[wasm] Disassemble wasm code from script

test/mjsunit/wasm/debug-disassembly.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.
+
+// Flags: --expose-wasm --expose-debug-as debug
+
+load("test/mjsunit/wasm/wasm-constants.js");
+load("test/mjsunit/wasm/wasm-module-builder.js");
+
+Debug = debug.Debug
+
+// Initialized in setup().
+var exception;
+var break_count;
+var num_wasm_scripts;
+var module;
+
+function listener(event, exec_state, event_data, data) {
+  try {
+    if (event == Debug.DebugEvent.Break) {
+      ++break_count;
+      // Request frame details. This should trigger creation of the Script
+      // objects for all frames on the stack.
+      var num_frames = exec_state.frameCount();
+      for (var i = 0; i < num_frames; ++i) {
+        var frame = exec_state.frame(i);
+        var details = frame.details();
+        var script = details.script();
+        if (script.type == Debug.ScriptType.Wasm) {
+          var pos = frame.sourcePosition();
+          var name = script.nameOrSourceURL();
+          var disassembly = Debug.disassembleWasmFunction(script.id);
+          var offset_table = Debug.getWasmFunctionOffsetTable(script.id);
+          assertEquals(0, offset_table.length % 3);
+          var lineNr = null;
+          var columnNr = null;
+          for (var p = 0; p < offset_table.length; p += 3) {
+            if (offset_table[p] != pos) continue;
+            lineNr = offset_table[p+1];
+            columnNr = offset_table[p+2];
+          }
+          assertNotNull(lineNr, "position should occur in offset table");
+          assertNotNull(columnNr, "position should occur in offset table");
+          var line = disassembly.split("\n")[lineNr];
+          assertTrue(!!line, "line number must occur in disassembly");
+          assertTrue(line.length > columnNr, "column number must be valid");
+          var expected_string;
+          if (name.endsWith("/0")) {

[ahaas, 2016/06/17 06:57:50]

What's the idea behind this condition? Can you add a comment when name ends with
"/0"?

[Clemens Hammacher, 2016/06/17 18:01:55]

Done.

+            expected_string = "kExprCallImport,";
+          } else if (name.endsWith("/1")) {
+            expected_string = "kExprCallFunction,";
+          } else {
+            assertTrue(false, "Unexpected wasm script: " + name);
+          }
+          assertTrue(line.substr(columnNr).startsWith(expected_string),
+              "offset " + columnNr + " should start with '" + expected_string
+              + "': " + line);
+        }
+      }
+    } else if (event == Debug.DebugEvent.AfterCompile) {
+      var script = event_data.script();
+      if (script.scriptType() == Debug.ScriptType.Wasm) {
+        ++num_wasm_scripts;
+      }
+    }
+  } catch (e) {
+    print("exception: " + e);
+    exception = e;
+  }
+};
+
+var builder = new WasmModuleBuilder();
+
+builder.addImport("func", kSig_v_v);
+
+builder.addFunction("call_import", kSig_v_v)
+  .addBody([kExprCallImport, kArity0, 0])
+  .exportFunc();
+
+// Add a bit of unneccessary code to increase the byte offset.
+builder.addFunction("call_call_import", kSig_v_v)
+  .addLocals({i32_count: 2})
+  .addBody([
+      kExprI32Const, 27, kExprSetLocal, 0,
+      kExprI32Const, (-7 & 0x7f), kExprSetLocal, 1,
+        kExprGetLocal, 0, kExprGetLocal, 1, kExprI32Add, kExprI64UConvertI32,
+        kExprI64Const, 0,
+      kExprI64Ne, kExprIf,
+        kExprCallFunction, kArity0, 0,
+      kExprEnd
+  ])
+  .exportFunc();
+
+function call_debugger() {
+  debugger;
+}
+
+function setup() {
+  module = builder.instantiate({func: call_debugger});
+  exception = null;
+  break_count = 0;
+  num_wasm_scripts = 0;
+}
+
+(function testRegisteredWasmScripts1() {
+  setup();
+  Debug.setListener(listener);
+  // Initially 0 scripts.
+  assertEquals(0, num_wasm_scripts);
+  // Call the "call_import" function -> 1 script.
+  module.exports.call_import();
+  assertEquals(1, num_wasm_scripts);
+  // Call "call_import" again -> still just 1 script.
+  module.exports.call_import();
+  assertEquals(1, num_wasm_scripts);
+  // Call "call_call_import" -> now 2 scripts.
+  module.exports.call_call_import();
+  assertEquals(2, num_wasm_scripts);
+  Debug.setListener(null);
+
+  assertEquals(3, break_count);
+  if (exception) throw exception;
+})();
+
+(function testRegisteredWasmScripts2() {
+  setup();
+  Debug.setListener(listener);
+  // Initially 0 scripts.
+  assertEquals(0, num_wasm_scripts);
+  // Call the "call_call_import" function -> 2 scripts should be registered.
+  module.exports.call_call_import();
+  assertEquals(2, num_wasm_scripts);
+  Debug.setListener(null);
+
+  assertEquals(1, break_count);
+  if (exception) throw exception;
+})();