Re: [Qemu-devel] [PATCH 1/2] cutils: remove one unnecessary pointer operation

From: Wei Yang <richard.weiyang@gmail.com>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: quintela@redhat.com, Wei Yang <richardw.yang@linux.intel.com>,
	qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 1/2] cutils: remove one unnecessary pointer operation
Date: Tue, 11 Jun 2019 22:10:50 +0000	[thread overview]
Message-ID: <20190611221050.cvhyl2dypkw7d53s@master> (raw)
In-Reply-To: <20190611174954.GI2777@work-vm>

On Tue, Jun 11, 2019 at 06:49:54PM +0100, Dr. David Alan Gilbert wrote:
>* Wei Yang (richardw.yang@linux.intel.com) wrote:
>> Since we will not operate on the next address pointed by out, it is not
>> necessary to do addition on it.
>> 
>> After removing the operation, the function size reduced 16/18 bytes.
>
>For me with a -O3 it didn't make any difference - the compiler was
>already smart enough to spot it, but it is correct.
>

Ah, you are right.

>
>Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>
>> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>> ---
>>  util/cutils.c | 8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>> 
>> diff --git a/util/cutils.c b/util/cutils.c
>> index 9aacc422ca..1933a68da5 100644
>> --- a/util/cutils.c
>> +++ b/util/cutils.c
>> @@ -754,11 +754,11 @@ int uleb128_encode_small(uint8_t *out, uint32_t n)
>>  {
>>      g_assert(n <= 0x3fff);
>>      if (n < 0x80) {
>> -        *out++ = n;
>> +        *out = n;
>>          return 1;
>>      } else {
>>          *out++ = (n & 0x7f) | 0x80;
>> -        *out++ = n >> 7;
>> +        *out = n >> 7;
>>          return 2;
>>      }
>>  }
>> @@ -766,7 +766,7 @@ int uleb128_encode_small(uint8_t *out, uint32_t n)
>>  int uleb128_decode_small(const uint8_t *in, uint32_t *n)
>>  {
>>      if (!(*in & 0x80)) {
>> -        *n = *in++;
>> +        *n = *in;
>>          return 1;
>>      } else {
>>          *n = *in++ & 0x7f;
>> @@ -774,7 +774,7 @@ int uleb128_decode_small(const uint8_t *in, uint32_t *n)
>>          if (*in & 0x80) {
>>              return -1;
>>          }
>> -        *n |= *in++ << 7;
>> +        *n |= *in << 7;
>>          return 2;
>>      }
>>  }
>> -- 
>> 2.19.1
>> 
>--
>Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

-- 
Wei Yang
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