Messages in this thread | | | From | Segher Boessenkool <> | Subject | Re: -Os versus -O2 | Date | Mon, 25 Jun 2007 09:41:50 +0200 |
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>> -Os is "as fast as you can without bloating the code size", >> so that is the expected result for CPUs that don't need >> special hand-holding around certain performance pitfalls. > > this sounds like you are saying that people wanting performance should > pick -Os.
That is true on most CPUs. Some CPUs really really need some of things that -Os disables (compared to -O2) for decent performance though (branch target alignment...)
> what should people pick who care more about code size then anything > else? (examples being embedded development where you may be willing to > sacrafice speed to avoid having to add additional chips to the design)
-Os and tune some options. There is extensive work being done over the last few years to make GCC more suitable for embedded targets btw. But the -O1/-O2/-O3/-Os gives you four choices only, it's really not so hard to understand I hope that for more specific goals you need to add more specific options?
Segher
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