https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108341
--- Comment #5 from Andrew Macleod <amacleod at redhat dot com> ---
(In reply to Aldy Hernandez from comment #2)
> (In reply to Martin Liška from comment #1)
> > May be an opportunity for Ranger?
>
> Hmmm... I don't think so:
>
> <bb 2> :
> value.0_1 = (unsigned int) value_4(D);
> _2 = __builtin_ctz (value.0_1);
> r = _2;
> _3 = value_4(D) != 0;
> _7 = (int) _3;
> return _7;
>
> We could add an op1_range operator to class cfn_clz to return nonzero for
> op1, but that would only work if we knew _2 to be anything...and have no
> info on _2.
Seems more like a candidate for gimpe_infer::gimple_infer (gimple *s).
THe side effect to register would be to check if 's' is a builtin_ctz and if
so, call add_nonzero (operand1) if whatever those other conditions are are
matched which make it true.
That should register a non-zero inferred range on value.0_1 after the
assignment of _2.
=========== BB 2 ============
Partial equiv (value.0_1 pe32 value_4(D))
<bb 2> :
value.0_1 = (unsigned int) value_4(D);
_2 = __builtin_ctz (value.0_1);
r = _2;
_3 = value_4(D) != 0;
_7 = (int) _3;
return _7;
I see ranger also registers a 32 bit equivalence between value.0_1 and value_4,
so in theory we would then be able to determine that value_4 is also non-zero
for the comparison.
