BOLT optimizations fail on Linux aarch64

Bug report

Bug description:

When running the --pgo test suite with a BOLT instrumented binary, the interpreter crashes with

./python -m test --pgo --rerun --verbose3 --timeout=
python: ../cpython-ro-srcdir/Python/generated_cases.c.h:1074: _PyEval_EvalFrameDefault: Assertion `tp->tp_alloc == PyType_GenericAlloc' failed.
Aborted (core dumped)

I find this surprising since we include _PyEval_EvalFrameDefault in the BOLT skip functions — but am not familiar with the details.

The following patch successfully worked around that error

diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index 810beb61d0d..d24add0afab 100644
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -1071,7 +1071,7 @@
                 DEOPT_IF(FT_ATOMIC_LOAD_UINT32_RELAXED(tp->tp_version_tag) != type_version, CALL);
                 assert(tp->tp_new == PyBaseObject_Type.tp_new);
                 assert(tp->tp_flags & Py_TPFLAGS_HEAPTYPE);
-                assert(tp->tp_alloc == PyType_GenericAlloc);
+                assert(tp->tp_alloc == PyBaseObject_Type.tp_alloc);
                 PyHeapTypeObject *cls = (PyHeapTypeObject *)callable_o;
                 PyFunctionObject *init_func = (PyFunctionObject *)FT_ATOMIC_LOAD_PTR_ACQUIRE(cls->_spec_cache.init);
                 PyCodeObject *code = (PyCodeObject *)init_func->func_code;

Then, the profiling test run succeeded, but BOLT crashed during the apply step.

# Run bolt against the merged data to produce an optimized binary.
for bin in python; do \
  /usr/lib/llvm-19/bin/llvm-bolt "${bin}.prebolt" -o "${bin}.bolt" -data="${bin}.fdata" -update-debug-sections -skip-funcs=_PyEval_EvalFrameDefault,sre_ucs1_match/1,sre_ucs2_match/1,sre_ucs4_match/1  -reorder-blocks=ext-tsp -reorder-functions=cdsort -split-functions -icf=1 -inline-all -split-eh -reorder-functions-use-hot-size -peepholes=none -jump-tables=aggressive -inline-ap -indirect-call-promotion=all -dyno-stats -use-gnu-stack -frame-opt=hot ; \
  mv "${bin}.bolt" "${bin}"; \
done
BOLT-INFO: Target architecture: aarch64
BOLT-INFO: BOLT version: <unknown>
BOLT-INFO: first alloc address is 0x400000
BOLT-INFO: enabling relocation mode
BOLT-INFO: pre-processing profile using branch profile reader
BOLT-INFO: number of removed linker-inserted veneers: 0
BOLT-INFO: 8500 out of 12058 functions in the binary (70.5%) have non-empty execution profile
BOLT-INFO: 41 functions with profile could not be optimized
BOLT-INFO: profile for 1 objects was ignored
BOLT-INFO: removed 1 empty block
BOLT-INFO: ICF folded 678 out of 12439 functions in 5 passes. 0 functions had jump tables.
BOLT-INFO: Removing all identical functions will save 46.23 KB of code space. Folded functions were called 3909549484 times based on profile.
BOLT-INFO: ICP Total indirect calls = 1808544446, 153 callsites cover 99% of all indirect calls
 #0 0x0000aacc1be768cc (/usr/lib/llvm-19/bin/llvm-bolt+0x1ae68cc)
 #1 0x0000aacc1be74b80 (/usr/lib/llvm-19/bin/llvm-bolt+0x1ae4b80)
 #2 0x0000aacc1be77174 (/usr/lib/llvm-19/bin/llvm-bolt+0x1ae7174)
 #3 0x0000ff03feee37e0 (linux-vdso.so.1+0x7e0)
 #4 0x0000aacc1c397200 (/usr/lib/llvm-19/bin/llvm-bolt+0x2007200)
 #5 0x0000aacc1c39aa1c (/usr/lib/llvm-19/bin/llvm-bolt+0x200aa1c)
 #6 0x0000aacc1c39a9e4 (/usr/lib/llvm-19/bin/llvm-bolt+0x200a9e4)
 #7 0x0000aacc1c39a9e4 (/usr/lib/llvm-19/bin/llvm-bolt+0x200a9e4)
 #8 0x0000aacc1bf1ebc4 (/usr/lib/llvm-19/bin/llvm-bolt+0x1b8ebc4)
 #9 0x0000aacc1bf21328 (/usr/lib/llvm-19/bin/llvm-bolt+0x1b91328)
#10 0x0000aacc1becfe3c (/usr/lib/llvm-19/bin/llvm-bolt+0x1b3fe3c)
#11 0x0000aacc1aadf2f0 (/usr/lib/llvm-19/bin/llvm-bolt+0x74f2f0)
#12 0x0000ff03fe8684c4 __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:74:3
#13 0x0000ff03fe868598 call_init ./csu/../csu/libc-start.c:128:20
#14 0x0000ff03fe868598 __libc_start_main ./csu/../csu/libc-start.c:347:5
#15 0x0000aacc1aadd4f0 (/usr/lib/llvm-19/bin/llvm-bolt+0x74d4f0)
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: /usr/lib/llvm-19/bin/llvm-bolt python.prebolt -o python.bolt -data=python.fdata -update-debug-sections -skip-funcs=_PyEval_EvalFrameDefault,sre_ucs1_match/1,sre_ucs2_match/1,sre_ucs4_match/1 -reorder-blocks=ext-tsp -reorder-functions=cdsort -split-functions -icf=1 -inline-all -split-eh -reorder-functions-use-hot-size -peepholes=none -jump-tables=aggressive -inline-ap -indirect-call-promotion=all -dyno-stats -use-gnu-stack -frame-opt=hot
Segmentation fault (core dumped)

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

從 Python/generated_cases.c.h 中的重現和 --pgo 測試套件命令開始，接著檢查 llvm-bolt 的呼叫及其在 aarch64 上發生當機時的回溯。比較已回報的 assertion workaround 與之後 BOLT 套用步驟中的失敗。完成的標準是：--pgo profiling 執行和 BOLT 套用步驟在 Linux aarch64 上都能不發生當機而完成。