[Bug tree-optimization/113756] [14 regression] Wrong code at -O2 on x86_64-linux-gnu since r14-2780-g39f117d6c87

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113756

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I think the issue is that ABSU_EXPR is an unary operation with signed operand
and unsigned result.  And update_known_bitmask was using result rather than
operand sign to the operand's value/mask, so I think
--- gcc/range-op.cc.jj  2024-01-03 11:51:28.199777434 +0100
+++ gcc/range-op.cc     2024-02-06 16:51:55.549127825 +0100
@@ -435,8 +435,10 @@ update_known_bitmask (irange &r, tree_co
       bit_value_unop (code, sign, prec, &widest_value, &widest_mask,
                      TYPE_SIGN (lh.type ()),
                      TYPE_PRECISION (lh.type ()),
-                     widest_int::from (lh_bits.value (), sign),
-                     widest_int::from (lh_bits.mask (), sign));
+                     widest_int::from (lh_bits.value (),
+                                       TYPE_SIGN (lh.type ())),
+                     widest_int::from (lh_bits.mask (),
+                                       TYPE_SIGN (lh.type ())));
       break;
     case GIMPLE_BINARY_RHS:
       bit_value_binop (code, sign, prec, &widest_value, &widest_mask,
ought to fix this.  Of course even better would be rewrite tree-ssa-cpp.cc to
use wide_int rather than widest_int, but I'm afraid that is stage1 material.