gcc 的 -O2 选项有什么作用？

Question

gcc 的 -O2 选项有什么作用？

例如。gcc -O2 file1.c -o file1.o

Answer 1

这些-O选项打开编译器优化。从man gcc：

   -O2 Optimize even more.  GCC performs nearly all supported
       optimizations that do not involve a space-speed tradeoff.  As
       compared to -O, this option increases both compilation time and the
       performance of the generated code.

有关具体优化的列表，请参阅手册页。