[Bug ada/26797] [4.3 regression] ACATS cxh1001 fails

["baldrick at free dot fr" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #27 from baldrick at free dot fr  2007-03-08 16:06 -------
Subject: Re:  [4.3 regression] ACATS cxh1001 fails

> > y = __builtin_nop(x); valid = (y>=lower_bound && y <=upper_bound);
> > The point is that the intrinsic would be opaque to the optimizers,
> > and would only be lowered to the identity function *after* the tree
> > optimizers have run.  One annoyance is that presumably intrinsics
> > would be needed for all integer and float precisions, eg
> > __builtin_nop8, __builtin_nop16, etc.
> 
> More than each precision.  The VIEW_CONVERT_EXPR is to the base type
> and there can be an unlimited number of them for each precision.

I don't see what the problem is - you don't have to convert to the base
type, you can always convert to some standard type of that precision,
eg int32, before calling the builtin.

> Because it has to work with arbitrary types, a builtin won't do it.

See above.

> We could certainly add a new tree expression that says "don't look through
> this for VRP purposes", but we already have V_C_E.

Sure, it's just that overloading V_C_E like this feels somehow wrong to me.
However I haven't been able to put my finger on any technical obstacle to
this use of V_C_E.

Ciao,

D.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26797