From e76b224615f88255a3fd20d613983dde6cc240b3 Mon Sep 17 00:00:00 2001 From: Christian Biesinger Date: Thu, 3 Oct 2019 13:05:06 -0500 Subject: [PATCH] Precompute hash value for symbol_set_names We can also compute the hash for the mangled name on a background thread so make this function even faster (about a 7% speedup). gdb/ChangeLog: 2019-11-27 Christian Biesinger * minsyms.c (minimal_symbol_reader::install): Also compute the hash of the mangled name on the background thread. * symtab.c (symbol_set_names): Allow passing in the hash of the linkage_name. * symtab.h (symbol_set_names): Likewise. Change-Id: I044449e7eb60cffc1c43efd3412f2b485bd9faac --- gdb/ChangeLog | 8 ++++++++ gdb/minsyms.c | 27 +++++++++++++++++++++++++-- gdb/symtab.c | 9 ++++++--- gdb/symtab.h | 4 +++- 4 files changed, 42 insertions(+), 6 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 0816e73381b..c278a7746c6 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2019-11-27 Christian Biesinger + + * minsyms.c (minimal_symbol_reader::install): Also compute the hash + of the mangled name on the background thread. + * symtab.c (symbol_set_names): Allow passing in the hash of the + linkage_name. + * symtab.h (symbol_set_names): Likewise. + 2019-11-27 Kevin Buettner * dwarf2read.c (inherit_abstract_dies): Ensure that delayed diff --git a/gdb/minsyms.c b/gdb/minsyms.c index 03a193270e5..141c3d21935 100644 --- a/gdb/minsyms.c +++ b/gdb/minsyms.c @@ -1258,6 +1258,16 @@ clear_minimal_symbol_hash_tables (struct objfile *objfile) } } +/* This struct is used to store values we compute for msymbols on the + background threads but don't need to keep around long term. */ +struct computed_hash_values +{ + /* Length of the linkage_name of the symbol. */ + size_t name_length; + /* Hash code (using fast_hash) of the linkage_name. */ + hashval_t mangled_name_hash; +}; + /* Build (or rebuild) the minimal symbol hash tables. This is necessary after compacting or sorting the table since the entries move around thus causing the internal minimal_symbol pointers to become jumbled. */ @@ -1370,6 +1380,8 @@ minimal_symbol_reader::install () std::mutex demangled_mutex; #endif + std::vector hash_values (mcount); + msymbols = m_objfile->per_bfd->msymbols.get (); gdb::parallel_for_each (&msymbols[0], &msymbols[mcount], @@ -1377,6 +1389,8 @@ minimal_symbol_reader::install () { for (minimal_symbol *msym = start; msym < end; ++msym) { + size_t idx = msym - msymbols; + hash_values[idx].name_length = strlen (msym->name); if (!msym->name_set) { /* This will be freed later, by symbol_set_names. */ @@ -1386,6 +1400,9 @@ minimal_symbol_reader::install () (msym, demangled_name, &m_objfile->per_bfd->storage_obstack); msym->name_set = 1; + + hash_values[idx].mangled_name_hash + = fast_hash (msym->name, hash_values[idx].name_length); } } { @@ -1396,8 +1413,14 @@ minimal_symbol_reader::install () #endif for (minimal_symbol *msym = start; msym < end; ++msym) { - symbol_set_names (msym, msym->name, false, - m_objfile->per_bfd); + size_t idx = msym - msymbols; + symbol_set_names + (msym, + gdb::string_view(msym->name, + hash_values[idx].name_length), + false, + m_objfile->per_bfd, + hash_values[idx].mangled_name_hash); } } }); diff --git a/gdb/symtab.c b/gdb/symtab.c index 8f46321f43d..894a3230038 100644 --- a/gdb/symtab.c +++ b/gdb/symtab.c @@ -836,7 +836,8 @@ symbol_find_demangled_name (struct general_symbol_info *gsymbol, void symbol_set_names (struct general_symbol_info *gsymbol, gdb::string_view linkage_name, bool copy_name, - struct objfile_per_bfd_storage *per_bfd) + struct objfile_per_bfd_storage *per_bfd, + gdb::optional hash) { struct demangled_name_entry **slot; @@ -864,9 +865,11 @@ symbol_set_names (struct general_symbol_info *gsymbol, create_demangled_names_hash (per_bfd); struct demangled_name_entry entry (linkage_name); + if (!hash.has_value ()) + hash = hash_demangled_name_entry (&entry); slot = ((struct demangled_name_entry **) - htab_find_slot (per_bfd->demangled_names_hash.get (), - &entry, INSERT)); + htab_find_slot_with_hash (per_bfd->demangled_names_hash.get (), + &entry, *hash, INSERT)); /* If this name is not in the hash table, add it. */ if (*slot == NULL diff --git a/gdb/symtab.h b/gdb/symtab.h index 7a5145663a1..4cfdf06b4a8 100644 --- a/gdb/symtab.h +++ b/gdb/symtab.h @@ -553,7 +553,9 @@ extern char *symbol_find_demangled_name (struct general_symbol_info *gsymbol, (objfile)->per_bfd) extern void symbol_set_names (struct general_symbol_info *symbol, gdb::string_view linkage_name, bool copy_name, - struct objfile_per_bfd_storage *per_bfd); + struct objfile_per_bfd_storage *per_bfd, + gdb::optional hash + = gdb::optional ()); /* Return true if NAME matches the "search" name of SYMBOL, according to the symbol's language. */ -- 2.30.2