Handle a_2= &b properly in range calculations.

when processing assignments, we were using the type of b instead of type
of &b when computing a range.  This was usually filtered out by FRE.
turning it off exposed it.

	gcc/
	PR tree-optimization/97520
	* gimple-range.cc (range_of_non_trivial_assignment): Handle x = &a
	by returning a non-zero range.
	gcc/testsuite/
	* gcc.dg/pr97520.c: New.

gcc/gimple-range.cc

@@ -446,21 +446,35 @@ gimple_ranger::range_of_non_trivial_assignment (irange &r, gimple *stmt)
     return false;
 
   tree base = gimple_range_base_of_assignment (stmt);
-  if (base && TREE_CODE (base) == MEM_REF
-      && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
+  if (base)
+    {
+      if (TREE_CODE (base) == MEM_REF)
+	{
+	  if (TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
 	    {
 	      int_range_max range1;
 	      tree ssa = TREE_OPERAND (base, 0);
 	      if (range_of_expr (range1, ssa, stmt))
 		{
 		  tree type = TREE_TYPE (ssa);
-	  range_operator *op = range_op_handler (POINTER_PLUS_EXPR, type);
-	  int_range<2> offset (TREE_OPERAND (base, 1), TREE_OPERAND (base, 1));
+		  range_operator *op = range_op_handler (POINTER_PLUS_EXPR,
+							 type);
+		  int_range<2> offset (TREE_OPERAND (base, 1),
+				       TREE_OPERAND (base, 1));
 		  op->fold_range (r, type, range1, offset);
 		  return true;
 		}
 	    }
 	  return false;
+	}
+      if (gimple_assign_rhs_code (stmt) == ADDR_EXPR)
+	{
+	  // Handle "= &a"  and return non-zero.
+	  r = range_nonzero (TREE_TYPE (gimple_assign_rhs1 (stmt)));
+	  return true;
+	}
+    }
+  return false;
 }
 
 // Calculate a range for phi statement S and return it in R.

gcc/testsuite/gcc.dg/pr97520.c

@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-tree-fre" } */
+
+char a;
+void b() {
+  char *c[5];
+  char *d = &a;
+  &d;
+  *(c[4] = d);
+}
+int main() { return 0; }