Re: [gpsd-dev] register keyword?

[Gary E. Miller]

Yo Hal!

On Mon, 22 Jan 2018 14:32:25 -0800
Hal Murray <address@hidden> wrote:

> address@hidden said:
> >> Is there still a reason to keep the register keyword in gpsd?  
> > Maybe.  It is in the critical path of some time measurements.  
> 
> Do modern compilers pay attention to it?

The C11 standard states:

"A declaration of an identifier for an object with storage-class
specifier register suggests that access to the object be as fast as
possible.  The extent to which such suggestions are effective is
implementation-defined."

Does gcc, llvm, or any other compiler use it?  Dunno.  Someone should
check.

Does it make a measureable difference when used?  Dunno.  Someone should
check.

At one point, someone thought the register keyword made a difference.
There is no obvious win to removing it.  Until someone measures it, I'd
say:
         Ain't brokem don't fix it.

RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

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    "If you can’t measure it, you can’t improve it." - Lord Kelvin

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