Messages in this thread | | | Date | Fri, 23 Feb 2001 22:21:41 +0100 | From | Pavel Machek <> | Subject | Re: some char * optimizations in kernel |
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Hi!
> Hello everybody, > > looking through the sources I found several pieces like > lib/vsprintf.c, line 111: > const char *digits="0123456789abcdefghijklmnopqrstuvwxyz"; > > As tested with egcs-2.91.60 even with -O3 there is a difference > between > const char *digits="0123456789abcdefghijklmnopqrstuvwxyz"; > and > const char digits[]="0123456789abcdefghijklmnopqrstuvwxyz"; > > in the resulting assembler code. > > > Usage of this pointer results in it being loaded in a register, and then > pushed on the stack (for subrouting using); if it's an array, the address > is pushed directly. > > Furthermore, in the "char *"-case the pointer is stored in memory.
It has to be, no matter of optimalization level. Some other module might access that variable. You _could_ do static const char *..., but it would probably not help.
> As I'm not at home I can't give a complete reference of all these cases. > (But it's trivial [at least for me :-)] using perl). > > So if this changes are approved and I have the time I can post a diff in > the next few days. > > > BTW: For which size of patch is it possible to get included in the "Hall of > fame" (has helped with linux kernel)?
Try something bigger than this :-).
> And, btw too, where can I find a maintainer of a specific file? eg., one of > these cases is in init/version.c which has "Copyright (C) 1992 Theodore > Ts'o" - but I have to guess it's tytso@valinux.com. > Is there something like Documentation/maintainers?
It is something like MAINTAINERS in root.
-- I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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