How does C++ exception handling translate to machine code

user_87973 0
Viewed 14115

Mentally, I've always wondered how try/throw/catch looks behind the scenes, when the C++ compiles translates it to assembler. But since I never use it, I never got around to checking it out (some people would say lazy).

Is the normal stack used for keeping track of trys, or is a separate per-thread stack kept for this purpose alone? Is the implementation between MSVC and g++ big or small? Please show me some pseudo asm (IA-32 is ok too) so I never have to check it out myself! :)

Edit: Now I get the basics of MSVC's implementation on IA-32 handling. Anybody know for g++ on IA-32, or any other CPU for that matter?

Edit 2 (11 years later): Here are some data on performance. They've also made source code freely available.

assembly try-catch exception c++
3 Answers

Asm from the Godbolt compiler explorer, for the x86-64 System V calling convention with g++8.2's C++ABI, for a function that catches, and one that throws.

x86-64 System V uses the .eh_frame section for stack-unwind metadata, so the exception-helper library functions know how to walk the stack and restore registers. That's what .cfi directives do.

user_2241320
Related