Use value lists for call arguments.

Add a new kind of instruction format that keeps all of its value
arguments in a value list. These value lists are all allocated out of
the dfg.value_lists memory pool.

Instruction formats with the value_list property set store *all* of
their value arguments in a single value list. There is no distinction
between fixed arguments and variable arguments.

Change the Call instruction format to use the value list representation
for its arguments.

This change is only the beginning. The intent is to eliminate the
boxed_storage instruction formats completely. Value lists use less
memory, and when the transition is complete, InstructionData will have a
trivial Drop implementation.

lib/cretonne/src/ir/builder.rs

@@ -5,7 +5,7 @@
 
 use ir::{types, instructions};
 use ir::{InstructionData, DataFlowGraph, Cursor};
-use ir::{Opcode, Type, Inst, Value, Ebb, JumpTable, VariableArgs, SigRef, FuncRef};
+use ir::{Opcode, Type, Inst, Value, Ebb, JumpTable, VariableArgs, SigRef, FuncRef, ValueList};
 use ir::immediates::{Imm64, Uimm8, Ieee32, Ieee64, ImmVector};
 use ir::condcodes::{IntCC, FloatCC};
 
@@ -21,6 +21,7 @@ pub trait InstBuilderBase<'f>: Sized {
     /// Get an immutable reference to the data flow graph that will hold the constructed
     /// instructions.
     fn data_flow_graph(&self) -> &DataFlowGraph;
+    fn data_flow_graph_mut(&mut self) -> &mut DataFlowGraph;
 
     /// Insert a simple instruction and return a reference to it.
     ///
@@ -76,6 +77,10 @@ impl<'c, 'fc, 'fd> InstBuilderBase<'fd> for InsertBuilder<'c, 'fc, 'fd> {
         self.dfg
     }
 
+    fn data_flow_graph_mut(&mut self) -> &mut DataFlowGraph {
+        self.dfg
+    }
+
     fn simple_instruction(self, data: InstructionData) -> (Inst, &'fd mut DataFlowGraph) {
         let inst = self.dfg.make_inst(data);
         self.pos.insert_inst(inst);
@@ -129,6 +134,10 @@ impl<'f> InstBuilderBase<'f> for ReplaceBuilder<'f> {
         self.dfg
     }
 
+    fn data_flow_graph_mut(&mut self) -> &mut DataFlowGraph {
+        self.dfg
+    }
+
     fn simple_instruction(self, data: InstructionData) -> (Inst, &'f mut DataFlowGraph) {
         // The replacement instruction cannot generate multiple results, so verify that the old
         // instruction's secondary results have been detached.