0756511537
Calls with musttail attribute don't really work with -fsanitize=thread in GCC. The problem is that TSan instrumentation adds __tsan_func_entry (__builtin_return_address (0)); calls at the start of each instrumented function and __tsan_func_exit (); call at the end of those and the latter stands in a way of normal tail calls as well as musttail tail calls. Looking at what LLVM does, for normal calls -fsanitize=thread also prevents tail calls like in GCC (well, the __tsan_func_exit () call itself can be tail called in GCC (and from what I see not in clang)). But for [[clang::musttail]] calls it arranges to move the __tsan_func_exit () before the musttail call instead of after it. The following patch handles it similarly. If we for -fsanitize=thread instrumented function detect __builtin_tsan_func_exit () call, we process it normally (so that the call can be tail called in function returning void) but set a flag that the builtin has been seen (only for cfun->has_musttail in the diag_musttail phase). And then let tree_optimize_tail_calls_1 call find_tail_calls again in a new mode where the __tsan_func_exit () call is ignored and so we are able to find calls before it, but only accept that if the call before it is actually a musttail. For C++ it needs to verify that EH cleanup if any also has the __tsan_func_exit () call and if all goes well, the musttail call is registered for tailcalling with a flag that it has __tsan_func_exit () after it and when optimizing that we emit __tsan_func_exit (); call before the musttail tail call (or musttail tail recursion). 2025-04-15 Jakub Jelinek <jakub@redhat.com> PR sanitizer/119801 * sanitizer.def (BUILT_IN_TSAN_FUNC_EXIT): Use BT_FN_VOID rather than BT_FN_VOID_PTR. * tree-tailcall.cc: Include attribs.h and asan.h. (struct tailcall): Add has_tsan_func_exit member. (empty_eh_cleanup): Add eh_has_tsan_func_exit argument, set what it points to to 1 if there is exactly one __tsan_func_exit call and ignore that call otherwise. Adjust recursive call. (find_tail_calls): Add RETRY_TSAN_FUNC_EXIT argument, pass it to recursive calls. When seeing __tsan_func_exit call with RETRY_TSAN_FUNC_EXIT 0, set it to -1. If RETRY_TSAN_FUNC_EXIT is 1, initially ignore __tsan_func_exit calls. Adjust empty_eh_cleanup caller. When looking through stmts after the call, ignore exactly one __tsan_func_exit call but remember it in t->has_tsan_func_exit. Diagnose if EH cleanups didn't have __tsan_func_exit and normal path did or vice versa. (optimize_tail_call): Emit __tsan_func_exit before the tail call or tail recursion. (tree_optimize_tail_calls_1): Adjust find_tail_calls callers. If find_tail_calls changes retry_tsan_func_exit to -1, set it to 1 and call it again with otherwise the same arguments. * c-c++-common/tsan/pr119801.c: New test. |
||
|---|---|---|
| .forgejo | ||
| .github | ||
| c++tools | ||
| config | ||
| contrib | ||
| fixincludes | ||
| gcc | ||
| gnattools | ||
| gotools | ||
| include | ||
| INSTALL | ||
| libada | ||
| libatomic | ||
| libbacktrace | ||
| libcc1 | ||
| libcody | ||
| libcpp | ||
| libdecnumber | ||
| libffi | ||
| libgcc | ||
| libgcobol | ||
| libgfortran | ||
| libgm2 | ||
| libgo | ||
| libgomp | ||
| libgrust | ||
| libiberty | ||
| libitm | ||
| libobjc | ||
| libphobos | ||
| libquadmath | ||
| libsanitizer | ||
| libssp | ||
| libstdc++-v3 | ||
| libvtv | ||
| lto-plugin | ||
| maintainer-scripts | ||
| zlib | ||
| .b4-config | ||
| .dir-locals.el | ||
| .gitattributes | ||
| .gitignore | ||
| ABOUT-NLS | ||
| ar-lib | ||
| ChangeLog | ||
| ChangeLog.jit | ||
| ChangeLog.tree-ssa | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
| config.rpath | ||
| config.sub | ||
| configure | ||
| configure.ac | ||
| COPYING | ||
| COPYING.LIB | ||
| COPYING.RUNTIME | ||
| COPYING3 | ||
| COPYING3.LIB | ||
| depcomp | ||
| install-sh | ||
| libtool-ldflags | ||
| libtool.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| lt~obsolete.m4 | ||
| MAINTAINERS | ||
| Makefile.def | ||
| Makefile.in | ||
| Makefile.tpl | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| multilib.am | ||
| README | ||
| SECURITY.txt | ||
| symlink-tree | ||
| test-driver | ||
| ylwrap | ||
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.