Mark Mitchell wrote:
David Edelsohn wrote:
While we discuss whether this should be the default or enabled at
any optimization level, can we agree that users should be able to assert
with a commandline option that they want less strict induction variable
semantics? I hope that we can move forward with an option to address
these performance regressions and allow users to request this
optimzation
when they *do* want it, along the lines of the draft patch.
I would certainly agree. I think the first thing to do is to get a
patch that implements the semantics we want, in the aggressive mode;
then, we can decide whether we want it to be the default at some
optimization level or not.
I agree except that "less strict induction variable semantics" is
not an acceptable semantic description, and I think it is essential
to have a clear simple semantic description of what this means.
So to me, the first step is a spec that describes "the semantics we
want"
A patch is the second step, not the first!