gccrs: Add base for HIR to GCC GENERIC lowering

This pass walks the HIR crate and turns them into GCC `tree`s. We do not have
any Rust specific tree's. We are slowly removing the backend abstraction
which was ported over from gccgo in favour of using `tree`s directly.

	gcc/rust/
	* backend/rust-builtins.h: New.
	* backend/rust-compile-base.cc: New.
	* backend/rust-compile-base.h: New.
	* backend/rust-mangle.cc: New.
	* backend/rust-mangle.h: New.
	* backend/rust-tree.cc: New.
	* backend/rust-tree.h: New.
	* rust-backend.h: New.
	* rust-gcc.cc: New.

Co-authored-by: David Faust <david.faust@oracle.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/gcc/rust/backend/rust-mangle.h b/gcc/rust/backend/rust-mangle.h
new file mode 100644
index 0000000..6d5a64f
--- /dev/null
+++ b/gcc/rust/backend/rust-mangle.h
@@ -0,0 +1,52 @@
+// 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 3, 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/>.
+
+#ifndef RUST_MANGLE_H
+#define RUST_MANGLE_H
+
+#include "rust-system.h"
+#include "rust-tyty.h"
+
+namespace Rust {
+namespace Compile {
+
+class Mangler
+{
+public:
+  enum MangleVersion
+  {
+    // Values defined in rust/lang.opt
+    LEGACY = 0,
+    V0 = 1,
+  };
+
+  // this needs to support Legacy and V0 see github #429 or #305
+  std::string mangle_item (const TyTy::BaseType *ty,
+			   const Resolver::CanonicalPath &path) const;
+
+  static void set_mangling (int frust_mangling_value)
+  {
+    version = static_cast<MangleVersion> (frust_mangling_value);
+  }
+
+private:
+  static enum MangleVersion version;
+};
+
+} // namespace Compile
+} // namespace Rust
+
+#endif // RUST_MANGLE_H