RFR (trivial): 8219519: Remove linux_sparc.ad and linux_aarch64.ad

[Magnus Ihse Bursie]

On 2019-03-01 15:39, Andrew Dinn wrote:
> On 01/03/2019 14:25, Magnus Ihse Bursie wrote:
>> On 2019-02-27 03:25, Jie Fu wrote:
>>> It's a bit difficult for me to test this patch since I don't have a
>>> sparc or arm machine.
>>> I've analyzed the adlc processing logic in
>>> make/hotspot/gensrc/GensrcAdlc.gmk finding that ad-files under
>>> ./src/hotspot/os_cpu/$(HOTSPOT_TARGET_OS)_$(HOTSPOT_TARGET_CPU_ARCH)
>>> are optional.
>> What do you mean by "optional"? The build code does this:
>>
>>   
>> ##############################################################################
>>    # Concatenate all ad source files into a single file, which will be fed to
>>    # adlc.
>>
>> ...
>>
>>    AD_SRC_FILES := $(call uniq, $(wildcard $(foreach d, $(AD_SRC_ROOTS), \
>>        $d/cpu/$(HOTSPOT_TARGET_CPU_ARCH)/$(HOTSPOT_TARGET_CPU).ad \
>>        $d/cpu/$(HOTSPOT_TARGET_CPU_ARCH)/$(HOTSPOT_TARGET_CPU_ARCH).ad \
>>       
>> $d/os_cpu/$(HOTSPOT_TARGET_OS)_$(HOTSPOT_TARGET_CPU_ARCH)/$(HOTSPOT_TARGET_OS)_$(HOTSPOT_TARGET_CPU_ARCH).ad
>> \
>>      )))
>>
>> so it will definitely pick up both those files and use it in creating
>> the concatenated ad file.
> That's interesting because Pengfei Li claims he applied the patch and
> successfully built OpenJDK on AArch64.
>
>
> https://mail.openjdk.java.net/pipermail/aarch64-port-dev/2019-February/006975.html
>
> Does the build system actually need those files to exist when it builds
> the concatenated file?
No, the build system does not "need" it. If it is not there, it is not 
included (nor reported MIA), but if it is there, it is included.

>
>> That being said, maybe this is not the correct behavior.
> Well, something sounds fishy.
>
>> I see that the linux_sparc.ad file is essentially empty, so you can
>> probably remove that. The aarch64 file otoh seems to contain valid code.
>> I would not presume that you can just remove it!
> He is ok to remove it as far as any contents are concerned. Indeed, I
> told him this was ok in a review in the above thread after Pengfei
> reported that OpenJDK built without the file being present.
>
> As to the contents, the encoding defined in that file is completely
> redundant (I don't really know how it got there as I don't believe it
> was ever used)

Ok, it might very well be the case that the file is not needed since 
it's contents is redundant. I can't say anything about that; that's the 
domain of the adlc experts. However, it is incorrect to claim that the 
build does not use file in question. But from the build PoV, it's 
perfectly fine to remove it if it's not needed. But just not on the 
grounds that it is not used by the build system!

/Magnus
> regards,
>
>
> Andrew Dinn
> -----------
> Senior Principal Software Engineer
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