From 55fc1623f942fba10362cb199f9356d75ca5835b Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Thu, 3 Nov 2022 13:49:17 -0600 Subject: Add name canonicalization for C PR symtab/29105 shows a number of situations where symbol lookup can result in the expansion of too many CUs. What happens is that lookup_signed_typename will try to look up a type like "signed int". In cooked_index_functions::expand_symtabs_matching, when looping over languages, the C++ case will canonicalize this type name to be "int" instead. Then this method will proceed to expand every CU that has an entry for "int" -- i.e., nearly all of them. A crucial component of this is that the caller, objfile::lookup_symbol, does not do this canonicalization, so when it tries to find the symbol for "signed int", it fails -- causing the loop to continue. This patch fixes the problem by introducing name canonicalization for C. The idea here is that, by making C and C++ agree on the canonical name when a symbol name can have multiple spellings, we avoid the bad behavior in objfile::lookup_symbol (and any other such code -- I don't know if there is any). Unlike C++, C only has a few situations where canonicalization is needed. And, in particular, due to the lack of overloading (thus avoiding any issues in linespec) and due to the way c-exp.y works, I think that no canonicalization is needed during symbol lookup -- only during symtab construction. This explains why lookup_name_info is not touched. The stabs reader is modified on a "best effort" basis. The DWARF reader needed one small tweak in dwarf2_name to avoid a regression in dw2-unusual-field-names.exp. I think this is adequately explained by the comment, but basically this is a scenario that should not occur in real code, only the gdb test suite. lookup_signed_typename is simplified. It used to search for two different type names, but now gdb can search just for the canonical form. gdb.dwarf2/enum-type.exp needed a small tweak, because the canonicalizer turns "unsigned integer" into "unsigned int integer". It seems better here to use the correct C type name. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29105 Tested-by: Simon Marchi Reviewed-by: Andrew Burgess --- gdb/dbxread.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'gdb/dbxread.c') diff --git a/gdb/dbxread.c b/gdb/dbxread.c index b0047cf..ae726bd 100644 --- a/gdb/dbxread.c +++ b/gdb/dbxread.c @@ -48,6 +48,7 @@ #include "complaints.h" #include "cp-abi.h" #include "cp-support.h" +#include "c-lang.h" #include "psympriv.h" #include "block.h" #include "aout/aout64.h" @@ -1444,6 +1445,18 @@ read_dbx_symtab (minimal_symbol_reader &reader, new_name.get ()); } } + else if (psymtab_language == language_c) + { + std::string name (namestring, p - namestring); + gdb::unique_xmalloc_ptr new_name + = c_canonicalize_name (name.c_str ()); + if (new_name != nullptr) + { + sym_len = strlen (new_name.get ()); + sym_name = obstack_strdup (&objfile->objfile_obstack, + new_name.get ()); + } + } if (sym_len == 0) { -- cgit v1.1