On 1/4/26 4:56 PM, Andrew Pinski wrote:
On Sun, Jan 4, 2026 at 11:32 AM Jeffrey Law
<[email protected]> wrote:
On 12/30/2025 2:34 PM, Daniel Barboza wrote:
PR 102486
gcc/ChangeLog:
* match.pd (`popcount (X & -X) -> (X & -X) != 0`): New pattern.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/pr102486.c: New test.
So isn't it transformed into "X != 0" rather than "(X & -X) != 0)"?
Which means the subject line and ChangeLog entry need minor updates.
I'm not sure why Andrew suggested optimizing to (X & -X) != 0 since the
X & -X is zero when X == 0 and nonzero when X != 0.
I don't remember why I suggested optimizing it to `(X & -X) != 0`
instead of just `X != 0`. The bug report was filed 4 years ago and I
can't find my notes for what I was looking at that time or why 2 years
later mentioned `(X&-X) != 0` either. But yes it should be to `X !=
0`.
Should be an easier pattern then. I'll send a v3. Thanks,
Daniel
Thanks,
Andrew
I think Andrew also noted some additional type fixes that were needed in
the new gimple you're generating. So we probably need a V3 for that.
Jeff
