diff --git a/lib/cretonne/src/ir/entities.rs b/lib/cretonne/src/ir/entities.rs
index df7d81988f..4570a21009 100644
--- a/lib/cretonne/src/ir/entities.rs
+++ b/lib/cretonne/src/ir/entities.rs
@@ -98,6 +98,17 @@ impl Default for Inst {
 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 pub struct Value(u32);
 
+impl EntityRef for Value {
+    fn new(index: usize) -> Value {
+        assert!(index < (u32::MAX as usize));
+        Value(index as u32)
+    }
+
+    fn index(self) -> usize {
+        self.0 as usize
+    }
+}
+
 /// Value references can either reference an instruction directly, or they can refer to the
 /// extended value table.
 pub enum ExpandedValue {
diff --git a/lib/cretonne/src/ir/function.rs b/lib/cretonne/src/ir/function.rs
index 844101bf95..db6c811b5a 100644
--- a/lib/cretonne/src/ir/function.rs
+++ b/lib/cretonne/src/ir/function.rs
@@ -4,8 +4,8 @@
 //! instructions.
 
 use std::fmt::{self, Display, Debug, Formatter};
-use ir::{FunctionName, Signature, Inst, StackSlot, StackSlotData, JumpTable, JumpTableData,
-         DataFlowGraph, Layout};
+use ir::{FunctionName, Signature, Value, Inst, StackSlot, StackSlotData, JumpTable, JumpTableData,
+         ValueLoc, DataFlowGraph, Layout};
 use isa::Encoding;
 use entity_map::{EntityMap, PrimaryEntityData};
 use write::write_function;
@@ -37,6 +37,9 @@ pub struct Function {
     /// Encoding recipe and bits for the legal instructions.
     /// Illegal instructions have the `Encoding::default()` value.
     pub encodings: EntityMap<Inst, Encoding>,
+
+    /// Location assigned to every value.
+    pub locations: EntityMap<Value, ValueLoc>,
 }
 
 impl PrimaryEntityData for StackSlotData {}
@@ -53,6 +56,7 @@ impl Function {
             dfg: DataFlowGraph::new(),
             layout: Layout::new(),
             encodings: EntityMap::new(),
+            locations: EntityMap::new(),
         }
     }
 
diff --git a/lib/cretonne/src/ir/mod.rs b/lib/cretonne/src/ir/mod.rs
index b8cda7711c..738c6336d5 100644
--- a/lib/cretonne/src/ir/mod.rs
+++ b/lib/cretonne/src/ir/mod.rs
@@ -13,6 +13,7 @@ pub mod function;
 mod funcname;
 mod extfunc;
 mod builder;
+mod valueloc;
 
 pub use ir::funcname::FunctionName;
 pub use ir::extfunc::{Signature, ArgumentType, ArgumentExtension, ExtFuncData};
@@ -21,6 +22,7 @@ pub use ir::entities::{Ebb, Inst, Value, StackSlot, JumpTable, FuncRef, SigRef};
 pub use ir::instructions::{Opcode, InstructionData, VariableArgs};
 pub use ir::stackslot::StackSlotData;
 pub use ir::jumptable::JumpTableData;
+pub use ir::valueloc::ValueLoc;
 pub use ir::dfg::{DataFlowGraph, ValueDef};
 pub use ir::layout::{Layout, Cursor};
 pub use ir::function::Function;
diff --git a/lib/cretonne/src/ir/valueloc.rs b/lib/cretonne/src/ir/valueloc.rs
new file mode 100644
index 0000000000..3526c58190
--- /dev/null
+++ b/lib/cretonne/src/ir/valueloc.rs
@@ -0,0 +1,24 @@
+//! Value locations.
+//!
+//! The register allocator assigns every SSA value to either a register or a stack slot. This
+//! assignment is represented by a `ValueLoc` object.
+
+use isa::RegUnit;
+use ir::StackSlot;
+
+/// Value location.
+#[derive(Copy, Clone, Debug)]
+pub enum ValueLoc {
+    /// This value has not been assigned to a location yet.
+    Unassigned,
+    /// Value is assigned to a register.
+    Reg(RegUnit),
+    /// Value is assigned to a stack slot.
+    Stack(StackSlot),
+}
+
+impl Default for ValueLoc {
+    fn default() -> Self {
+        ValueLoc::Unassigned
+    }
+}