s390x does not handle PC offset correctly when using CREL

[miladfarca]

#include <iostream>

void c() {
    throw std::runtime_error("e");
}

void f() {
    try {
        c();
    } catch (...) {
        std::cerr << "caught\n";
    }
}

int main() {
    f();
    return 0;
}

This could cause a segfault or an infinite loop when compiled with --crel:

# clang++ -fuse-ld=lld -Wa,--crel,--allow-experimental-crel 0.cc
# ./a.out
<does not exit>

a brasl seems to be branching into itself:

0x1001d04 <main+20>                     brasl  %r14,0x1001d04 <main+20>

Version details:

# clang++ -v
clang version 19.1.7 ( 19.1.7-2.module+el8.10.0+23045+e1f8e80e)
Target: s390x-redhat-linux-gnu

Seems to be similar to this issue on arm: #141678

[nico]

@MaskRay

[llvmbot]

@llvm/issue-subscribers-lld-elf

Author: Milad Fa (miladfarca)

```cpp #include <iostream>

void c() {
throw std::runtime_error("e");
}

void f() {
try {
c();
} catch (...) {
std::cerr << "caught\n";
}
}

int main() {
f();
return 0;
}

This could cause a segfault or an infinite loop when compiled with --crel:

clang++ -fuse-ld=lld -Wa,--crel,--allow-experimental-crel 0.cc

./a.out

<does not exit>

a `brasl` seems to be branching into itself:

0x1001d04 <main+20> brasl %r14,0x1001d04 <main+20>

Version details:

clang++ -v

clang version 19.1.7 ( 19.1.7-2.module+el8.10.0+23045+e1f8e80e)
Target: s390x-redhat-linux-gnu

Seems to be similar to this issue on arm: https://github.com/llvm/llvm-project/issues/141678
</details>