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| author | George Burgess IV <gbiv@google.com> | 2022-06-21 17:06:52 -0700 |
|---|---|---|
| committer | Chromeos LUCI <chromeos-scoped@luci-project-accounts.iam.gserviceaccount.com> | 2022-06-29 21:03:49 +0000 |
| commit | 3c36449dd4c66f7415f0a23b7908f5496b0dd743 (patch) | |
| tree | 74824ae005bb6874221040c4b7a9fbc4bdf7900e /compiler_wrapper/README.md | |
| parent | d31ac0b99b083f51dbb88031e8329f336d0a666b (diff) | |
| download | toolchain-utils-3c36449dd4c66f7415f0a23b7908f5496b0dd743.tar.gz | |
compiler_wrapper: add autocrash logic
As outlined in the attached bug, we want to be able to crash the
compiler based on a handful of heuristics. Crashing Clang helps get us
self-contained reproducers fairly easily.
This CL provides (off-by-default) functionality to do the above. The
expectation is that a SWE will hack at it to make it work as they need
to.
BUG=b:236736327
TEST=Installed the new wrapper; observed autocrashes.
Change-Id: I76ec753ec37baa5e9b6dab92668081fa7c605725
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3714885
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Jordan Abrahams-Whitehead <ajordanr@google.com>
Commit-Queue: George Burgess <gbiv@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>
Diffstat (limited to 'compiler_wrapper/README.md')
| -rw-r--r-- | compiler_wrapper/README.md | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/compiler_wrapper/README.md b/compiler_wrapper/README.md index 0228e27d..bb63798a 100644 --- a/compiler_wrapper/README.md +++ b/compiler_wrapper/README.md @@ -73,3 +73,31 @@ Generated wrappers are stored here: `/usr/bin/clang_host_wrapper` - Gcc host wrapper: `/usr/x86_64-pc-linux-gnu/gcc-bin/10.2.0/host_wrapper` + +## Using the compiler wrapper to crash arbitrary compilations + +When Clang crashes, its output can be extremely useful. Often, it will provide +the user with a stack trace, and messages like: + +``` +clang-15: unable to execute command: Illegal instruction +clang-15: note: diagnostic msg: /tmp/clang_crash_diagnostics/foo-5420d2.c +clang-15: note: diagnostic msg: /tmp/clang_crash_diagnostics/foo-5420d2.sh +``` + +Where the artifacts at `/tmp/clang_crash_diagnostics/foo-*` are a full, +self-contained reproducer of the inputs that caused the crash in question. +Often, such a reproducer is very valuable to have even for cases where a crash +_doesn't_ happen (e.g., maybe Clang is now emitting an error where it used to +not do so, and we want to bisect upstream LLVM with that info). Normally, +collecting and crafting such a reproducer is a multi-step process, and can be +error-prone; compile commands may rely on env vars, they may be done within +`chroot`s, they may rely on being executed in a particular directory, they may +rely on intermediate state, etc. + +Because of the usefulness of these crash reports, our wrapper supports crashing +Clang even on files that ordinarily don't cause Clang to crash. For various +reasons (b/236736327), this support currently requires rebuilding and +redeploying the wrapper in order to work. That said, this could be a valuable +tool for devs interested in creating a self-contained reproducer without having +to manually reproduce the environment in which a particular build was performed. |