为什么在XCode中默认情况下循环展开？-WhyisloopunrollingoffbydefaultinXCode?

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It seems it is disabled to avoid increasing the size of the generated code.

它似乎被禁用以避免增加生成的代码的大小。

Tuning for Performance and Responsiveness

调整性能和响应能力

Table 6-1 Compiler optimization options

表6-1编译器优化选项

Faster

更快

The compiler performs nearly all supported optimizations that do not require a space-time tradeoff. The compiler does not perform loop unrolling or function inlining with this option. This option increases both compilation time and the performance of generated code.

编译器几乎执行所有支持的优化，不需要空时权衡。编译器不使用此选项执行循环展开或函数内联。此选项会增加编译时间和生成代码的性能。

Fastest

最快的

The compiler performs all optimizations in an attempt to improve the speed of the generated code. This option can increase the size of generated code as the compiler performs aggressive inlining of functions. This option is generally not recommended.

编译器执行所有优化以尝试提高生成代码的速度。当编译器执行积极的函数内联时，此选项可以增加生成代码的大小。通常不建议使用此选项。