RFR: 8332894: ubsan: vmError.cpp:2090:26: runtime error: division by zero

[Matthias Baesken]

When running with ubsan enabled on Linux x86_64, I get in the HS :tier1 tests this error :

runtime/ErrorHandling/TestDwarf_dontCheckDecoder.jtr

/jdk/src/hotspot/share/utilities/vmError.cpp:2090:26: runtime error: division by zero
    #0 0x7f16bc531f32 in crash_with_sigfpe /jdk/src/hotspot/share/utilities/vmError.cpp:2090
    #1 0x7f16bc531f32 in VMError::controlled_crash(int) /jdk/src/hotspot/share/utilities/vmError.cpp:2137
    #2 0x7f16bea2d8fd in JNI_CreateJavaVM_inner /jdk/src/hotspot/share/prims/jni.cpp:3621
    #3 0x7f16bea2d8fd in JNI_CreateJavaVM /jdk/src/hotspot/share/prims/jni.cpp:3672
    #4 0x7f16c5dbd0e5 in InitializeJVM /jdk/src/java.base/share/native/libjli/java.c:1550
    #5 0x7f16c5dbd0e5 in JavaMain /jdk/src/java.base/share/native/libjli/java.c:491
    #6 0x7f16c5dc6748 in ThreadJavaMain /jdk/src/java.base/unix/native/libjli/java_md.c:642
    #7 0x7f16c5d756e9 in start_thread (/lib64/libpthread.so.0+0xa6e9) (BuildId: 2f8d3c2d0f4d7888c2598d2ff6356537f5708a73)
    #8 0x7f16c531550e in clone (/lib64/libc.so.6+0x11850e) (BuildId: f732026552f6adff988b338e92d466bc81a01c37)

Reason is that we do a float division by zero to get a signal . This is desired by us so not really an error but ubsan cannot know this.
So add an attribute to this function that it has undefined behavior.
See https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html   (division by zero) . "Floating point division by zero. This is undefined per the C and C++ standards"

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Commit messages:
 - JDK-8332894

Changes: https://git.openjdk.org/jdk/pull/19394/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19394&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8332894
  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/19394.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19394/head:pull/19394

PR: https://git.openjdk.org/jdk/pull/19394