Move library crates under 'lib/'.

Give these crates each a more standard directory layout with sources in
a 'src' sub-sirectory and Cargo.toml in the top lib/foo directory.

Add license and description fields to each.

The build script for the cretonne crate now lives in
'lib/cretonne/build.rs' separating it from the normal library sources
under 'lib/cretonne/src'.

lib/cretonne/src/ir/function.rs

@@ -0,0 +1,80 @@
+//! Intermediate representation of a function.
+//!
+//! The `Function` struct defined in this module owns all of its extended basic blocks and
+//! instructions.
+
+use std::fmt::{self, Display, Debug, Formatter};
+use ir::{FunctionName, Signature, Inst, StackSlot, StackSlotData, JumpTable, JumpTableData,
+         DataFlowGraph, Layout};
+use isa::Encoding;
+use entity_map::{EntityMap, PrimaryEntityData};
+use write::write_function;
+
+/// A function.
+///
+/// Functions can be cloned, but it is not a very fast operation.
+/// The clone will have all the same entity numbers as the original.
+#[derive(Clone)]
+pub struct Function {
+    /// Name of this function. Mostly used by `.cton` files.
+    pub name: FunctionName,
+
+    /// Signature of this function.
+    signature: Signature,
+
+    /// Stack slots allocated in this function.
+    pub stack_slots: EntityMap<StackSlot, StackSlotData>,
+
+    /// Jump tables used in this function.
+    pub jump_tables: EntityMap<JumpTable, JumpTableData>,
+
+    /// Data flow graph containing the primary definition of all instructions, EBBs and values.
+    pub dfg: DataFlowGraph,
+
+    /// Layout of EBBs and instructions in the function body.
+    pub layout: Layout,
+
+    /// Encoding recipe and bits for the legal instructions.
+    /// Illegal instructions have the `Encoding::default()` value.
+    pub encodings: EntityMap<Inst, Encoding>,
+}
+
+impl PrimaryEntityData for StackSlotData {}
+impl PrimaryEntityData for JumpTableData {}
+
+impl Function {
+    /// Create a function with the given name and signature.
+    pub fn with_name_signature(name: FunctionName, sig: Signature) -> Function {
+        Function {
+            name: name,
+            signature: sig,
+            stack_slots: EntityMap::new(),
+            jump_tables: EntityMap::new(),
+            dfg: DataFlowGraph::new(),
+            layout: Layout::new(),
+            encodings: EntityMap::new(),
+        }
+    }
+
+    /// Create a new empty, anomymous function.
+    pub fn new() -> Function {
+        Self::with_name_signature(FunctionName::default(), Signature::new())
+    }
+
+    /// Get the signature of this function.
+    pub fn own_signature(&self) -> &Signature {
+        &self.signature
+    }
+}
+
+impl Display for Function {
+    fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
+        write_function(fmt, self, None)
+    }
+}
+
+impl Debug for Function {
+    fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
+        write_function(fmt, self, None)
+    }
+}