[Bug tree-optimization/15524] [4.0 Regression] jump threading on trees is slow with switch statements with large # of cases

["law at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From law at redhat dot com  2004-12-22 19:28 -------
Subject: Re:  [4.0 Regression] jump threading
	on trees is slow with switch statements with large # of cases

On Wed, 2004-12-22 at 19:18 +0000, steven at gcc dot gnu dot org wrote:
> ------- Additional Comments From steven at gcc dot gnu dot org  2004-12-22 19:18 -------
> That may all be true, but the fact is that you're now talking about  
> missed-optimizations, and not a real compile time hog.  Yes we can 
> win.  No, this is not a hog anymore, it's just not as good as it 
> could be.  You're also talking about RTL, not tree jump threading. 
I'm talking strictly about compile-time hogs.  It's insanely dumb that
we're burning 5% of compilation time just trying to hoist the
fake GLOBAL_VAR variable out of empty loops.  It's insanely dumb that
we're burning 5% of compilation time threading jumps at the RTL
level when they all should have been threaded at the tree level.

>  
> In fact I think it's plain wrong to keep this bug open.  It's just 
> keeping the number of real regressions artificially high.  We have 
> compile time slowdowns, and that's a regression.  But we don't need 
> to keep bugs open when the issue of that bug was been fixed. 
I stongly disagree.  Please do not close this bug report.

jeff




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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15524