From 5396ae1717ade2dbbdb73790eafcdd885045860b Mon Sep 17 00:00:00 2001 From: Christian Biesinger Date: Sun, 13 Oct 2019 06:56:58 -0500 Subject: [PATCH] Don't make an extra copy + allocation of the demangled name We can just keep around the malloc()-ed name we got from bfd and free it later. gdb/ChangeLog: 2019-10-25 Christian Biesinger * symtab.c (struct demangled_name_entry): Change demangled name to a unique_xmalloc_ptr, now that we don't allocate it as part of the struct anymore. (symbol_set_names): No longer obstack allocate + copy the demangled name, just store the allocated name from bfd. Change-Id: Ie6ad50e1e1e73509f55d756f0a437897bb93e3b0 --- gdb/ChangeLog | 8 ++++++++ gdb/symtab.c | 38 +++++++++++++------------------------- 2 files changed, 21 insertions(+), 25 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 84fb9aa822..55c46473ab 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2019-10-25 Christian Biesinger + + * symtab.c (struct demangled_name_entry): Change demangled name + to a unique_xmalloc_ptr, now that we don't allocate it as + part of the struct anymore. + (symbol_set_names): No longer obstack allocate + copy the demangled + name, just store the allocated name from bfd. + 2019-10-25 Tom Tromey * dwarf2-frame.c (dwarf2_cie_table): Now a typedef. diff --git a/gdb/symtab.c b/gdb/symtab.c index 160a4c08e9..adf9e08067 100644 --- a/gdb/symtab.c +++ b/gdb/symtab.c @@ -723,7 +723,7 @@ struct demangled_name_entry gdb::string_view mangled; enum language language; - char demangled[1]; + gdb::unique_xmalloc_ptr demangled; }; /* Hash function for the demangled name hash. */ @@ -839,7 +839,7 @@ symbol_set_names (struct general_symbol_info *gsymbol, { /* In Ada, we do the symbol lookups using the mangled name, so we can save some space by not storing the demangled name. */ - if (!copy_name) + if (!copy_name && linkage_name_copy == linkage_name) gsymbol->name = linkage_name; else { @@ -880,20 +880,17 @@ symbol_set_names (struct general_symbol_info *gsymbol, if (*slot == NULL /* A C version of the symbol may have already snuck into the table. This happens to, e.g., main.init (__go_init_main). Cope. */ - || (gsymbol->language == language_go - && (*slot)->demangled[0] == '\0')) + || (gsymbol->language == language_go && (*slot)->demangled == nullptr)) { - char *demangled_name_ptr - = symbol_find_demangled_name (gsymbol, linkage_name_copy); - gdb::unique_xmalloc_ptr demangled_name (demangled_name_ptr); - int demangled_len = demangled_name ? strlen (demangled_name.get ()) : 0; + gdb::unique_xmalloc_ptr demangled_name_ptr + (symbol_find_demangled_name (gsymbol, linkage_name_copy)); /* Suppose we have demangled_name==NULL, copy_name==0, and linkage_name_copy==linkage_name. In this case, we already have the mangled name saved, and we don't have a demangled name. So, you might think we could save a little space by not recording this in the hash table at all. - + It turns out that it is actually important to still save such an entry in the hash table, because storing this name gives us better bcache hit rates for partial symbols. */ @@ -902,42 +899,33 @@ symbol_set_names (struct general_symbol_info *gsymbol, *slot = ((struct demangled_name_entry *) obstack_alloc (&per_bfd->storage_obstack, - offsetof (struct demangled_name_entry, demangled) - + demangled_len + 1)); + sizeof (demangled_name_entry))); new (*slot) demangled_name_entry (gdb::string_view (linkage_name, len)); } else { - char *mangled_ptr; - /* If we must copy the mangled name, put it directly after - the demangled name so we can have a single - allocation. */ + the struct so we can have a single allocation. */ *slot = ((struct demangled_name_entry *) obstack_alloc (&per_bfd->storage_obstack, - offsetof (struct demangled_name_entry, demangled) - + len + demangled_len + 2)); - mangled_ptr = &((*slot)->demangled[demangled_len + 1]); + sizeof (demangled_name_entry) + len + 1)); + char *mangled_ptr = reinterpret_cast (*slot + 1); strcpy (mangled_ptr, linkage_name_copy); new (*slot) demangled_name_entry (gdb::string_view (mangled_ptr, len)); } + (*slot)->demangled = std::move (demangled_name_ptr); (*slot)->language = gsymbol->language; - - if (demangled_name != NULL) - strcpy ((*slot)->demangled, demangled_name.get ()); - else - (*slot)->demangled[0] = '\0'; } else if (gsymbol->language == language_unknown || gsymbol->language == language_auto) gsymbol->language = (*slot)->language; gsymbol->name = (*slot)->mangled.data (); - if ((*slot)->demangled[0] != '\0') - symbol_set_demangled_name (gsymbol, (*slot)->demangled, + if ((*slot)->demangled != nullptr) + symbol_set_demangled_name (gsymbol, (*slot)->demangled.get (), &per_bfd->storage_obstack); else symbol_set_demangled_name (gsymbol, NULL, &per_bfd->storage_obstack);