RFR: 8254072: AArch64: Get rid of --disable-warnings-as-errors on Windows+ARM64 build

[Bernhard Urban-Forster]

On Tue, 6 Oct 2020 18:09:05 GMT, Bernhard Urban-Forster <burban at openjdk.org> wrote:

> I organized this PR so that each commit contains the warning emitted by MSVC as commit message and its relevant fix.
> 
> Verified on
> * Linux+ARM64: `{hotspot,jdk,langtools}:tier1`, no failures.
> * Windows+ARM64: `{hotspot,jdk,langtools}:tier1`, no (new) failures.
> * internal macOS+ARM64 port: build without `--disable-warnings-as-errors` still works. Just mentioning this here, because
>   it's yet another toolchain (Xcode / clang) that needs to be kept happy [going
>   forward](https://openjdk.java.net/jeps/391).

Thank you Andrew for your comments!

> _Mailing list message from [Andrew Haley](mailto:aph at redhat.com) on [hotspot-dev](mailto:hotspot-dev at openjdk.java.net):_
> IMO this warning:
>
> warning C4146: unary minus operator applied to unsigned type, result still unsigned
>
> should not be used.

Okay, added to the Makefile and reverted those changes.

> // Generate stack overflow check
> if (UseStackBanging) {
> - __ bang_stack_with_offset(JavaThread::stack_shadow_zone_size());
> + __ bang_stack_with_offset((int)JavaThread::stack_shadow_zone_size());
> } else {
> Unimplemented();
> 
> Could this one be fixed by changing stack_shadow_zone_size() or
> bang_stack_with_offset() ? I would have thought that whatever type
> stack_shadow_zone_size() returns should be compatible with
> bang_stack_with_offset().

The x86_64 backend and others do the same:
https://github.com/openjdk/jdk/blob/5351ba6cfa8078f503f1cf0c375b692905c607ff/src/hotspot/cpu/x86/sharedRuntime_x86_64.cpp#L2176-L2178

So should we (1) do the same, (2) diverge or (3) fix all of them?



For the remaining comments, I've updated the PR, please have another look.

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

PR: https://git.openjdk.java.net/jdk/pull/530