[wasm] Add inspector test for stepping

This also fixes bugs found by the new test. It only tests stepping
inside of wasm code. Wasm to JS and vice versa will follow in another
CL.

R=yangguo@chromium.org, titzer@chromium.org, kozyatinskiy@chromium.org
BUG=v8:5822

Review-Url: https://codereview.chromium.org/2651043004
Cr-Commit-Position: refs/heads/master@{#42729}

src/wasm/wasm-debug.cc

@@ -165,7 +165,7 @@ class InterpreterHandle {
         return thread->Step();
       case StepOut:
         thread->AddBreakFlags(WasmInterpreter::BreakFlag::AfterReturn);
-        return thread->Step();
+        return thread->Run();
       case StepNext: {
         int stack_depth = thread->GetFrameCount();
         if (stack_depth == last_step_stack_depth_) return thread->Step();

src/wasm/wasm-interpreter.cc

@@ -1203,13 +1203,11 @@ class ThreadImpl {
           // skip breakpoint by switching on original code.
           skip = "[skip]  ";
         } else {
-          state_ = WasmInterpreter::PAUSED;
           TRACE("@%-3zu: [break] %-24s:", pc,
                 WasmOpcodes::OpcodeName(static_cast<WasmOpcode>(orig)));
           TraceValueStack();
           TRACE("\n");
-          break_pc_ = pc;
-          return CommitPc(pc);
+          break;
         }
       }
 
@@ -1638,6 +1636,9 @@ class ThreadImpl {
 
       pc += len;
     }
+    // Set break_pc_, even though we might have stopped because max was reached.
+    // We don't want to stop after executing zero instructions next time.
+    break_pc_ = pc;
     state_ = WasmInterpreter::PAUSED;
     CommitPc(pc);
   }

test/inspector/debugger/wasm-stepping-expected.txt

@@ -0,0 +1,83 @@
+Installing code an global variable.
+Calling instantiate function.
+Waiting for two wasm scripts to be parsed.
+Ignoring script with url v8://test/callInstantiate
+Got wasm script: wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-0
+Requesting source for wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-0...
+Got wasm script: wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1
+Requesting source for wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1...
+func $wasm_A
+  nop
+  nop
+end
+
+func $wasm_B (param i32)
+  loop
+    get_local 0
+    if
+      get_local 0
+      i32.const 1
+      i32.sub
+      set_local 0
+      call 0
+      br 1
+    end
+  end
+end
+
+Setting breakpoint on line 7 (on the setlocal before the call), url wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1
+{
+    columnNumber : 6
+    lineNumber : 7
+    scriptId : <scriptId>
+}
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:7:6:       >set_local 0
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:8:6:       >call 0
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-0:1:2:   >nop
+Step action: stepOver
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-0:2:2:   >nop
+Step action: stepOut
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:9:6:       >br 1
+Step action: stepOut
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:7:6:       >set_local 0
+Step action: stepOver
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:8:6:       >call 0
+Step action: stepOver
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:9:6:       >br 1
+Step action: resume
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:7:6:       >set_local 0
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:8:6:       >call 0
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-0:1:2:   >nop
+Step action: stepOut
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:9:6:       >br 1
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:1:2:   >loop
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:2:4:     >get_local 0
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:3:4:     >if
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:4:6:       >get_local 0
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:5:6:       >i32.const 1
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:6:6:       >i32.sub
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:7:6:       >set_local 0
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-1:8:6:       >call 0
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-0:1:2:   >nop
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-0:2:2:   >nop
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-0:3:0: >end
+Step action: stepInto
+Paused at wasm://wasm/wasm-ccfaf3fa/wasm-ccfaf3fa-0:0:0: >func $wasm_A
+Step action: resume
+exports.main returned!
+Finished!

test/inspector/debugger/wasm-stepping.js

@@ -0,0 +1,160 @@
+// 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.
+
+load('test/mjsunit/wasm/wasm-constants.js');
+load('test/mjsunit/wasm/wasm-module-builder.js');
+
+var builder = new WasmModuleBuilder();
+
+var func_a_idx =
+    builder.addFunction('wasm_A', kSig_v_v).addBody([kExprNop, kExprNop]).index;
+
+// wasm_B calls wasm_A <param0> times.
+builder.addFunction('wasm_B', kSig_v_i)
+    .addBody([
+      // clang-format off
+      kExprLoop, kWasmStmt,               // while
+        kExprGetLocal, 0,                 // -
+        kExprIf, kWasmStmt,               // if <param0> != 0
+          kExprGetLocal, 0,               // -
+          kExprI32Const, 1,               // -
+          kExprI32Sub,                    // -
+          kExprSetLocal, 0,               // decrease <param0>
+          kExprCallFunction, func_a_idx,  // -
+          kExprBr, 1,                     // continue
+          kExprEnd,                       // -
+        kExprEnd,                         // break
+      // clang-format on
+    ])
+    .exportAs('main');
+
+var module_bytes = builder.toArray();
+
+function instantiate(bytes) {
+  var buffer = new ArrayBuffer(bytes.length);
+  var view = new Uint8Array(buffer);
+  for (var i = 0; i < bytes.length; ++i) {
+    view[i] = bytes[i] | 0;
+  }
+
+  var module = new WebAssembly.Module(buffer);
+  // Set global variable.
+  instance = new WebAssembly.Instance(module);
+}
+
+var evalWithUrl = (code, url) => Protocol.Runtime.evaluate(
+    {'expression': code + '\n//# sourceURL=v8://test/' + url});
+
+Protocol.Debugger.onPaused(handlePaused);
+var wasm_B_scriptId;
+var step_actions = [
+  'stepInto',  // == stepOver, to call instruction
+  'stepInto',  // into call to wasm_A
+  'stepOver',  // over first nop
+  'stepOut',   // out of wasm_A
+  'stepOut',   // out of wasm_B, stop on breakpoint again
+  'stepOver',  // to call
+  'stepOver',  // over call
+  'resume',    // to next breakpoint (third iteration)
+  'stepInto',  // to call
+  'stepInto',  // into wasm_A
+  'stepOut',   // out to wasm_B
+  // now step 9 times, until we are in wasm_A again.
+  'stepInto', 'stepInto', 'stepInto', 'stepInto', 'stepInto', 'stepInto',
+  'stepInto', 'stepInto', 'stepInto',
+  // 3 more times, back to wasm_B.
+  'stepInto', 'stepInto', 'stepInto',
+  // then just resume.
+  'resume'
+];
+var sources = {};
+var urls = {};
+var afterTwoSourcesCallback;
+
+Protocol.Debugger.enable()
+    .then(() => InspectorTest.log('Installing code an global variable.'))
+    .then(
+        () => evalWithUrl('var instance;\n' + instantiate.toString(), 'setup'))
+    .then(() => InspectorTest.log('Calling instantiate function.'))
+    .then(
+        () =>
+            (evalWithUrl(
+                 'instantiate(' + JSON.stringify(module_bytes) + ')',
+                 'callInstantiate'),
+             0))
+    .then(waitForTwoWasmScripts)
+    .then(
+        () => InspectorTest.log(
+            'Setting breakpoint on line 7 (on the setlocal before the call), url ' +
+            urls[wasm_B_scriptId]))
+    .then(
+        () => Protocol.Debugger.setBreakpoint(
+            {'location': {'scriptId': wasm_B_scriptId, 'lineNumber': 7}}))
+    .then(printFailure)
+    .then(msg => InspectorTest.logMessage(msg.result.actualLocation))
+    .then(() => evalWithUrl('instance.exports.main(4)', 'runWasm'))
+    .then(() => InspectorTest.log('exports.main returned!'))
+    .then(() => InspectorTest.log('Finished!'))
+    .then(InspectorTest.completeTest);
+
+function printFailure(message) {
+  if (!message.result) {
+    InspectorTest.logMessage(message);
+  }
+  return message;
+}
+
+function waitForTwoWasmScripts() {
+  var num = 0;
+  InspectorTest.log('Waiting for two wasm scripts to be parsed.');
+  var promise = new Promise(fulfill => gotBothSources = fulfill);
+  function waitForMore() {
+    if (num == 2) return promise;
+    Protocol.Debugger.onceScriptParsed()
+        .then(handleNewScript)
+        .then(waitForMore);
+  }
+  function handleNewScript(msg) {
+    var url = msg.params.url;
+    if (!url.startsWith('wasm://')) {
+      InspectorTest.log('Ignoring script with url ' + url);
+      return;
+    }
+    num += 1;
+    var scriptId = msg.params.scriptId;
+    urls[scriptId] = url;
+    InspectorTest.log('Got wasm script: ' + url);
+    if (url.substr(-2) == '-1') wasm_B_scriptId = scriptId;
+    InspectorTest.log('Requesting source for ' + url + '...');
+    Protocol.Debugger.getScriptSource({scriptId: scriptId})
+        .then(printFailure)
+        .then(msg => sources[scriptId] = msg.result.scriptSource)
+        .then(InspectorTest.log)
+        .then(() => Object.keys(sources).length == 2 ? gotBothSources() : 0);
+  }
+  waitForMore();
+  return promise;
+}
+
+function printPauseLocation(scriptId, lineNr, columnNr) {
+  var lines = sources[scriptId].split('\n');
+  var line = '<illegal line number>';
+  if (lineNr < lines.length) {
+    line = lines[lineNr];
+    if (columnNr < line.length) {
+      line = line.substr(0, columnNr) + '>' + line.substr(columnNr);
+    }
+  }
+  InspectorTest.log(
+      'Paused at ' + urls[scriptId] + ':' + lineNr + ':' + columnNr + ': ' +
+      line);
+}
+
+function handlePaused(msg) {
+  var loc = msg.params.callFrames[0].location;
+  printPauseLocation(loc.scriptId, loc.lineNumber, loc.columnNumber);
+  var action = step_actions.shift();
+  InspectorTest.log('Step action: ' + action);
+  Protocol.Debugger[action]();
+}

test/inspector/protocol-test.js

@@ -20,7 +20,8 @@ Protocol = new Proxy({}, {
           var eventName = match[2];
           eventName = eventName.charAt(0).toLowerCase() + eventName.slice(1);
           if (match[1])
-            return (args) => InspectorTest._waitForEventPromise(`${agentName}.${eventName}`, args || {});
+            return () => InspectorTest._waitForEventPromise(
+                       `${agentName}.${eventName}`);
           else
             return (listener) => { InspectorTest._eventHandler[`${agentName}.${eventName}`] = listener };
         }