[Bug ipa/114985] [15 regression] internal compiler error: in discriminator_fail during stage2

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114985

--- Comment #25 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
prange has been enabled again, after testing on x86-64 and ppc64le linux. 
Aarch has no space to run tests on the compile farm, and sparc bootstrap was
already broken.

The problem in this PR can be triggered by commenting the two new
operand_check_p conditionals:

diff --git a/gcc/ipa-cp.cc b/gcc/ipa-cp.cc
index 09cab761822..76548f31853 100644
--- a/gcc/ipa-cp.cc
+++ b/gcc/ipa-cp.cc
@@ -1744,7 +1744,7 @@ ipa_value_range_from_jfunc (vrange &vr,
                 pointer type to hold the result instead of a boolean
                 type.  Avoid trapping in the sanity check in
                 fold_range until this is fixed.  */
-             || !handler.operand_check_p (vr_type, srcvr.type (), op_vr.type
())
+             /*|| !handler.operand_check_p (vr_type, srcvr.type (), op_vr.type
())*/
              || !handler.fold_range (op_res, vr_type, srcvr, op_vr))
            op_res.set_varying (vr_type);

@@ -2556,9 +2556,11 @@ propagate_vr_across_jump_function (cgraph_edge *cs,
ipa_jump_func *jfunc,
                 pointer type to hold the result instead of a boolean
                 type.  Avoid trapping in the sanity check in
                 fold_range until this is fixed.  */
+             /*
              || !handler.operand_check_p (operand_type,
                                           src_lats->m_value_range.m_vr.type
(),
                                           op_vr.type ())
+             */
              || !handler.fold_range (op_res, operand_type,
                                      src_lats->m_value_range.m_vr, op_vr))
            op_res.set_varying (param_type);

You can reproduce on x86-64 as well as ppc64le, and the problem can be seen
with and without prange support enabled.