Re: [PATCHv3, resent] Add a warning for suspicious use of conditional expressions in boolean context

[Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot com>]

On 20/09/16 16:30, Bernd Schmidt wrote:
> On 09/20/2016 05:18 PM, Jeff Law wrote:
> > > I assume HARD_FRAME_POINTER_REGNUM is never zero.
> > It could be zero.  It's just a hard register number.  No target has the
> > property that its hard frame pointer register is 0 though :-)
>
> git blame to the rescue. The current state comes from one of tbsaunde's cleanup patches:
>
> > diff --git a/gcc/regrename.c b/gcc/regrename.c
> index 174d3b5..e5248a5 100644
> --- a/gcc/regrename.c
> +++ b/gcc/regrename.c
> @@ -442,12 +442,10 @@ rename_chains (void)
>         continue;
>
>        if (fixed_regs[reg] || global_regs[reg]
> -#if !HARD_FRAME_POINTER_IS_FRAME_POINTER
> -         || (frame_pointer_needed && reg == HARD_FRAME_POINTER_REGNUM)
> -#else
> -         || (frame_pointer_needed && reg == FRAME_POINTER_REGNUM)
> -#endif
> -         )
> +         || (!HARD_FRAME_POINTER_IS_FRAME_POINTER && frame_pointer_needed
> +             && reg == HARD_FRAME_POINTER_REGNUM)
> +         || (HARD_FRAME_POINTER_REGNUM && frame_pointer_needed
> +             && reg == FRAME_POINTER_REGNUM))
>         continue;
>
>        COPY_HARD_REG_SET (this_unavailable, unavailable);
>
> Looks like it never got reviewed and was committed as preapproved.
>
> The #ifdef we had before looks odd too. Maybe this should just read
>
>  if (fixed_regs[reg] || global_regs[reg]
>      || (frame_pointer_needed && reg == HARD_FRAME_POINTER_REGNUM))

I'll try bootstrapping and testing this change on arm-none-linux-gnueabihf.

Thanks,
Kyrill

> Bernd