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Re: PROP_KILL_DEAD_CODE / REG_EQUAL problems


> Running life_analysis (in order to setup things need by VRP)
> causes insn 109 to be deleted since QI 135 is never used,
> however the REG_EQUAL note on insn 112 is still present.
> 
> Should life_analysis remove any REG_EQUAL notes which it
> potently invalidates, is the problem elsewhere, or is
> this not a problem?
I was always wondering about it.  I think only viable solution
is to remove invalidated notes, but thats quite dificult to implement.

Easier to implement it is at df.c framework (in fact it can be an
nice excercise to modify existing ssa-dce.c to work at top of df.c).

It records the definitions for each REG_EQUAL note so one can update
the stream.

This is, of course, somewhat intrusive solution, but I would love to implement
it if it is considered acceptable over weekend (I hope it won't take much
longer).

Honza
> 
> -- John
> -------------------------------------------------------------------------
> |   Feith Systems  |   Voice: 1-215-646-8000  |  Email: john@feith.com  |
> |    John Wehle    |     Fax: 1-215-540-5495  |                         |
> -------------------------------------------------------------------------


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