Re: [dpdk-dev] [PATCH] A fix to work around strict-aliasing rules breaking

[Pawel Wodkowski <pawelx.wodkowski@intel.com>]

On 2015-03-02 11:32, Bruce Richardson wrote:
> On Mon, Mar 02, 2015 at 05:03:50PM +0800, zhihong.wang@intel.com wrote:
>> Fixed strict-aliasing rules breaking errors for some GCC version.
>>
>
> This looks messy. Also, I believe the definition of memcpy should include
> the "restrict" keyword to indicate that source and dest can't overlap. Might
> that help fix the issue?
>

Is this error related with overlapping or casting 'void *' to 'uintXX_t 
*' that make compiler report aliasing rule breaking?

>
>> Signed-off-by: Zhihong Wang <zhihong.wang@intel.com>
>> ---
>>   .../common/include/arch/x86/rte_memcpy.h           | 44 ++++++++++++----------
>>   1 file changed, 24 insertions(+), 20 deletions(-)
>>
>> diff --git a/lib/librte_eal/common/include/arch/x86/rte_memcpy.h b/lib/librte_eal/common/include/arch/x86/rte_memcpy.h
>> index 69a5c6f..f412099 100644
>> --- a/lib/librte_eal/common/include/arch/x86/rte_memcpy.h
>> +++ b/lib/librte_eal/common/include/arch/x86/rte_memcpy.h
>> @@ -195,6 +195,8 @@ rte_mov256blocks(uint8_t *dst, const uint8_t *src, size_t n)
>>   static inline void *
>>   rte_memcpy(void *dst, const void *src, size_t n)
>>   {
>> +	uintptr_t dstu = (uintptr_t)dst;
>> +	uintptr_t srcu = (uintptr_t)src;

If so maybe using union here would be good solution or 'char *'.

-- 
Pawel