RFR: 8257679: Improved unix compatibility layer in Windows build (winenv) [v7]

[Bernhard Urban-Forster]

On Sat, 5 Dec 2020 01:13:34 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> For the build to work on Windows, we need a unix compatibility layer (known as the "winenv" in the build system). This can be e.g. Cygwin or Msys. The build system then needs to adapt various aspect to get the build to work in this winenv. Over time, our current solutions (which were never that well-designed) has collapsed into an unmaintainable mess.
>> 
>> This rewrite takes on a fresh approach, by giving up on the native "fixpath.exe" converter, and instead relying on a platform-independent shell script "fixpath.sh", which can dynamically adapt to the current winenv. It also provides a proper framework on how to categorize, and support, different winenvs. As a result, we now easily support Cygwin, Msys2, WSL1 and WSL2 (the latter is unfortunately not mature enough to be able to compile the JDK).
>> 
>> Furthermore, this rewrite removes all the kludges and hacks that were put in place all over the code base, and consolidates all tricky part of handling the winenv to basically two places: setting up in configure, and run-time handling by fixpath.sh.
>> 
>> This patch also cleans up our handling of how we detect tools in configure, and makes a proper framework for cross-compilation on Windows.
>
> Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Extract only the actual contents added to the PATH by VS SetEnv.cmd.

Tested the cross compilation bits with a win-aarch64 build from win-x86_64:
- Cygwin: `--openjdk-target=aarch64-unknown-cygwin --with-boot-jdk=/cygdrive/c/work/jdk-16+22`
- WSL1: `--openjdk-target=aarch64-unknown-cygwin --with-boot-jdk=/mnt/c/work/jdk-16+22`

And smoke tested each one on win-aarch64 with `jtreg:tier1_compiler_1`.


Cosmetic: I get a bunch of warnings for non-existing paths in `$PATH` during configure on the wsl1 build, e.g.:
configure: Setting extracted environment variables for x86_64



I'll give the "native compilation" on win-aarch64 a try again when this change has landed. Some bits (e.g. config.guess) required for it have made it into this PR, but some things are still missing (e.g. choose x86 binaries for MSVC, since no native bits are available for MSVC).

Thank you for the hard work on this!

make/autoconf/toolchain_microsoft.m4 line 632:

> 630:       [path to Microsoft Windows Kit UCRT DLL dir (Windows only) @<:@probed@:>@])])
> 631: 
> 632:   if test "x$USE_UCRT" = "xtrue" && test "x$OPENJDK_TARGET_CPU" != xaarch64; then

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Marked as reviewed by burban (Author).

PR: https://git.openjdk.java.net/jdk/pull/1597