Add a 'v8_optimized_debug' option to the build flags

build/common.gypi

 # 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
@@ skipping 59 matching lines @@
     'v8_enable_debugger_support%': 1,
 
     'v8_enable_backtrace%': 0,
 
     'v8_enable_disassembler%': 0,
 
     'v8_enable_gdbjit%': 0,
 
     'v8_object_print%': 0,
 
+    # Turns on compiler optimizations in Debug builds (#defines are unaffected).
+    'v8_optimized_debug%': 0,
+
     # Enable profiling support. Only required on Windows.
     'v8_enable_prof%': 0,
 
     'v8_enable_verify_heap%': 0,
 
     # Some versions of GCC 4.5 seem to need -fno-strict-aliasing.
     'v8_no_strict_aliasing%': 0,
 
     # Chrome needs this definition unconditionally. For standalone V8 builds,
     # it's handled in build/standalone.gypi.
@@ skipping 403 matching lines @@
         },
         'defines': [
           'DEBUG',
           'ENABLE_DISASSEMBLER',
           'V8_ENABLE_CHECKS',
           'OBJECT_PRINT',
           'VERIFY_HEAP',
         ],
         'msvs_settings': {
           'VCCLCompilerTool': {
-            'Optimization': '0',
 
             'conditions': [
               ['OS=="win" and component=="shared_library"', {
                 'RuntimeLibrary': '3',  # /MDd
               }, {
                 'RuntimeLibrary': '1',  # /MTd
               }],
+              ['v8_optimized_debug==1', {
+                'Optimization': '2',
+                'InlineFunctionExpansion': '2',
+                'EnableIntrinsicFunctions': 'true',
+                'FavorSizeOrSpeed': '0',
+                'StringPooling': 'true',
+                'BasicRuntimeChecks': '0',
+              }, {
+                'Optimization': '0',
+              }],
             ],
           },
           'VCLinkerTool': {
             'LinkIncremental': '2',
           },
         },
         'conditions': [
           ['v8_enable_extra_checks==1', {
             'defines': ['ENABLE_EXTRA_CHECKS',],
           }],
           ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="netbsd"', {
             'cflags': [ '-Wall', '<(werror)', '-W', '-Wno-unused-parameter',
                         '-Wnon-virtual-dtor', '-Woverloaded-virtual' ],
+            'conditions': [
+              ['v8_optimized_debug==1', {
+                'cflags!': [
+                  '-O0',
+                  '-O2',
+                  '-Os',
+                ],
+                'cflags': [
+                  '-fdata-sections',
+                  '-ffunction-sections',
+                  '-O3',
+                ],
+              }],
+              ['v8_optimized_debug==1 and gcc_version==44 and clang==0', {
+                'cflags': [
+                  # Avoid crashes with gcc 4.4 in the v8 test suite.
+                  '-fno-tree-vrp',
+                ],
+              }],
+            ],
           }],
           ['OS=="linux" and v8_enable_backtrace==1', {
             # Support for backtrace_symbols.
             'ldflags': [ '-rdynamic' ],
           }],
           ['OS=="android"', {
             'variables': {
               'android_full_debug%': 1,
             },
             'conditions': [
               ['android_full_debug==0', {
                 # Disable full debug if we want a faster v8 in a debug build.
                 # TODO(2304): pass DISABLE_DEBUG_ASSERT instead of hiding DEBUG.
                 'defines!': [
                   'DEBUG',
                 ],
               }],
             ],
           }],
           ['OS=="mac"', {
             'xcode_settings': {
-              'GCC_OPTIMIZATION_LEVEL': '0',  # -O0
+               'conditions': [
+                 ['v8_optimized_debug==1', {
+                   'GCC_OPTIMIZATION_LEVEL': '3',  # -O3
+                   'GCC_STRICT_ALIASING': 'YES',
+                 }, {
+                   'GCC_OPTIMIZATION_LEVEL': '0',  # -O0
+                 }]
+               ],
             },
           }],
         ],
       },  # Debug
       'Release': {
         'variables': {
           'v8_enable_extra_checks%': 0,
         },
         'conditions': [
           ['v8_enable_extra_checks==1', {
             'defines': ['ENABLE_EXTRA_CHECKS',],
           }],
           ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="netbsd"', {
             'cflags!': [
+              '-O0',
               '-O2',
               '-Os',
             ],
             'cflags': [
               '-fdata-sections',
               '-ffunction-sections',
               '-O3',
             ],
             'conditions': [
               [ 'gcc_version==44 and clang==0', {
                 'cflags': [
                   # Avoid crashes with gcc 4.4 in the v8 test suite.
                   '-fno-tree-vrp',
                 ],
               }],
             ],
           }],
           ['OS=="android"', {
             'cflags!': [
+              '-O0',
               '-O3',
               '-Os',
             ],
             'cflags': [
               '-fdata-sections',
               '-ffunction-sections',
               '-O2',
             ],
             'conditions': [
               [ 'gcc_version==44 and clang==0', {
@@ skipping 40 matching lines @@
                 'OptimizeReferences': '2',
                 'EnableCOMDATFolding': '2',
               },
             },
           }],  # OS=="win"
         ],  # conditions
       },  # Release
     },  # configurations
   },  # target_defaults
 }