[Qemu-devel] [Discuss] Qemu TCG-IR VS LLVM IR

[Chaos Shu]

Hi all

 

Recently I am investigating is there better BT solution? I got two kinds of popular method.

 

1.       Qemu TCG-IR is offered by Qemu, translate all to op then to target insn

2.       With Qemu runtime information convert all insn to LLVM IR, then with LLVM backend and kinds of opt on IR. Such as qemu-llvm and many other projects

 

According to their finally test[1][2]. Seems that LLVM IR method is slower than Qemu’s TCG-IR. But according last reply from linaro engineer once work in Transitive, the QuickTransit is much better in performance, it uses IR and DAG just as LLVM IR does.

 

And what’s more, I found result from ICT/Loongson, they work on Qemu-TCG years and opt on IR and devote much to hardware register mapping and peephole-like opt on generated code after TCG, and finally seems to get a good-ending.

 

Those two directions, which one is better? I mean which one can be the finally product level app in future arm/x86 competition.

 

 

[1]: https://code.google.com/p/llvm-qemu/wiki/Status

[2]: http://infoscience.epfl.ch/record/149975/files/x86-llvm-translator-chipounov_2.pdf