CUs/DSOs (usually 10 or 100). In all cases, the follow-up tests with more CUs/DSOs is never more than 3% difference to the baseline, unpatched GDB. In my opinion, these results are satisfactory. gdb/ChangeLog: PR gdb/23712 * dictionary.c: Include unordered_map. (pending_to_vector): New function. (dict_create_hashed_1, dict_create_linear_1, dict_add_pending_1): Rewrite the non-"_1" functions to take vector instead of linked list. (dict_create_hashed, dict_create_linear, dict_add_pending): Use the "new" _1 versions of the same name. (multidictionary): Define. (std::hash + + PR gdb/23712 + * dictionary.c: Include unordered_map. + (pending_to_vector): New function. + (dict_create_hashed_1, dict_create_linear_1, dict_add_pending_1): + Rewrite the non-"_1" functions to take vector instead + of linked list. + (dict_create_hashed, dict_create_linear, dict_add_pending): Use the + "new" _1 versions of the same name. + (multidictionary): Define. + (std::hash * aarch64-tdep.c (aapcs_is_vfp_call_or_return_candidate_1): diff --git a/gdb/dictionary.c b/gdb/dictionary.c index da8b7da208..83d8126682 100644 --- a/gdb/dictionary.c +++ b/gdb/dictionary.c @@ -27,6 +27,7 @@ #include "buildsym.h" #include "dictionary.h" #include "safe-ctype.h" +#include /* This file implements dictionaries, which are tables that associate symbols to names. They are represented by an opaque type 'struct @@ -341,53 +342,66 @@ static void insert_symbol_hashed (struct dictionary *dict, static void expand_hashtable (struct dictionary *dict); +/* A function to convert a linked list into a vector. */ + +static std::vector +pending_to_vector (const struct pending *symbol_list) +{ + std::vector symlist; + + for (const struct pending *list_counter = symbol_list; + list_counter != nullptr; list_counter = list_counter->next) + { + for (int i = list_counter->nsyms - 1; i >= 0; --i) + symlist.push_back (list_counter->symbol[i]); + } + + return symlist; +} + /* The creation functions. */ -/* See dictionary.h. */ +/* A function to transition dict_create_hashed to new API. */ -struct dictionary * -dict_create_hashed (struct obstack *obstack, - enum language language, - const struct pending *symbol_list) +static struct dictionary * +dict_create_hashed_1 (struct obstack *obstack, + enum language language, + const std::vector &symbol_list) { - struct dictionary *retval; - int nsyms = 0, nbuckets, i; - struct symbol **buckets; - const struct pending *list_counter; - - retval = XOBNEW (obstack, struct dictionary); + /* Allocate the dictionary. */ + struct dictionary *retval = XOBNEW (obstack, struct dictionary); DICT_VECTOR (retval) = &dict_hashed_vector; DICT_LANGUAGE (retval) = language_def (language); - /* Calculate the number of symbols, and allocate space for them. */ - for (list_counter = symbol_list; - list_counter != NULL; - list_counter = list_counter->next) - { - nsyms += list_counter->nsyms; - } - nbuckets = DICT_HASHTABLE_SIZE (nsyms); + /* Allocate space for symbols. */ + int nsyms = symbol_list.size (); + int nbuckets = DICT_HASHTABLE_SIZE (nsyms); DICT_HASHED_NBUCKETS (retval) = nbuckets; - buckets = XOBNEWVEC (obstack, struct symbol *, nbuckets); + struct symbol **buckets = XOBNEWVEC (obstack, struct symbol *, nbuckets); memset (buckets, 0, nbuckets * sizeof (struct symbol *)); DICT_HASHED_BUCKETS (retval) = buckets; /* Now fill the buckets. */ - for (list_counter = symbol_list; - list_counter != NULL; - list_counter = list_counter->next) - { - for (i = list_counter->nsyms - 1; i >= 0; --i) - { - insert_symbol_hashed (retval, list_counter->symbol[i]); - } - } + for (const auto &sym : symbol_list) + insert_symbol_hashed (retval, sym); return retval; } /* See dictionary.h. */ +struct dictionary * +dict_create_hashed (struct obstack *obstack, + enum language language, + const struct pending *symbol_list) +{ + std::vector symlist = pending_to_vector (symbol_list); + + return dict_create_hashed_1 (obstack, language, symlist); +} + +/* See dictionary.h. */ + extern struct dictionary * dict_create_hashed_expandable (enum language language) { @@ -403,52 +417,45 @@ dict_create_hashed_expandable (enum language language) return retval; } -/* See dictionary.h. */ +/* A function to transition dict_create_linear to new API. */ -struct dictionary * -dict_create_linear (struct obstack *obstack, - enum language language, - const struct pending *symbol_list) +static struct dictionary * +dict_create_linear_1 (struct obstack *obstack, + enum language language, + const std::vector &symbol_list) { - struct dictionary *retval; - int nsyms = 0, i, j; - struct symbol **syms; - const struct pending *list_counter; - - retval = XOBNEW (obstack, struct dictionary); + struct dictionary *retval = XOBNEW (obstack, struct dictionary); DICT_VECTOR (retval) = &dict_linear_vector; DICT_LANGUAGE (retval) = language_def (language); - /* Calculate the number of symbols, and allocate space for them. */ - for (list_counter = symbol_list; - list_counter != NULL; - list_counter = list_counter->next) - { - nsyms += list_counter->nsyms; - } + /* Allocate space for symbols. */ + int nsyms = symbol_list.size (); DICT_LINEAR_NSYMS (retval) = nsyms; - syms = XOBNEWVEC (obstack, struct symbol *, nsyms ); + struct symbol **syms = XOBNEWVEC (obstack, struct symbol *, nsyms); DICT_LINEAR_SYMS (retval) = syms; - /* Now fill in the symbols. Start filling in from the back, so as - to preserve the original order of the symbols. */ - for (list_counter = symbol_list, j = nsyms - 1; - list_counter != NULL; - list_counter = list_counter->next) - { - for (i = list_counter->nsyms - 1; - i >= 0; - --i, --j) - { - syms[j] = list_counter->symbol[i]; - } - } + /* Now fill in the symbols. */ + int idx = nsyms - 1; + for (const auto &sym : symbol_list) + syms[idx--] = sym; return retval; } /* See dictionary.h. */ +struct dictionary * +dict_create_linear (struct obstack *obstack, + enum language language, + const struct pending *symbol_list) +{ + std::vector symlist = pending_to_vector (symbol_list); + + return dict_create_linear_1 (obstack, language, symlist); +} + +/* See dictionary.h. */ + struct dictionary * dict_create_linear_expandable (enum language language) { @@ -483,20 +490,26 @@ dict_add_symbol (struct dictionary *dict, struct symbol *sym) (DICT_VECTOR (dict))->add_symbol (dict, sym); } +/* A function to transition dict_add_pending to new API. */ + +static void +dict_add_pending_1 (struct dictionary *dict, + const std::vector &symbol_list) +{ + /* Preserve ordering by reversing the list. */ + for (auto sym = symbol_list.rbegin (); sym != symbol_list.rend (); ++sym) + dict_add_symbol (dict, *sym); +} + /* Utility to add a list of symbols to a dictionary. DICT must be an expandable dictionary. */ void dict_add_pending (struct dictionary *dict, const struct pending *symbol_list) { - const struct pending *list; - int i; + std::vector symlist = pending_to_vector (symbol_list); - for (list = symbol_list; list != NULL; list = list->next) - { - for (i = 0; i < list->nsyms; ++i) - dict_add_symbol (dict, list->symbol[i]); - } + dict_add_pending_1 (dict, symlist); } /* Initialize ITERATOR to point at the first symbol in DICT, and @@ -929,3 +942,408 @@ add_symbol_linear_expandable (struct dictionary *dict, DICT_LINEAR_SYM (dict, nsyms - 1) = sym; } + +/* Multi-language dictionary support. */ + +/* The structure describing a multi-language dictionary. */ + +struct multidictionary +{ + /* An array of dictionaries, one per language. All dictionaries + must be of the same type. This should be free'd for expandable + dictionary types. */ + struct dictionary **dictionaries; + + /* The number of language dictionaries currently allocated. + Only used for expandable dictionaries. */ + unsigned short n_allocated_dictionaries; +}; + +/* A hasher for enum language. Injecting this into std is a convenience + when using unordered_map with C++11. */ + +namespace std +{ + template<> struct hash + { + typedef enum language argument_type; + typedef std::size_t result_type; + + result_type operator() (const argument_type &l) const noexcept + { + return static_cast (l); + } + }; +} /* namespace std */ + +/* A helper function to collate symbols on the pending list by language. */ + +static std::unordered_map> +collate_pending_symbols_by_language (const struct pending *symbol_list) +{ + std::unordered_map> nsyms; + + for (const struct pending *list_counter = symbol_list; + list_counter != nullptr; list_counter = list_counter->next) + { + for (int i = list_counter->nsyms - 1; i >= 0; --i) + { + enum language language = SYMBOL_LANGUAGE (list_counter->symbol[i]); + nsyms[language].push_back (list_counter->symbol[i]); + } + } + + return nsyms; +} + +/* See dictionary.h. */ + +struct multidictionary * +mdict_create_hashed (struct obstack *obstack, + const struct pending *symbol_list) +{ + struct multidictionary *retval + = XOBNEW (obstack, struct multidictionary); + std::unordered_map> nsyms + = collate_pending_symbols_by_language (symbol_list); + + /* Loop over all languages and create/populate dictionaries. */ + retval->dictionaries + = XOBNEWVEC (obstack, struct dictionary *, nsyms.size ()); + retval->n_allocated_dictionaries = nsyms.size (); + + int idx = 0; + for (const auto &pair : nsyms) + { + enum language language = pair.first; + std::vector symlist = pair.second; + + retval->dictionaries[idx++] + = dict_create_hashed_1 (obstack, language, symlist); + } + + return retval; +} + +/* See dictionary.h. */ + +struct multidictionary * +mdict_create_hashed_expandable (enum language language) +{ + struct multidictionary *retval = XNEW (struct multidictionary); + + /* We have no symbol list to populate, but we create an empty + dictionary of the requested language to populate later. */ + retval->n_allocated_dictionaries = 1; + retval->dictionaries = XNEW (struct dictionary *); + retval->dictionaries[0] = dict_create_hashed_expandable (language); + + return retval; +} + +/* See dictionary.h. */ + +struct multidictionary * +mdict_create_linear (struct obstack *obstack, + const struct pending *symbol_list) +{ + struct multidictionary *retval + = XOBNEW (obstack, struct multidictionary); + std::unordered_map> nsyms + = collate_pending_symbols_by_language (symbol_list); + + /* Loop over all languages and create/populate dictionaries. */ + retval->dictionaries + = XOBNEWVEC (obstack, struct dictionary *, nsyms.size ()); + retval->n_allocated_dictionaries = nsyms.size (); + + int idx = 0; + for (const auto &pair : nsyms) + { + enum language language = pair.first; + std::vector symlist = pair.second; + + retval->dictionaries[idx++] + = dict_create_linear_1 (obstack, language, symlist); + } + + return retval; +} + +/* See dictionary.h. */ + +struct multidictionary * +mdict_create_linear_expandable (enum language language) +{ + struct multidictionary *retval = XNEW (struct multidictionary); + + /* We have no symbol list to populate, but we create an empty + dictionary to populate later. */ + retval->n_allocated_dictionaries = 1; + retval->dictionaries = XNEW (struct dictionary *); + retval->dictionaries[0] = dict_create_linear_expandable (language); + + return retval; +} + +/* See dictionary.h. */ + +void +mdict_free (struct multidictionary *mdict) +{ + /* Grab the type of dictionary being used. */ + enum dict_type type = mdict->dictionaries[0]->vector->type; + + /* Loop over all dictionaries and free them. */ + for (unsigned short idx = 0; idx < mdict->n_allocated_dictionaries; ++idx) + dict_free (mdict->dictionaries[idx]); + + /* Free the dictionary list, if needed. */ + switch (type) + { + case DICT_HASHED: + case DICT_LINEAR: + /* Memory was allocated on an obstack when created. */ + break; + + case DICT_HASHED_EXPANDABLE: + case DICT_LINEAR_EXPANDABLE: + xfree (mdict->dictionaries); + break; + } +} + +/* Helper function to find the dictionary associated with LANGUAGE + or NULL if there is no dictionary of that language. */ + +static struct dictionary * +find_language_dictionary (const struct multidictionary *mdict, + enum language language) +{ + for (unsigned short idx = 0; idx < mdict->n_allocated_dictionaries; ++idx) + { + if (DICT_LANGUAGE (mdict->dictionaries[idx])->la_language == language) + return mdict->dictionaries[idx]; + } + + return nullptr; +} + +/* Create a new language dictionary for LANGUAGE and add it to the + multidictionary MDICT's list of dictionaries. If MDICT is not + based on expandable dictionaries, this function throws an + internal error. */ + +static struct dictionary * +create_new_language_dictionary (struct multidictionary *mdict, + enum language language) +{ + struct dictionary *retval = nullptr; + + /* We use the first dictionary entry to decide what create function + to call. Not optimal but sufficient. */ + gdb_assert (mdict->dictionaries[0] != nullptr); + switch (mdict->dictionaries[0]->vector->type) + { + case DICT_HASHED: + case DICT_LINEAR: + internal_error (__FILE__, __LINE__, + _("create_new_language_dictionary: attempted to expand " + "non-expandable multidictionary")); + + case DICT_HASHED_EXPANDABLE: + retval = dict_create_hashed_expandable (language); + break; + + case DICT_LINEAR_EXPANDABLE: + retval = dict_create_linear_expandable (language); + break; + } + + /* Grow the dictionary vector and save the new dictionary. */ + mdict->dictionaries + = (struct dictionary **) xrealloc (mdict->dictionaries, + (++mdict->n_allocated_dictionaries + * sizeof (struct dictionary *))); + mdict->dictionaries[mdict->n_allocated_dictionaries - 1] = retval; + + return retval; +} + +/* See dictionary.h. */ + +void +mdict_add_symbol (struct multidictionary *mdict, struct symbol *sym) +{ + struct dictionary *dict + = find_language_dictionary (mdict, SYMBOL_LANGUAGE (sym)); + + if (dict == nullptr) + { + /* SYM is of a new language that we haven't previously seen. + Create a new dictionary for it. */ + dict = create_new_language_dictionary (mdict, SYMBOL_LANGUAGE (sym)); + } + + dict_add_symbol (dict, sym); +} + +/* See dictionary.h. */ + +void +mdict_add_pending (struct multidictionary *mdict, + const struct pending *symbol_list) +{ + std::unordered_map> nsyms + = collate_pending_symbols_by_language (symbol_list); + + for (const auto &pair : nsyms) + { + enum language language = pair.first; + std::vector symlist = pair.second; + struct dictionary *dict = find_language_dictionary (mdict, language); + + if (dict == nullptr) + { + /* The language was not previously seen. Create a new dictionary + for it. */ + dict = create_new_language_dictionary (mdict, language); + } + + dict_add_pending_1 (dict, symlist); + } +} + +/* See dictionary.h. */ + +struct symbol * +mdict_iterator_first (const multidictionary *mdict, + struct mdict_iterator *miterator) +{ + miterator->mdict = mdict; + miterator->current_idx = 0; + + for (unsigned short idx = miterator->current_idx; + idx < mdict->n_allocated_dictionaries; ++idx) + { + struct symbol *result + = dict_iterator_first (mdict->dictionaries[idx], &miterator->iterator); + + if (result != nullptr) + { + miterator->current_idx = idx; + return result; + } + } + + return nullptr; +} + +/* See dictionary.h. */ + +struct symbol * +mdict_iterator_next (struct mdict_iterator *miterator) +{ + struct symbol *result = dict_iterator_next (&miterator->iterator); + + if (result != nullptr) + return result; + + /* The current dictionary had no matches -- move to the next + dictionary, if any. */ + for (unsigned short idx = ++miterator->current_idx; + idx < miterator->mdict->n_allocated_dictionaries; ++idx) + { + result + = dict_iterator_first (miterator->mdict->dictionaries[idx], + &miterator->iterator); + if (result != nullptr) + { + miterator->current_idx = idx; + return result; + } + } + + return nullptr; +} + +/* See dictionary.h. */ + +struct symbol * +mdict_iter_match_first (const struct multidictionary *mdict, + const lookup_name_info &name, + struct mdict_iterator *miterator) +{ + miterator->mdict = mdict; + miterator->current_idx = 0; + + for (unsigned short idx = miterator->current_idx; + idx < mdict->n_allocated_dictionaries; ++idx) + { + struct symbol *result + = dict_iter_match_first (mdict->dictionaries[idx], name, + &miterator->iterator); + + if (result != nullptr) + return result; + } + + return nullptr; +} + +/* See dictionary.h. */ + +struct symbol * +mdict_iter_match_next (const lookup_name_info &name, + struct mdict_iterator *miterator) +{ + /* Search the current dictionary. */ + struct symbol *result = dict_iter_match_next (name, &miterator->iterator); + + if (result != nullptr) + return result; + + /* The current dictionary had no matches -- move to the next + dictionary, if any. */ + for (unsigned short idx = ++miterator->current_idx; + idx < miterator->mdict->n_allocated_dictionaries; ++idx) + { + result + = dict_iter_match_first (miterator->mdict->dictionaries[idx], + name, &miterator->iterator); + if (result != nullptr) + { + miterator->current_idx = idx; + return result; + } + } + + return nullptr; +} + +/* See dictionary.h. */ + +int +mdict_size (const struct multidictionary *mdict) +{ + int size = 0; + + for (unsigned short idx = 0; idx < mdict->n_allocated_dictionaries; ++idx) + size += dict_size (mdict->dictionaries[idx]); + + return size; +} + +/* See dictionary.h. */ + +bool +mdict_empty (const struct multidictionary *mdict) +{ + for (unsigned short idx = 0; idx < mdict->n_allocated_dictionaries; ++idx) + { + if (!dict_empty (mdict->dictionaries[idx])) + return false; + } + + return true; +} diff --git a/gdb/dictionary.h b/gdb/dictionary.h index c80a4b4fe2..d9c4ad491c 100644 --- a/gdb/dictionary.h +++ b/gdb/dictionary.h @@ -113,6 +113,21 @@ struct dict_iterator struct symbol *current; }; +/* The multi-language dictionary iterator. Like dict_iterator above, + these contents should be considered private. */ + +struct mdict_iterator +{ + /* The multidictionary with whcih this iterator is associated. */ + const struct multidictionary *mdict; + + /* The iterator used to iterate through individual dictionaries. */ + struct dict_iterator iterator; + + /* The current index of the dictionary being iterated over. */ + unsigned short current_idx; +}; + /* Initialize ITERATOR to point at the first symbol in DICT, and return that first symbol, or NULL if DICT is empty. */