On Tue, 16 May 2023 11:18:09 GMT, Maurizio Cimadamore <mcimadam...@openjdk.org> wrote:
> The FFM API exposes layout constants for Java primitives. Among those there > are constants for `JAVA_LONG` and `JAVA_DOUBLE`. Currently, the alignment of > these layouts is set the same as their size (e.g. 8 bytes). > > This is obviously correct on 64-bit platforms, but on 32-bit platform it is > not, as such platforms cannot guarantee that doubles and longs will be always > 64-bit aligned. This will also result in problems when trying to use e.g. > `JAVA_DOUBLE` to model a C double for the linker API on 32-bit platforms. > > For these reasons, it would be preferable to define the alignment of > `JAVA_LONG` and `JAVA_DOUBLE` constants as `ADDRESS.byteSize()`. > > This patch rectifies alignment of those layout constants to reflect > platform-dependent constraints. It also fixes the maximum alignment > constraint supported by heap segments, so that it is 4 for long[] and > double[] on 32-bit platforms. This pull request has now been integrated. Changeset: 44218b1c Author: Maurizio Cimadamore <mcimadam...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/44218b1c9e5daa33557aac9336251cf8398d81eb Stats: 68 lines in 6 files changed: 29 ins; 6 del; 33 mod 8308248: Revisit alignment of layout constants on 32-bit platforms Reviewed-by: psandoz, pminborg ------------- PR: https://git.openjdk.org/jdk/pull/14007
