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| author | Anthony Tran <atran881@usc.edu> | 2025-07-26 08:50:25 -0700 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2025-07-26 08:50:25 -0700 |
| commit | 29992cfd628ed5b968ccb73b17ed0521382ba317 (patch) | |
| tree | 1c223a6d8a8ff94a357ff8624b8f9ce080c16648 /clang/docs | |
| parent | fa79c23ecc23d6e8a6956d9caedd0443ecdb5853 (diff) | |
| download | llvm-main.zip llvm-main.tar.gz llvm-main.tar.bz2 | |
This patch adds a human readable trap category and message to UBSan
traps. The category and message are encoded in a fake frame in the debug
info where the function is a fake inline function where the name encodes
the trap category and message. This is the same mechanism used by
Clang’s `__builtin_verbose_trap()`.
This change allows consumers of binaries built with trapping UBSan to
more easily identify the reason for trapping. In particular LLDB already
has a frame recognizer that recognizes the fake function names emitted
in debug info by this patch. A patch testing this behavior in LLDB will
be added in a separately.
The human readable trap messages are based on the messages currently
emitted by the userspace runtime for UBSan in compiler-rt. Note the
wording is not identical because the userspace UBSan runtime has access
to dynamic information that is not available during Clang’s codegen.
Test cases for each UBSan trap kind are included.
This complements the [`-fsanitize-annotate-debug-info`
feature](https://github.com/llvm/llvm-project/pull/141997). While
`-fsanitize-annotate-debug-info` attempts to annotate all UBSan-added
instructions, this feature (`-fsanitize-debug-trap-reasons`) only
annotates the final trap instruction using SanitizerHandler information.
This work is part of a GSoc 2025 project.
Diffstat (limited to 'clang/docs')
| -rw-r--r-- | clang/docs/ReleaseNotes.rst | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index ec51ffd..95a0bbf 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -89,9 +89,18 @@ Non-comprehensive list of changes in this release ------------------------------------------------- - Added ``__builtin_elementwise_minnumnum`` and ``__builtin_elementwise_maxnumnum``. +- Trapping UBSan (e.g. ``-fsanitize-trap=undefined``) now emits a string describing the reason for + trapping into the generated debug info. This feature allows debuggers (e.g. LLDB) to display + the reason for trapping if the trap is reached. The string is currently encoded in the debug + info as an artificial frame that claims to be inlined at the trap location. The function used + for the artificial frame is an artificial function whose name encodes the reason for trapping. + The encoding used is currently the same as ``__builtin_verbose_trap`` but might change in the future. + This feature is enabled by default but can be disabled by compiling with + ``-fno-sanitize-annotate-debug-info-traps``. New Compiler Flags ------------------ +- New option ``-fno-sanitize-annotate-debug-info-traps`` added to disable emitting trap reasons into the debug info when compiling with trapping UBSan (e.g. ``-fsanitize-trap=undefined``). Deprecated Compiler Flags ------------------------- |