Remove C language front end dependencies.

* tree-convert.c: New file.
* treetree.c: Don't include c-tree.h.  Include target.h.
(struct lang_identifier, union lang_tree_node, struct lang_type,
struct lang_function): New, minimal language-specific datastructs.
(tree_lang_truthvalue_conversion, tree_mark_addressable,
tree_lang_type_for_size, tree_lang_type_for_mode,
tree_lang_unsigned_type, tree_lang_signed_type,
tree_lang_signed_or_unsigned): New functions.
(LANG_HOOKS_*): Don't use C front end langhooks.  Use new functions.
(pushlevel, poplevel, global_bindings_p, insert_block, set_block,
pushdecl, getdecls, kept_level_p, tree_push_type_decl,
tree_push_atomic_type_decl): New functions.
(struct resword, struct reswords): Remove.
* Make-lang.in: Update.  Don't depend on C front end objects.
* config-lang.in: Likewise.

Co-Authored-By: Steven Bosscher <steven@gcc.gnu.org>

From-SVN: r69178

1 files changed, 108 insertions, 0 deletions

diff --git a/gcc/treelang/tree-convert.c b/gcc/treelang/tree-convert.c
new file mode 100644
index 00000000000..6d50ef5a76a
--- /dev/null
+++ b/gcc/treelang/tree-convert.c
@@ -0,0 +1,108 @@
+/* Language-level data type conversion for Treelang.
+   This is a very slightly modified copy of c-convert.c.
+   Copyright (C) 1987, 1988, 1991, 1998, 2002 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 2, 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 COPYING.  If not, write to the Free
+Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+02111-1307, USA.  */
+
+
+/* This file contains the functions for converting C expressions
+   to different data types.  The only entry point is `convert'.
+   Every language front end must have a `convert' function
+   but what kind of conversions it does will depend on the language.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "diagnostic.h"
+#include "tree.h"
+#include "flags.h"
+#include "convert.h"
+#include "toplev.h"
+#include "langhooks.h"
+
+/* Change of width--truncation and extension of integers or reals--
+   is represented with NOP_EXPR.  Proper functioning of many things
+   assumes that no other conversions can be NOP_EXPRs.
+
+   Conversion between integer and pointer is represented with CONVERT_EXPR.
+   Converting integer to real uses FLOAT_EXPR
+   and real to integer uses FIX_TRUNC_EXPR.
+
+   Here is a list of all the functions that assume that widening and
+   narrowing is always done with a NOP_EXPR:
+     In convert.c, convert_to_integer.
+     In c-typeck.c, build_binary_op (boolean ops), and
+	c_common_truthvalue_conversion.
+     In expr.c: expand_expr, for operands of a MULT_EXPR.
+     In fold-const.c: fold.
+     In tree.c: get_narrower and get_unwidened.  */
+
+/* Create an expression whose value is that of EXPR,
+   converted to type TYPE.  The TREE_TYPE of the value
+   is always TYPE.  This function implements all reasonable
+   conversions; callers should filter out those that are
+   not permitted by the language being compiled.  */
+
+tree
+convert (type, expr)
+     tree type, expr;
+{
+  tree e = expr;
+  enum tree_code code = TREE_CODE (type);
+
+  if (type == TREE_TYPE (expr)
+      || TREE_CODE (expr) == ERROR_MARK
+      || code == ERROR_MARK || TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
+    return expr;
+
+  if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)))
+    return fold (build1 (NOP_EXPR, type, expr));
+  if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
+    return error_mark_node;
+  if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)
+    {
+      error ("void value not ignored as it ought to be");
+      return error_mark_node;
+    }
+  if (code == VOID_TYPE)
+    return build1 (CONVERT_EXPR, type, e);
+  if (code == INTEGER_TYPE || code == ENUMERAL_TYPE)
+    return fold (convert_to_integer (type, e));
+  if (code == BOOLEAN_TYPE)
+    {
+      tree t = (*lang_hooks.truthvalue_conversion) (expr);
+      /* If it returns a NOP_EXPR, we must fold it here to avoid
+	 infinite recursion between fold () and convert ().  */
+      if (TREE_CODE (t) == NOP_EXPR)
+	return fold (build1 (NOP_EXPR, type, TREE_OPERAND (t, 0)));
+      else
+	return fold (build1 (NOP_EXPR, type, t));
+    }
+  if (code == POINTER_TYPE || code == REFERENCE_TYPE)
+    return fold (convert_to_pointer (type, e));
+  if (code == REAL_TYPE)
+    return fold (convert_to_real (type, e));
+  if (code == COMPLEX_TYPE)
+    return fold (convert_to_complex (type, e));
+  if (code == VECTOR_TYPE)
+    return fold (convert_to_vector (type, e));
+
+  error ("conversion to non-scalar type requested");
+  return error_mark_node;
+}