[graalvm-dev] Graal's fdlibm clone

[Christian Wimmer]

Hi,

Having our own copy is a historical leftover from the time when we did 
not have static library builds of the JDK C code. It is on our cleanup list.

Note that just using JNI to call the JDK for these methods does not 
work, since we have use cases where native image needs to work with JNI 
support disabled.

If you have an urgent need to fix this yourself before we get to it, 
please open a GitHub issue and I'll write up details about the 
requirements and approach to take.

 > A diff between jdk7 and jdk11 [3] indicates that several methods have
 > been removed from fdlibm, does GraalVM rely on these methods being 
present?

There is a long-term plan in OpenJDK to re-write all of these methods in 
Java. As soon as a pure Java version is available, the C version is no 
longer needed. So newer JDK versions require fewer C methods. This is 
currently not reflected in our implementation.

-Christian


On 5/28/20 06:26, Foivos Zakkak wrote:
> Hello all,
> 
> GraalVM includes fdlibm in its source tree [1].
> According to [2] this tree is a verbatim copy of 
> `src/share/native/java/lang/fdlibm` from JDK 7 update 40.
> Since fdlibm is part of the OpenJDK (and LabsJDK) why does GraalVM need 
> to link against an older version of fdlibm?
> 
> A diff between jdk7 and jdk11 [3] indicates that several methods have 
> been removed from fdlibm, does GraalVM rely on these methods being present?
> Would you consider linking native-images with OpenJDK's fdlibm safe?
> If not, what is nesseccary to achieve this?
> 
> Thanks,
> Foivos
> 
> [1] 
> https://github.com/oracle/graal/tree/8f5732eac5ae8aea4b3aeba7ec44205f4d20c50b/substratevm/src/com.oracle.svm.native.strictmath/src/fdlibm
> [2] 
> https://github.com/oracle/graal/blob/8f5732eac5ae8aea4b3aeba7ec44205f4d20c50b/substratevm/src/com.oracle.svm.native.strictmath/src/StrictMath.c#L28-L34
> [3] https://gist.github.com/zakkak/f50b96f62f81a56886fd6f411f3c762e
> 
> 
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