RFR(XS): 8015437: SPARC cbcond offset value out of range

[David Chase]

Wouldn't we want to call it ba_without_delay or something like that?

David

On 2013-06-07, at 11:47 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:

> David is right.
> 
> We have a lot of places in sparc code where we are sloppy with annulled bit for direct branch and nop() in delay slot. I count about 10 cases which br() instruction and 15 with ba() which is not really bad.
> 
> We need separate macroassembler instruction for such case.
> ba_with_nop()?
> 
> Good starter task :)
> 
> Thanks,
> Vladimir
> 
> On 6/7/13 4:59 AM, David Chase wrote:
>> Huh.  ba,a (annulled branch -- if I recall, the sense of the annulled bit is reversed for ba) ought to get the job done without the delay-slot nop.
>> 
>> David
>> 
>> On 2013-06-07, at 6:54 AM, Morris Meyer <morris.meyer at oracle.com> wrote:
>> 
>>> I needed to have the delayed()->nop() in there as ba() crashed for me.
>>> 
>>> 
>>>      --mm
>>> 
>>> 
>>> On Jun 7, 2013, at 12:35 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
>>> 
>>>> Morris,
>>>> 
>>>> Why you used br(always, false, pt, slow_case) instead of ba(slow_case)?
>>>> 
>>>> Which is the same but simpler and it was specially added to avoid messing with parameters of br() instruction.
>>>> 
>>>> Thanks,
>>>> Vladimir
>>>> 
>>>> On 6/6/13 9:22 PM, Morris Meyer wrote:
>>>>> Folks,
>>>>> 
>>>>> Could I get a review for this issue?  The problem exists that we
>>>>> optimistically assign forward branch labels and re-patch later. When we
>>>>> emit a cbcond instruction - we check if the Label out of bounds.  If it
>>>>> is already bound the check is fine - if not bound a zero offset is
>>>>> emitted and the label is patched later
>>>>> 
>>>>> With Vladimir Kozlov's urgings I put about 4,000 lines of changes to add
>>>>> __FILE__ and __LINE__ parameters to every assembler.bind() call and
>>>>> checked the return of every patched branch to find out the line and
>>>>> location of the offending bind.  The bind distance from
>>>>> NewInstanceStub::emit_code() in c1_CodeStubs_sparc.cpp was to far from
>>>>> __ allocate_object macro assembler call in LIRGenerator::new_instance
>>>>> which uses the short branch in MacroAssembler::eden_allocate()
>>>>> 
>>>>> This change has been through JPRT.
>>>>> 
>>>>>        --morris
>>>>> 
>>>>> WEBREV - http://cr.openjdk.java.net/~morris/JDK-8015437.01
>>>>> JBS - https://jbs.oracle.com/bugs/browse/JDK-8015437
>>>>> 
>>>>> 
>>