chore(ssa): rename codegen to ssa_gen + reorg of Value struct (#797)

* [multi]

- move value into its own module
- remove _ from match clause

* move IRGenerator impl into code_gen.rs

* rename codegen to ssa_gen

* rename codegen methods to ssa_gen

* Revert "[multi]" + git magic

This reverts commit cd78b1b.

* Fix incorrect description

* - rename `Single` to `Node
- slight change to the error messages

* resolve merge

crates/noirc_evaluator/src/lib.rs

@@ -11,7 +11,7 @@ use errors::{RuntimeError, RuntimeErrorKind};
 use iter_extended::btree_map;
 use noirc_abi::{AbiType, AbiVisibility};
 use noirc_frontend::monomorphization::ast::*;
-use ssa::{code_gen::IRGenerator, node};
+use ssa::{node, ssa_gen::IRGenerator};
 use std::collections::BTreeMap;
 
 pub struct Evaluator {
@@ -114,7 +114,7 @@ impl Evaluator {
         self.parse_abi_alt(&mut ir_gen);
 
         // Now call the main function
-        ir_gen.codegen_main()?;
+        ir_gen.ssa_gen_main()?;
 
         //Generates ACIR representation:
         ir_gen.context.ir_to_acir(self, enable_logging)?;

crates/noirc_evaluator/src/ssa/function.rs

@@ -1,11 +1,11 @@
 use crate::errors::RuntimeError;
 use crate::ssa::{
     block::BlockId,
-    code_gen::IRGenerator,
     conditional::{AssumptionId, DecisionTree, TreeBuilder},
     context::SsaContext,
     mem::ArrayId,
     node::{Node, NodeId, ObjectType, Opcode, Operation},
+    ssa_gen::IRGenerator,
     {block, builtin, node, ssa_form},
 };
 use iter_extended::try_vecmap;
@@ -173,7 +173,7 @@ impl IRGenerator {
         self.context.functions.insert(func_id, func.clone());
 
         let function_body = self.program.take_function_body(func_id);
-        let last_value = self.codegen_expression(&function_body)?;
+        let last_value = self.ssa_gen_expression(&function_body)?;
         let return_values = last_value.to_node_ids();
 
         func.result_types.clear();
@@ -227,8 +227,8 @@ impl IRGenerator {
 
     //generates an instruction for calling the function
     pub fn call(&mut self, call: &Call) -> Result<Vec<NodeId>, RuntimeError> {
-        let func = self.codegen_expression(&call.func)?.unwrap_id();
-        let arguments = self.codegen_expression_list(&call.arguments);
+        let func = self.ssa_gen_expression(&call.func)?.unwrap_id();
+        let arguments = self.ssa_gen_expression_list(&call.arguments);
 
         if let Some(opcode) = self.context.get_builtin_opcode(func) {
             return self.call_low_level(opcode, arguments);

crates/noirc_evaluator/src/ssa/mod.rs

@@ -2,7 +2,6 @@ pub mod acir_gen;
 mod anchor;
 mod block;
 mod builtin;
-pub mod code_gen;
 mod conditional;
 mod context;
 mod flatten;
@@ -13,3 +12,5 @@ mod mem;
 pub mod node;
 mod optimizations;
 mod ssa_form;
+pub mod ssa_gen;
+mod value;