From 8d76ceb7f1d2f0d25b76b0a16afd25dc0ba74dca Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Thu, 3 Aug 2023 18:35:23 +0200 Subject: [PATCH] [gdb/symtab] Remove superfluous handling of Ada main in write_cooked_index I filed PR29179 about the following FAIL in test-case gdb.ada/O2_float_param.exp with target board cc-with-gdb-index: ... (gdb) break increment^M Function "increment" not defined.^M Make breakpoint pending on future shared library load? (y or [n]) n^M (gdb) FAIL: gdb.ada/O2_float_param.exp: scenario=all: gdb_breakpoint: \ set breakpoint at increment ... The FAIL was a regression since commit 2cf349be0e3 ("Do not put linkage names into .gdb_index"). Before that commit we had: ... $ readelf -w foo > READELF $ grep callee.*increment READELF [1568] callee__increment: 5 [global, function] [3115] callee.increment: 5 [global, function] ... but after only: ... $ grep callee.*increment READELF [3115] callee.increment: 5 [global, function] ... The regression was fixed by commit 67e83a0deef ("Fix regression in c-linkage-name.exp with gdb index"), which got us again: ... $ grep callee.*increment READELF [1568] callee__increment: 5 [global, function] [3115] callee.increment: 5 [global, function] ... The commit however did not claim that particular PR. A subsequent commit, commit 5fea9794325 ("Improve Ada support in .gdb_index") did claim to fix it, together with commit dd05fc7071a ("Change .gdb_index de-duplication implementation"). The commit 5fea9794325 contained the following addition in write_cooked_index: ... + if (entry->per_cu->lang () == language_ada) + { + /* We want to ensure that the Ada main function's name + appears verbatim in the index. However, this name will + be of the form "_ada_mumble", and will be rewritten by + ada_decode. So, recognize it specially here and add it + to the index by hand. */ + if (entry->tag == DW_TAG_subprogram + && strcmp (main_for_ada, name) == 0) + { + /* Leave it alone. */ + } + else + { + /* In order for the index to work when read back into + gdb, it has to use the encoded name, with any + suffixes stripped. */ + std::string encoded = ada_encode (name, false); + name = obstack_strdup (&symtab->m_string_obstack, + encoded.c_str ()); + } + } ... The code contains some special handling related to the Ada main function, so let's look at that one: foo. Before commit 67e83a0deef we have: ... $ grep foo.*function READELF [3733] foo: 7 [global, function] ... and after: ... $ grep foo.*function READELF [2738] _ada_foo: 7 [global, function] [3733] foo: 7 [global, function] ... so that looks identical to the callee.increment case. At commit 5fea9794325, we have slightly different index numbers: ... $ grep foo.*function READELF [1658] foo: 7 [global, function] [2738] _ada_foo: 7 [global, function] ... but otherwise the same result. If we disable the special handling of the Ada main function like so: ... - if (entry->tag == DW_TAG_subprogram + if (false && entry->tag == DW_TAG_subprogram ... we still have the exact same result because: ... (gdb) p main_for_ada $1 = 0x352e6a0 "_ada_foo" ... and ada_encode ("_ada_foo", false) == "_ada_foo". The comment seems to be copied from debug_names::insert, which does indeed use ada_decode, while the code in write_cooked_index uses ada_encode instead. Remove the superfluous special handling of Ada main in write_cooked_index. Tested on x86_64-linux, with target boards unix and cc-with-gdb-index. Approved-By: Tom Tromey --- gdb/dwarf2/index-write.c | 27 ++++++--------------------- 1 file changed, 6 insertions(+), 21 deletions(-) diff --git a/gdb/dwarf2/index-write.c b/gdb/dwarf2/index-write.c index 62c2cc6ac7d..66c5378d677 100644 --- a/gdb/dwarf2/index-write.c +++ b/gdb/dwarf2/index-write.c @@ -1128,8 +1128,6 @@ write_cooked_index (cooked_index *table, const cu_index_map &cu_index_htab, struct mapped_symtab *symtab) { - const char *main_for_ada = main_name (); - for (const cooked_index_entry *entry : table->all_entries ()) { const auto it = cu_index_htab.find (entry->per_cu); @@ -1139,25 +1137,12 @@ write_cooked_index (cooked_index *table, if (entry->per_cu->lang () == language_ada) { - /* We want to ensure that the Ada main function's name - appears verbatim in the index. However, this name will - be of the form "_ada_mumble", and will be rewritten by - ada_decode. So, recognize it specially here and add it - to the index by hand. */ - if (entry->tag == DW_TAG_subprogram - && strcmp (main_for_ada, name) == 0) - { - /* Leave it alone. */ - } - else - { - /* In order for the index to work when read back into - gdb, it has to use the encoded name, with any - suffixes stripped. */ - std::string encoded = ada_encode (name, false); - name = obstack_strdup (&symtab->m_string_obstack, - encoded.c_str ()); - } + /* In order for the index to work when read back into + gdb, it has to use the encoded name, with any + suffixes stripped. */ + std::string encoded = ada_encode (name, false); + name = obstack_strdup (&symtab->m_string_obstack, + encoded.c_str ()); } else if (entry->per_cu->lang () == language_cplus && (entry->flags & IS_LINKAGE) != 0) -- 2.30.2