Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings

[Arnd Bergmann]

On Fri, Mar 3, 2017 at 12:05 AM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:

> I assume '-Wdiv-by-zero' is enabled and gcc isn't showing the "division
> by zero" warning for either of these?  The 'ud2' is guaranteed to
> trigger since the function has no branches.  Surely at least the missing
> warning is a gcc bug.
>
> The good news is objtool is flushing these out, albeit with a confusing
> message.

I'm still not sure if it's intentional or not. I've reduced the test case to the
simple

static inline int return0(void) { return 0; }
int provoke_div0_warning(void) { return 1 / return0(); }

which does not generate a compile-time warning, but will generate
an unconditional runtime warning if built with -fsanitze=integer-divide-by-zero.

     Arnd