Subject: [bug#41871] [PATCH 0/7] IcedTea: Build (efficiently) on aarch64-linux

From: Simon South <[email-masked]>
Date: Mon, 15 Jun 2020 11:18:56 -0400

This patch series applies a number of changes to the icedtea-6, -7 and -8
packages that allow them to build (efficiently) on aarch64-linux systems.

It assumes the patches in issues 41748 and 41648 have already been applied, in
that order.

With these three sets of patches I've been able to complete the entire Java
bootstrap process on both AArch64 and x86_64 and have successfully compiled
and run a Java application on AArch64 using OpenJDK 14.

The changes in this series

- Ensure the correct number of parallel build jobs is used. The
  "--with-parallel-jobs" option to IcedTea's configure script enables a
  parallel build but by default, the script uses its own heuristic to decide
  how many jobs to run simultaneously. This can produce a poor result: On my
  dual-core, hyperthreaded x86_64 machine, IcedTea 6 picks five jobs (anything
  above two is inefficient); on my six-core AArch64 machine, IcedTea 7 picks
  only two (on a machine where engaging every core is important!). In any
  case, there is no guarantee the figure the script chooses will match the
  number of jobs requested by the user.

  These patches address this by ensuring the "--with-parallel-jobs" parameter
  is passed to configure along with a parameter explicitly specifying the
  correct number of jobs to use.

- Remove an obsolete and architecture-dependent patch. The "gcc-segfault"
  patches yield a broken JIT on AArch64 because they embed a constant value,
  11, that is architecture-dependent and apparently valid only for
  x86_64. This number represents the length of an array whose size is
  determined by the HotSpot build process and output in code it generates (at
  src/share/vm/adlc/output_h.cpp:893).

  Presumably the patches could be fixed, but I've been unable to reproduce the
  problem they're meant to solve and I suspect it was only ever an issue with
  gcc 5, meaning the patches are now obsolete. (The move to gcc 7 occurred
  about three months after they were added.)

  My changes remove these patches, including (for completeness and
  consistency) the patch to IcedTea 6 which doesn't actually interfere with
  the AArch64 build as it doesn't produce a JIT for that platform.

- Allow all three IcedTea packages to build on aarch64-linux. For IcedTea 6,
  this means applying a backport of a patch to JDK 9 (see
  http://openjdk.java.net/jeps/237) that extends the support for AArch64 in
  HotSpot's shared code and allows the portable Zero VM to be built. For
  IcedTea 7, it means removing an unneeded C++ template that causes the build
  to fail when using gcc 7 and its default support for only the C++98
  standard.

  IcedTea 8 (and subsequent versions of OpenJDK) support AArch64 and gcc 7
  out-of-the-box and require no specific changes.

--
Simon South
[email-masked]

Simon South (7):
  gnu: icedtea-6: Build in parallel using correct number of jobs.
  gnu: icedtea-6: Remove obsolete, architecture-dependent patch.
  gnu: icedtea-6: Fix build on aarch64-linux.
  gnu: icedtea-7: Build in parallel using correct number of jobs.
  gnu: icedtea-7: Fix build on aarch64-linux.
  gnu: icedtea-8: Build in parallel using correct number of jobs.
  gnu: icedtea-8: Fix build on aarch64-linux.

 gnu/local.mk                                  |    4 +-
 gnu/packages/java.scm                         |   32 +-
 ...tea-6-extend-hotspot-aarch64-support.patch | 1831 +++++++++++++++++
 ...ea-6-hotspot-gcc-segfault-workaround.patch |   42 -
 .../icedtea-7-hotspot-aarch64-use-c++98.patch |   33 +
 ...ea-7-hotspot-gcc-segfault-workaround.patch |   45 -
 6 files changed, 1879 insertions(+), 108 deletions(-)
 create mode 100644 gnu/packages/patches/icedtea-6-extend-hotspot-aarch64-support.patch
 delete mode 100644 gnu/packages/patches/icedtea-6-hotspot-gcc-segfault-workaround.patch
 create mode 100644 gnu/packages/patches/icedtea-7-hotspot-aarch64-use-c++98.patch
 delete mode 100644 gnu/packages/patches/icedtea-7-hotspot-gcc-segfault-workaround.patch

-- 
2.26.2