Re: [tree-ssa] Avoid nondeterminism in tree-ssanames

[Jan Hubicka <jh at suse dot cz>]

> In message <1070476847.9315.2389.camel@p4>, Andrew MacLeod writes:
>  >On Wed, 2003-12-03 at 13:39, Gerald Pfeifer wrote:
>  >> On Mon, 1 Dec 2003, Jan Hubicka wrote:
>  >> > It makes 11% performance difference on Gerald's testcase on my setup,
>  >> > just FYI.
>  >> 
>  >> If I read this correctly...
>  >> 
>  >> On Mon, 1 Dec 2003, Diego Novillo wrote:
>  >> > Unless it's a huge win, I would *really* want to go back to the previous
>  >> > scheme of having unique SSA numbers across the whole compilation unit.
>  >> 
>  >> ...you might be able to convince Diego. :-)
>  >> 
>  >> 11% on PR8361 is quite impressive an improvement!
>  >
>  >I'd want to know where that 11% came from, it sounds like one (or more)
>  >of the optimizations are doing something pretty inefficient and ought to
>  >be looked at first. Just reducing the number of SSA_NAME ought not have
>  >that significant an effect if everyone is being reasonably intelligent
>  >about how they do things.
>  >
>  >Its definately worth investigating.
> Well, I'm not sure I believe the 11% number to start with.  If it is
> believable, then like you, I'd think we've got an optimizer that is
> doing something dumb.
I don't trust it really either.  My system used to go into swap while
compiling the testcase (don't do anymore after PHI and
cgraph_preserve_function_body changes) and I re-tested with not very
noticeable differences now.

Lets wait for zones before going crazy here :)

Honza
> 
> Jeff
>