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Re: -funsafe-loop-optimizations


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!



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