[libc][setjmp] disable -ftrivial-auto-var-init=pattern for now #92796
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This would consistently fail for me locally, to the point where I could not run ninja libc-unit-tests without ninja libc_setjmp_unittests failing. Turns out that since I enabled -ftrivial-auto-var-init=pattern in commit 1d5c16d ("[libc] default enable -ftrivial-auto-var-init=pattern (llvm#78776)") this has been a problem. Our x86_64 setjmp definition disabled -Wuninitialized, so we wound up clobbering these registers and instead backing up 0xAAAAAAAAAAAAAAAA rather than the actual register value. The implemenation should be rewritten entirely. I've proposed three different ways to do so (linked below). Until we decide which way to go, at least disable this hardening feature for this function for now so that the unit tests go back to green. Link: llvm#87837 Link: llvm#88054 Link: llvm#88157 Fixes: llvm#91164
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@llvm/pr-subscribers-libc Author: Nick Desaulniers (paternity leave) (nickdesaulniers) ChangesThis would consistently fail for me locally, to the point where I could not run Turns out that since I enabled -ftrivial-auto-var-init=pattern in The implemenation should be rewritten entirely. I've proposed three different Link: #87837 Full diff: https://github.com/llvm/llvm-project/pull/92796.diff 1 Files Affected:
diff --git a/libc/src/setjmp/x86_64/CMakeLists.txt b/libc/src/setjmp/x86_64/CMakeLists.txt
index 9899c00e7c4a6..ae84322a65401 100644
--- a/libc/src/setjmp/x86_64/CMakeLists.txt
+++ b/libc/src/setjmp/x86_64/CMakeLists.txt
@@ -9,6 +9,11 @@ add_entrypoint_object(
COMPILE_OPTIONS
-O3
-fno-omit-frame-pointer
+ # TODO: Remove once one of these lands:
+ # https://github.com/llvm/llvm-project/pull/87837
+ # https://github.com/llvm/llvm-project/pull/88054
+ # https://github.com/llvm/llvm-project/pull/88157
+ -ftrivial-auto-var-init=uninitialized
)
add_entrypoint_object(
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mea culpa: it was very bad that I did not fix this BEFORE starting paternity leave! |
This would consistently fail for me locally, to the point where I could not run
ninja libc-unit-tests without ninja libc_setjmp_unittests failing.
Turns out that since I enabled -ftrivial-auto-var-init=pattern in
commit 1d5c16d ("[libc] default enable -ftrivial-auto-var-init=pattern (#78776)")
this has been a problem. Our x86_64 setjmp definition disabled -Wuninitialized,
so we wound up clobbering these registers and instead backing up
0xAAAAAAAAAAAAAAAA rather than the actual register value.
The implemenation should be rewritten entirely. I've proposed three different
ways to do so (linked below). Until we decide which way to go, at least disable
this hardening feature for this function for now so that the unit tests go back
to green.
Link: #87837
Link: #88054
Link: #88157
Fixes: #91164