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Re: Fully flow and context sensitive points-to analysis in GCC 4.6.0




Andrew Pinski wrote, On Friday 12 October 2012 11:26 AM:


Except the problem here is just about what f1 clobbers.  Since a has
not escaped by the time f1 is called, f1 cannot clobber a (or d).
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23384 for reference on why
GCC gets this incorrect.  GCC does not have a flow sensitive clobber
list yet.


Agreed. However, two pertinent points are:


- I can replace the call to f1 by some statically indeterminate boolean
  condition that does not involve any function call. So my basic point
  although details could vary.

- It is this flow insensitivity that I dislike :-) I have been trying for
  over five years to do away with flow and context insensitivity without
  hampering efficiency. Now I know that avoiding them could actually aid
  efficiency, apart from the guaranteed benefit of precision :-)

Uday.


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