I'm looking for the most portable assembler library, like asmjit or jitasm.
When I say 'most portable' I mean, that has the most support for a wide verity of architectures. Language doesn't matter so much, but C++ would be the best solution, especially when coupled with GCC.
Important architectures for me, are x86/64, PowerPC and ARM.
DynASM, used by LuaJIT, supports x86, x64, ARM, MIPS and PowerPC.