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[Qemu-devel] Re: [PATCH] Correct use of ! and &
From: |
Aurelien Jarno |
Subject: |
[Qemu-devel] Re: [PATCH] Correct use of ! and & |
Date: |
Fri, 14 Jan 2011 23:25:51 +0100 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Fri, Jan 14, 2011 at 10:05:11PM +0000, Blue Swirl wrote:
> Combining bitwise AND and logical NOT is suspicious.
>
> Fixed by this Coccinelle script:
> // From http://article.gmane.org/gmane.linux.kernel/646367
> @@ expression E1,E2; @@
> (
> !E1 & !E2
> |
> - !E1 & E2
> + !(E1 & E2)
> )
>
> Signed-off-by: Blue Swirl <address@hidden>
> ---
> target-sh4/helper.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/target-sh4/helper.c b/target-sh4/helper.c
> index 2343366..c6af959 100644
> --- a/target-sh4/helper.c
> +++ b/target-sh4/helper.c
> @@ -380,7 +380,7 @@ static int get_mmu_address(CPUState * env,
> target_ulong * physical,
> MMU_DTLB_VIOLATION_READ;
> } else if ((rw == 1) && !(matching->pr & 1)) {
> n = MMU_DTLB_VIOLATION_WRITE;
> - } else if ((rw == 1) & !matching->d) {
> + } else if (!(matching->d & (rw == 1))) {
Here, we really want to do a logical comparison, so && is probably
better. Note however that matching->d is a single bit so the code is
doing what it is supposed to do.
> n = MMU_DTLB_INITIAL_WRITE;
> } else {
> *prot = PAGE_READ;
> @@ -430,7 +430,7 @@ static int get_physical_address(CPUState * env,
> target_ulong * physical,
> }
>
> /* If MMU is disabled, return the corresponding physical page */
> - if (!env->mmucr & MMUCR_AT) {
> + if (!(env->mmucr & MMUCR_AT)) {
> *physical = address & 0x1FFFFFFF;
> *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
> return MMU_OK;
This one is correct.
Thanks for spotting these issues.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net