2015-09-01 13:17 GMT+02:00 Kai Tietz <ktiet...@googlemail.com>:
> 2015-09-01 10:43 GMT+02:00 Kai Tietz <ktiet...@googlemail.com>:
>> 2015-09-01 10:15 GMT+02:00 Kai Tietz <ktiet...@googlemail.com>:
>>> 2015-08-31 22:19 GMT+02:00 Kai Tietz <ktiet...@googlemail.com>:
>>>> 2015-08-31 21:43 GMT+02:00 Kai Tietz <ktiet...@googlemail.com>:
>>>>> 2015-08-31 21:29 GMT+02:00 Jason Merrill <ja...@redhat.com>:
>>>>>> On 08/31/2015 03:08 PM, Kai Tietz wrote:
>>>>>>>
>>>>>>> I will need to verify that this patch doesn't introduce regressions.
>>>>>>> The wacky thing here is the encapsulation of overflowed-arguments in
>>>>>>> maybe_constant_value function by nop-expr.
>>>>>>
>>>>>>
>>>>>> Do we need to worry about that? If one of the operands is overflowed, we
>>>>>> don't care whether the result is overflowed.
>>>>>
>>>>> Well, we would introduce, if we don't see in condition that operand
>>>>> already overflowed, double overflow-warning, which seems to be
>>>>> something we avoided until now. So I would say, it matters.
>>>>>
>>>>> Kai
>>>>
>>>> Similar to the binary-operation we want to do then the same for
>>>> unary-operations, too.
>>>>
>>>> Eg. testcase:
>>>>
>>>> #include <limits.h>
>>>>
>>>> constexpr int f() { return INT_MIN; }
>>>>
>>>> int main()
>>>> {
>>>> return -f(); // { dg-warning "overflow" }
>>>> }
>>>> With following patch we do diagnostics for it.
>>>>
>>>> Kai
>>>>
>>>> Index: semantics.c
>>>> ===================================================================
>>>> --- semantics.c (Revision 227339)
>>>> +++ semantics.c (Arbeitskopie)
>>>> @@ -2553,9 +2553,11 @@ finish_unary_op_expr (location_t loc, enum tree_co
>>>> tree result = build_x_unary_op (loc, code, expr, complain);
>>>> tree result_ovl = result;
>>>>
>>>> - expr_ovl = fold_simple (expr_ovl);
>>>> - result_ovl = fold_simple (result);
>>>> -
>>>> + expr_ovl = maybe_constant_value (expr_ovl);
>>>> + result_ovl = maybe_constant_value (result);
>>>> + /* Strip nop-expressions added by maybe_constant_value on overflow. */
>>>> + STRIP_NOPS (expr_ovl);
>>>> + STRIP_NOPS (result_ovl);
>>>> if ((complain & tf_warning)
>>>> && TREE_OVERFLOW_P (result_ovl) && !TREE_OVERFLOW_P (expr_ovl))
>>>> overflow_warning (input_location, result_ovl);
>>>
>>> I committed patches for binary & unary operations together with
>>> testcases. Regression-run still running. There seems to be
>>> additional expressions needed in constexpr for this. For now we have
>>> a bootstrap-issue due cast_expr in cxx_eval_constant_expression.
>>> There might be more of them ...
>>
>> I had to add for now that cxx_eval_constant_expr ignores on CAST_EXPR,
>> STATIC_CAST_EXPR, OVERLOAD, and TREE_LIST. Additionally we need to
>> handle for increments that offset is NULL_TREE (TREE_OPERAND (,1)) .
>
> Issue was easier to resolve by checking in binary/unary
> overflow-checking-functions that we aren't processing template
> declarations. If we aren't within template-declaration processing we
> can call maybe_constant_value. This avoids that we feed
> maybe_constant_value with mentioned C++-template specific expressions.
>
> Bootstrap ran successful, regression-testing still running for it. I
> committed additional check already to branch.
All tests passed as expected.
Kai
