JIT binary translation using libgccjit?

[Basile Starynkevitch]

On 10/20/2015 01:08 AM, Kaz Nishimura wrote:
> I am looking for a "light-weight" (that is not much slower than direct
> instruction emulation) code generator.  If libgccjit is currently
> invokes external tools to generate "host" code, I feel it is too heavy
> for my plan.  Because binary code has no strict function structure, I
> guess it will be tricky to translate "guest" code by a
> function-oriented JIT code generator.


Yes, GCCJIT requires to have functions.

If you cannot afford functions (like C have them, and most ELF files also)
  then you cannot follow the common existing ABI. And you need
a target-specific JIT library. For x86-64 consider asmjit. 
https://github.com/kobalicek/asmjit


Notice also that without functions, you probably won't be able to get 
optimized code. Hence
to get a little bit of efficiency, you'll need to somehow deal yourself 
with things like register allocation and instruction scheduling. At the 
very least, you want to avoid emitting the store of a register into some 
call stack slot followed by the reload of the same register from the 
same slot (like e.g. TinyCC is doing).

Cheers

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