Messages in this thread | | | From | Andi Kleen <> | Subject | Re: Unnecessary Relocation Hiding? | Date | Fri, 25 Aug 2006 08:18:49 +0200 |
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On Friday 25 August 2006 03:30, Dong Feng wrote: > Sorry for perhaps extending the specific question to a more generic > one. In which cases shall we, in current or future development, > prevent gcc from knowing a pointer-addition in the way RELOC_HIDE? And > in what cases shall we just write pure C point addition? > > After all, we are writing an OS in C not in pure assembly, so I am > just trying to learn some generial rules to mimize the raw assembly in > development.
In theory anything that is undefined in the C standard should be avoided because gcc is free to make assumptions about it and generate unexpected code.
In practice Linux does a lot of not-quite-legal-in-portable-C things already, but tries to avoid areas that are known to have miscompiled in the past.
Best is to avoid undefined behaviour in new code.
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