Re: [PATCH] Fix MMC warnings

Russell King
2005-01-02T11:55:29Z

On Sun, Jan 02, 2005 at 08:44:09AM +0000, Russell King wrote:
> On Sun, Jan 02, 2005 at 01:07:31AM +0100, Pierre Ossman wrote:
> > Here's a patch that fixes the compiler warnings in mmc.c.
>
> I'd rather the compiler was fixed so that it does proper analysis of
> the code, rather than blatently issuing warnings for code which is
> unreachable.

Actually, you're quite correct about the first instance - 'mask' may
be generated from 1 << 32 - 1, which is definitely reachable, and gcc
will warn about. There's also another bug - an out by one on whether
to use the second word to construct the value.

However, the other 5 warnings are due to (corrected version):

if (16 + 0 > 32)
__res |= resp[__off-1] << (32 - 0);

Obviously, this code is not reachable since the if condition is false.
Therefore, gcc's whinging about the shift being >= 32 is wrong.

That said, the fix doesn't change gcc's code generation, so I think I'll
apply the changes. Thanks.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core