From 9a56fae565b641d6e7557e8c59adf9018d304041 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Fri, 18 Oct 2024 00:18:24 +0200 Subject: [PATCH] [gdb/build] Use -fno-hoist-adjacent-loads for gcc <= 13 When building gdb with gcc 12 and -fsanitize=threads while renabling background dwarf reading by setting dwarf_synchronous to false, I run into: ... (gdb) file amd64-watchpoint-downgrade Reading symbols from amd64-watchpoint-downgrade... (gdb) watch global_var ================== WARNING: ThreadSanitizer: data race (pid=20124) Read of size 8 at 0x7b80000500d8 by main thread: #0 cooked_index_entry::full_name(obstack*, bool) const cooked-index.c:220 #1 cooked_index::get_main_name(obstack*, language*) const cooked-index.c:735 #2 cooked_index_worker::wait(cooked_state, bool) cooked-index.c:559 #3 cooked_index::wait(cooked_state, bool) cooked-index.c:631 #4 cooked_index_functions::wait(objfile*, bool) cooked-index.h:729 #5 cooked_index_functions::compute_main_name(objfile*) cooked-index.h:806 #6 objfile::compute_main_name() symfile-debug.c:461 #7 find_main_name symtab.c:6503 #8 main_language() symtab.c:6608 #9 set_initial_language_callback symfile.c:1634 #10 get_current_language() language.c:96 ... Previous write of size 8 at 0x7b80000500d8 by thread T1: #0 cooked_index_shard::finalize(parent_map_map const*) \ dwarf2/cooked-index.c:409 #1 operator() cooked-index.c:663 ... ... SUMMARY: ThreadSanitizer: data race cooked-index.c:220 in \ cooked_index_entry::full_name(obstack*, bool) const ================== Hardware watchpoint 1: global_var (gdb) PASS: gdb.arch/amd64-watchpoint-downgrade.exp: watch global_var ... This was also reported in PR31715. This is due do gcc PR110799 [1], generating wrong code with -fhoist-adjacent-loads, and causing a false positive for -fsanitize=threads. Work around the gcc PR by forcing -fno-hoist-adjacent-loads for gcc <= 13 and -fsanitize=threads. Tested in that same configuration on x86_64-linux. Remaining ThreadSanitizer problems are the ones reported in PR31626 (gdb.rust/dwindex.exp) and PR32247 (gdb.trace/basic-libipa.exp). PR gdb/31715 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31715 Tested-By: Bernd Edlinger Approved-By: Tom Tromey [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110799 --- gdbsupport/common-defs.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/gdbsupport/common-defs.h b/gdbsupport/common-defs.h index 6120719480b..d246a84bf75 100644 --- a/gdbsupport/common-defs.h +++ b/gdbsupport/common-defs.h @@ -20,6 +20,13 @@ #ifndef COMMON_COMMON_DEFS_H #define COMMON_COMMON_DEFS_H +#if defined (__SANITIZE_THREAD__) && defined (__GNUC__) \ + && !defined (__clang__) && __GNUC__ <= 13 + +/* Work around PR gcc/110799. */ +#pragma GCC optimize("-fno-hoist-adjacent-loads") +#endif + #include #undef PACKAGE_NAME