This patch fixes various issues in C1 and C2 (11 bugs in total) when running with `-XX:+UseCompactObjectHeaders`.
Most of the bugs could either be traced back to: - Unconditionally assuming old layout with klass pointer following immediately the mark word. - Small mistakes when merging JEP 450. - Using the wrong basic type `T_OBJECT` for flat arrays instead of `T_FLAT_ELEMENT`. In Valhalla, we require that the elements of an array are aligned:https://github.com/openjdk/valhalla/blob/04efe5c66b70b9dca1a5c538c9a04e7ad93c107a/src/hotspot/share/oops/arrayOop.hpp#L94-L97 https://github.com/openjdk/valhalla/blob/04efe5c66b70b9dca1a5c538c9a04e7ad93c107a/src/hotspot/share/oops/arrayOop.hpp#L57-L61 When we now wrongly use `T_OBJECT`, it is not a problem with default flags (using compressed klass pointers and no COH): An array has a 12 byte header + 4 byte length which is 16 bytes in total - no alignment required. But with COH, we now have a header of 8 bytes + 4 byte length. We now require alignment but when we pass in `T_OBJECT`, we miss the alignment which leads to crashes down the line. I went through all the uses of `base_offset_in_bytes()` and fixed more such issues. To review: I made separate commits for each fixed bug, each message summarizing the found issue. To better understand individual changes of the patch, it might help to look at the commits separately. **Testing:** - Apart from one bug, I could trigger them with existing tests. So, I have not added new tests for these issues separately. - One bug only manifested with a new test (`test127a`) which I added with this patch. - tier1-5 + compiler stress: - No additional flags, i.e. (mostly) without COH: Looks good and only known failures - With explicitly setting COH: - A lot of CDS related failures on which @matias9927 is working ([JDK-8367959](https://bugs.openjdk.org/browse/JDK-8367959)) - Test timeout with `TestIntrinsics`: Unrelated to COH but only triggering with COH ([JDK-8368274](https://bugs.openjdk.org/browse/JDK-8368274)). - Otherwise, looks good with only known failures. Thanks, Christian ------------- Commit messages: - Unproblemlist tests - C2: store_inline_type_fields_to_buf() wrongly loads InlineKlassFixedBlock from wrong register on aarch with COH - C2: Fix wrong prototype klass word in expand_mh_intrinsic_return with COH - C2: Fix wrong header computation in ArrayCopyNode::modifies with COH - C2: Fix wrong header computation for System.arraycopy() with COH - C2: Fix wrong header computation in ArrayCopyNode::prepare_array_copy() for copyOf() with COH - C2: Fix header computation in array_element_address() with COH - C2: Wrong header size computation when attaching value object fields to safepoint with COH - C2: First element of array was wrongly fetched with T_OBJECT instead of T_FLAT_ELEMENT which ignored forced alignment checked with element_type_should_be_aligned() - C2: store_inline_type_fields_to_buf() wrongly loads InlineKlassFixedBlock from markword instead of klass pointer with COH - ... and 2 more: https://git.openjdk.org/valhalla/compare/01225ee2...dc06e1e9 Changes: https://git.openjdk.org/valhalla/pull/1632/files Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1632&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8348972 Stats: 157 lines in 12 files changed: 93 ins; 37 del; 27 mod Patch: https://git.openjdk.org/valhalla/pull/1632.diff Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1632/head:pull/1632 PR: https://git.openjdk.org/valhalla/pull/1632
