Why is gcc not catching an exception from a multi target function?-CodePudding

I'm using the target attribute to generate different function implementations depending on the CPU architecture. If one of the functions throws an exception it doesn't get caught if I compile with gcc, but with clang it works as expected. If there is only a single implementation of the function it does work for gcc as well.

Is this a bug in gcc?

Example (godbolt):

#include <stdexcept>
#include <iostream>

using namespace std;

__attribute__((target("default")))
void f() {
    throw 1;

}

__attribute__((target("sse4.2,bmi")))
void f() {
    throw 2;
}

int main()
{
    try {
        f();
    }
    catch(... )
    {
        std::cout << "Caught exception" << std::endl;
    }
}

Output of gcc:

terminate called after throwing an instance of 'int'

Output of clang:

Caught exception

CodePudding user response：

I reported this and a GCC developer confirmed it as a bug: link

For now a workaround seems to wrap the function and use the gnu::noipa attribute to disable interprocedural optimizations:

__attribute__((target("default")))
void f() {
    throw 1;
}

__attribute__((target("sse4.2")))
void f() {
    throw 2;
}
[[gnu::noipa]]
void f1()
{
    f();
}

int main()
{
    try {
        f1();
    }
    catch(... )
    {
        return 0;
    }
    return 1;
}