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The modern aggressive undefined-behavior based optimizations ruins any remaining appeal of the "simplicity" of C for me. The extremely broad definition of unde

The modern aggressive undefined-behavior based optimizations ruins any remaining appeal of the "simplicity" of C for me. The extremely broad definition of undefined behavior may allow the compiler to, for example, silently delete explicit checks for signed integer overflow [1] among other things and still claim standards compliance, but I don't think that programming model can reasonably be described as simple. It many ways Go feels like an updated C. It retains most of the basic abilities of C, while cleaning up some things (headers, etc), having more basic libraries included, and choosing some defaults around things like out-of-bounds array access that are probably more appropriate for the majority of most programs (outside of particular hot loops, etc) in an era where software is often connected to the network and security is a bigger concern. [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30475 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30475, http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html http://blog.llvm.org/2011/05/what-every-c-programmer-should-...

astrange 7y ago
Lots of programs don't need efficiency in "hot loops". You want efficient code size everywhere (usually smaller is faster), and realtime programs like games are CPU-bound everywhere not just in one loop. Undefined behavior is a great way to help the language help you; for instance, most loops look like infinite loops without it. All you need to do is test with ubsan to see if you're dynamically undefined anywhere.
- throwaway34241 7y ago
  >realtime programs like games are CPU-bound everywhere not just in one loop Isn't this a simplification? Even for games, I'd expect most often to be GPU bound, then memory bandwidth bound, and only then CPU bound. Although I get that the hot loop thing/10% rule is not universally true for every CPU bound program (especially after code has already been heavily optimized). But I'm not sure what you are disagreeing with. I didn't mean to totally deny the usefulness of UB in C++ (although I think the core rendering code of AAA games are more performance sensitive than "the majority of most programs"). I was just pointing out that C is certainly not as simple as it first appears, and many people new to it are not familiar with the rules around UB. Go's able to design around some of the performance aspects without UB (using the native word size for ints by default can help some of the signed integer stuff, range loops can elide bounds checks, etc), but probably can't generate as optimal code as C can without dropping to assembly language.

astrange 7y ago

Lots of programs don't need efficiency in "hot loops". You want efficient code size everywhere (usually smaller is faster), and realtime programs like games are CPU-bound everywhere not just in one loop. Undefined behavior is a great way to help the language help you; for instance, most loops look like infinite loops without it. All you need to do is test with ubsan to see if you're dynamically undefined anywhere.

throwaway34241 7y ago
>realtime programs like games are CPU-bound everywhere not just in one loop Isn't this a simplification? Even for games, I'd expect most often to be GPU bound, then memory bandwidth bound, and only then CPU bound. Although I get that the hot loop thing/10% rule is not universally true for every CPU bound program (especially after code has already been heavily optimized). But I'm not sure what you are disagreeing with. I didn't mean to totally deny the usefulness of UB in C++ (although I think the core rendering code of AAA games are more performance sensitive than "the majority of most programs"). I was just pointing out that C is certainly not as simple as it first appears, and many people new to it are not familiar with the rules around UB. Go's able to design around some of the performance aspects without UB (using the native word size for ints by default can help some of the signed integer stuff, range loops can elide bounds checks, etc), but probably can't generate as optimal code as C can without dropping to assembly language.