Optimization, inline functions

[Lee, Newbie]

I thought function inlining is simple and easy thing.

But I read that gcc doesn't make function inline without optimization flag,

and function inlining is the last thing to do when gcc optimize something.

So I compiled a cpp file with -S and -O1, -O2, -O3 flags.

Document says that only -O3 turns on function inlining, 

but with -O2, gcc also eliminated function calls.

The result was better than I expected.  But I am confusing.


0. Does 'gcc -O2' make functions inline?

1. Is function inlining is dangerous?

2. Is 'gcc -O3 ' safe? (I heard -O2 is recommended)

and any advice about this will help me.

Thanks.

(Here's my test cpp.  and .s results)
http://www.nabble.com/file/p18273137/test.cpp test.cpp 
http://www.nabble.com/file/p18273137/testO1.s testO1.s 
http://www.nabble.com/file/p18273137/testO2.s testO2.s 
http://www.nabble.com/file/p18273137/testO3.s testO3.s 
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