Messages in this thread | | | Date | Mon, 28 Feb 2005 08:33:24 -0500 (EST) | From | linux-os <> | Subject | Re: [patch 3/2] drivers/char/vt.c: remove unnecessary code |
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On Mon, 28 Feb 2005 colbuse@ensisun.imag.fr wrote:
> We could change an affectation into an incrementation by this patch, and, > so far I know, incrementing is quicker than or as quick as setting > a variable (depends on the architecture). > > Please _don't_ apply this, but tell me what you think about it. > Note that npar is unsigned. > > Signed-off-by: Emmanuel Colbus <emmanuel.colbus@ensimag.imag.fr> >
Since it is common practice to write code as: for(npar = 0 ; npar < NPAR ; npar++) ... it is quite likely that the compiler does a better job with that code than what you substitute. And, if you did a check of the code generation, it might be different between different compiler versions.
This kind of "code optimization" won't optimize anything in the long-run.
> --- old/drivers/char/vt.c 2004-12-24 22:35:25.000000000 +0100 > +++ new/drivers/char/vt.c 2005-02-28 12:53:57.933256631 +0100 > @@ -1655,9 +1655,9 @@ > vc_state = ESnormal; > return; > case ESsquare: > - for(npar = 0 ; npar < NPAR ; npar++) > + for(npar = NPAR-1; npar < NPAR; npar--) > par[npar] = 0; > + npar++; > - npar = 0; > vc_state = ESgetpars; > if (c == '[') { /* Function key */ > vc_state=ESfunckey; > > > -- > Emmanuel Colbus > Club GNU/Linux > ENSIMAG - departement telecoms >
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