Re:If Java Is Dying, It Sure Looks Awfully Healthy
by exDM69 on Thursday October 10, 2013 @05:34AM
(#6526538)
> C++ does not support any processor extensions, they are not defined anywhere in ANSI/ISO C++ language standard.
> They are a language extension not guaranteed to be available in all C++ compilers in the same form, thus not portable.
This is true only if you're a language lawyer, but there's very little point to sticking pedantically to a language standard and not take advantage of the ubiqtuitous language extensions available. All the popular compilers out there support all the latest CPU instruction sets with the same syntax, etc. E.g. xmmintrin.h for SSE, avxintrin.h for AVX.
> Java can make use of processor extensions by writing a small Assembly snippet callable via JNI.
While this is true, you destroy any performance gain with the complexity of the JNI calling convention. It only pays off if you're doing a quite long stints of SSE/AVX/NEON code at once. Wrapping a small vector dot product or matrix multiplication in JNI will not yield any performance gain in practice. So while you can call native code via JNI, it's nowhere near as practical as writing it with intrinsics in C code. In addition, you get compiler optimizations to your native code if you use intrinsics from C, if you do it via JNI you lose all interprocedural optimization.
This is true only if you're a language lawyer, but there's very little point to sticking pedantically to a language standard and not take advantage of the ubiqtuitous language extensions available. All the popular compilers out there support all the latest CPU instruction sets with the same syntax, etc. E.g. xmmintrin.h for SSE, avxintrin.h for AVX.
> Java can make use of processor extensions by writing a small Assembly snippet callable via JNI.
While this is true, you destroy any performance gain with the complexity of the JNI calling convention. It only pays off if you're doing a quite long stints of SSE/AVX/NEON code at once. Wrapping a small vector dot product or matrix multiplication in JNI will not yield any performance gain in practice. So while you can call native code via JNI, it's nowhere near as practical as writing it with intrinsics in C code. In addition, you get compiler optimizations to your native code if you use intrinsics from C, if you do it via JNI you lose all interprocedural optimization.