* Allows incremental porting of large codebases to ARM. (It's not always feasible to port everything at once-- I have a few projects with lots of hand-optimized SSE code, for example.)
* Allows usage of third-party x64 DLLs in ARM apps without recompilation. (Source isn't always available or might be too much of a headache to port on your own.)
3. Improve x64 emulation performance for everybody. Windows 11 on ARM ships system DLLs compiled as Arm64EC - makes the x64 binaries run native ARM code at least within system libraries.
It's not worth using ARM64EC for just for incremental porting -- it's an unusual mode with even less build/project support than Windows ARM64 and there are EC-specific issues like missing x64 intrinsic emulations and slower indirect calls. I wouldn't recommend it except for the second case with external x64 DLLs.
At that point why trust the emulator over the port? Either you have sufficient tests for your workload or you don’t, anything else is voodoo/tarot/tea leaves/SWAG.
"Why trust the emulator?" sounds a lot like asking "why trust the compiler?". It's going to be much more widely-used and broadly-tested than your own code, and probably more thoroughly optimized.
> Allows incremental porting of large codebases to ARM. (It's not always feasible to port everything at once-- I have a few projects with lots of hand-optimized SSE code, for example.)
Wouldn't it make more sense to have a translator that translates the assembly, instead of an emulator that runs the machine code?
The SIMD part will be emulated as normal, as far as I understand. So you can ship a first version with all-emulated code, and then incrementally port hotspots to native code, while letting the emulator handle the non-critical parts.
At least in theory, we'll see how it actually pans out in practice.
I feel like binary translation is a better approach. It’s a temporary workaround that allows users to use non-native programs while they are ported properly. ARM64EC seems like it will incentivize “eh that’s good enough” partial porting efforts that will never result in a full port, while making the whole system more complicated, with a larger attack surface (binary translation also makes the system more complicated, but it seems more isolated/less integrated with the rest of OS).
The use-case is huge apps that have a native plugin ecosystem, think Photoshop and friends. Regular apps will typically just compile separate x64 and ARM64 versions
Yes, bite the bullet and port. Of course it makes no sense.
These sorts of things are only conceived in conversations between two huge corporations.
Like Microsoft needs game developers to build for ARM. There’s no market there. So their “people” author GPT-like content at each other, with a ratio of like 10 middlemen hours per 1 engineer hour, to agree to something that narratively fulfills a desire to build games for ARM. I can speculate endlessly how a conversation between MS and EA led to this exact standard but it’s meaningless, I mean both MS and EA do a ton of things that make no sense, and I can’t come up with nonsense answers.
Anyway, so this thing gets published many, many months after it got on some MS PM’s boss’s partner’s radar. Like the fucking devices are out! It’s too late for any of this to matter.
* Allows incremental porting of large codebases to ARM. (It's not always feasible to port everything at once-- I have a few projects with lots of hand-optimized SSE code, for example.)
* Allows usage of third-party x64 DLLs in ARM apps without recompilation. (Source isn't always available or might be too much of a headache to port on your own.)