[Bug tree-optimization/114666] [14 Regression] Signed single bit comparison miscompile at -O2

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114666

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |pinskia at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---

Folding statement: _3 = _2 ^ 1;
Matching expression match.pd:2835, gimple-match-2.cc:35
Matching expression match.pd:2838, gimple-match-1.cc:66
Matching expression match.pd:2845, gimple-match-2.cc:96
Matching expression match.pd:2243, gimple-match-5.cc:20
Matching expression match.pd:2835, gimple-match-2.cc:35
Matching expression match.pd:2838, gimple-match-1.cc:66
Matching expression match.pd:2845, gimple-match-2.cc:96
Applying pattern match.pd:6795, gimple-match-4.cc:1721
Matching expression match.pd:2243, gimple-match-5.cc:20
Matching expression match.pd:2286, gimple-match-3.cc:23
Matching expression match.pd:2255, gimple-match-4.cc:67
Matching expression match.pd:2243, gimple-match-5.cc:20
Applying pattern match.pd:7103, gimple-match-8.cc:47279
Applying pattern match.pd:5898, gimple-match-8.cc:47191
gimple_simplified to _7 = (long unsigned int) _1;
_8 = -_7;
_3 = _8 ^ 1;

That is wrong.

I can't figure out how we got there though. 
match.pd:6795 is the pattern which does `(convert)a CMP b` into `a CMP
(convert)b` which I assume VRP does `_3 == 0 ? 1 : -2u` which then we get `_1
== 0 ? 1 : -2u` (which seems reasonable) and then we apply match.pd:5898 which
gets us to `_1 ? -2u : 1` which seems wrong as not a boolean  type nor an one
bit unsigned integer.

So the problem is with:
 /* !A ? B : C -> A ? C : B.  */
 (simplify
  (cnd (logical_inverted_value truth_valued_p@0) @1 @2)
  (cnd @0 @2 @1)))

which does not check the types correctly for gimple. Note this pattern has been
there since 2014.
Just been exposed the issue when I added match.pd:7103 in
r14-3110-g7fb65f10285124.

Let me try to figure out what to do here to fix the issue.