[tree-ssa] Re-use SSA_NAME expressions

[Gerald Pfeifer]

On Wed, 19 Nov 2003 law@redhat.com wrote:
> For a testcase like PR8361, we waste about 10M of memory in trivially
> reusable SSA_NAME nodes.  In general, with this patch we're able to
> reduce the number of SSA_NAME nodes created by 20-25%.

Hah, progress on 8361 -- thanks a lot! :-)

> My components of cc1 test shows just under a 2% improvement in compile
> times, which helps show that these changes are useful for general code
> not just extreme cases like PR8361.

In C++-land the code from 8361 is quite general, or at least not too
extreme, so I believe improvements like this one really will help C++
on tree-ssa in general.

Gerald