[wasm] prototype for breakpoint support.

test/mjsunit/wasm/debug-break.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_positions;
+var module;
+var scripts;
+var first;
+
+function listener(event, exec_state, event_data, data) {
+  try {
+    if (event == Debug.DebugEvent.Break) {
+      var num_frames = exec_state.frameCount();
+      assertTrue(num_frames > 0);
+      // Record the position in all wasm frames.
+      var wasm_positions = [];
+      for (var i = 0; i < num_frames; ++i) {
+        var frame = exec_state.frame(i);
+        var script = frame.details().script();
+        if (script.type != Debug.ScriptType.Wasm) continue;
+        var pos = frame.sourcePosition();
+        wasm_positions.push(pos);
+      }
+      print("break at wasm positions [" + wasm_positions+"]");
+      break_positions.push(wasm_positions);
+    } else if (event == Debug.DebugEvent.AfterCompile) {
+      var script = event_data.script();
+      if (script.scriptType() == Debug.ScriptType.Wasm) {
+        var name = script.name();
+        // Wasm script URLs end in /$func_index.
+        var func = parseInt(name.substr(name.lastIndexOf("/")+1));
+        scripts[func] = script;
+      }
+    }
+  } catch (e) {
+    print("exception: " + e);
+    exception = e;
+  }
+};
+
+var builder = new WasmModuleBuilder();
+
+builder.addImport("dbg", kSig_v_v);
+
+builder.addFunction("nop", makeSig([kAstI32], []))
+  .addBody([kExprNop, kExprNop, kExprNop,
+                              // offset 6
+            kExprGetLocal, 0, kExprIf,
+              // offset 7
+              kExprCallImport, kArity0, 0,
+            kExprEnd]);
+
+// First parameter determines the number of calls to nop(), the second one
+// determines whether the imported function should be called.
+builder.addFunction("call_nop", makeSig([kAstI32, kAstI32], []))
+  .addBody([
+      kExprLoop,
+        kExprI32Const, 0,
+        // offset 4
+        kExprGetLocal, 0,
+        kExprI32Ne, kExprIf,
+          kExprI32Const, (-1 & 0x7f), kExprGetLocal, 0, kExprI32Add, kExprSetLocal, 0,
+            // offset 15
+            kExprGetLocal, 1,
+          // offset 17
+          kExprCallFunction, kArity1, 0,
+          kExprBr, kArity0, 1,
+          kExprEnd,
+        kExprEnd,
+  ])
+  .exportAs("main");
+
+function dbg() {
+  if (first) debugger;
+  first = 0;
+}
+
+function setup() {
+  first = 1;
+  module = builder.instantiate({"dbg": dbg});
+  exception = null;
+  break_positions = [];
+  scripts = [];
+}
+
+// Test setting break points.
+// We set 1 or more breakpoints in 1 or more functions, and remove some or all
+// of them again.
+// One function is called from wasm, the other one as exported function via
+// JavaScript.
+(function testWasmBreakpoint() {
+  setup();
+  Debug.setListener(listener);
+
+  // Call the program with indirect call, should have one break with positions
+  // at the wasm call sites.
+  module.exports.main(1, 1);
+  assertArrayEquals([[7, 17]], break_positions);
+  // But both scripts should be there now.
+  assertEquals(2, scripts.length);
+  assertArrayEquals(["0", "1"], Object.keys(scripts));
+
+  // Set break point in "nop" function, offset 1.
+  print("set break point at position 1");
+  var break_1 = Debug.setBreakPointByScriptIdAndPosition(scripts[0].id(), 1, undefined, 1);
+  // Call the program again without indirect call -> now 1 break in the inner
+  // wasm function.
+  break_positions = [];
+  module.exports.main(1, 0);
+  assertArrayEquals([[1, 17]], break_positions);
+
+  // Set another break point in "nop" function, offset 6.
+  print("set break point at position 6");
+  var break_6 = Debug.setBreakPointByScriptIdAndPosition(scripts[0].id(), 6, undefined, 1);
+  // See if we hit both breakpoints.
+  break_positions = [];
+  module.exports.main(1, 0);
+  assertArrayEquals([[1, 17], [6, 17]], break_positions);
+
+  // Remove first break point, and add two in "call_nop", offsets 4 and 15.
+  print("disable break point at position 1");
+  break_1.disable();
+  print("set break point at position 4");
+  var break_4 = Debug.setBreakPointByScriptIdAndPosition(scripts[1].id(), 4, undefined, 1);
+  print("set break point at position 15");
+  var break_15 = Debug.setBreakPointByScriptIdAndPosition(scripts[1].id(), 15, undefined, 1);
+  // Now call the program to run two iterations of nop, and check the
+  // breakpoints.
+  break_positions = [];
+  module.exports.main(2, 0);
+  assertArrayEquals([[4], [15], [6, 17], [4], [15], [6, 17], [4]], break_positions);
+
+  // Remove all break points, check that no break is triggered.
+  print("disable break points at positions 6, 4 and 15");
+  break_6.disable();
+  break_4.disable();
+  break_15.disable();
+  break_positions = [];
+  module.exports.main(1, 0);
+  assertArrayEquals([], break_positions);
+
+  Debug.setListener(null);
+  if (exception) throw exception;
+})();