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Kenneth Prugh wrote: |
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> Volker Armin Hemmann wrote: |
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>> On Montag, 23. Juli 2007, Alexander Skwar wrote: |
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>>> Volker Armin Hemmann <volker.armin.hemmann@××××××××××××.de> wrote: |
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>>>> And then Os. That is a big nono. |
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>>> Why's that? |
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>>> |
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>>> Alexander Skwar |
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>> because several gcc have compiled crap with that flag in the past? |
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>> |
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>> |
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> |
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> That was the past, -Os generally works fine on AMD64 now. That can be |
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> evidenced by my fully -Os built system that works fine. |
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|
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From my experience, the main "problem" with -Os is that it's rarely |
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used, and not all that useful. It's essentially the same as -O2 with |
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some optimizations turned off, to save space. The difference in binary |
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size between -O2 and -Os has no, in my experience, been very |
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significant. And -Os produces slower code than -O2. |
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|
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More importantly, -O2 seems to be the "typical" optimization setting, |
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and almost all free software packages are built and tested and generally |
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"supported", for whatever that means in an open-source world, under -O2. |
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If you report a bug in a package and you use -Os, the first thing the |
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devs will ask is "recompile it using normal CFLAGS and try again." |
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|
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So yes, recent gcc versions have been much better at not breaking code |
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under -Os. At least, it's no more broken under -Os than under -O2. But |
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given that disk space is dirt cheap and modern OS don't need to read |
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an entire binary into memory to execute it, the actual, tangible |
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benefits of using -Os over -O2 are minimal compared against the possible |
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problems it might cause. |
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|
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--Mike |
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-- |
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