superfluous TEST instruction

[Vladimir Kozlov]

It was filed before we start work in open.
Anyway, currently it is not the problem since new x86 cpus fuse
test+jcc instructions into one so there is no performance loss,
only code size is affected.

To implement 5044093 requires a lot of work so, most like,
we will not do it soon.

Vladimir

Ulf Zibis wrote:
> Much thanks, but not visible on the web. :-(
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5044093
> 
> -Ulf
> 
> 
> Am 19.03.2010 19:43, schrieb Vladimir Kozlov:
>> RFE: 5044093
>>
>> Vladimir
>>
>> Ulf Zibis wrote:
>>> If I understand the Intel manual right, the zero flag is already set 
>>> from the SHR instruction, so newly testing on 0 by TEST instruction 
>>> seems superfluous.
>>>
>>> Am I wrong ?
>>>
>>>
>>>   0x00b88942: shr    $0x10,%eax         ;*iushr
>>>                                         ; - 
>>> java.lang.Character::isBMPCodePoint at 3 (line 2737)
>>>                                         ; - 
>>> java.lang.Character::charCount at 1 (line 2907)
>>>                                         ; - 
>>> java.lang.Character::charCount at 26 (line 2946)
>>>   0x00b88945: test   %eax,%eax
>>>   0x00b88947: je     0x00b88973         ;*ifeq
>>>                                         ; - 
>>> java.lang.Character::charCount at 4 (line 2907)
>>>                                         ; - 
>>> java.lang.Character::charCount at 26 (line 2946)
>>>
>>>
>>> -Ulf
>>>
>>>
>>
>>
>