RFR: 8295159: DSO created with -ffast-math breaks Java floating-point arithmetic

[Vladimir Ivanov]

On Wed, 26 Oct 2022 17:10:00 GMT, David Holmes <david.holmes at oracle.com> wrote:

> At most an expanded -Xcheck:jni check for FP-state manipulation, with an
enhanced/fixed RestoreMXCSROnJNICalls is in order IMVHO.

FTR both `-Xcheck:jni` and `-XX:+RestoreMXCSROnJNICalls` already catch the problematic case being discussed.


$ .../jdk/bin/java ... compiler/floatingpoint/TestDenormalDouble
Exception in thread "main" java.lang.AssertionError: TEST FAILED: 0.0
        at compiler.floatingpoint.TestDenormalDouble.testDoubles(TestDenormalDouble.java:42)
        at compiler.floatingpoint.TestDenormalDouble.main(TestDenormalDouble.java:52)


$ .../jdk/bin/java ... -Xcheck:jni compiler/floatingpoint/TestDenormalDouble
Loading libfast-math.so
Java HotSpot(TM) 64-Bit Server VM warning: MXCSR changed by native JNI code, use -XX:+RestoreMXCSROnJNICall
Test passed.


$ .../jdk/bin/java ... -XX:+RestoreMXCSROnJNICalls compiler/floatingpoint/TestDenormalDouble
Loading libfast-math.so
Test passed.

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PR: https://git.openjdk.org/jdk/pull/10661