Re: alias time explosion

[Andrew MacLeod <amacleod at redhat dot com>]

On Tue, 2006-03-21 at 10:10 +0100, Richard Guenther wrote:
> On 3/21/06, Andrew MacLeod <amacleod@redhat.com> wrote:
> > On Mon, 2006-03-20 at 18:55 -0500, Andrew Pinski wrote:
> > > On Mar 20, 2006, at 5:18 PM, Andrew MacLeod wrote:
> > 
> > It looks like sometime between 10/30 and 01/23 alias analysis got out of
> > hand. Odd it hasn't been noted before.
> 
> Can you do a comparison to 4.1.0 and file a PR with the testcase please?

I will do so in a day or so when I get a chance. until then:


I seem to  have narrowed it down to this patch:

http://gcc.gnu.org/ml/gcc-patches/2006-01/msg00908.html



Dan, this appear to *not* be compile time neutral:

        Timings on this patch show that it is not faster or slower than
        what we
        do now (even with the removal of the call clobbering patch).  This is
        true even on fortran tests i had that clobber a lot of stuff.
        
        
running cpgram.ii shows a regression:

before patch:

 tree alias analysis   :   2.49 ( 7%) usr   0.25 ( 5%) sys   6.13 ( 5%) wall    4971 kB ( 1%) ggc
 TOTAL                 :  36.90             4.72           130.34             467341 kB

after patch:

 tree alias analysis   :  59.00 (63%) usr   0.40 ( 7%) sys  70.43 (36%) wall    4957 kB ( 1%) ggc
 TOTAL                 :  94.13             5.43           193.85             468339 kB


on a 386 linux machine bootstrapped with checking disabled.


Andrew