4 ms·

Can you elaborate on your first point a bit? How, specifically, does C's machine model not fit current architectures well, aside from multiple cores. How is F

• jbooth 14y ago
  C is based on a simplistic view of the computer as a turing machine (or von neumann machine, if you'd prefer). Since the 70s or 80s, CPUs have gotten a lot faster while memory access has only gotten incrementally faster. This means that CPU manufacturers have put an increasingly sophisticated caching system on the CPU die to speed up access to main memory contents. C's simple model allowing pointer arithmetic, aliased pointers that overlap to the same memory, etc, mean that compilers can't produce the optimal cache behavior on the CPU, because they can't reason definitively about when a given region of memory will be accessed based on the variables being accessed (pointer might have been modified or might overlap another one). They also have trouble invoking things like SIMD instructions which do math quickly on vectors. Fortran, with stricter rules about arrays, is more conducive to this.
  • gsg 14y ago
    Aliasing is not really an architecture specific concern. Furthermore the vast majority of languages allow free aliasing, differing from C in what things pointers are allowed to point at and not in the number of pointers which may point at them.
  • AnIrishDuck 14y ago
    Pointer aliasing can cause additional problems with today's multiple dispatch CPUs, which are nothing like the CPUs of the 80s. Because pointer aliasing ties the compiler's hands, compilers may have trouble reordering code to maximize a single core's instruction level parallelism.