[llvm-dev] High memory use and LVI/Correlated Value Propagation

[Joerg Sonnenberger via llvm-dev]

On Wed, Jan 13, 2016 at 03:38:24PM -0800, Philip Reames wrote:
> I don't think that arbitrary limiting the complexity of the search is the
> right approach.  There are numerous ways the LVI infrastructure could be
> made more memory efficient.  Fixing the existing code to be memory efficient
> is the right approach.  Only once there's no more low hanging fruit should
> we even consider clamping the search.

Memory efficiency is only half of the problem. I.e. groonga's expr.c
needs 4m to build on my laptop, a 2.7GHz i7. That doesn't sound
reasonable for a -O2. Unlike the GVN issue, the cases I have run into do
finish after a(n unreasonable) while, so at least it is not trivially
superlinear.

Joerg