LibWasm: Make the Module ctor generate a list of module functions

This list is supposed to be accessed rather frequently, so there's no
reason to make things slower by generating it many times on the spot.

Userland/Libraries/LibWasm/Parser/Parser.cpp

@@ -970,7 +970,7 @@ ParseResult<Locals> Locals::parse(InputStream& stream)
     return Locals { static_cast<u32>(count), type.release_value() };
 }
 
-ParseResult<Func> Func::parse(InputStream& stream)
+ParseResult<CodeSection::Func> CodeSection::Func::parse(InputStream& stream)
 {
     ScopeLogger<WASM_BINPARSER_DEBUG> logger("Func");
     auto locals = parse_vector<Locals>(stream);
@@ -1227,6 +1227,28 @@ ParseResult<Module> Module::parse(InputStream& stream)
     return Module { move(sections) };
 }
 
+void Module::populate_sections()
+{
+    const FunctionSection* function_section { nullptr };
+    for_each_section_of_type<FunctionSection>([&](const FunctionSection& section) { function_section = &section; });
+    for_each_section_of_type<CodeSection>([&](const CodeSection& section) {
+        // FIXME: This should be considered invalid once validation is implemented.
+        if (!function_section)
+            return;
+        size_t index = 0;
+        for (auto& entry : section.functions()) {
+            auto& type_index = function_section->types()[index];
+            Vector<ValueType> locals;
+            for (auto& local : entry.func().locals()) {
+                for (size_t i = 0; i < local.n(); ++i)
+                    locals.append(local.type());
+            }
+            m_functions.empend(type_index, move(locals), entry.func().body());
+            ++index;
+        }
+    });
+}
+
 String parse_error_to_string(ParseError error)
 {
     switch (error) {

Userland/Libraries/LibWasm/Printer/Printer.cpp

@@ -242,7 +242,7 @@ void Printer::print(const Wasm::Expression& expression)
         print(instr);
 }
 
-void Printer::print(const Wasm::Func& func)
+void Printer::print(const Wasm::CodeSection::Func& func)
 {
     print_indent();
     print("(function\n");

Userland/Libraries/LibWasm/Printer/Printer.h

@@ -11,14 +11,16 @@
 namespace Wasm {
 
 struct Printer {
-    explicit Printer(OutputStream& stream)
+    explicit Printer(OutputStream& stream, size_t initial_indent = 0)
         : m_stream(stream)
+        , m_indent(initial_indent)
     {
     }
 
     void print(const Wasm::BlockType&);
     void print(const Wasm::CodeSection&);
     void print(const Wasm::CodeSection::Code&);
+    void print(const Wasm::CodeSection::Func&);
     void print(const Wasm::ConstrainedStream&);
     void print(const Wasm::CustomSection&);
     void print(const Wasm::DataCountSection&);
@@ -29,7 +31,6 @@ struct Printer {
     void print(const Wasm::ExportSection&);
     void print(const Wasm::ExportSection::Export&);
     void print(const Wasm::Expression&);
-    void print(const Wasm::Func&);
     void print(const Wasm::FunctionSection&);
     void print(const Wasm::FunctionType&);
     void print(const Wasm::GlobalSection&);

Userland/Libraries/LibWasm/Types.h

@@ -799,27 +799,26 @@ private:
     ValueType m_type;
 };
 
-// https://webassembly.github.io/spec/core/bikeshed/#binary-func
-class Func {
-public:
-    explicit Func(Vector<Locals> locals, Expression body)
-        : m_locals(move(locals))
-        , m_body(move(body))
-    {
-    }
-
-    auto& locals() const { return m_locals; }
-    auto& body() const { return m_body; }
-
-    static ParseResult<Func> parse(InputStream& stream);
-
-private:
-    Vector<Locals> m_locals;
-    Expression m_body;
-};
-
 class CodeSection {
 public:
+    // https://webassembly.github.io/spec/core/bikeshed/#binary-func
+    class Func {
+    public:
+        explicit Func(Vector<Locals> locals, Expression body)
+            : m_locals(move(locals))
+            , m_body(move(body))
+        {
+        }
+
+        auto& locals() const { return m_locals; }
+        auto& body() const { return m_body; }
+
+        static ParseResult<Func> parse(InputStream& stream);
+
+    private:
+        Vector<Locals> m_locals;
+        Expression m_body;
+    };
     class Code {
     public:
         explicit Code(u32 size, Func func)
@@ -916,10 +915,10 @@ class Module {
 public:
     class Function {
     public:
-        explicit Function(TypeIndex type, Vector<ValueType> local_types, Expression body)
+        explicit Function(TypeIndex type, Vector<ValueType> local_types, const Expression& body)
             : m_type(type)
             , m_local_types(move(local_types))
-            , m_body(move(body))
+            , m_body(body)
         {
         }
 
@@ -930,7 +929,7 @@ public:
     private:
         TypeIndex m_type;
         Vector<ValueType> m_local_types;
-        Expression m_body;
+        const Expression& m_body;
     };
 
     using AnySection = Variant<
@@ -954,13 +953,35 @@ public:
     explicit Module(Vector<AnySection> sections)
         : m_sections(move(sections))
     {
+        populate_sections();
     }
 
     auto& sections() const { return m_sections; }
+    auto& functions() const { return m_functions; }
+
+    template<typename T, typename Callback>
+    void for_each_section_of_type(Callback&& callback) const
+    {
+        for (auto& section : m_sections) {
+            if (auto ptr = section.get_pointer<T>())
+                callback(*ptr);
+        }
+    }
+    template<typename T, typename Callback>
+    void for_each_section_of_type(Callback&& callback)
+    {
+        for (auto& section : m_sections) {
+            if (auto ptr = section.get_pointer<T>())
+                callback(*ptr);
+        }
+    }
 
     static ParseResult<Module> parse(InputStream& stream);
 
 private:
+    void populate_sections();
+
     Vector<AnySection> m_sections;
+    Vector<Function> m_functions;
 };
 }