Move entry_block() into Layout.

The single entry block in a function is simply the first block in the layout.

Remove the 'entry' keyword from the textual IL, the lexer and parser.

src/libcretonne/ir/mod.rs

@@ -10,7 +10,7 @@ pub mod layout;
 
 use ir::types::{FunctionName, Signature};
 use entity_map::EntityRef;
-use ir::entities::{Ebb, NO_EBB, StackSlot};
+use ir::entities::StackSlot;
 use ir::dfg::DataFlowGraph;
 use ir::layout::Layout;
 use std::fmt::{self, Debug, Display, Formatter};
@@ -24,9 +24,6 @@ pub struct Function {
     /// Signature of this function.
     signature: Signature,
 
-    /// The entry block.
-    pub entry_block: Ebb,
-
     /// Stack slots allocated in this function.
     stack_slots: Vec<StackSlotData>,
 
@@ -43,7 +40,6 @@ impl Function {
         Function {
             name: name,
             signature: sig,
-            entry_block: NO_EBB,
             stack_slots: Vec::new(),
             dfg: DataFlowGraph::new(),
             layout: Layout::new(),