RE: [PATCH 9/9] hw/timer/renesas_tmr: silence the compiler warnings

[Chenqun (kuhn)]

> -----Original Message-----
> From: Philippe Mathieu-Daudé [mailto:philippe.mathieu.daude@gmail.com]
> On Behalf Of Philippe Mathieu-Daudé
> Sent: Wednesday, October 28, 2020 6:00 PM
> To: Chenqun (kuhn) <kuhn.chenqun@huawei.com>; qemu-devel@nongnu.org;
> qemu-trivial@nongnu.org
> Cc: Zhanghailiang <zhang.zhanghailiang@huawei.com>; Yoshinori Sato
> <ysato@users.sourceforge.jp>; Magnus Damm <magnus.damm@gmail.com>;
> ganqixin <ganqixin@huawei.com>; Euler Robot <euler.robot@huawei.com>
> Subject: Re: [PATCH 9/9] hw/timer/renesas_tmr: silence the compiler warnings
> 
> On 10/28/20 5:18 AM, Chen Qun wrote:
> > When using -Wimplicit-fallthrough in our CFLAGS, the compiler showed
> warning:
> > ../hw/timer/renesas_tmr.c: In function ‘tmr_read’:
> > ../hw/timer/renesas_tmr.c:221:19: warning: this statement may fall through
> [-Wimplicit-fallthrough=]
> >   221 |         } else if (ch == 0) {i
> >       |                   ^
> > ../hw/timer/renesas_tmr.c:224:5: note: here
> >   224 |     case A_TCORB:
> >       |     ^~~~
> >
> > Add the corresponding "fall through" comment to fix it.
> >
> > Reported-by: Euler Robot <euler.robot@huawei.com>
> > Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
> > ---
> > Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> > Cc: Magnus Damm <magnus.damm@gmail.com>
> > ---
> >  hw/timer/renesas_tmr.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/hw/timer/renesas_tmr.c b/hw/timer/renesas_tmr.c index
> > 446f2eacdd..e03a8155b2 100644
> > --- a/hw/timer/renesas_tmr.c
> > +++ b/hw/timer/renesas_tmr.c
> > @@ -221,6 +221,7 @@ static uint64_t tmr_read(void *opaque, hwaddr addr,
> unsigned size)
> >          } else if (ch == 0) {
> >              return concat_reg(tmr->tcora);
> >          }
> > +        /* fall through */
> >      case A_TCORB:
> >          if (size == 1) {
> >              return tmr->tcorb[ch];
> >
> 
> You fixed A_TCORA but not A_TCORB...
> 
Hi Philippe,
 My first feeling is the same as you when this warning found.
But, the number of branches for A_TCORA and A_TCORB is different.

In A_TCORA case："} else if (ch == 0) {"
In A_TCORB case："} else {"

Obviously, A_TCOB have all return values. But A_TCOA is not, it need to fall 
through or break.

> How the Euler Robot works? Like Coverity?

No, unlike Coverity, Coverity is essentially a good discovery bug tool.
But EulerRobot is a virtualization software quality automation project that 
integrates some tools and test suites such as gcc/clang make test, qemu ut, 
qtest, coccinelle scripts and avocado-vt.

Thanks,
Chen Qun