http://cr.openjdk.java.net/~vlivanov/8148518/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8148518
Current Unsafe::getCharUnaligned Java implementation isn't fully
optimized by C2: it never constant folds such loads from char fields.
C2 matches the types of a load and a location and does constant folding
only if they match. For getCharUnaligned it sees a load of a short
value, but the field is of type char.
The fix is to call Unsafe::getChar when offset is aligned. It doesn't
matter what is used for unaligned case, so I decided to keep makeShort().
Testing: failing test, JPRT.
Best regards,
Vladimir Ivanov
PS: I don't update the test because it was refactored in Jigsaw [1]. To
avoid unnecessary conflicts during merges, I filed an RFE [2] to adjust
the test once the fix and Jake are integrated.
[1]
http://hg.openjdk.java.net/jigsaw/jake/hotspot/file/f6daf3633512/test/compiler/unsafe/UnsafeGetConstantField.java
[2] https://bugs.openjdk.java.net/browse/JDK-8149844
