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This is really interesting. "ExaGear is a dynamic binary translation layer to run x86_32 and x86_64 applications on Arm 64-bit Linux systems." Couldn't this e

This is really interesting. "ExaGear is a dynamic binary translation layer to run x86_32 and x86_64 applications on Arm 64-bit Linux systems." Couldn't this eventually be used in combination with Asahi Linux (project aiming to run Linux on Apple M1)? That would be incredible. Too bad it's from Huawei and doesn't seem to be open source though? I'm unable to find any additional information about this.

StillBored 6y ago
That is possible today with qemu/TCG. The assumption with exagear and some of these other JITs is that they are faster.
- my123 6y ago
  And they are, Qemu isn't even remotely in the same performance category. (it was intended to be easily retargetable to other platforms instead of being tailored to them, not even using the hardware FPU at all for example)
  - stsquad 6y ago
    We do use the host FPU for a subset of floating point operations now. However it only really works for clean 32/64 IEEE FP so anything that goes through the x87 still needs software emulation.
    - my123 6y ago
      Wow, since which release did that finally happen? (I might also look at the other issues that I have with TCG code quality sometime) Might be worth it to update the wiki too.
      - stsquad 6y ago
        Since v4.0.0 (see https://git.qemu.org/?p=qemu.git;a=commitdiff;h=a94b783952cc493cb241aabb1da8c7a830385baa https://git.qemu.org/?p=qemu.git;a=commitdiff;h=a94b783952cc...). We are always up for improving the code generation quality but of course there is a trade off with JITs given we are not compilers. I suspect there are still big wins if we can come up with a reasonable solution for re-generating a hot-path of basic blocks with much better optimisation.
        my123 6y ago
        Thank you. A tiered JIT will indeed cause much more optimisations to be made possible. I made a Qemu backend targeting LLVM before, but that turned out to be way too heavy to be usable, I wonder if it's worth revisiting that idea nowadays...

StillBored 6y ago

That is possible today with qemu/TCG. The assumption with exagear and some of these other JITs is that they are faster.

my123 6y ago
And they are, Qemu isn't even remotely in the same performance category. (it was intended to be easily retargetable to other platforms instead of being tailored to them, not even using the hardware FPU at all for example)
- stsquad 6y ago
  We do use the host FPU for a subset of floating point operations now. However it only really works for clean 32/64 IEEE FP so anything that goes through the x87 still needs software emulation.
  - my123 6y ago
    Wow, since which release did that finally happen? (I might also look at the other issues that I have with TCG code quality sometime) Might be worth it to update the wiki too.
    - stsquad 6y ago
      Since v4.0.0 (see https://git.qemu.org/?p=qemu.git;a=commitdiff;h=a94b783952cc493cb241aabb1da8c7a830385baa https://git.qemu.org/?p=qemu.git;a=commitdiff;h=a94b783952cc...). We are always up for improving the code generation quality but of course there is a trade off with JITs given we are not compilers. I suspect there are still big wins if we can come up with a reasonable solution for re-generating a hot-path of basic blocks with much better optimisation.
      - my123 6y ago
        Thank you. A tiered JIT will indeed cause much more optimisations to be made possible. I made a Qemu backend targeting LLVM before, but that turned out to be way too heavy to be usable, I wonder if it's worth revisiting that idea nowadays...