Refactor module builder

test/mjsunit/wasm/wasm-module-builder.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-function WasmFunctionBuilder(name, sig_index) {
+class Binary extends Array {

[bradnelson, 2016/06/21 19:05:00]

Nice pithy name :-)

+  emit_u8(val) {
+    this.push(val);
+  }
+
+  emit_u16(val) {
+    this.push(val & 0xff);
+    this.push((val >> 8) & 0xff);
+  }
+
+  emit_u32(val) {
+    this.push(val & 0xff);
+    this.push((val >> 8) & 0xff);
+    this.push((val >> 16) & 0xff);
+    this.push((val >> 24) & 0xff);
+  }
+
+  emit_varint(val) {
+    while (true) {
+      let v = val & 0xff;
+      val = val >>> 7;
+      if (val == 0) {
+        this.push(v);
+        break;
+      }
+      this.push(v | 0x80);
+    }
+  }
+
+  emit_bytes(data) {
+    for (let i = 0; i < data.length; i++) {
+      this.push(data[i] & 0xff);
+    }
+  }
+
+  emit_string(string) {
+    // When testing illegal names, we pass a byte array directly.
+    if (string instanceof Array) {
+      this.emit_varint(string.length);
+      this.emit_bytes(string);
+      return;
+    }
+
+    // This is the hacky way to convert a JavaScript string to a UTF8 encoded
+    // string only containing single-byte characters.
+    let string_utf8 = unescape(encodeURIComponent(string));
+    this.emit_varint(string_utf8.length);
+    for (let i = 0; i < string_utf8.length; i++) {
+      this.emit_u8(string_utf8.charCodeAt(i));
+    }
+  }
+
+  emit_header() {
+    this.push(kWasmH0, kWasmH1, kWasmH2, kWasmH3,
+              kWasmV0, kWasmV1, kWasmV2, kWasmV3);
+  }
+
+  emit_section(section_code, content_generator) {
+    // Emit section name.
+    this.emit_string(section_names[section_code]);
+    // Emit the section to a temporary buffer: its full length isn't know yet.
+    let section = new Binary;
+    content_generator(section);
+    // Emit section length.
+    this.emit_varint(section.length);
+    // Copy the temporary buffer.
+    this.push(...section);
+  }
+}
+
+class WasmFunctionBuilder {
+  constructor(name, type_index) {
     this.name = name;
-    this.sig_index = sig_index;
+    this.type_index = type_index;
     this.exports = [];
+  }
+
+  exportAs(name) {
+    this.exports.push(name);
+    return this;
+  }
+
+  exportFunc() {
+    this.exports.push(this.name);
+    return this;
+  }
+
+  addBody(body) {
+    this.body = body;
+    return this;
+  }
+
+  addLocals(locals) {
+    this.locals = locals;
+    return this;
+  }
 }
 
-WasmFunctionBuilder.prototype.exportAs = function(name) {
-    this.exports.push(name);
-    return this;
-}
-
-WasmFunctionBuilder.prototype.exportFunc = function() {
-  this.exports.push(this.name);
-  return this;
-}
-
-WasmFunctionBuilder.prototype.addBody = function(body) {
-    this.body = body;
-    return this;
-}
-
-WasmFunctionBuilder.prototype.addLocals = function(locals) {
-    this.locals = locals;
-    return this;
-}
-
-function WasmModuleBuilder() {
-    this.signatures = [];
+class WasmModuleBuilder {
+  constructor() {
+    this.types = [];
     this.imports = [];
     this.functions = [];
     this.exports = [];
-    this.function_table = [];
-    this.data_segments = [];
+    this.table = [];
+    this.segments = [];
     this.explicit = [];
-    return this;
-}
-
-WasmModuleBuilder.prototype.addStart = function(start_index) {
+  }
+
+  addStart(start_index) {
     this.start_index = start_index;
-}
-
-WasmModuleBuilder.prototype.addMemory = function(min, max, exp) {
+  }
+
+  addMemory(min, max, exp) {
     this.memory = {min: min, max: max, exp: exp};
     return this;
-}
-
-WasmModuleBuilder.prototype.addExplicitSection = function(bytes) {
-  this.explicit.push(bytes);
-  return this;
-}
-
-// Add a signature; format is [param_count, param0, param1, ..., retcount, ret0]
-WasmModuleBuilder.prototype.addSignature = function(sig) {
-    // TODO: canonicalize signatures?
-    this.signatures.push(sig);
-    return this.signatures.length - 1;
-}
-
-WasmModuleBuilder.prototype.addFunction = function(name, sig) {
-    var sig_index = (typeof sig) == "number" ? sig : this.addSignature(sig);
-    var func = new WasmFunctionBuilder(name, sig_index);
+  }
+
+  addExplicitSection(bytes) {
+    this.explicit.push(bytes);
+    return this;
+  }
+
+  addType(type) {
+    // TODO: canonicalize types?
+    this.types.push(type);
+    return this.types.length - 1;
+  }
+
+  addFunction(name, type) {
+    let type_index = (typeof type) == "number" ? type : this.addType(type);
+    let func = new WasmFunctionBuilder(name, type_index);
     func.index = this.functions.length;
     this.functions.push(func);
     return func;
-}
-
-WasmModuleBuilder.prototype.addImportWithModule = function(module, name, sig) {
-  var sig_index = (typeof sig) == "number" ? sig : this.addSignature(sig);
-  this.imports.push({module: module, name: name, sig_index: sig_index});
-  return this.imports.length - 1;
-}
-
-WasmModuleBuilder.prototype.addImport = function(name, sig) {
-  this.addImportWithModule(name, undefined, sig);
-}
-
-WasmModuleBuilder.prototype.addDataSegment = function(addr, data, init) {
-    this.data_segments.push({addr: addr, data: data, init: init});
-    return this.data_segments.length - 1;
-}
-
-WasmModuleBuilder.prototype.appendToFunctionTable = function(array) {
-    this.function_table = this.function_table.concat(array);
-    return this;
-}
-
-function emit_u8(bytes, val) {
-    bytes.push(val & 0xff);
-}
-
-function emit_u16(bytes, val) {
-    bytes.push(val & 0xff);
-    bytes.push((val >> 8) & 0xff);
-}
-
-function emit_u32(bytes, val) {
-    bytes.push(val & 0xff);
-    bytes.push((val >> 8) & 0xff);
-    bytes.push((val >> 16) & 0xff);
-    bytes.push((val >> 24) & 0xff);
-}
-
-function emit_string(bytes, string) {
-    // When testing illegal names, we pass a byte array directly.
-    if (string instanceof Array) {
-      emit_varint(bytes, string.length);
-      emit_bytes(bytes, string);
-      return;
-    }
-
-    // This is the hacky way to convert a JavaScript scring to a UTF8 encoded
-    // string only containing single-byte characters.
-    var string_utf8 = unescape(encodeURIComponent(string));
-    emit_varint(bytes, string_utf8.length);
-    for (var i = 0; i < string_utf8.length; i++) {
-      emit_u8(bytes, string_utf8.charCodeAt(i));
-    }
-}
-
-function emit_varint(bytes, val) {
-    while (true) {
-        var v = val & 0xff;
-        val = val >>> 7;
-        if (val == 0) {
-            bytes.push(v);
-            break;
-        }
-        bytes.push(v | 0x80);
-    }
-}
-
-function emit_bytes(bytes, data) {
-  for (var i = 0; i < data.length; i++) {
-    bytes.push(data[i] & 0xff);
-  }
-}
-
-function emit_section(bytes, section_code, content_generator) {
-    // Emit section name.
-    emit_string(bytes, section_names[section_code]);
-    // Emit the section to a temporary buffer: its full length isn't know yet.
-    var tmp_bytes = [];
-    content_generator(tmp_bytes);
-    // Emit section length.
-    emit_varint(bytes, tmp_bytes.length);
-    // Copy the temporary buffer.
-    Array.prototype.push.apply(bytes, tmp_bytes);
-}
-
-WasmModuleBuilder.prototype.toArray = function(debug) {
-    // Add header bytes
-    var bytes = [];
-    bytes = bytes.concat([kWasmH0, kWasmH1, kWasmH2, kWasmH3,
-                          kWasmV0, kWasmV1, kWasmV2, kWasmV3]);
-
-    var wasm = this;
-
-    // Add signatures section
-    if (wasm.signatures.length > 0) {
-        if (debug) print("emitting signatures @ " + bytes.length);
-        emit_section(bytes, kDeclSignatures, function(bytes) {
-            emit_varint(bytes, wasm.signatures.length);
-            for (sig of wasm.signatures) {
-                emit_u8(bytes, kWasmFunctionTypeForm);
-                for (var j = 0; j < sig.length; j++) {
-                    emit_u8(bytes, sig[j]);
-                }
-            }
-        });
+  }
+
+  addImportWithModule(module, name, type) {
+    let type_index = (typeof type) == "number" ? type : this.addType(type);
+    this.imports.push({module: module, name: name, type: type_index});
+    return this.imports.length - 1;
+  }
+
+  addImport(name, type) {
+    return this.addImportWithModule(name, undefined, type);
+  }
+
+  addDataSegment(addr, data, init) {
+    this.segments.push({addr: addr, data: data, init: init});
+    return this.segments.length - 1;
+  }
+
+  appendToTable(array) {
+    this.table.push(...array);
+    return this;
+  }
+
+  toArray(debug) {
+    let binary = new Binary;
+    let wasm = this;
+
+    // Add header
+    binary.emit_header();
+
+    // Add type section
+    if (wasm.types.length > 0) {
+      if (debug) print("emitting types @ " + binary.length);
+      binary.emit_section(kDeclTypes, section => {
+        section.emit_varint(wasm.types.length);
+        for (let type of wasm.types) {
+          section.emit_u8(kWasmFunctionTypeForm);
+          section.emit_varint(type.params.length);
+          for (let param of type.params) {
+            section.emit_u8(param);
+          }
+          section.emit_varint(type.results.length);
+          for (let result of type.results) {
+            section.emit_u8(result);
+          }
+        }
+      });
     }
 
     // Add imports section
     if (wasm.imports.length > 0) {
-        if (debug) print("emitting imports @ " + bytes.length);
-        emit_section(bytes, kDeclImportTable, function(bytes) {
-            emit_varint(bytes, wasm.imports.length);
-            for (imp of wasm.imports) {
-                emit_varint(bytes, imp.sig_index);
-                emit_string(bytes, imp.module);
-                emit_string(bytes, imp.name || '');
-            }
-        });
+      if (debug) print("emitting imports @ " + binary.length);
+      binary.emit_section(kDeclImports, section => {
+        section.emit_varint(wasm.imports.length);
+        for (let imp of wasm.imports) {
+          section.emit_varint(imp.type);
+          section.emit_string(imp.module);
+          section.emit_string(imp.name || '');
+        }
+      });
     }
 
     // Add functions declarations
-    var names = false;
-    var exports = 0;
+    let has_names = false;
+    let names = false;
+    let exports = 0;
     if (wasm.functions.length > 0) {
-        var has_names = false;
-
-        // emit function signatures
-        if (debug) print("emitting function sigs @ " + bytes.length);
-        emit_section(bytes, kDeclFunctionSignatures, function(bytes) {
-            emit_varint(bytes, wasm.functions.length);
-            for (func of wasm.functions) {
-              has_names = has_names || (func.name != undefined &&
-                                        func.name.length > 0);
-              exports += func.exports.length;
-
-              emit_varint(bytes, func.sig_index);
-            }
-        });
-
-    }
-
-    // Add function table.
-    if (wasm.function_table.length > 0) {
-        if (debug) print("emitting function table @ " + bytes.length);
-        emit_section(bytes, kDeclFunctionTable, function(bytes) {
-            emit_varint(bytes, wasm.function_table.length);
-            for (index of wasm.function_table) {
-                emit_varint(bytes, index);
-            }
-        });
+      if (debug) print("emitting function decls @ " + binary.length);
+      binary.emit_section(kDeclFunctions, section => {
+        section.emit_varint(wasm.functions.length);
+        for (let func of wasm.functions) {
+          has_names = has_names || (func.name != undefined &&
+                                   func.name.length > 0);
+          exports += func.exports.length;
+          section.emit_varint(func.type_index);
+        }
+      });
+    }
+
+    // Add table.
+    if (wasm.table.length > 0) {
+      if (debug) print("emitting table @ " + binary.length);
+      binary.emit_section(kDeclTable, section => {
+        section.emit_varint(wasm.table.length);
+        for (let index of wasm.table) {
+          section.emit_varint(index);
+        }
+      });
     }
 
     // Add memory section
     if (wasm.memory != undefined) {
-        if (debug) print("emitting memory @ " + bytes.length);
-        emit_section(bytes, kDeclMemory, function(bytes) {
-            emit_varint(bytes, wasm.memory.min);
-            emit_varint(bytes, wasm.memory.max);
-            emit_u8(bytes, wasm.memory.exp ? 1 : 0);
-        });
+      if (debug) print("emitting memory @ " + binary.length);
+      binary.emit_section(kDeclMemory, section => {
+        section.emit_varint(wasm.memory.min);
+        section.emit_varint(wasm.memory.max);
+        section.emit_u8(wasm.memory.exp ? 1 : 0);
+      });
     }
 
 
     // Add export table.
     if (exports > 0) {
-        if (debug) print("emitting exports @ " + bytes.length);
-        emit_section(bytes, kDeclExportTable, function(bytes) {
-            emit_varint(bytes, exports);
-            for (func of wasm.functions) {
-                for (exp of func.exports) {
-                    emit_varint(bytes, func.index);
-                    emit_string(bytes, exp);
-                }
-            }
-        });
+      if (debug) print("emitting exports @ " + binary.length);
+      binary.emit_section(kDeclExports, section => {
+        section.emit_varint(exports);
+        for (let func of wasm.functions) {
+          for (let exp of func.exports) {
+            section.emit_varint(func.index);
+            section.emit_string(exp);
+          }
+        }
+      });
     }
 
     // Add start function section.
     if (wasm.start_index != undefined) {
-        if (debug) print("emitting start function @ " + bytes.length);
-        emit_section(bytes, kDeclStartFunction, function(bytes) {
-            emit_varint(bytes, wasm.start_index);
-        });
+      if (debug) print("emitting start function @ " + binary.length);
+      binary.emit_section(kDeclStart, section => {
+        section.emit_varint(wasm.start_index);
+      });
     }
 
     // Add function bodies.
     if (wasm.functions.length > 0) {
-        // emit function bodies
-        if (debug) print("emitting function bodies @ " + bytes.length);
-        emit_section(bytes, kDeclFunctionBodies, function(bytes) {
-            emit_varint(bytes, wasm.functions.length);
-            for (func of wasm.functions) {
-                // Function body length will be patched later.
-                var local_decls = [];
-                var l = func.locals;
-                if (l != undefined) {
-                  var local_decls_count = 0;
-                  if (l.i32_count > 0) {
-                    local_decls.push({count: l.i32_count, type: kAstI32});
-                  }
-                  if (l.i64_count > 0) {
-                    local_decls.push({count: l.i64_count, type: kAstI64});
-                  }
-                  if (l.f32_count > 0) {
-                    local_decls.push({count: l.f32_count, type: kAstF32});
-                  }
-                  if (l.f64_count > 0) {
-                    local_decls.push({count: l.f64_count, type: kAstF64});
-                  }
-                }
-                var header = new Array();
-
-                emit_varint(header, local_decls.length);
-                for (decl of local_decls) {
-                  emit_varint(header, decl.count);
-                  emit_u8(header, decl.type);
-                }
-
-                emit_varint(bytes, header.length + func.body.length);
-                emit_bytes(bytes, header);
-                emit_bytes(bytes, func.body);
+      // emit function bodies
+      if (debug) print("emitting code @ " + binary.length);
+      binary.emit_section(kDeclCode, section => {
+        section.emit_varint(wasm.functions.length);
+        for (let func of wasm.functions) {
+          // Function body length will be patched later.
+          let local_decls = [];
+          let l = func.locals;
+          if (l != undefined) {
+            let local_decls_count = 0;
+            if (l.i32_count > 0) {
+              local_decls.push({count: l.i32_count, type: kAstI32});
             }
-        });
+            if (l.i64_count > 0) {
+              local_decls.push({count: l.i64_count, type: kAstI64});
+            }
+            if (l.f32_count > 0) {
+              local_decls.push({count: l.f32_count, type: kAstF32});
+            }
+            if (l.f64_count > 0) {
+              local_decls.push({count: l.f64_count, type: kAstF64});
+            }
+          }
+
+          let header = new Binary;
+          header.emit_varint(local_decls.length);
+          for (let decl of local_decls) {
+            header.emit_varint(decl.count);
+            header.emit_u8(decl.type);
+          }
+
+          section.emit_varint(header.length + func.body.length);
+          section.emit_bytes(header);
+          section.emit_bytes(func.body);
+        }
+      });
     }
 
     // Add data segments.
-    if (wasm.data_segments.length > 0) {
-        if (debug) print("emitting data segments @ " + bytes.length);
-        emit_section(bytes, kDeclDataSegments, function(bytes) {
-            emit_varint(bytes, wasm.data_segments.length);
-            for (seg of wasm.data_segments) {
-                emit_varint(bytes, seg.addr);
-                emit_varint(bytes, seg.data.length);
-                emit_bytes(bytes, seg.data);
-            }
-        });
+    if (wasm.segments.length > 0) {
+      if (debug) print("emitting data segments @ " + binary.length);
+      binary.emit_section(kDeclData, section => {
+        section.emit_varint(wasm.segments.length);
+        for (let seg of wasm.segments) {
+          section.emit_varint(seg.addr);
+          section.emit_varint(seg.data.length);
+          section.emit_bytes(seg.data);
+        }
+      });
     }
 
     // Add any explicitly added sections
-    for (exp of wasm.explicit) {
-        if (debug) print("emitting explicit @ " + bytes.length);
-        emit_bytes(bytes, exp);
+    for (let exp of wasm.explicit) {
+      if (debug) print("emitting explicit @ " + binary.length);
+      binary.emit_bytes(exp);
     }
 
     // Add function names.
     if (has_names) {
-        if (debug) print("emitting names @ " + bytes.length);
-        emit_section(bytes, kDeclNames, function(bytes) {
-            emit_varint(bytes, wasm.functions.length);
-            for (func of wasm.functions) {
-                var name = func.name == undefined ? "" : func.name;
-                emit_string(bytes, name);
-                emit_u8(bytes, 0);  // local names count == 0
-            }
-        });
-    }
-
-    // End the module.
-    if (debug) print("emitting end @ " + bytes.length);
-    emit_section(bytes, kDeclEnd, function(bytes) {});
-
-    return bytes;
+      if (debug) print("emitting names @ " + binary.length);
+      binary.emit_section(kDeclNames, section => {
+        section.emit_varint(wasm.functions.length);
+        for (let func of wasm.functions) {
+          var name = func.name == undefined ? "" : func.name;
+          section.emit_string(name);
+          section.emit_u8(0);  // local names count == 0
+        }
+      });
+    }
+
+    return binary;
+  }
+
+  toBuffer(debug) {
+    let bytes = this.toArray(debug);
+    let buffer = new ArrayBuffer(bytes.length);
+    let view = new Uint8Array(buffer);
+    for (let i = 0; i < bytes.length; i++) {
+      let val = bytes[i];
+      if ((typeof val) == "string") val = val.charCodeAt(0);
+      view[i] = val | 0;
+    }
+    return buffer;
+  }
+
+  instantiate(...args) {
+    let module = new WebAssembly.Module(this.toBuffer());
+    let instance = new WebAssembly.Instance(module, ...args);
+    return instance;
+  }
 }
-
-WasmModuleBuilder.prototype.toBuffer = function(debug) {
-    var bytes = this.toArray(debug);
-    var buffer = new ArrayBuffer(bytes.length);
-    var view = new Uint8Array(buffer);
-    for (var i = 0; i < bytes.length; i++) {
-        var val = bytes[i];
-        if ((typeof val) == "string") val = val.charCodeAt(0);
-        view[i] = val | 0;
-    }
-    return buffer;
-}
-
-WasmModuleBuilder.prototype.instantiate = function(...args) {
-  var module = new WebAssembly.Module(this.toBuffer());
-  var instance = new WebAssembly.Instance(module, ...args);
-  return instance;
-}