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Re: [RFC] Contributing tree-ssa to mainline
On Jan 19, 2004, at 07:48, Diego Novillo wrote:
On Mon, 2004-01-19 at 07:26, Richard Kenner wrote:
A case I know about in Ada is check elimination. Because the default
for Ada
is enabling checking, it's quite important to eliminate checks that
can be
proven not to fail. Theoretically, a lot this could be
language-independent
optimizers by value range propagation and related optimizations. But
the
front-end can do a much better job because it has information only it
knows.
Such as? Full FE type information is available in GIMPLE. VRP is one
of the passes I'm planning to work on in the immediate future. The
goal
is to eliminate mudflap checks, though it should help Java and Ada as
well.
There are many cases where we need to expand the original code in order
to generate checks. Some Ada constructs generate a non-trivial amount of
code, with calls to the Ada run time library, exception handlers etc.
Once we expand such code, it is unlikely it could be optimized away.
I agree with Richard that we need optimize away such constructs as early
as possible, which is in the front end before expansion.
-Geert