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Re: Patch: New implementation of -Wstrict-aliasing
On 1/20/07, Daniel Jacobowitz <drow@false.org> wrote:
On Sat, Jan 20, 2007 at 08:43:06PM -0800, Ian Lance Taylor wrote:
> I believe that this warning is an example of those which can not be
> emitted from the frontends.
Could you give me a rough estimate of the amount of optimization
required for this warning? i.e. in a hypothetical world where we
use SSA at -O0, how expensive would it be to do the necessary analysis?
If you had SSA at O0, you could do this warning only computing the
may-aliasing information.
If you don't do dead code elimination and conditional constant
propagation first though,
1. You will get more false positives, unless you keep a list of
reachable blocks/edges in the alias analyzer, like the propagation
engine does.
2. It will take more time than it would at O1, due to the input being
so much bigger.