[wasm] Fix WasmMemoryObject constructor for when a module has no initial memory

test/mjsunit/regress/wasm/regression-727560.js

Index: test/mjsunit/regress/wasm/regression-727560.js
diff --git a/test/mjsunit/regress/wasm/regression-727560.js b/test/mjsunit/regress/wasm/regression-727560.js
new file mode 100644
index 0000000000000000000000000000000000000000..b44c210e05b28b4959d4a77c4e823de0aa72c0a3
--- /dev/null
+++ b/test/mjsunit/regress/wasm/regression-727560.js
@@ -0,0 +1,143 @@
+// Copyright 2017 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.
+
+class Binary extends Array {

[Clemens Hammacher, 2017/05/31 07:56:37]

Please reduce this test case to also use wasm-module-builder.js.

[gdeepti, 2017/06/01 07:01:37]

Done.

+  emit_u8(val) {
+    this.push(val);
+  }
+  emit_u32v(val) {
+    while (true) {
+      let v = val & 0xff;
+        this.push(v);
+        break;
+    }
+  }
+  emit_bytes() {
+  }
+  emit_string(string) {
+    let string_utf8 = unescape(string);
+    this.emit_u32v(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) {
+    this.emit_u8(section_code);
+    let section = new Binary;
+    content_generator(section);
+    this.emit_u32v(section.length);
+    this.push(...section);
+  }
+}
+class WasmFunctionBuilder {
+  constructor() {
+  }
+}
+class WasmModuleBuilder {
+  constructor() {
+    this.imports = [];
+    this.exports = [];
+  }
+  addMemory(min, max, exp) {
+    this.memory = {};
+  }
+  addFunction() {
+  }
+  addImportedGlobal() {
+    let o = {
+             mutable: false}
+  }
+  addImportedMemory(module = "", name, maximum) {
+    let o = {module: module, name: name, kind: kExternalMemory,
+             maximum: maximum};
+    this.imports.push(o);
+  }
+  exportMemoryAs(name) {
+    this.exports.push({name: name, kind: kExternalMemory});
+  }
+  toArray() {
+    let binary = new Binary;
+    let wasm = this;
+    binary.emit_header();
+ section => {
+      };
+      binary.emit_section(kImportSectionCode, section => {
+        section.emit_u32v(wasm.imports.length);
+        for (let imp of wasm.imports) {
+          section.emit_string(imp.module);
+          section.emit_string(imp.name || '');
+          section.emit_u8(imp.kind);
+            section.emit_u8(); // flags
+            section.emit_u32v(); // initial
+        }
+      });
+    if (wasm.memory !== undefined) {
+      binary.emit_section(kMemorySectionCode, section => {
+        section.emit_u32v(kResizableMaximumFlag);
+        section.emit_u32v();
+        section.emit_u32v();
+      });
+ section => {
+            switch (global.type) {
+            }
+      };
+    }
+    var mem_export = (wasm.memory !== undefined && wasm.memory.exp);
+    var exports_count = wasm.exports.length + (mem_export ? 1 : 0);
+      binary.emit_section(kExportSectionCode, section => {
+        section.emit_u32v(exports_count);
+        for (let exp of wasm.exports) {
+          section.emit_string(exp.name);
+          section.emit_u8(exp.kind);
+          section.emit_u32v();
+        }
+      });
+    return binary;
+  }
+  toBuffer() {
+    let bytes = this.toArray();
+    let buffer = new ArrayBuffer(bytes.length);
+    let view = new Uint8Array(buffer);
+    for (let i = 0; i < bytes.length; i++) {
+      let val = bytes[i];
+      view[i] = val | 0;
+    }
+    return buffer;
+  }
+  instantiate(ffi) {
+    let module = new WebAssembly.Module(this.toBuffer());
+    let instance = new WebAssembly.Instance(module, ffi);
+    return instance;
+  }
+}
+var kWasmH0 = 0;
+var kWasmH1 = 0x61;
+var kWasmH2 = 0x73;
+var kWasmH3 = 0x6d;
+var kWasmV0 = 0x1;
+var kWasmV1 = 0;
+var kWasmV2 = 0;
+var kWasmV3 = 0;
+let kImportSectionCode = 2;    // Import declarations
+let kMemorySectionCode = 5;    // Memory attributes
+let kExportSectionCode = 7;    // Exports
+let kResizableMaximumFlag = 1;
+let kExternalMemory = 2;
+function makeSig(params, results) {
+}
+  {
+    let builder = new WasmModuleBuilder();
+    builder.addMemory();
+    builder.exportMemoryAs("exported_mem");
+    i1 = builder.instantiate();
+  }
+  {
+    let builder = new WasmModuleBuilder();
+    builder.addImportedMemory("fil", "imported_mem");
+    i2 = builder.instantiate({fil: {imported_mem: i1.exports.exported_mem}});
+  }