| Issue |
91262
|
| Summary |
Clang omits variable with "used" attribute
|
| Labels |
clang:codegen
|
| Assignees |
|
| Reporter |
pogo59
|
[GCC](https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html) specifies the "used" attribute as:
> This attribute, attached to a variable with static storage, means that the variable must be emitted even if it appears that the variable is not referenced.
Inside a constant "if" condition, clang will fail to emit a "used" variable in the not-taken branch. This differs from GCC behavior.
```
void foo() {
if (sizeof(double) == sizeof(long double)) {
__attribute__((used)) static int my_item(__LINE__);
} else {
__attribute__((used)) static int my_item(__LINE__);
}
}
```
Clang allocates only one variable, GCC allocates both. Given it's a GCC-defined attribute, we should behave the way GCC does. This appears to be a Clang codegen bug, as `-emit-llvm -disable-llvm-passes` shows only one item.
(Why would I need this? It's part of the instrumentation for my Rotten Green Tests project. My static variables are actually allocated into a custom section, but that's not needed to trigger the bug.)
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