> Change the default code entry alignment to 64 bytes from 32 bytes.  This 
> allows for maintaining proper 64-byte alignment of data within a code 
> segment, which is required by several AVX-512 instructions.
> 
> I ran into this while implementing Base64 encoding and decoding.  Code 
> segments which were allocated with the address mod 32 == 0 but with the 
> address mod 64 != 0 would cause the align() macro to misalign.  This is 
> because the align macro aligns to the size of the code segment and not the 
> offset of the PC.  So align(64) would align the PC to a multiple of 64 bytes 
> from the start of the segment, and not to a pure 64-byte boundary as 
> requested.  Changing the alignment of the segment to 64 bytes fixes the issue.
> 
> I have not seen any measurable difference in either performance or memory 
> usage with the tests I have run.
> 
> See [this 
> ](https://mail.openjdk.java.net/pipermail/hotspot-dev/2021-August/054180.html)
>  article for the discussion thread.

Scott Gibbons has updated the pull request with a new target base due to a 
merge or a rebase. The incremental webrev excludes the unrelated changes 
brought in by the merge/rebase. The pull request contains seven additional 
commits since the last revision:

 - Merge branch 'openjdk:master' into asgibbons-align-fix
 - Revert alignment of 64-bytes; Add align64()
 - Change default code entry alignment to 64 bytes
 - Fix align() directive
   
   Change align(x) to be relative to the current section's end rather than its 
size.  Issue was uncovered with a raw align(64).
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - Fixing .gitignore

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5547/files
  - new: https://git.openjdk.java.net/jdk/pull/5547/files/f6eefd34..e897dcfd

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5547&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5547&range=01-02

  Stats: 56646 lines in 1747 files changed: 37537 ins; 10004 del; 9105 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5547.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5547/head:pull/5547

PR: https://git.openjdk.java.net/jdk/pull/5547

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