-Os到底开了哪些优化选项？

Question

摘自GCC 4.1.2
3.10 Options That Control Optimization

Not all optimizations are controlled directly by a flag. Only optimizations that have a
flag are listed.

-Os Optimize for size. ‘-Os’ enables all ‘-O2’ optimizations that do not typically
increase code size. It also performs further optimizations designed to reduce
code size.
‘-Os’ disables the following optimization flags:
-falign-functions -falign-jumps -falign-loops
-falign-labels -freorder-blocks -freorder-blocks-and-partition
-fprefetch-loop-arrays -ftree-vect-loop-version

有没有办法输出我当前的全部编译优化flag？
比如我用gcc -fno-builtin -fdelayed-branch -fthread-jumps -fno-pic -Os helloworld.c
这样的shell去编译的时候通过某种途径输出所有的编译优化flag列表：
-fno-builtin
-fdelayed-branch
-fthread-jumps
-fno-pic
-fXXXXX
-fXXXXX
-fXXXXX
..........

谢谢

Answer 1

好像说的和我问的不是一个问题吧