3 ms·

C is not that deep. In the end its just something that produces assembly/machine code: jumps, reads writes etc. you need to get a feeling for what the compiler

by emsy 4y ago

C is not that deep. In the end its just something that produces assembly/machine code: jumps, reads writes etc. you need to get a feeling for what the compiler outputs for a given input (try Godbolt!). Then you need to know how those outputs will perform on your target hardware. This video is a good example: it states, modern compilers unroll loops, because they usually perform better on modern systems, but not the N64. So knowing your hardware is just as important.

MaxBarraclough 4y ago
> C is not that deep. It absolutely is. Look at its memory model, or look at any StackOverflow question or HackerNews discussion about edge-cases of undefined behaviour. Example: [0]. Alternatively, look at challenging interview questions that require a deep understanding of the C language. C gives the appearance of being a simple language, but has many dark corners that many programmers are unaware of. [0] https://news.ycombinator.com/item?id=22867059 https://news.ycombinator.com/item?id=22867059
- saagarjha 4y ago
  Very little of this is relevant for performance. It’s important to know what’s UB so the compiler doesn’t miscompile your code, but most performance improvements don’t come from “oh the compiler can run aliasing analysis on this better so it’s 10x faster” but “this loop is O(n^3)” or “I should convert this linked list to a flat array”.
  - emsy 4y ago
    That's basically what I meant. But even taking all the ugly parts of C into consideration, they are shallow. You don't need to dig into 10 layers of abstraction to get to the bottom of things. And the example posted is about what others say about how to interpret the C standard. I don't care. At the end of the day you can look at the asm output and understand what's happening for the compiler you're using.

3 ms·

C is not that deep. In the end its just something that produces assembly/machine code: jumps, reads writes etc. you need to get a feeling for what the compiler

by emsy 4y ago

MaxBarraclough 4y ago
> C is not that deep. It absolutely is. Look at its memory model, or look at any StackOverflow question or HackerNews discussion about edge-cases of undefined behaviour. Example: [0]. Alternatively, look at challenging interview questions that require a deep understanding of the C language. C gives the appearance of being a simple language, but has many dark corners that many programmers are unaware of. [0] https://news.ycombinator.com/item?id=22867059 https://news.ycombinator.com/item?id=22867059
- saagarjha 4y ago
  Very little of this is relevant for performance. It’s important to know what’s UB so the compiler doesn’t miscompile your code, but most performance improvements don’t come from “oh the compiler can run aliasing analysis on this better so it’s 10x faster” but “this loop is O(n^3)” or “I should convert this linked list to a flat array”.
  - emsy 4y ago
    That's basically what I meant. But even taking all the ugly parts of C into consideration, they are shallow. You don't need to dig into 10 layers of abstraction to get to the bottom of things. And the example posted is about what others say about how to interpret the C standard. I don't care. At the end of the day you can look at the asm output and understand what's happening for the compiler you're using.