Bug report
Bug description:
On the Linux LoongArch64 platform, the test_c_stack_unwind test fails because CPython's manually implemented frame-pointer unwinding mechanism fails to recognize the LoongArch stack frame layout (as it relies on the default FRAME_POINTER_NEXT_OFFSET and FRAME_POINTER_RETURN_OFFSET). This issue affects builds using both GCC and Clang.
In the LoongArch architecture, the frame pointer points to the caller's stack pointer; the previous frame pointer is stored at fp[-2], and the return address is stored at fp[-1].
Additionally, for CPython builds compiled with Clang, unexpected failures occur in test sections involving the GNU backtrace() function. By default, Clang/LoongArch generates .debug_frame sections but does not generate the .eh_frame unwinding tables required for runtime unwinding of CPython's C objects. Consequently, glibc's backtrace() returns only a single stack frame and cannot unwind through Python stack frames.
Reproducer
GCC build:
../cpython/configure --with-pydebug CC=gcc
make -j8
PYTHON_JIT=0 ./python -m test -v test_c_stack_unwindclang build:
../cpython/configure --with-pydebug CC=clang
make -j8
PYTHON_JIT=0 ./python -m test -v test_c_stack_unwindEnvironment
- CPython main
- Linux LoongArch64
- GCC version: 15.3.0
- Clang 20.1.8
- glibc 2.42
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux