AArch64: CMake build settings

[knn-k]

This commit adds some changes to CMake build settings for aarch64.

Signed-off-by: knn-k konno@jp.ibm.com

[knn-k]

1. The GNU toolchain for aarch64 does not accept the option -m64. gnu.cmake is changed so that it adds -m64 option only when the target processor is not aarch64.
2. Some C/C++ files in OMR expect a symbol AARCH64 instead of J9AARCH64 or AARCH64GNU. Added -DAARCH64 to aarch64.cmake.
3. Set TR_TARGET_ARCH and TR_TARGET_BITS explicitly instead of from TR_HOST_ARCH and TR_HOST_BITS.
4. Add TR_TARGET_ARM64 and TR_TARGET_64BIT to TR_COMPILE_DEFINITIONS.
5. Add .cpp files in aarch64/codegen to CMakeLists.txt.

[knn-k]

You need a toolchain file for running cmake for cross-compilation. Where should the toolchain file be in the OMR source tree?

[knn-k]

Removed "WIP:".

[0xdaryl]

Changes look reasonsonable to me. Could one of @Leonardo2718 or @rwy0717 please eyeball them?

[rwy7]

You want to cross compile a JIT that runs on aarch64 and targets aarch64. Here, it looks like you're trying to make TR itself a cross compiler? Am I reading this right? Is this needed?

[rwy7]

For the toolchain, I would put it in a new cmake/toolchains/ directory.

[rwy7]

Does TR_HOST_ARCH describe the build environment, or the runtime environment?

[knn-k]

@rwy0717
I am trying to build the JIT that runs on aarch64 by running a cross-compiling GCC on x86-64, and I have already built triltest that runs on aarch64 linux in my local environment using the changes in this PR.

I thought TR_HOST_ARCH was the build environment.

I remember the old J9 on x86 generated JXE files with AOT code for another processor. Does the comment "Currently not doing cross, so assume HOST == TARGET" in OmrCompilerSupport.cmake mean such case ?
If so, setting aarch64 to both TR_HOST_ARCH and TR_TARGET_ARCH is the right thing to do?

[rwy7]

OK, it appears that TR_HOST_ARCH is set but not used anywhere--it's meaningless. It's possible someone was thinking about producing a cross-jit, but didn't get anywhere...

Where and how are you setting the TR_TARGET_ARCH? In a toolchain file?

[knn-k]

TR_TARGET_ARCH is set in cmake/modules/platform/arch/aarch64.cmake. Other platforms set TR_HOST_ARCH in cmake/modules/platform/arch/*.cmake.

I can set TR_HOST_ARCH in aarch64.cmake like other platforms do, and revert my change in OmrCompilerSupport.cmake.

(Update)
I am trying to do the above, but the attempt has been unsuccessful. cmake generates files for x86 instead of aarch64.

[knn-k]

Updated the files.

[rwy7]

Toolchain looks good.

I checked with others, and host definitely refers to the runtime environment. It looks like you've removed the check already 👍

With the changes currently in the PR, are you still having trouble getting cmake to cross compile?

[knn-k]

No, my trouble was solved. I can build for aarch64.

[knn-k]

I think this can be merged now.

[rwy7]

LGTM

[0xdaryl]

@genie-omr build all

[charliegracie]

@genie-omr build xcplinux

[0xdaryl]

@charliegracie : What is the xcplinux build? Some kind of cross-compile build?

[charliegracie]

that was the temporary name I picked for the Linux x86-64 compressed references build... I have since switched it to xcrlinux as to not conflict with plinux. Once we have all of the builds move to the OMR CI I will open an Issue to discuss how we want to name the builds so appropriate builds can be launched with the bot.

[0xdaryl]

ah, ok. I though it was some kind of pLinux cross-compile build.