RFR: JDK-8217739: Cannot reuse java.base UnixConstants.java from target in BuildJDK when cross compiling

[Erik Joelsson]

Hello Ao Qi,

In my testing, I tried building ppc64le (which I first identified as 
generating a UnixConstants.java that differed from an x64 build). With 
this patch, the buildjdk and target version of UnixConstants.java differ 
the same way. How did you configure your build? I'm suspecting something 
in the setup of the buildjdk compilers is different from my configuration.

/Erik

On 2019-06-04 21:48, Ao Qi wrote:
> Hi Erik,
>
> Thank you a lot for taking care of this. I mainly like your approach.
> I tested the patch by cross building mips64-zero, by which we found
> this problem. However, it seems the problem still exists. The reason I
> found is that UnixConstants.java of buildjdk is generated by cross
> compiler, so the macro definitions are defined by the target. Here is
> a preliminary workaround for your reference only (only worked for
> gcc):
>
> $ hg diff make/gensrc/GensrcMisc.gmk
> diff -r f4df9d4201cc make/gensrc/GensrcMisc.gmk
> --- a/make/gensrc/GensrcMisc.gmk Tue Jun 04 16:50:25 2019 -0700
> +++ b/make/gensrc/GensrcMisc.gmk Wed Jun 05 12:39:43 2019 +0800
> @@ -61,6 +61,13 @@
>     CPP_FLAGS += -nologo
>   endif
>
> +ifeq ($(CREATING_BUILDJDK), true)
> +  # Only worked for gcc
> +  TEMP_CPP=gcc -E
> +else
> +  TEMP_CPP=$(CPP)
> +endif
> +
>   # Generate a java source file from a template through the C
> preprocessor for the
>   # target system. First extract the copyright notice at the start of the file.
>   # Run the preprocessor. Filter out the default compiler stderr output on
> @@ -71,7 +78,7 @@
>   define generate-preproc-src
>    $(call MakeDir, $(@D))
>    ( $(NAWK) '/@@END_COPYRIGHT@@/{exit}1' $< && \
> -   $(CPP) $(CPP_FLAGS) $(SYSROOT_CFLAGS) $(CFLAGS_JDKLIB) $< \
> +   $(TEMP_CPP) $(CPP_FLAGS) $(SYSROOT_CFLAGS) $(CFLAGS_JDKLIB) $< \
>          2> >($(GREP) -v '^$(<F)$$' >&2) \
>          | $(NAWK) '/@@START_HERE@@/,0' \
>          |  $(SED) -e 's/@@START_HERE@@/\/\/ AUTOMATICALLY GENERATED
> FILE - DO NOT EDIT/' \
>
>
> Cheers,
> Ao Qi
>
> On Wed, Jun 5, 2019 at 12:00 AM Erik Joelsson <erik.joelsson at oracle.com> wrote:
>> Thanks!
>>
>> During testing, I found an intermittent race issue. The command line
>> that runs the interim langtools version of javac still always points to
>> the buildtools/interim-langtools dir of the normal build. This variable
>> also needs to be rewritten in buildjdk-spec.gmk.in. New webrev, only
>> changed in buildjdk-spec.gmk.in:
>>
>> http://cr.openjdk.java.net/~erikj/8217739/webrev.02/
>>
>> /Erik
>>
>> On 2019-06-04 07:53, Tim Bell wrote:
>>> Erik:
>>>
>>> Looks good.
>>>
>>> Tim
>>>
>>>> This is a fix for a problem brought up on this list [1]. The main issue
>>>> is that when cross compiling, and creating a buildjdk during the build,
>>>> the UnixConstants.java cannot necessarily be reused between the target
>>>> JDK and the buildjdk. While investigating this, I came to the conclusion
>>>> that we really should stop trying to reuse anything between the buildjdk
>>>> and target JDK. It's just becoming too complex to maintain (due to the
>>>> intricate interactions with the interim-image, generate-link-opt-data
>>>> and exploded-image-optimize targets, causing circular dependencies and
>>>> endless incremental rebuilds).
>>>>
>>>> So this fix simply removes all the reuse of buildtools, gensrc and java
>>>> compilation when creating a buildjdk. Hopefully this is making Main.gmk
>>>> a bit less convoluted.
>>>>
>>>> While working on this, I came up with the idea of adding a log prefix
>>>> functionality, to more easily discern which log lines were printed by
>>>> the buildjdk build and which were part of the normal build. I liked this
>>>> a lot so including that in the same fix, and applied it to the bootcycle
>>>> build as well.
>>>>
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8217739
>>>>
>>>> Webrev: http://cr.openjdk.java.net/~erikj/8217739/webrev.01/index.html
>>>>
>>>> /Erik
>>>>
>>>> [1]
>>>> http://mail.openjdk.java.net/pipermail/build-dev/2019-January/024729.html
>>>>
>>>
>>>