compiler: Allow configuring UBSan mode at the module level. #23582
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alexrp
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Apr 16, 2025
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| .sanitize_trap, .no_sanitize_trap => |t| { | ||
| const enable = t == .sanitize_trap; | ||
| var san_it = std.mem.splitScalar(u8, it.only_arg, ','); | ||
| var recognized_any = false; | ||
| while (san_it.next()) |sub_arg| { | ||
| // This logic doesn't match Clang 1:1, but it's probably good enough, and avoids | ||
| // significantly complicating the resolution of the options. | ||
| if (mem.eql(u8, sub_arg, "undefined")) { | ||
| if (mod_opts.sanitize_c) |sc| switch (sc) { | ||
| .off => if (enable) { | ||
| mod_opts.sanitize_c = .trap; | ||
| }, | ||
| .trap => if (!enable) { | ||
| mod_opts.sanitize_c = .full; | ||
| }, | ||
| .full => if (enable) { | ||
| mod_opts.sanitize_c = .trap; | ||
| }, | ||
| } else { | ||
| if (enable) { | ||
| mod_opts.sanitize_c = .trap; | ||
| } else { | ||
| // This means we were passed `-fno-sanitize-trap=undefined` and nothing else. In | ||
| // this case, ideally, we should use whatever value `sanitize_c` resolves to by | ||
| // default, except change `trap` to `full`. However, we don't yet know what | ||
| // `sanitize_c` will resolve to! So we either have to pick `off` or `full`. | ||
| // | ||
| // `full` has the potential to be problematic if `optimize_mode` turns out to | ||
| // be `ReleaseFast`/`ReleaseSmall` because the user will get a slower and larger | ||
| // binary than expected. On the other hand, if `optimize_mode` turns out to be | ||
| // `Debug`/`ReleaseSafe`, `off` would mean UBSan would unexpectedly be disabled. | ||
| // | ||
| // `off` seems very slightly less bad, so let's go with that. | ||
| mod_opts.sanitize_c = .off; | ||
| } | ||
| } | ||
| recognized_any = true; | ||
| } | ||
| } | ||
| if (!recognized_any) { | ||
| try cc_argv.appendSlice(arena, it.other_args); | ||
| } | ||
| }, |
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I kind of hate this, but I'm not sure what to do about it.
I considered splitting sanitize_c into two fields: sanitize_c and sanitize_c_prefer_trap. But that just runs into the problem that we can't assign a meaningful value here:
Lines 2948 to 2954 in 9d6b20f
(Because the user might only have provided one or the other explicitly, and we need both to answer the question of whether any module in the compilation needs the UBSan runtime.)
It almost seems like iterating the full module graph here to determine whether the UBSan runtime is needed would be easier:
Lines 1290 to 1297 in 9d6b20f
Anyway, ideas welcome.
|
cc @Rexicon226 |
* Accept -fsanitize-c=trap|full in addition to the existing form. * Accept -f(no-)sanitize-trap=undefined in zig cc. * Change type of std.Build.Module.sanitize_c to std.zig.SanitizeC. * Add some missing Compilation.Config fields to the cache. Closes ziglang#23216.
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-fsanitize-c=trap|fullin addition to the existing form.-f(no-)sanitize-trap=undefinedinzig cc.std.Build.Module.sanitize_ctostd.zig.SanitizeC.Compilation.Configfields to the cache.Closes #23216.