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Translating Why const Doesn't Make C Code Faster.

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LazyWolf Lin 2019-09-08 20:57:39 +08:00
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translated/tech/20190812 Why const Doesn-t Make C Code Faster.md
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@ -224,12 +224,10 @@ y += x;
printf("%d %d\n", x, y);
```
TL;DR: `const` is almost useless for optimisation because
1. Except for special cases, the compiler has to ignore it because other code might legally cast it away
2. In most of the exceptions to #1, the compiler can figure out a variable is constant, anyway
总而言之，`const` 对优化而言几乎无用，因为：
1. 除了特殊情况，编译器需要忽略它，因为其他代码可能合法地移除它
2. 在 #1 以外地大多数例外中，编译器无论如何都能推断出该变量是常量
### C++