On 5/18/25 10:38 AM, Andrew Pinski wrote:
While working on improving forwprop and removal of
forward_propagate_into_gimple_cond/forward_propagate_into_comparison,
I came cross a case where we end up with SSA_NAME in the resulting
gimple_match_op and one statement in the sequence. This was the result
of simplification of:
```
_3 = MIN_EXPR <maxlen_2(D), 264> > 16
if (_3 > 16) ...
```
Which simplifies down to:
(maxlen_2(D) > 16) & (264 > 16)
into
(maxlen_2(D) > 16) & 1
Which `maxlen_2(D) > 16` gets pushed onto the sequence
and then the & 1 is removed via the match pattern:
```
/* x & ~0 -> x */
(simplify
(bit_and @0 integer_all_onesp)
(non_lvalue @0))
```
So what this patch does is to undo the push extracting the new op
from the pushed statement and remove the sequence as it is not used
any more.
Bootstrapped and tested on x86_64-linux-gnu.
gcc/ChangeLog:
PR tree-optimization/120331
* gimple-match-exports.cc (maybe_undo_push): New function.
(gimple_simplify): Call maybe_undo_push if resimplify was successfull.
OK, but this isn't my strongest area. So give Richi until Monday AM to
chime in if he's got concerns.
Thanks,
jeff
