add mir

rust2/src/mir/mod.rs

@@ -0,0 +1,94 @@
+//! an experimental MIR (mid-level-ir)
+#![allow(dead_code)]
+
+mod opts;
+mod state;
+
+use std::fmt::{Debug, Formatter};
+
+use bumpalo::Bump;
+
+use crate::{
+    hir::{Hir, StmtKind as HirStmtKind},
+    mir::state::{MemoryState, Store, StoreInner},
+    parse::Span,
+    BumpVec,
+};
+
+#[derive(Debug, Clone)]
+pub struct Mir<'mir> {
+    stmts: BumpVec<'mir, Stmt<'mir>>,
+}
+
+#[derive(Clone)]
+struct Stmt<'mir> {
+    kind: StmtKind<'mir>,
+    state: MemoryState<'mir>,
+    span: Span,
+}
+
+impl Debug for Stmt<'_> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Stmt")
+            .field("kind", &self.kind)
+            .field("state", &self.state)
+            .finish()
+    }
+}
+
+#[derive(Debug, Clone)]
+enum StmtKind<'mir> {
+    /// Add or sub, the value has the valid range -255..=255
+    AddSub(i32, i16, Store),
+    /// Sets the current cell to 0 and adds that value of the cell to another cell at `offset`
+    MoveAddTo {
+        offset: i32,
+        store_set_null: Store,
+        store_move: Store,
+    },
+    /// Left or Right pointer move (`<>`)
+    PointerMove(i32),
+    Loop(Mir<'mir>),
+    Out,
+    In(Store),
+    SetN(u8, Store),
+}
+
+#[tracing::instrument]
+pub fn optimized_mir<'mir>(alloc: &'mir Bump, hir: &Hir<'_>) -> Mir<'mir> {
+    let mut mir = hir_to_mir(alloc, hir);
+    opts::pass_get_state_info(alloc, &mut mir);
+    mir
+}
+
+/// compiles hir down to a minimal mir
+fn hir_to_mir<'mir>(alloc: &'mir Bump, hir: &Hir<'_>) -> Mir<'mir> {
+    let mut stmts = Vec::new_in(alloc);
+    let iter = hir.stmts.iter().map(|hir_stmt| {
+        let kind = match *hir_stmt.kind() {
+            HirStmtKind::Add(offset, n) => StmtKind::AddSub(offset, i16::from(n), Store::unknown()),
+            HirStmtKind::Sub(offset, n) => {
+                StmtKind::AddSub(offset, -i16::from(n), Store::unknown())
+            }
+            HirStmtKind::MoveAddTo { offset } => StmtKind::MoveAddTo {
+                offset,
+                store_set_null: Store::unknown(),
+                store_move: Store::unknown(),
+            },
+            HirStmtKind::Right(n) => StmtKind::PointerMove(i32::try_from(n).unwrap()),
+            HirStmtKind::Left(n) => StmtKind::PointerMove(-i32::try_from(n).unwrap()),
+            HirStmtKind::Loop(ref body) => StmtKind::Loop(hir_to_mir(alloc, body)),
+            HirStmtKind::Out => StmtKind::Out,
+            HirStmtKind::In => StmtKind::In(StoreInner::Unknown.into()),
+            HirStmtKind::SetN(n) => StmtKind::SetN(n, Store::unknown()),
+        };
+        Stmt {
+            kind,
+            span: hir_stmt.span,
+            state: MemoryState::empty(alloc),
+        }
+    });
+    stmts.extend(iter);
+
+    Mir { stmts }
+}