Split EntityMap into entity::PrimaryMap and entity::EntityMap.

The new PrimaryMap replaces the primary EntityMap and the PrimaryEntityData
marker trait which was causing some confusion. We now have a clear
division between the two types of maps:

- PrimaryMap is used to assign entity numbers to the primary data for an
  entity.
- EntityMap is a secondary mapping adding additional info.

The split also means that the secondary EntityMap can now behave as if
all keys have a default value. This means that we can get rid of the
annoying ensure() and get_or_default() methods ther were used everywhere
instead of indexing. Just use normal indexing now; non-existent keys
will return the default value.

lib/cretonne/src/ir/function.rs

@@ -3,9 +3,10 @@
 //! The `Function` struct defined in this module owns all of its extended basic blocks and
 //! instructions.
 
-use entity_map::{EntityMap, PrimaryEntityData};
-use ir::{FunctionName, CallConv, Signature, JumpTableData, GlobalVarData, DataFlowGraph, Layout};
-use ir::{JumpTables, InstEncodings, ValueLocations, StackSlots, GlobalVars, EbbOffsets};
+use entity::{PrimaryMap, EntityMap};
+use ir;
+use ir::{FunctionName, CallConv, Signature, DataFlowGraph, Layout};
+use ir::{InstEncodings, ValueLocations, JumpTables, StackSlots, EbbOffsets};
 use isa::TargetIsa;
 use std::fmt;
 use write::write_function;
@@ -26,7 +27,7 @@ pub struct Function {
     pub stack_slots: StackSlots,
 
     /// Global variables referenced.
-    pub global_vars: GlobalVars,
+    pub global_vars: PrimaryMap<ir::GlobalVar, ir::GlobalVarData>,
 
     /// Jump tables used in this function.
     pub jump_tables: JumpTables,
@@ -52,9 +53,6 @@ pub struct Function {
     pub offsets: EbbOffsets,
 }
 
-impl PrimaryEntityData for JumpTableData {}
-impl PrimaryEntityData for GlobalVarData {}
-
 impl Function {
     /// Create a function with the given name and signature.
     pub fn with_name_signature(name: FunctionName, sig: Signature) -> Function {
@@ -62,8 +60,8 @@ impl Function {
             name,
             signature: sig,
             stack_slots: StackSlots::new(),
-            global_vars: GlobalVars::new(),
-            jump_tables: EntityMap::new(),
+            global_vars: PrimaryMap::new(),
+            jump_tables: PrimaryMap::new(),
             dfg: DataFlowGraph::new(),
             layout: Layout::new(),
             encodings: EntityMap::new(),