[COMMITTED] [PR tree-optimization/107052] range-ops: Pass nonzero masks through cast.

[Aldy Hernandez <aldyh@redhat.com>]

Track nonzero masks through a cast in range-ops.

We could also track through a truncating cast if the mask fits in the
outer type.  I will do that as a follow-up patch because I already have
this patchset tested.

	PR tree-optimization/107052

gcc/ChangeLog:

	* range-op.cc (operator_cast::fold_range): Set nonzero mask.
---
 gcc/range-op.cc | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 4f647abd91c..6fa27a8904e 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -2515,6 +2515,14 @@ operator_cast::fold_range (irange &r, tree type ATTRIBUTE_UNUSED,
       if (r.varying_p ())
 	return true;
     }
+
+  // Pass nonzero mask through the cast.
+  if (!truncating_cast_p (inner, outer))
+    {
+      wide_int nz = inner.get_nonzero_bits ();
+      nz = wide_int::from (nz, TYPE_PRECISION (type), TYPE_SIGN (inner.type ()));
+      r.set_nonzero_bits (nz);
+    }
   return true;
 }
 
-- 
2.37.1