Optionally export metadata with libv8 to enable debuggers to inspect V8 state.

tools/gen-postmortem-metadata.py

Index: tools/gen-postmortem-metadata.py
===================================================================
--- tools/gen-postmortem-metadata.py	(revision 0)
+++ tools/gen-postmortem-metadata.py	(revision 0)
@@ -0,0 +1,478 @@
+#!/usr/bin/env python
+
+#
+# Copyright 2012 the V8 project authors. All rights reserved.
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+#       copyright notice, this list of conditions and the following
+#       disclaimer in the documentation and/or other materials provided
+#       with the distribution.
+#     * Neither the name of Google Inc. nor the names of its
+#       contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+
+#
+# Emits a C++ file to be compiled and linked into libv8 to support postmortem
+# debugging tools.  Most importantly, this tool emits constants describing V8
+# internals:
+#
+#    v8dbg_type_CLASS__TYPE = VALUE             Describes class type values
+#    v8dbg_class_CLASS__FIELD__TYPE = OFFSET    Describes class fields
+#    v8dbg_parent_CLASS__PARENT                 Describes class hierarchy
+#    v8dbg_frametype_NAME = VALUE               Describes stack frame values
+#    v8dbg_off_fp_NAME = OFFSET                 Frame pointer offsets
+#    v8dbg_prop_NAME = OFFSET                   Object property offsets
+#    v8dbg_NAME = VALUE                         Miscellaneous values
+#
+# These constants are declared as global integers so that they'll be present in
+# the generated libv8 binary.
+#
+
+import re
+import sys
+
+#
+# Miscellaneous constants, tags, and masks used for object identification.
+#
+consts_misc = [
+    { 'name': 'FirstNonstringType',     'value': 'FIRST_NONSTRING_TYPE' },
+
+    { 'name': 'IsNotStringMask',        'value': 'kIsNotStringMask' },
+    { 'name': 'StringTag',              'value': 'kStringTag' },
+    { 'name': 'NotStringTag',           'value': 'kNotStringTag' },
+
+    { 'name': 'StringEncodingMask',     'value': 'kStringEncodingMask' },
+    { 'name': 'TwoByteStringTag',       'value': 'kTwoByteStringTag' },
+    { 'name': 'AsciiStringTag',         'value': 'kAsciiStringTag' },
+
+    { 'name': 'StringRepresentationMask',
+        'value': 'kStringRepresentationMask' },
+    { 'name': 'SeqStringTag',           'value': 'kSeqStringTag' },
+    { 'name': 'ConsStringTag',          'value': 'kConsStringTag' },
+    { 'name': 'ExternalStringTag',      'value': 'kExternalStringTag' },
+
+    { 'name': 'FailureTag',             'value': 'kFailureTag' },
+    { 'name': 'FailureTagMask',         'value': 'kFailureTagMask' },
+    { 'name': 'HeapObjectTag',          'value': 'kHeapObjectTag' },
+    { 'name': 'HeapObjectTagMask',      'value': 'kHeapObjectTagMask' },
+    { 'name': 'SmiTag',                 'value': 'kSmiTag' },
+    { 'name': 'SmiTagMask',             'value': 'kSmiTagMask' },
+    { 'name': 'SmiValueShift',          'value': 'kSmiTagSize' },
+    { 'name': 'PointerSizeLog2',        'value': 'kPointerSizeLog2' },
+
+    { 'name': 'prop_idx_content',
+        'value': 'DescriptorArray::kContentArrayIndex' },
+    { 'name': 'prop_idx_first',
+        'value': 'DescriptorArray::kFirstIndex' },
+    { 'name': 'prop_type_field',
+        'value': 'FIELD' },
+    { 'name': 'prop_type_first_phantom',
+        'value': 'MAP_TRANSITION' },
+    { 'name': 'prop_type_mask',
+        'value': 'PropertyDetails::TypeField::kMask' },
+
+    { 'name': 'off_fp_context',
+        'value': 'StandardFrameConstants::kContextOffset' },
+    { 'name': 'off_fp_marker',
+        'value': 'StandardFrameConstants::kMarkerOffset' },
+    { 'name': 'off_fp_function',
+        'value': 'JavaScriptFrameConstants::kFunctionOffset' },
+    { 'name': 'off_fp_args',
+        'value': 'JavaScriptFrameConstants::kLastParameterOffset' },
+];
+
+#
+# The following useful fields are missing accessors, so we define fake ones.
+#
+extras_accessors = [
+    'HeapObject, map, Map, kMapOffset',
+    'JSObject, elements, Object, kElementsOffset',
+    'FixedArray, data, uintptr_t, kHeaderSize',
+    'Map, instance_attributes, int, kInstanceAttributesOffset',
+    'Map, instance_descriptors, int, kInstanceDescriptorsOrBitField3Offset',
+    'Map, inobject_properties, int, kInObjectPropertiesOffset',
+    'Map, instance_size, int, kInstanceSizeOffset',
+    'HeapNumber, value, double, kValueOffset',
+    'ConsString, first, String, kFirstOffset',
+    'ConsString, second, String, kSecondOffset',
+    'ExternalString, resource, Object, kResourceOffset',
+    'SeqAsciiString, chars, char, kHeaderSize',
+];
+
+#
+# The following is a whitelist of classes we expect to find when scanning the
+# source code. This list is not exhaustive, but it's still useful to identify
+# when this script gets out of sync with the source. See load_objects().
+#
+expected_classes = [
+    'ConsString', 'FixedArray', 'HeapNumber', 'JSArray', 'JSFunction',
+    'JSObject', 'JSRegExp', 'JSValue', 'Map', 'Oddball', 'Script',
+    'SeqAsciiString', 'SharedFunctionInfo'
+];
+
+
+#
+# The following structures store high-level representations of the structures
+# for which we're going to emit descriptive constants.
+#
+types = {};             # set of all type names
+typeclasses = {};       # maps type names to corresponding class names
+klasses = {};           # known classes, including parents
+fields = [];            # field declarations
+
+header = '''
+/*
+ * This file is generated by %s.  Do not edit directly.
+ */
+
+#include "v8.h"
+#include "frames.h"
+#include "frames-inl.h" /* for architecture-specific frame constants */
+
+using namespace v8::internal;
+
+extern "C" {
+
+/* stack frame constants */
+#define FRAME_CONST(value, klass)       \
+    int v8dbg_frametype_##klass = StackFrame::value;
+
+STACK_FRAME_TYPE_LIST(FRAME_CONST)
+
+#undef FRAME_CONST
+
+''' % sys.argv[0];
+
+footer = '''
+}
+'''
+
+#
+# Loads class hierarchy and type information from "objects.h".
+#
+def load_objects():
+        objfilename = sys.argv[2];
+        objfile = open(objfilename, 'r');
+        in_insttype = False;
+
+        typestr = '';
+
+        #
+        # Construct a dictionary for the classes we're sure should be present.
+        #
+        checktypes = {};
+        for klass in expected_classes:
+                checktypes[klass] = True;
+
+        #
+        # Iterate objects.h line-by-line to collect type and class information.
+        # For types, we accumulate a string representing the entire InstanceType
+        # enum definition and parse it later because it's easier to do so
+        # without the embedded newlines.
+        #
+        for line in objfile:
+                if (line.startswith('enum InstanceType {')):
+                        in_insttype = True;
+                        continue;
+
+                if (in_insttype and line.startswith('};')):
+                        in_insttype = False;
+                        continue;
+
+                line = re.sub('//.*', '', line.rstrip().lstrip());
+
+                if (in_insttype):
+                        typestr += line;
+                        continue;
+
+                match = re.match('class (\w[^\s:]*)(: public (\w[^\s{]*))?\s*{',
+                    line);
+
+                if (match):
+                        klass = match.group(1);
+                        pklass = match.group(3);
+                        klasses[klass] = { 'parent': pklass };
+
+        #
+        # Process the instance type declaration.
+        #
+        entries = typestr.split(',');
+        for entry in entries:
+                types[re.sub('\s*=.*', '', entry).lstrip()] = True;
+
+        #
+        # Infer class names for each type based on a systematic transformation.
+        # For example, "JS_FUNCTION_TYPE" becomes "JSFunction".  We find the
+        # class for each type rather than the other way around because there are
+        # fewer cases where one type maps to more than one class than the other
+        # way around.
+        #
+        for type in types:
+                #
+                # Symbols and Strings are implemented using the same classes.
+                #
+                usetype = re.sub('SYMBOL_', 'STRING_', type);
+
+                #
+                # REGEXP behaves like REG_EXP, as in JS_REGEXP_TYPE => JSRegExp.
+                #
+                usetype = re.sub('_REGEXP_', '_REG_EXP_', usetype);
+
+                #
+                # Remove the "_TYPE" suffix and then convert to camel case,
+                # except that a "JS" prefix remains uppercase (as in
+                # "JS_FUNCTION_TYPE" => "JSFunction").
+                #
+                if (not usetype.endswith('_TYPE')):
+                        continue;
+
+                usetype = usetype[0:len(usetype) - len('_TYPE')];
+                parts = usetype.split('_');
+                cctype = '';
+
+                if (parts[0] == 'JS'):
+                        cctype = 'JS';
+                        start = 1;
+                else:
+                        cctype = '';
+                        start = 0;
+
+                for ii in range(start, len(parts)):
+                        part = parts[ii];
+                        cctype += part[0].upper() + part[1:].lower();
+
+                #
+                # Mapping string types is more complicated.  Both types and
+                # class names for Strings specify a representation (e.g., Seq,
+                # Cons, External, or Sliced) and an encoding (TwoByte or Ascii),
+                # In the simplest case, both of these are explicit in both
+                # names, as in:
+                #
+                #       EXTERNAL_ASCII_STRING_TYPE => ExternalAsciiString
+                #
+                # However, either the representation or encoding can be omitted
+                # from the type name, in which case "Seq" and "TwoByte" are
+                # assumed, as in:
+                #
+                #       STRING_TYPE => SeqTwoByteString
+                #
+                # Additionally, sometimes the type name has more information
+                # than the class, as in:
+                #
+                #       CONS_ASCII_STRING_TYPE => ConsString
+                #
+                # To figure this out dynamically, we first check for a
+                # representation and encoding and add them if they're not
+                # present.  If that doesn't yield a valid class name, then we
+                # strip out the representation.
+                #
+                if (cctype.endswith('String')):
+                        if (cctype.find('Cons') == -1 and
+                            cctype.find('External') == -1 and
+                            cctype.find('Sliced') == -1):
+                                if (cctype.find('Ascii') != -1):
+                                        cctype = re.sub('AsciiString$',
+                                            'SeqAsciiString', cctype);
+                                else:
+                                        cctype = re.sub('String$',
+                                            'SeqString', cctype);
+
+                        if (cctype.find('Ascii') == -1):
+                                cctype = re.sub('String$', 'TwoByteString',
+                                    cctype);
+
+                        if (not (cctype in klasses)):
+                                cctype = re.sub('Ascii', '', cctype);
+                                cctype = re.sub('TwoByte', '', cctype);
+
+                #
+                # Despite all that, some types have no corresponding class.
+                #
+                if (cctype in klasses):
+                        typeclasses[type] = cctype;
+                        if (cctype in checktypes):
+                                del checktypes[cctype];
+
+        if (len(checktypes) > 0):
+                for klass in checktypes:
+                        print('error: expected class \"%s\" not found' % klass);
+
+                sys.exit(1);
+
+
+#
+# For a given macro call, pick apart the arguments and return an object
+# describing the corresponding output constant.  See load_fields().
+#
+def parse_field(call):
+        # Replace newlines with spaces.
+        for ii in range(0, len(call)):
+                if (call[ii] == '\n'):
+                        call[ii] == ' ';
+
+        idx = call.find('(');
+        kind = call[0:idx];
+        rest = call[idx + 1: len(call) - 1];
+        args = re.split('\s*,\s*', rest);
+
+        consts = [];
+
+        if (kind == 'ACCESSORS' or kind == 'ACCESSORS_GCSAFE'):
+                klass = args[0];
+                field = args[1];
+                dtype = args[2];
+                offset = args[3];
+
+                return ({
+                    'name': 'class_%s__%s__%s' % (klass, field, dtype),
+                    'value': '%s::%s' % (klass, offset)
+                });
+
+        assert(kind == 'SMI_ACCESSORS');
+        klass = args[0];
+        field = args[1];
+        offset = args[2];
+
+        return ({
+            'name': 'class_%s__%s__%s' % (klass, field, 'SMI'),
+            'value': '%s::%s' % (klass, offset)
+        });
+
+#
+# Load field offset information from objects-inl.h.
+#
+def load_fields():
+        inlfilename = sys.argv[3];
+        inlfile = open(inlfilename, 'r');
+
+        #
+        # Each class's fields and the corresponding offsets are described in the
+        # source by calls to macros like "ACCESSORS" (and friends).  All we do
+        # here is extract these macro invocations, taking into account that they
+        # may span multiple lines and may contain nested parentheses.  We also
+        # call parse_field() to pick apart the invocation.
+        #
+        prefixes = [ 'ACCESSORS', 'ACCESSORS_GCSAFE', 'SMI_ACCESSORS' ];
+        current = '';
+        opens = 0;
+
+        for line in inlfile:
+                if (opens > 0):
+                        # Continuation line
+                        for ii in range(0, len(line)):
+                                if (line[ii] == '('):
+                                        opens += 1;
+                                elif (line[ii] == ')'):
+                                        opens -= 1;
+
+                                if (opens == 0):
+                                        break;
+
+                        current += line[0:ii + 1];
+                        continue;
+
+                for prefix in prefixes:
+                        if (not line.startswith(prefix + '(')):
+                                continue;
+
+                        if (len(current) > 0):
+                                fields.append(parse_field(current));
+                                current = '';
+
+                        for ii in range(len(prefix), len(line)):
+                                if (line[ii] == '('):
+                                        opens += 1;
+                                elif (line[ii] == ')'):
+                                        opens -= 1;
+
+                                if (opens == 0):
+                                        break;
+
+                        current += line[0:ii + 1];
+
+        if (len(current) > 0):
+                fields.append(parse_field(current));
+                current = '';
+
+        for body in extras_accessors:
+                fields.append(parse_field('ACCESSORS(%s)' % body));
+
+#
+# Emit a block of constants.
+#
+def emit_set(out, consts):
+        for ii in range(0, len(consts)):
+                out.write('int v8dbg_%s = %s;\n' %
+                    (consts[ii]['name'], consts[ii]['value']));
+        out.write('\n');
+
+#
+# Emit the whole output file.
+#
+def emit_config():
+        out = file(sys.argv[1], 'w');
+
+        out.write(header);
+
+        out.write('/* miscellaneous constants */\n');
+        emit_set(out, consts_misc);
+
+        out.write('/* class type information */\n');
+        consts = [];
+        keys = typeclasses.keys();
+        keys.sort();
+        for typename in keys:
+                klass = typeclasses[typename];
+                consts.append({
+                    'name': 'type_%s__%s' % (klass, typename),
+                    'value': typename
+                });
+
+        emit_set(out, consts);
+
+        out.write('/* class hierarchy information */\n');
+        consts = [];
+        keys = klasses.keys();
+        keys.sort();
+        for klassname in keys:
+                pklass = klasses[klassname]['parent'];
+                if (pklass == None):
+                        continue;
+
+                consts.append({
+                    'name': 'parent_%s__%s' % (klassname, pklass),
+                    'value': 0
+                });
+
+        emit_set(out, consts);
+
+        out.write('/* field information */\n');
+        emit_set(out, fields);
+
+        out.write(footer);
+
+if (len(sys.argv) < 4):
+        print('usage: %s output.cc objects.h objects-inl.h' % sys.argv[0]);
+        sys.exit(2);
+
+load_objects();
+load_fields();
+emit_config();