how to make gcc warn about arithmetic signed overflow
Mon Sep 23 19:43:00 GMT 2013
On Mon, 2013-09-23 at 13:38 -0600, Dave Allured - NOAA Affiliate wrote:
> On Sun, Sep 22, 2013 at 10:03 PM, James K. Lowden
> <firstname.lastname@example.org> wrote:
> > Regarding the OP's query
> >> > int r = ab * bc;
> > although the provided example is simple enough, it's the compiler's
> > job is to generate object code, not to do static analysis.
> > Even if the values are const, in the general case they could be
> > modified by another module or another thread. The compiler simply
> > doesn't have enough information to warn of every runtime overflow.
> I believe the CPU overflow flag is updated after most integer
> arithmetic instructions. Does GCC have any facility for checking this
> flag after each integer operation? This would be a runtime check, of
> course, not a compile time check.
See -ftrapv option. Although trapping math is not supported on every
or SH related http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54272
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