From: Stephen Hemminger
...
> On Sat, 17 Oct 2015 00:21:44 -0400
> Michael Chan <mc...@broadcom.com> wrote:
>
> > +static bool bnxt_vf_pciid(int idx)
> > +{
> > + if (idx == BCM57304_VF || idx == BCM57404_VF)
> > + return true;
> > + return false;
> > +}
> > +
>
> I prefer just returning result of logical operation
> rather than adding unnecessary if statement.
> And never use (signed) int when unsigned is the real
> data type. Also avoid any unnecessary expansion of 16 bit
> value.
Actually 16-bit (and 8-bit) values always have to be extended to 'int'
before any arithmetic operations.
On systems with 16-bit arithmetic instructions (like x86) the
compiler can only use them if it can determine that result would be
the same (as if they were extended).
This can mean a lot of extra instructions if you do arithmetic
on 16-bit values the compiler is holding in registers.
Similarly using 16-bit values as function parameters/results
can require additional masking instructions.
IMHO This really all means that you should use [unsigned] int for
local variables even when the domain of the value is known
to be much smaller.
David
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