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Re: Why not 03 ?

On Mon, Jun 02, 2014 at 10:36:01AM -0300, Henrique de Moraes Holschuh wrote:
> As long as you have a way to regression-test.  And I don't mean performance
> regressions, either.  Although issues with -O3 are rare, they're not unheard
> of.

Looking at the `man gcc' page, I fail to see, outside compiler bugs, what could cause issues at 03 vs. O2.

I have the feeling that most "dangerous" (ie. breaking dirty code, or code using non-specified C behavior) features are already on O2:
  * -fstrict-aliasing (code aliasing the same pointer wirh a different type)
  * -fstrict-overflow (signed arithmetic overflow being undefined)

Outside architecture issues, such as "will produce bytecode unsupported by old processors", what typical optimizations can harm us at O3 ?

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