aarch64: jdk9: 8078245: fails to build from source
david.holmes at oracle.com
Thu Apr 30 05:34:22 UTC 2015
On 30/04/2015 3:26 PM, David Holmes wrote:
> Hi Nevill,
> Just realized this was sent to hotspot-dev (attempting bcc) but is not a
> hotspot issue. With your new approach this is a build issue so cc'ing
> The new approach seems better to me but build folk need to confirm the
> On 29/04/2015 8:52 PM, Edward Nevill wrote:
>> On Fri, 2015-04-24 at 17:11 +1000, David Holmes wrote:
>>> Hi Ed,
>>> On 21/04/2015 7:16 PM, Edward Nevill wrote:
>>>> The current jdk9 tip fails to build from source on aarch64 with the
>>>> following error message
>>>> In function `png_init_filter_functions':
>>>> undefined reference to `png_init_filter_functions_neon'
>>>> collect2: error: ld returned 1 exit status
>>>> The following webrev gets it building again.
>>> Shouldn't the guard be Aarch64 specific rather than just __arm__ ? I'm
>>> also wondering how we would get __ARM_NEON defined but not __arm__?
>> On arm 32 bit gcc defines the symbol __ARM_NEON if the flag -mfpu=neon
>> is specified. Since this is not specified as part of the OpenJDK build
>> the symbol is not defined and the build succeeds.
>> On aarch64 the symbol __ARM_NEON is always defined (the theory being
>> that aarch64 always supports Neon). Personally I think this is borken
>> as it causes builds to fail (and not just OpenJDK, several other
>> projects have had the same build failure - try googling the above
>> error message). But we are stuck with gcc as it is.
>> However, I don't like the above fix because it not only modifies the
>> jdk, it modifies an external component which is pulled into jdk, which
>> means every time a new revision of linpng is pulled in, the patch will
>> have to be applied again.
>> A better approach I think is to define the symbol PNG_ARM_NEON_OPT=0
>> in the build (only if aarch64).
>> The failing code in pngpriv.h reads
>> #ifndef PNG_ARM_NEON_OPT
>> # if (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \
>> # define PNG_ARM_NEON_OPT 2
>> # else
>> # define PNG_ARM_NEON_OPT 0
>> # endif
>> So, if we just predefine PNG_ARM_NEON=0 in the build this will have
>> the same effect as adding defined(__arm__) or !defined(__aarch64__)
>> The following patch webrev does this:-
>> If you are happy with this and if I could have another reviewer I will
>> push this.
>> All the best,
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