[Bug middle-end/44786] -fsanitize=undefined: Turn on runtime code generation to check for undefined behavior

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44786

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|-fcatch-undefined-behavior: |-fsanitize=undefined: Turn
                   |Turn on runtime code        |on runtime code generation
                   |generation to check for     |to check for undefined
                   |undefined behavior          |behavior

--- Comment #7 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2012-11-08 13:21:54 UTC ---
> It didn't get very far (haven't looked deeper yet):

This PR is for implementing those checks in GCC. For things broken in GCC, you
should open new PRs.

BTW, Clang now supports all these checks:

    -fsanitize=alignment: Use of a misaligned pointer or creation of a
misaligned reference.
    -fsanitize=divide-by-zero: Division by zero.
    -fsanitize=float-cast-overflow: Conversion to, from, or between
floating-point types which would overflow the destination.
    -fsanitize=null: Use of a null pointer or creation of a null reference.
    -fsanitize=object-size: An attempt to use bytes which the optimizer can
determine are not part of the object being accessed. The sizes of objects are
determined using __builtin_object_size, and consequently may be able to detect
more problems at higher optimization levels.
    -fsanitize=return: In C++, reaching the end of a value-returning function
without returning a value.
    -fsanitize=shift: Shift operators where the amount shifted is greater or
equal to the promoted bit-width of the left hand side or less than zero, or
where the left hand side is negative. For a signed left shift, also checks for
signed overflow in C, and for unsigned overflow in C++.
    -fsanitize=signed-integer-overflow: Signed integer overflow, including all
the checks added by -ftrapv, and checking for overflow in signed division
(INT_MIN / -1).
    -fsanitize=unreachable: If control flow reaches __builtin_unreachable.
    -fsanitize=vla-bound: A variable-length array whose bound does not evaluate
to a positive value.
    -fsanitize=vptr: Use of an object whose vptr indicates that it is of the
wrong dynamic type, or that its lifetime has not begun or has ended.
Incompatible with -fno-rtti.