Commonize handling of attr-fnspec

	* attr-fnspec.h: New file.
	* calls.c (decl_return_flags): Use attr_fnspec.
	* gimple.c (gimple_call_arg_flags): Use attr_fnspec.
	(gimple_call_return_flags): Use attr_fnspec.
	* tree-into-ssa.c (pass_build_ssa::execute): Use attr_fnspec.
	* tree-ssa-alias.c (attr_fnspec::verify): New member fuction.

1 files changed, 145 insertions, 0 deletions

diff --git a/gcc/attr-fnspec.h b/gcc/attr-fnspec.h
new file mode 100644
index 0000000..607c0cf
--- /dev/null
+++ b/gcc/attr-fnspec.h
@@ -0,0 +1,145 @@
+/* Handling of fnspec attribute specifiers
+   Copyright (C) 2008-2020 Free Software Foundation, Inc.
+   Contributed by Richard Guenther  <rguenther@suse.de>
+
+   This file is part of GCC.
+
+   GCC is free software; you can redistribute it and/or modify
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   GCC is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with GCC; see the file COPYING3.  If not see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Parse string of attribute "fn spec".  This is an internal attribute
+   describing side effects of a function as follows:
+
+   character 0  specifies properties of return values as follows:
+     '1'...'4'  specifies number of argument function returns (as in memset)
+     'm'	specifies that returned value is noalias (as in malloc)
+     '.'	specifies that nothing is known.
+
+   character 1+i specifies properties of argument number i as follows:
+     'x' or 'X' specifies that parameter is unused.
+     'r' or 'R' specifies that parameter is only read and memory pointed to is
+		never dereferenced.
+     'w' or 'W' specifies that parameter is only written to.
+     '.'	specifies that nothing is known.
+   The uppercase letter in addition specifies that parameter
+   is non-escaping.  */
+
+#ifndef ATTR_FNSPEC_H
+#define ATTR_FNSPEC_H
+
+class attr_fnspec
+{
+private:
+  /* fn spec attribute string.  */
+  const char *str;
+  /* length of the fn spec string.  */
+  const unsigned len;
+  /* Number of characters specifying return value.  */
+  const unsigned int return_desc_size = 1;
+  /* Number of characters specifying size.  */
+  const unsigned int arg_desc_size = 1;
+
+  /* Return start of specifier of arg i.  */
+  unsigned int arg_idx (int i)
+  {
+    return return_desc_size + arg_desc_size * i;
+  }
+
+public:
+  attr_fnspec (const char *str, unsigned len)
+  : str (str), len (len)
+  {
+    if (flag_checking)
+      verify ();
+  }
+  attr_fnspec (const_tree identifier)
+  : str (TREE_STRING_POINTER (identifier)),
+    len (TREE_STRING_LENGTH (identifier))
+  {
+    if (flag_checking)
+      verify ();
+  }
+
+  /* Return true if arg I is specified.  */
+  bool
+  arg_specified_p (unsigned int i)
+  {
+    return len >= arg_idx (i + 1);
+  }
+
+  /* True if the argument is not dereferenced recursively, thus only
+     directly reachable memory is read or written.  */
+  bool
+  arg_direct_p (unsigned int i)
+  {
+    unsigned int idx = arg_idx (i);
+    gcc_checking_assert (arg_specified_p (i));
+    return str[idx] == 'R' || str[idx] == 'W';
+  }
+
+  /* True if argument is used.  */
+  bool
+  arg_used_p (unsigned int i)
+  {
+    unsigned int idx = arg_idx (i);
+    gcc_checking_assert (arg_specified_p (i));
+    return str[idx] != 'x' && str[idx] != 'X';
+  }
+
+  /* True if memory reached by the argument is readonly (not clobbered).  */
+  bool
+  arg_readonly_p (unsigned int i)
+  {
+    unsigned int idx = arg_idx (i);
+    gcc_checking_assert (arg_specified_p (i));
+    return str[idx] == 'r' || str[idx] == 'R';
+  }
+
+  /* True if the argument does not escape.  */
+  bool
+  arg_noescape_p (unsigned int i)
+  {
+    unsigned int idx = arg_idx (i);
+    gcc_checking_assert (arg_specified_p (i));
+    return str[idx] == 'w' || str[idx] == 'W'
+	   || str[idx] == 'R' || str[idx] == 'r';
+  }
+
+  /* Return true if function returns value of its parameter.  If ARG_NO is
+     non-NULL return initialize it to the argument returned.  */
+  bool
+  returns_arg (unsigned int *arg_no)
+  {
+    if (str[0] >= '1' && str[0] <= '4')
+      {
+	if (arg_no)
+	  *arg_no = str[0] - '1';
+	return true;
+      }
+    return false;
+  }
+
+  /* Nonzero if the return value does not alias with anything.  Functions
+     with the malloc attribute have this set on their return value.  */
+  bool
+  returns_noalias_p ()
+  {
+    return str[0] == 'm';
+  }
+
+  /* Check validity of the string.  */
+  void verify ();
+};
+
+#endif /* ATTR_FNSPEC_H  */