chore(ssa refactor): Add Context structs and start ssa gen pass (#1196)

* Add Context structs and start ssa gen pass

* Fix block arguments

* Fix clippy lint

* Use the correct dfg

* Rename contexts to highlight the inner contexts are shared rather than used directly

* Update crates/noirc_evaluator/src/ssa_refactor/ssa_gen/value.rs

Co-authored-by: kevaundray <kevtheappdev@gmail.com>

---------

Co-authored-by: kevaundray <kevtheappdev@gmail.com>

crates/noirc_evaluator/src/lib.rs

@@ -304,7 +304,7 @@ impl Evaluator {
         // u8 and arrays are assumed to be private
         // This is not a short-coming of the ABI, but of the grammar
         // The new grammar has been conceived, and will be implemented.
-        let main = ir_gen.program.main();
+        let main = ir_gen.program.main_mut();
         let main_params = std::mem::take(&mut main.parameters);
         let abi_params = std::mem::take(&mut ir_gen.program.main_function_signature.0);
 

crates/noirc_evaluator/src/ssa_refactor.rs

@@ -5,9 +5,8 @@
 //! elimination and constant folding.
 //!
 //! This module heavily borrows from Cranelift
-#[allow(dead_code)]
-mod basic_block;
-#[allow(dead_code)]
-mod dfg;
-#[allow(dead_code)]
+#![allow(dead_code)]
+
 mod ir;
+mod ssa_builder;
+mod ssa_gen;

crates/noirc_evaluator/src/ssa_refactor/ir.rs

@@ -1,5 +1,6 @@
-pub(crate) mod extfunc;
-mod function;
+pub(crate) mod basic_block;
+pub(crate) mod dfg;
+pub(crate) mod function;
 pub(crate) mod instruction;
 pub(crate) mod map;
 pub(crate) mod types;

crates/noirc_evaluator/src/ssa_refactor/basic_block.rs → crates/noirc_evaluator/src/ssa_refactor/ir/basic_block.rs

@@ -1,4 +1,8 @@
-use super::ir::instruction::{Instruction, TerminatorInstruction};
+use super::{
+    instruction::{InstructionId, TerminatorInstruction},
+    map::Id,
+    value::ValueId,
+};
 
 /// A Basic block is a maximal collection of instructions
 /// such that there are only jumps at the end of block
@@ -8,10 +12,11 @@ use super::ir::instruction::{Instruction, TerminatorInstruction};
 /// block, then all instructions are executed. ie single-entry single-exit.
 #[derive(Debug, PartialEq, Eq, Hash, Clone)]
 pub(crate) struct BasicBlock {
-    /// Arguments to the basic block.
-    phi_nodes: Vec<BlockArguments>,
+    /// Parameters to the basic block.
+    parameters: Vec<ValueId>,
+
     /// Instructions in the basic block.
-    instructions: Vec<Instruction>,
+    instructions: Vec<InstructionId>,
 
     /// A basic block is considered sealed
     /// if no further predecessors will be added to it.
@@ -21,17 +26,16 @@ pub(crate) struct BasicBlock {
 
     /// The terminating instruction for the basic block.
     ///
-    /// This will be a control flow instruction.
-    terminator: TerminatorInstruction,
+    /// This will be a control flow instruction. This is only
+    /// None if the block is still being constructed.
+    terminator: Option<TerminatorInstruction>,
 }
 
-#[derive(Debug, PartialEq, Eq, Hash, Clone)]
 /// An identifier for a Basic Block.
-pub(crate) struct BasicBlockId;
+pub(crate) type BasicBlockId = Id<BasicBlock>;
 
-#[derive(Debug, PartialEq, Eq, Hash, Clone)]
-/// Arguments to the basic block.
-/// We use the modern Crane-lift strategy
-/// of representing phi nodes as basic block
-/// arguments.
-pub(crate) struct BlockArguments;
+impl BasicBlock {
+    pub(super) fn new(parameters: Vec<ValueId>) -> Self {
+        Self { parameters, instructions: Vec::new(), is_sealed: false, terminator: None }
+    }
+}

crates/noirc_evaluator/src/ssa_refactor/dfg.rs → crates/noirc_evaluator/src/ssa_refactor/ir/dfg.rs

@@ -1,14 +1,11 @@
 use super::{
     basic_block::{BasicBlock, BasicBlockId},
-    ir::{
-        extfunc::Signature,
-        instruction::{Instruction, InstructionId, Instructions},
-        map::{Id, SparseMap},
-        types::Type,
-        value::{Value, ValueId},
-    },
+    function::Signature,
+    instruction::{Instruction, InstructionId},
+    map::{DenseMap, Id, SecondaryMap},
+    types::Type,
+    value::{Value, ValueId},
 };
-use std::collections::HashMap;
 
 #[derive(Debug, Default)]
 /// A convenience wrapper to store `Value`s.
@@ -39,7 +36,7 @@ impl ValueList {
 #[derive(Debug, Default)]
 pub(crate) struct DataFlowGraph {
     /// All of the instructions in a function
-    instructions: Instructions,
+    instructions: DenseMap<Instruction>,
 
     /// Stores the results for a particular instruction.
     ///
@@ -50,17 +47,17 @@ pub(crate) struct DataFlowGraph {
     /// Currently, we need to define them in a better way
     /// Call instructions require the func signature, but
     /// other instructions may need some more reading on my part
-    results: HashMap<InstructionId, ValueList>,
+    results: SecondaryMap<Instruction, ValueList>,
 
     /// Storage for all of the values defined in this
     /// function.
-    values: SparseMap<Value>,
+    values: DenseMap<Value>,
 
     /// Function signatures of external methods
-    signatures: SparseMap<Signature>,
+    signatures: DenseMap<Signature>,
 
     /// All blocks in a function
-    blocks: SparseMap<BasicBlock>,
+    blocks: DenseMap<BasicBlock>,
 }
 
 impl DataFlowGraph {
@@ -71,13 +68,17 @@ impl DataFlowGraph {
 
     /// Inserts a new instruction into the DFG.
     pub(crate) fn make_instruction(&mut self, instruction_data: Instruction) -> InstructionId {
-        let id = self.instructions.push(instruction_data);
+        let id = self.instructions.insert(instruction_data);
 
         // Create a new vector to store the potential results for the instruction.
         self.results.insert(id, Default::default());
         id
     }
 
+    pub(crate) fn make_value(&mut self, value: Value) -> ValueId {
+        self.values.insert(value)
+    }
+
     /// Attaches results to the instruction.
     ///
     /// Returns the number of results that this instruction
@@ -126,9 +127,9 @@ impl DataFlowGraph {
         let results = self.results.get_mut(&instruction_id).unwrap();
         let expected_res_position = results.len();
 
-        let value_id = self.values.push(Value::Instruction {
+        let value_id = self.values.insert(Value::Instruction {
             typ,
-            position: expected_res_position as u16,
+            position: expected_res_position,
             instruction: instruction_id,
         });
 

crates/noirc_evaluator/src/ssa_refactor/ir/function.rs

@@ -1,25 +1,70 @@
-use crate::ssa_refactor::basic_block::{BasicBlock, BasicBlockId};
-
+use super::basic_block::{BasicBlock, BasicBlockId};
+use super::dfg::DataFlowGraph;
 use super::instruction::Instruction;
+use super::map::{DenseMap, Id, SecondaryMap};
+use super::types::Type;
+use super::value::Value;
 
+use iter_extended::vecmap;
 use noirc_errors::Location;
-use std::collections::HashMap;
 
 /// A function holds a list of instructions.
-/// These instructions are further grouped into
-/// Basic blocks
+/// These instructions are further grouped into Basic blocks
+///
+/// Like Crane-lift all functions outside of the current function is seen as external.
+/// To reference external functions, one must first import the function signature
+/// into the current function's context.
 #[derive(Debug)]
 pub(crate) struct Function {
     /// Basic blocks associated to this particular function
-    basic_blocks: HashMap<BasicBlockId, BasicBlock>,
+    basic_blocks: DenseMap<BasicBlock>,
 
     /// Maps instructions to source locations
-    source_locations: HashMap<Instruction, Location>,
+    source_locations: SecondaryMap<Instruction, Location>,
 
     /// The first basic block in the function
     entry_block: BasicBlockId,
+
+    dfg: DataFlowGraph,
+}
+
+impl Function {
+    pub(crate) fn new(parameter_count: usize) -> Self {
+        let mut dfg = DataFlowGraph::default();
+        let mut basic_blocks = DenseMap::default();
+
+        // The parameters for each function are stored as the block parameters
+        // of the function's entry block
+        let entry_block = basic_blocks.insert_with_id(|entry_block| {
+            // TODO: Give each parameter its correct type
+            let parameters = vecmap(0..parameter_count, |i| {
+                dfg.make_value(Value::Param { block: entry_block, position: i, typ: Type::Unit })
+            });
+
+            BasicBlock::new(parameters)
+        });
+
+        Self { basic_blocks, source_locations: SecondaryMap::new(), entry_block, dfg }
+    }
+
+    pub(crate) fn entry_block(&self) -> BasicBlockId {
+        self.entry_block
+    }
 }
 
 /// FunctionId is a reference for a function
-#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)]
-pub(crate) struct FunctionId(pub(crate) u32);
+pub(crate) type FunctionId = Id<Function>;
+
+#[derive(Debug, Default, Clone)]
+pub(crate) struct Signature {
+    pub(crate) params: Vec<Type>,
+    pub(crate) returns: Vec<Type>,
+}
+
+#[test]
+fn sign_smoke() {
+    let mut signature = Signature::default();
+
+    signature.params.push(Type::Numeric(super::types::NumericType::NativeField));
+    signature.returns.push(Type::Numeric(super::types::NumericType::Unsigned { bit_size: 32 }));
+}

crates/noirc_evaluator/src/ssa_refactor/ir/instruction.rs

@@ -1,15 +1,8 @@
 use acvm::FieldElement;
 
 use super::{
-    function::FunctionId,
-    map::{Id, SparseMap},
-    types::Type,
-    value::ValueId,
+    basic_block::BasicBlockId, function::FunctionId, map::Id, types::Type, value::ValueId,
 };
-use crate::ssa_refactor::basic_block::{BasicBlockId, BlockArguments};
-
-// Container for all Instructions, per-function
-pub(crate) type Instructions = SparseMap<Instruction>;
 
 /// Reference to an instruction
 pub(crate) type InstructionId = Id<Instruction>;
@@ -134,12 +127,12 @@ pub(crate) enum TerminatorInstruction {
         condition: ValueId,
         then_destination: BasicBlockId,
         else_destination: BasicBlockId,
-        arguments: BlockArguments,
+        arguments: Vec<ValueId>,
     },
     /// Unconditional Jump
     ///
     /// Jumps to specified `destination` with `arguments`
-    Jmp { destination: BasicBlockId, arguments: BlockArguments },
+    Jmp { destination: BasicBlockId, arguments: Vec<ValueId> },
 }
 
 /// A binary instruction in the IR.
@@ -181,34 +174,3 @@ pub(crate) enum BinaryOp {
     /// false otherwise.
     Ne,
 }
-
-#[test]
-fn smoke_instructions_map_duplicate() {
-    let id = Id::test_new(0);
-
-    let ins = Instruction::Not(id);
-    let same_ins = Instruction::Not(id);
-
-    let mut ins_map = Instructions::default();
-
-    // Document what happens when we insert the same instruction twice
-    let id = ins_map.push(ins);
-    let id_same_ins = ins_map.push(same_ins);
-
-    // The map is quite naive and does not check if the instruction has ben inserted
-    // before. We simply assign a different Id.
-    assert_ne!(id, id_same_ins)
-}
-
-#[test]
-fn num_instructions_smoke() {
-    let n = 100;
-
-    let mut ins_map = Instructions::default();
-    for i in 0..n {
-        let ins = Instruction::Not(Id::test_new(i));
-        ins_map.push(ins);
-    }
-
-    assert_eq!(n, ins_map.len())
-}