On 26 April 2014 01:13, Kugan kugan.vivekanandarajah@linaro.org wrote:
What is AArch64 vs. ARM64. Is that something specific to LLVM?
Yes, they're two different AArch64 back-ends, and are being merged into one official. AArch64 is the one created by Tim at ARM and was feature complete, while ARM64 is the one created by Apple and kept secret until last year (for their iOS 64), but contributed upstream recently. The ARM64 back-end is a little more performing (since it had tests on real hardware for a longer time) but it's less complete. Since completeness problems are easier to fix than performance ones, the decision was to merge the AArch64 into the ARM64 and rename it AArch64.
It's a bit of a mess, but it's better to have something that works for everybody than two independent (one open and one closed) back-ends.
On my tests, I'm just making sure we don't regress in performance or conformance. ARM and Apple are doing the same on their sides.
cheers, --renato