[Bug tree-optimization/26854] [4.3/4.4 Regression] Inordinate compile times on large routines

[lucier at math dot purdue dot edu]

------- Comment #90 from lucier at math dot purdue dot edu  2009-02-13 17:37 -------
Subject: Re:  [4.3/4.4 Regression] Inordinate
 compile times on large routines

On Fri, 2009-02-13 at 16:54 +0000, bonzini at gnu dot org wrote:
> 
> 
> ------- Comment #87 from bonzini at gnu dot org  2009-02-13 16:54 -------

> The problem is that -O1 was never meant to give "very fast" code.

I'm not looking for "very fast" code, I'm looking for code that doesn't
get > 30% slower from one SVN revision number to the next.

> You
> are using it only because our throttling of expensive passes is
> insufficient.

I am using -O1 because code of this type compiled with -O2 runs
significantly more slowly than code of this type compiled with -O1. I
have never used -O2 on this type of code.

> Fixing that has two sides, as done in PR39157's
> discussion: 1) disabling more passes at -O1, 2) establishing some
> parameters to throttle down passes at -O2.

I don't see that (1) and (2) form the main strategy to fix "that", it
seems that understanding the existing optimizations that are being
disabled in preference for new ones is a good start.  And generally
ensuring that -O1 code doesn't get significantly slower while compile
times get significantly higher.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26854