Merge r11643, r11597, and a tiny piece from r11486 to the 3.9 branch.

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 132 matching lines @@
                   'CAN_USE_VFP_INSTRUCTIONS',
                 ],
                 'cflags': [
                   '-mfloat-abi=hard',
                 ],
               }, {
                 'defines': [
                   'USE_EABI_HARDFLOAT=0',
                 ],
               }],
-              # The ARM assembler assumes the host is 32 bits,
-              # so force building 32-bit host tools.
-              ['host_arch=="x64" or OS=="android"', {
-                'target_conditions': [
-                  ['_toolset=="host"', {
-                    'cflags': ['-m32'],
-                    'ldflags': ['-m32'],
-                  }],
-                ],
-              }],
             ],
           }],
           ['v8_target_arch=="ia32"', {
             'defines': [
               'V8_TARGET_ARCH_IA32',
             ],
           }],
           ['v8_target_arch=="mips"', {
             'defines': [
               'V8_TARGET_ARCH_MIPS',
@@ skipping 38 matching lines @@
                 'defines': [
                   '__mips_soft_float=1'
                 ],
               }],
               ['mips_arch_variant=="mips32r2"', {
                 'defines': ['_MIPS_ARCH_MIPS32R2',],
               }],
               ['mips_arch_variant=="loongson"', {
                 'defines': ['_MIPS_ARCH_LOONGSON',],
               }],
-              # The MIPS assembler assumes the host is 32 bits,
-              # so force building 32-bit host tools.
-              ['host_arch=="x64"', {
-                'target_conditions': [
-                  ['_toolset=="host"', {
-                    'cflags': ['-m32'],
-                    'ldflags': ['-m32'],
-                  }],
-                ],
-              }],
             ],
           }],
           ['v8_target_arch=="x64"', {
             'defines': [
               'V8_TARGET_ARCH_X64',
             ],
           }],
         ],
       }],
       ['v8_use_liveobjectlist=="true"', {
@@ skipping 24 matching lines @@
       ['OS=="win" and v8_target_arch=="x64"', {
         'msvs_settings': {
           'VCLinkerTool': {
             'StackReserveSize': '2097152',
           },
         },
       }],
       ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
          or OS=="netbsd"', {
         'conditions': [
-          [ 'target_arch=="ia32"', {
-            'cflags': [ '-m32' ],
-            'ldflags': [ '-m32' ],
-          }],
           [ 'v8_no_strict_aliasing==1', {
             'cflags': [ '-fno-strict-aliasing' ],
           }],
         ],  # conditions
       }],
       ['OS=="solaris"', {
         'defines': [ '__C99FEATURES__=1' ],  # isinf() etc.
       }],
+      ['(OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
+         or OS=="netbsd" or OS=="mac" or OS=="android") and \
+        (v8_target_arch=="arm" or v8_target_arch=="ia32" or \
+         v8_target_arch=="mips")', {
+        # Check whether the host compiler and target compiler support the
+        # '-m32' option and set it if so.
+        'target_conditions': [
+          ['_toolset=="host"', {
+            'variables': {
+              'm32flag': '<!((echo | $(echo ${CXX_host:-$(which g++)}) -m32 -E - > /dev/null 2>&1) && echo -n "-m32" || true)',
+            },
+            'cflags': [ '<(m32flag)' ],
+            'ldflags': [ '<(m32flag)' ],
+          }],
+          ['_toolset=="target"', {
+            'variables': {
+              'm32flag': '<!((echo | $(echo ${CXX_target:-${CXX:-$(which g++)}}) -m32 -E - > /dev/null 2>&1) && echo -n "-m32" || true)',
+            },
+            'cflags': [ '<(m32flag)' ],
+            'ldflags': [ '<(m32flag)' ],
+          }],
+        ],
+      }],
     ],  # conditions
     'configurations': {
       'Debug': {
         'defines': [
           'DEBUG',
           'ENABLE_DISASSEMBLER',
           'V8_ENABLE_CHECKS',
           'OBJECT_PRINT',
         ],
         'msvs_settings': {
@@ skipping 93 matching lines @@
                 'OptimizeReferences': '2',
                 'EnableCOMDATFolding': '2',
               },
             },
           }],  # OS=="win"
         ],  # conditions
       },  # Release
     },  # configurations
   },  # target_defaults
 }