Invalidate releases when optimizer inserts registers

inputs/passing/optimizerBug.ts

@@ -1,4 +1,4 @@
-// //! test_output(1)
+//! test_output(1)
 
 export default function main() {
   return f([1]);

valuescript_compiler/src/optimization/kal.rs

@@ -363,6 +363,8 @@ pub struct FnState {
   pub pointer_kals: HashMap<Pointer, Kal>,
   pub mutable_this_established: bool,
   pub registers: BTreeMap<String, Kal>,
+  pub register_releases: HashMap<String, Vec<usize>>,
+  pub invalidated_releases: Vec<usize>,
   pub new_instructions: Vec<Instruction>,
 }
 
@@ -404,6 +406,8 @@ impl FnState {
       pointer_kals,
       mutable_this_established: Default::default(),
       registers: Default::default(),
+      register_releases: Default::default(),
+      invalidated_releases: Default::default(),
       new_instructions: take(&mut self.new_instructions),
     }
   }
@@ -726,7 +730,17 @@ impl FnState {
       | InstanceOf(_, _, dst)
       | In(_, _, dst)
       | Sub(_, _, dst) => {
-        if let Some(value) = self.get(dst.name.clone()).try_to_value() {
+        if let Some(mut value) = self.get(dst.name.clone()).try_to_value() {
+          value.visit_registers_mut_rev(&mut |rvm| {
+            if let Some(release_locations) = self.register_releases.get(&rvm.register.name) {
+              self
+                .invalidated_releases
+                .append(&mut release_locations.clone());
+
+              self.register_releases.remove(&rvm.register.name);
+            }
+          });
+
           *instr = Instruction::Mov(value, dst.clone())
         }
       }

valuescript_compiler/src/optimization/simplify.rs

@@ -37,6 +37,15 @@ pub fn simplify(module: &mut Module, take_registers: bool) {
   }
 }
 
+/**
+ * Handle releases due to mutation.
+ *
+ * When you write to a register:
+ *   mov 123 %reg
+ *
+ * The content of that register at that point is unused, so we treat it as a
+ * release.
+ */
 fn handle_mutation_releases(body: &mut [FnLine], i: usize, take_registers: bool) {
   let mut calls = Vec::<(Register, usize)>::new();
 
@@ -145,7 +154,12 @@ fn simplify_fn(mut state: FnState, fn_: &mut Function, take_registers: bool) {
       FnLine::Instruction(instr) => {
         state.eval_instruction(instr);
 
-        // FIXME: Hacky side effect mechanism (eval_instruction populates new_instructions)
+        // FIXME: Hacky side effect mechanisms (eval_instruction populates things to do up here)
+
+        for invalid_release_i in take(&mut state.invalidated_releases) {
+          fn_.body[invalid_release_i] = FnLine::Comment("invalidated release".into())
+        }
+
         for instr in take(&mut state.new_instructions) {
           fn_.body.insert(i, FnLine::Instruction(instr));
           i += 1;
@@ -153,7 +167,15 @@ fn simplify_fn(mut state: FnState, fn_: &mut Function, take_registers: bool) {
       }
       FnLine::Label(_) => state.clear_local(),
       FnLine::Empty | FnLine::Comment(_) => {}
-      FnLine::Release(reg) => pending_releases.push(reg.clone()),
+      FnLine::Release(reg) => {
+        pending_releases.push(reg.clone());
+
+        state
+          .register_releases
+          .entry(reg.name.clone())
+          .or_default()
+          .push(i);
+      }
     }
 
     handle_mutation_releases(&mut fn_.body, i, take_registers);