Added support to backtrace from botton of stack to debugger protocol.

Fixed backtrace in D8 debugger and added gdb like syntax 'bt n' and 'bt -n' in addition to the already existing 'bt from to'.
Review URL: http://codereview.chromium.org/99342

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1929 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/d8.js

@@ -498,9 +498,26 @@ DebugRequest.prototype.stepCommandToJSONRequest_ = function(args) {
 DebugRequest.prototype.backtraceCommandToJSONRequest_ = function(args) {
   // Build a backtrace request from the text command.
   var request = this.createRequest('backtrace');
+  
+  // Default is to show top 10 frames.
+  request.arguments = {};
+  request.arguments.fromFrame = 0;
+  request.arguments.toFrame = 10;
+
   args = args.split(/\s*[ ]+\s*/g);
-  if (args.length == 2) {
-    request.arguments = {};
+  if (args.length == 1 && args[0].length > 0) {
+    var frameCount = parseInt(args[0]);
+    if (frameCount > 0) {
+      // Show top frames.
+      request.arguments.fromFrame = 0;
+      request.arguments.toFrame = frameCount;
+    } else {
+      // Show bottom frames.
+      request.arguments.fromFrame = 0;
+      request.arguments.toFrame = -frameCount;
+      request.arguments.bottom = true;
+    }
+  } else if (args.length == 2) {
     var fromFrame = parseInt(args[0]);
     var toFrame = parseInt(args[1]);
     if (isNaN(fromFrame) || fromFrame < 0) {
@@ -513,9 +530,13 @@ DebugRequest.prototype.backtraceCommandToJSONRequest_ = function(args) {
       throw new Error('Invalid arguments start frame cannot be larger ' +
                       'than end frame.');
     }
+    // Show frame range.
     request.arguments.fromFrame = fromFrame;
     request.arguments.toFrame = toFrame + 1;
+  } else if (args.length > 2) {
+    throw new Error('Invalid backtrace arguments.');
   }
+
   return request.toJSONProtocol();
 };
 
@@ -755,7 +776,7 @@ DebugRequest.prototype.helpCommand_ = function(args) {
   print('  break on function: location is #<id>#');
   print('  break on script position: location is name:line[:column]');
   print('clear <breakpoint #>');
-  print('backtrace [from frame #] [to frame #]]');
+  print('backtrace [n] | [-n] | [from to]');
   print('frame <frame #>');
   print('step [in | next | out| min [step count]]');
   print('print <expression>');

src/debug-delay.js

@@ -1452,12 +1452,18 @@ DebugCommandProcessor.prototype.backtraceRequest_ = function(request, response)
 
   // Get the range from the arguments.
   if (request.arguments) {
-    from_index = request.arguments.fromFrame;
-    if (from_index < 0) {
-      return response.failed('Invalid frame number');
+    if (request.arguments.fromFrame) {
+      from_index = request.arguments.fromFrame;
     }
-    to_index = request.arguments.toFrame;
-    if (to_index < 0) {
+    if (request.arguments.toFrame) {
+      to_index = request.arguments.toFrame;
+    }
+    if (request.arguments.bottom) {
+      var tmp_index = total_frames - from_index;
+      from_index = total_frames - to_index
+      to_index = tmp_index;
+    }
+    if (from_index < 0 || to_index < 0) {
       return response.failed('Invalid frame number');
     }
   }

test/mjsunit/debug-backtrace.js

@@ -37,7 +37,7 @@ var m = function() {
 };
 
 function g() {
- m();
+  m();
 };
 
 
@@ -80,8 +80,9 @@ function listener(event, exec_state, event_data, data) {
   {
     // The expected backtrace is
     // 0: f
-    // 1: g
-    // 2: [anonymous]
+    // 1: m
+    // 2: g
+    // 3: [anonymous]
     
     var response;
     var backtrace;
@@ -133,6 +134,23 @@ function listener(event, exec_state, event_data, data) {
     assertEquals(2, frames[1].index);
     assertEquals("g", response.lookup(frames[1].func.ref).name);
 
+    // Get backtrace with bottom two frames.
+    json = '{"seq":0,"type":"request","command":"backtrace","arguments":{"fromFrame":0,"toFrame":2, "bottom":true}}'
+    response = new ParsedResponse(dcp.processDebugJSONRequest(json));
+    backtrace = response.body();
+    assertEquals(2, backtrace.fromFrame);
+    assertEquals(4, backtrace.toFrame);
+    assertEquals(4, backtrace.totalFrames);
+    var frames = backtrace.frames;
+    assertEquals(2, frames.length);
+    for (var i = 0; i < frames.length; i++) {
+      assertEquals('frame', frames[i].type);
+    }
+    assertEquals(2, frames[0].index);
+    assertEquals("g", response.lookup(frames[0].func.ref).name);
+    assertEquals(3, frames[1].index);
+    assertEquals("", response.lookup(frames[1].func.ref).name);
+
     // Get the individual frames.
     json = '{"seq":0,"type":"request","command":"frame"}'
     response = new ParsedResponse(dcp.processDebugJSONRequest(json));