perf2bolt Assertion when bolt MySQL

[valuenumbering]

I tried bolt to optimize mysql, using GCC 10.2.1 and adding -Wl, -q on Intel platform. But perf2bolt asserted! Perf version: 4.14.105-1

1) $ perf record -e cycles:u -j any,u 2) $ perf2bolt -p /data/perf_data/perf.data -o perf.fdata mysqld BOLT-INFO: enabling relocation mode PERF2BOLT: read 6670837 samples and 207213185 LBR entries PERF2BOLT: 0 samples (0.0%) were ignored PERF2BOLT: traces mismatching disassembled function contents: 114656 (0.1%) PERF2BOLT: out of range traces involving unknown regions: 36288826 (18.1%) perf2bolt: /data/bolt/bolt/lib/Core/BinaryContext.cpp:765: const llvm::MCSymbol* llvm::bolt::BinaryContext::getOrCreateJumpTable(llvm::bolt::BinaryFunction&, uint64_t, llvm::bolt::JumpTable::JumpTableType): Assertion `JT->Parent == &Function && "cannot re-use jump table of a different function"' failed.

 #0 0x0000000000d45440 PrintStackTraceSignalHandler(void*) Signals.cpp:0:0
 #1 0x0000000000d4332e SignalHandler(int) Signals.cpp:0:0
 #2 0x00007f54bab1e630 __restore_rt sigaction.c:0:0
 #3 0x00007f54b970b3d7 raise /usr/src/debug/glibc-2.17-c758a686/signal/../nptl/sysdeps/unix/sysv/linux/raise.c:55:0
 #4 0x00007f54b970cac8 abort /usr/src/debug/glibc-2.17-c758a686/stdlib/abort.c:92:0
 #5 0x00007f54b97041a6 __assert_fail_base /usr/src/debug/glibc-2.17-c758a686/assert/assert.c:92:0
 #6 0x00007f54b9704252 (/lib64/libc.so.6+0x2f252)
 #7 0x0000000001b75b83 llvm::bolt::BinaryContext::getOrCreateJumpTable(llvm::bolt::BinaryFunction&, unsigned long, llvm::bolt::JumpTable::JumpTableType) (/data/bolt_install/bin/perf2bolt+0x1b75b83)
 #8 0x0000000001b75d43 llvm::bolt::BinaryContext::handleAddressRef(unsigned long, llvm::bolt::BinaryFunction&, bool) (/data/bolt_install/bin/perf2bolt+0x1b75d43)
 #9 0x0000000001b8c569 llvm::bolt::BinaryFunction::disassemble()::'lambda'(llvm::MCInst&, unsigned long, unsigned long)::operator()(llvm::MCInst&, unsigned long, unsigned long) const BinaryFunction.cpp:0:0
#10 0x0000000001ba3463 llvm::bolt::BinaryFunction::disassemble() (/data/bolt_install/bin/perf2bolt+0x1ba3463)
#11 0x0000000000b20260 llvm::bolt::RewriteInstance::disassembleFunctions() (/data/bolt_install/bin/perf2bolt+0xb20260)
#12 0x0000000000b78de5 llvm::bolt::RewriteInstance::run() (/data/bolt_install/bin/perf2bolt+0xb78de5)
#13 0x000000000040e0e0 main (/data/bolt_install/bin/perf2bolt+0x40e0e0)
#14 0x00007f54b96f7555 __libc_start_main /usr/src/debug/glibc-2.17-c758a686/csu/../csu/libc-start.c:300:0
#15 0x00000000004757b5 _start (/data/bolt_install/bin/perf2bolt+0x4757b5)
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace.
Stack dump:
0.      Program arguments: perf2bolt -p /test/perf.data -o perf.fdata /test/mysqld
Aborted

== But I try a simple helloworld program, it is OK. Can anyone know how to debug the issue?

[aaupov]

Hi @valuenumbering! I would guess the reason for that assertion is GCC-style split jump tables with entries pointing to the function and the cold fragment. Did you enable the following gcc flag: -fno-reorder-blocks-and-partition? If that doesn't fix the issue, please share the exact steps to build mysqld binary.

[valuenumbering]

Hi @aaupov, It is OK with -fno-reorder-blocks-and-partition. Thanks a ton!! Could you help another issue ? :). #264

[aaupov]

Great! I've left the comment in #264. Closing this one.