[Bug middle-end/42749] [4.5 Regression] -O2 and verify_stmts failed again

[rakdver at kam dot mff dot cuni dot cz]

------- Comment #12 from rakdver at kam dot mff dot cuni dot cz  2010-01-16 13:24 -------
Subject: Re:  [4.5 Regression] -O2 and verify_stmts
        failed again

> > ------- Comment #10 from rakdver at gcc dot gnu dot org  2010-01-16 12:53 -------
> >  /* Reject a tailcall if the type conversion might need
> > 285                       additional code.  */
> > 286                    if (gimple_assign_cast_p (stmt)
> > 287                        && TYPE_MODE (TREE_TYPE (dest)) != TYPE_MODE
> > (TREE_TYPE (src_var)))
> > 288                      return false;
> > 
> > This is suspicious; replacing the weird TYPE_MODE check with
> > useless_type_conversion_p fixes the problem.
> 
> Correct, but for useless_type_conversion_p we can reject any conversions
> in the IL since only !useless_type_conversion_p remain.

right

> I suppose the code was explicitly trying to allow sign-changing
> (but not precision changing as it does), or conversion to/from
> pointers.
> 
> Thus, if you want to go the useless_type_conversion_p route simply
> reject all conversions and only allow plain SSA name copies...

this might be overly restrictive; it should be quite easy to add the
appropriate casts, instead.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42749