[tree-ssa] Initial formal temporary table PATCH, not applied

Diego Novillo dnovillo@redhat.com
Mon Apr 28 01:33:00 GMT 2003

On Sun, 2003-04-27 at 21:18, Jason Merrill wrote:

> This dramatically reduces the number of temporaries created during
> gimplification (I saw a reduction of 20% on one arbitrarily chosen file
> from the gcc sources), but produces a minor increase in total compile time,
> mostly in the global alloc pass.
Excellent!  Have you noticed any change in runtime performance?

> I suspect that for this transformation to be an overall win, we would need
> to harness it to eliminate some redundant expressions during gimplification
> (which would require us to track when an expression temporary is killed
> within the current block, which doesn't really fit the current gimplifier
> model) and SSA renaming.
We eliminate fully redundant expressions during SSA renaming.  If there
are any fully redundant expressions that we are not catching, that would
be a bug in the SSA renaming pass.


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