RFR: 8234535: Cross compilation fails due to missing CFLAGS for the BUILD_CC

[Erik Joelsson]

Hello Christoph,

On 2019-11-20 10:22, christoph.goettschkes at microdoc.com wrote:
> Hi,
>
> please review the following change.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8234535
> Webrev: https://cr.openjdk.java.net/~cgo/8234535/webrev.00/
>
> The removed lines are completely out of place and have no use at all. for
> the CC variable, for instance, the script does the following:
>
> CC_OLD="$CC"
> CC="$BUILD_CC"
> CC="$CC_OLD"
>
> without executing any function between those lines. I think that, while
> restructuring the build system, those lines have been copied to the wrong
> location. I copied them around the "FLAGS_SETUP_CFLAGS_CPU_DEP" call for
> the BUILD_CC, in order to make configure not use the target CFLAGS while
> discovering possible CFLAGS for the BUILD_CC, which was happening in our
> case.
Wow, I had not noticed that. Your fix looks correct.
> I am also not sure if the variable BUILD_CC_DISABLE_WARNING_PREFIX is
> actually used anywhere. I could not find any user and it might be possible
> to simply remove it.
It's used to override DISABLE_WARNING_PREFIX in buildjdk-spec.gmk so I 
think it serves a purpose, even if we don't actually support different 
toolchain types for cross and native compiler. If we ever will, then 
this variable will be needed, so I think it should stay.
> I tried the change and compiled on an amd64 linux machine for amd64, and
> cross-compiled for linux on armv7 and linux on aarch64. I don't have
> access to other cross-compilation environments and would like to ask
> others to review and try out the change.

I applied the patch and tried a few of our configurations. Since we use 
the same (or close to the same) compiler versions across architectures, 
I don't actually see any difference in the generated spec files. The 
reason you see this is the large version difference between your compilers.

Looks good, thanks for finding and fixing this!

/Erik

> Thanks,
> Christoph
>