[gcc r13-3085] [PR tree-optimization/107052] range-ops: Pass nonzero masks through cast.

[Aldy Hernandez <aldyh@gcc.gnu.org>]

https://gcc.gnu.org/g:ae56d600d223e996054483d7d7033ec8e258d39d

commit r13-3085-gae56d600d223e996054483d7d7033ec8e258d39d
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Tue Oct 4 17:03:54 2022 +0200

    [PR tree-optimization/107052] range-ops: Pass nonzero masks through cast.
    
    Track nonzero masks through a cast in range-ops.
    
            PR tree-optimization/107052
    
    gcc/ChangeLog:
    
            * range-op.cc (operator_cast::fold_range): Set nonzero mask.

Diff:
---
 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;
 }