https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78473
Bug ID: 78473
Summary: Enhancement request: __builtin_div_overflow
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: webrown.cpp at gmail dot com
Target Milestone: ---
https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html documents gcc
intrinsic functions to perform integer arithmetic with overflow checking.
Addition, subtraction, and multiplication are supported, but division is not.
However, division can overflow, for any of at least three different reasons:
(1) For a signed 2s-complement integer type T, consider dividing the most
negative value by T(-1); the result can't be represented in T.
(2) There are also cases involving mixed types such that the quotient can't be
represented in the smaller type or in a too-small third type.
(3) There's also the always-delightful division by zero opportunity.
I am therefore writing to request that division be supported as a future
enhancement to current functionality. Both the __builtin_*div_overflow and
__builtin_div_overflow_p forms would be useful, IMO.
It also seems useful to support a remainder operation in some manner, either as
a separate set of functions or perhaps via extra arguments to the division
functions.
Thanks very much.
