Hi! I trying to improved -Wunsequenced by taking into account the volatile qualifier and found suspicious use volatile qualified variable in file libc/src/__support/math/log1p.h:
```c++
volatile float tp = 1.0f;
volatile float tn = -1.0f;
bool rdp = (tp - 0x1p-25f != tp);
bool rdn = (tn - 0x1p-24f != tn)
```
For C and C++ standards order of evaluate binary operator != is unsequence and unsequence access for same volatile variable is UB(because read volatile qualified variable is side-effects).
I created issue:
I can’t continue working on my PR because -Wunsequenced fail on log1p.h. now. I’m not familiar with libc, could you please tell me what to do in this situation?