https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106070
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
+Applying pattern match.pd:4591, gimple-match.cc:59644
...
@@ -31,7 +41,7 @@
var_4.3_3 = (unsigned int) var_4.2_2;
iftmp.0_9 = (long unsigned int) var_2.1_1;
iftmp.0_10 = (long unsigned int) var_4.2_2;
_4 = var_2.1_1 != var_4.3_3;
- iftmp.0_6 = _4 ? iftmp.0_10 : iftmp.0_9;
+ iftmp.0_6 = (long unsigned int) var_4.3_3;
<bb 4> [local count: 955630225]:
# a_16 = PHI <a_12(7), 0(3)>
so that's
var_2 != (unsigned) var_4 ? -> (unsigned long) var_4 : (unsigned long) var_2
which we turn into (unsigned long) (unsigned) var_4. I thought that's what
generic also does but I have to double-check operand_equal_for_comparison_p
here.
Ah, it checks
/* Discard a single widening conversion from ARG1 and see if the inner
value is the same as ARG0. */
if (CONVERT_EXPR_P (arg1)
&& INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (arg1, 0)))
&& TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (arg1, 0)))
< TYPE_PRECISION (TREE_TYPE (arg1))
&& operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0))
and the operand_equal_p matches against the non-NOP-stripped arg0. So it's
either a same precision or widening of the comparison op.
Hmm, will have to think how to translate that into a sign check to make it
fit match.pd (I don't want to export and use operand_equal_for_comparison_p)
