[Bolt] question: error on recursive function with suffix .localalias/1

[miz2019]

I have a program got LTO+PGO, when instrumented by BOLT, the code is genereated , but the program can not run correctly and no data is generated.
Given the normal mangled name A, the function will getname as A.localalias/1, the name is get from BinaryFunction::getOneName().
1: the function has suffix .localalias
2: the function will call itself, i.e. recursively.

Does anyone know why localalias is generated? and any clue on solving this error .

The program under test is very huge and complicated.

I am on Aarch64

Thanks.

[miz2019]

I am very sure the error is caused by the function, because if only this function is not instrucmented. ALL is OK.

[miz2019]

after some investigation, comment a line code in "Instrumentation.cpp" wil OK for all.

// Handle indirect calls -- could be direct calls with unknown targets
// or secondary entry points of known functions, so check it is indirect
// to be sure.
if (0 && opts::InstrumentCalls && BC.MIB->isIndirectCall(*I)) //comment here by add 0&&
instrumentIndirectTarget(BB, I, Function, FromOffset);

[miz2019]

I found the instrument context use X16 reg, but the bolt builtin also use X16

although the comments says
// Here we load address of the next function which should be called in the
// original binary to X16 register. Writing to X16 is permitted without
// needing to restore.
is it a problem ?

[liusy58]

Could you please provide reproducer?

[miz2019]

sorry, I can't reproduce the problem in small test case. The target binary is very big.
I did another test, because the target address is stored in X2.
41f404: aa0203e0 mov x0, x2
so I changed the bolt code createInstrumentedIndCallHandlerExitBB to use X2 instead of X16, the instrumented binary works fine.
The function has multimple indirect call, and I just only enabled the problematic one.

[miz2019]

one solution:?
the instument not direct call target in bolt createInstrumentedIndCallHandlerExitBB , instread, return from there and call target in user code context, in there bolt can know the target register, and use the same register.