On 5/20/23 09:04, Andrew Pinski via Gcc-patches wrote:
This is a case which I noticed while working on the previous patch.
Sometimes we end up with `a == CST` instead of comparing against 0.
This happens in the following code:
```
unsigned f(unsigned t)
{
if (t & ~(1<<30)) __builtin_unreachable();
t ^= (1<<30);
return t != 0;
}
```
We should handle the case where the nonzero bits is the same as the
comparison operand.
Changes from v1:
* v2: Updated for the bit extraction changes.
OK? Bootstrapped and tested on x86_64-linux-gnu.
gcc/ChangeLog:
* expr.cc (do_store_flag): Improve for single bit testing
not against zero but against that single bit.
OK
jeff
