(draft) Use SourceSliceIndex for string literal

crates/ast/ast.json

@@ -210,7 +210,7 @@
       "unicode": "bool"
     },
     "LiteralStringExpression": {
-      "value": "SourceAtomSetIndex"
+      "value": "SourceSliceIndex"
     },
     "ArrayExpression": "ArrayExpression",
     "ArrowExpression": {

crates/ast/generate_ast.py

@@ -429,7 +429,6 @@ def emit_variant_none_call(indent, enum_name, variant_name):
         write(0, "#![allow(dead_code)]")
         write(0, "")
         write(0, "use crate::arena;")
-        write(0, "use crate::source_atom_set::SourceAtomSetIndex;")
         write(0, "use crate::source_slice_list::SourceSliceIndex;")
         write(0, "use crate::types::*;")
         write(0, "")

crates/ast/src/source_atom_set.rs

@@ -111,7 +111,6 @@ macro_rules! for_all_common_atoms {
             ("while", while_, While),
             ("with", with, With),
             ("yield", yield_, Yield),
-            ("use strict", use_strict, UseStrict),
             ("__proto__", __proto__, Proto),
         );
     }

crates/emitter/src/ast_emitter.rs

@@ -453,7 +453,7 @@ impl<'alloc, 'opt> AstEmitter<'alloc, 'opt> {
             }
 
             Expression::LiteralStringExpression { value, .. } => {
-                let str_index = self.emit.get_atom_gcthing_index(*value);
+                let str_index = self.emit.get_slice_gcthing_index(*value);
                 self.emit.string(str_index);
             }
 

crates/emitter/src/emitter.rs

@@ -6,6 +6,7 @@
 #![allow(dead_code)]
 
 use ast::source_atom_set::SourceAtomSetIndex;
+use ast::source_slice_list::SourceSliceIndex;
 use byteorder::{ByteOrder, LittleEndian};
 use std::cmp;
 use std::collections::HashMap;
@@ -1384,6 +1385,10 @@ impl InstructionWriter {
         }
     }
 
+    pub fn get_slice_gcthing_index(&mut self, slice: SourceSliceIndex) -> GCThingIndex {
+        self.gcthings.push_slice(slice)
+    }
+
     pub fn get_function_gcthing_index(&mut self, fun_index: ScriptStencilIndex) -> GCThingIndex {
         self.gcthings.push_function(fun_index)
     }

crates/generated_parser/src/ast_builder.rs

@@ -766,8 +766,9 @@ impl<'alloc> AstBuilder<'alloc> {
         let loc = token.loc;
         // Hack: Prevent emission for scripts with "use strict"
         // directive.
-        let value = token.value.as_atom();
-        if value == CommonSourceAtomSetIndices::use_strict() {
+        let value = token.value.as_slice();
+        let slice = self.slices.borrow().get(value);
+        if slice == "use strict" {
             return Err(ParseError::NotImplemented("use strict directive").into());
         }
 
@@ -1050,7 +1051,10 @@ impl<'alloc> AstBuilder<'alloc> {
         &self,
         token: arena::Box<'alloc, Token>,
     ) -> Result<'alloc, arena::Box<'alloc, PropertyName<'alloc>>> {
-        let value = token.value.as_atom();
+        let name = self.slices.borrow().get(token.value.as_slice());
+
+        let value = self.atoms.borrow_mut().insert(name);
+
         if value == CommonSourceAtomSetIndices::__proto__() {
             return Err(ParseError::NotImplemented("__proto__ as property name").into());
         }

crates/interpreter/src/evaluate.rs

@@ -39,6 +39,12 @@ trait Helpers<'alloc> {
     fn read_offset(&self, offset: usize) -> isize;
     fn read_atom(&self, offset: usize, gcthings: &Vec<GCThing>, atoms: &Vec<&'alloc str>)
         -> String;
+    fn read_slice(
+        &self,
+        offset: usize,
+        gcthings: &Vec<GCThing>,
+        slices: &Vec<&'alloc str>,
+    ) -> String;
 }
 
 impl<'alloc> Helpers<'alloc> for ImmutableScriptData {
@@ -77,6 +83,18 @@ impl<'alloc> Helpers<'alloc> for ImmutableScriptData {
             _ => panic!("Unexpected GC things for string"),
         }
     }
+
+    fn read_slice(
+        &self,
+        offset: usize,
+        gcthings: &Vec<GCThing>,
+        slices: &Vec<&'alloc str>,
+    ) -> String {
+        match gcthings[self.read_i32(offset) as usize] {
+            GCThing::Slice(index) => slices[usize::from(index)].to_string(),
+            _ => panic!("Unexpected GC things for string"),
+        }
+    }
 }
 
 /// This functions can partially interpreter the bytecode shared with SpiderMonkey.
@@ -96,6 +114,7 @@ pub fn evaluate(result: &EmitResult, global: Rc<RefCell<Object>>) -> Result<JSVa
     let immutable_script_data = &result.script_data_list[script_data_index];
     let gcthings = &script.gcthings;
     let atoms = &result.atoms;
+    let slices = &result.slices;
 
     loop {
         let op = match Opcode::try_from(immutable_script_data.bytecode[pc]) {
@@ -424,10 +443,10 @@ pub fn evaluate(result: &EmitResult, global: Rc<RefCell<Object>>) -> Result<JSVa
             }
 
             Opcode::String => {
-                stack.push(JSValue::String(immutable_script_data.read_atom(
+                stack.push(JSValue::String(immutable_script_data.read_slice(
                     pc + 1,
                     gcthings,
-                    atoms,
+                    slices,
                 )));
             }
 

crates/parser/src/lexer.rs

@@ -1378,7 +1378,7 @@ impl<'alloc> Lexer<'alloc> {
 
                 Some(c @ '"') | Some(c @ '\'') => {
                     if c == delimiter {
-                        let value = self.string_to_token_value(builder.finish_without_push(&self));
+                        let value = self.slice_to_token_value(builder.finish_without_push(&self));
                         return self.set_result(
                             TerminalId::StringLiteral,
                             SourceLocation::new(offset, self.offset()),

crates/stencil/src/gcthings.rs

@@ -2,13 +2,15 @@ use crate::regexp::RegExpIndex;
 use crate::scope::ScopeIndex;
 use crate::script::ScriptStencilIndex;
 use ast::source_atom_set::SourceAtomSetIndex;
+use ast::source_slice_list::SourceSliceIndex;
 
 /// Corresponds to js::frontend::GCThingList::ListType
 /// in m-c/js/src/frontend/BytecodeSection.h.
 #[derive(Debug)]
 pub enum GCThing {
     Null,
     Atom(SourceAtomSetIndex),
+    Slice(SourceSliceIndex),
     Function(ScriptStencilIndex),
     RegExp(RegExpIndex),
     Scope(ScopeIndex),
@@ -51,6 +53,12 @@ impl GCThingList {
         GCThingIndex::new(index)
     }
 
+    pub fn push_slice(&mut self, slice_index: SourceSliceIndex) -> GCThingIndex {
+        let index = self.things.len();
+        self.things.push(GCThing::Slice(slice_index));
+        GCThingIndex::new(index)
+    }
+
     pub fn push_function(&mut self, fun_index: ScriptStencilIndex) -> GCThingIndex {
         let index = self.things.len();
         self.things.push(GCThing::Function(fun_index));

gecko-patches.txt

@@ -1 +1 @@
-D85363:1648574
+D86376:1657937