In JDK-8305895, the following tests have some disabled sub-tests:

test/hotspot/jtreg/compiler/loopopts/superword/TestAlignVector.java
test/hotspot/jtreg/compiler/loopopts/superword/TestMulAddS2I.java

Some tests are failing with UseCompactObjectHeaders, but only with UseSSE<=3:

test/hotspot/jtreg/compiler/c2/irTests/TestVectorizationNotRun.java
test/hotspot/jtreg/compiler/c2/irTests/TestVectorizationMismatchedAccess.java
test/hotspot/jtreg/compiler/vectorization/runner/LoopCombinedOpTest.java

I think the issue with all of them is that vectorization in those scenarios only works when the operations inside the loop start at an array index that addresses an element at 8-byte-aligned offset.

We could either improve the tests to run with different loop indices, or - even better - improve vectorization, if this is possible.