| Issue |
126200
|
| Summary |
Miscompilation: Missing prefixes for emulatedTLS variables on macOS/ARM64 with -O0
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
sschaller
|
Reproducer:
https://alive2.llvm.org/ce/z/6Xr9_c
```cpp
struct T {
T() {} // required
int a = 0;
};
thread_local T aa;
int main() {
return 0;
}
```
Trying to compile this code on macOS / ARM64 with `clang -stdlib=libc++ -std=c++17 -femulated-tls main.cpp`
leads to a linker error for undefined symbols `___tls_guard` and `_aa` (4-5, 60-61 in the reproducer).
Inspecting the generated assembly code shows that both symbols are used as operands instead of the prefixed variables `___emutls_v.__tls_guard` and `___emutls_v.aa`.
Compiling with `-O1` correctly prefixes the operands and fixes the issue.
I'm not quite sure what is missing and would appreciate any pointers.
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