Remove unused labels

valuescript_compiler/src/optimization/mod.rs

@@ -4,6 +4,7 @@ mod kal;
 mod optimize;
 mod reduce_instructions;
 mod remove_meta_lines;
+mod remove_unused_labels;
 mod shake_tree;
 mod simplify;
 pub mod try_to_kal;

valuescript_compiler/src/optimization/optimize.rs

@@ -5,6 +5,7 @@ use super::collapse_pointers_of_pointers::collapse_pointers_of_pointers;
 use super::extract_constants::extract_constants;
 use super::reduce_instructions::reduce_instructions;
 use super::remove_meta_lines::remove_meta_lines;
+use super::remove_unused_labels::remove_unused_labels;
 use super::shake_tree::shake_tree;
 use super::simplify::simplify;
 
@@ -18,6 +19,7 @@ pub fn optimize(module: &mut Module, pointer_allocator: &mut NameAllocator) {
   }
 
   remove_meta_lines(module);
+  remove_unused_labels(module);
   extract_constants(module, pointer_allocator);
 
   // After possibly repeated optimization, this ensures that the pointers are ordered correctly.

valuescript_compiler/src/optimization/remove_unused_labels.rs

@@ -0,0 +1,45 @@
+use std::{collections::HashSet, mem::take};
+
+use crate::{
+  asm::{DefinitionContent, FnLine, Function, Module},
+  instruction::InstructionFieldMut,
+};
+
+pub fn remove_unused_labels(module: &mut Module) {
+  for defn in &mut module.definitions {
+    if let DefinitionContent::Function(fn_) = &mut defn.content {
+      remove_unused_labels_fn(fn_);
+    }
+  }
+}
+
+fn remove_unused_labels_fn(fn_: &mut Function) {
+  let mut used_labels = HashSet::<String>::new();
+
+  for line in &mut fn_.body {
+    match line {
+      FnLine::Instruction(instr) => {
+        instr.visit_fields_mut(&mut |field| match field {
+          InstructionFieldMut::LabelRef(label_ref) => {
+            used_labels.insert(label_ref.name.clone());
+          }
+          InstructionFieldMut::Value(_) | InstructionFieldMut::Register(_) => {}
+        });
+      }
+      FnLine::Label(_) | FnLine::Empty | FnLine::Comment(_) | FnLine::Release(_) => {}
+    }
+  }
+
+  for line in take(&mut fn_.body) {
+    match &line {
+      FnLine::Label(label) => {
+        if !used_labels.contains(&label.name) {
+          continue;
+        }
+      }
+      FnLine::Instruction(_) | FnLine::Empty | FnLine::Comment(_) | FnLine::Release(_) => {}
+    }
+
+    fn_.body.push(line);
+  }
+}