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Re: Where does the time go?
On Thu, May 20, 2010 at 2:09 PM, Ian Lance Taylor <iant@google.com> wrote:
> Steven Bosscher <stevenb.gcc@gmail.com> writes:
>
>> And finally: expand. This should be just a change of IR format, from
>> GIMPLE to RTL. I have no idea why this pass always shows up in the top
>> 10 of slowest parts of GCC. ?Lowering passes on e.g. WHIRL, or GENERIC
>> lowering to GIMPLE, never show up in the compile time overviews.
>
> expand unfortunately does more than just convert IR. ?It also does
> things like changing division by a constant into multiplication by a
> constant, and changing multiplication by a constant into a set of
> shifts and adds. ?It does various optimizations involving store flags
> (a = b == c;). ?When expanding function calls, it generates
> instructions to put arguments in the right place in registers and on
> the stack. ?Etc.
stack variable overlay and stack slot assignments is here too.
David
>
> Ian
>