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/cfg.rs

@@ -104,11 +104,8 @@ impl ControlFlowGraph {
         &self.data[ebb].successors
     }
 
-    pub fn postorder_ebbs(&self) -> Vec<Ebb> {
-        if self.len() < 1 {
-            return Vec::new();
-        }
-        let mut stack_a = vec![Ebb::with_number(0).unwrap()];
+    pub fn postorder_ebbs(&self, entry: Ebb) -> Vec<Ebb> {
+        let mut stack_a = vec![entry];
         let mut stack_b = Vec::new();
         while stack_a.len() > 0 {
             let cur = stack_a.pop().unwrap();
@@ -282,7 +279,7 @@ mod tests {
         func.layout.append_inst(jmp_ebb2_ebb5, ebb2);
 
         let cfg = ControlFlowGraph::new(&func);
-        assert_eq!(cfg.postorder_ebbs(),
+        assert_eq!(cfg.postorder_ebbs(func.layout.entry_block().unwrap()),
                    vec![ebb0, ebb2, ebb5, ebb4, ebb1, ebb3]);
     }
 
@@ -309,6 +306,7 @@ mod tests {
         func.layout.append_inst(jmp_ebb2_ebb3, ebb2);
 
         let cfg = ControlFlowGraph::new(&func);
-        assert_eq!(cfg.postorder_ebbs(), vec![ebb0, ebb1, ebb2, ebb3]);
+        assert_eq!(cfg.postorder_ebbs(func.layout.entry_block().unwrap()),
+                   vec![ebb0, ebb1, ebb2, ebb3]);
     }
 }

src/libcretonne/ir/layout.rs

@@ -108,6 +108,12 @@ impl Layout {
             next: self.first_ebb,
         }
     }
+
+    /// Get the function's entry block.
+    /// This is simply the first EBB in the layout order.
+    pub fn entry_block(&self) -> Option<Ebb> {
+        self.first_ebb
+    }
 }
 
 #[derive(Clone, Debug, Default)]
@@ -414,8 +420,11 @@ mod tests {
         let e0 = Ebb::new(0);
         let e1 = Ebb::new(1);
 
+        assert_eq!(layout.entry_block(), None);
         layout.append_ebb(e0);
+        assert_eq!(layout.entry_block(), Some(e0));
         layout.append_ebb(e1);
+        assert_eq!(layout.entry_block(), Some(e0));
 
         let i0 = Inst::new(0);
         let i1 = Inst::new(1);

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(),