Enable Android x64 build

build/common.gypi

Index: build/common.gypi
===================================================================
--- build/common.gypi	(revision 256167)
+++ build/common.gypi	(working copy)
@@ -792,10 +792,10 @@
           'test_isolation_mode%': 'noop',
         }],
         # Whether Android ARM or x86 build uses OpenMAX DL FFT.
-        ['OS=="android" and ((target_arch=="arm" and arm_version >= 7) or target_arch=="ia32") and android_webview_build==0', {
-          # Currently only supported on Android ARMv7+, or ia32
+        ['OS=="android" and ((target_arch=="arm" and arm_version >= 7) or target_arch=="ia32" or target_arch=="x64") and android_webview_build==0', {
+          # Currently only supported on Android ARMv7+, ia32 or x64
           # without webview.  When enabled, this will also enable
-          # WebAudio support on Android ARM and ia32.  Default is
+          # WebAudio support on Android ARM, ia32 and x64.  Default is
           # enabled.  Whether WebAudio is actually available depends
           # on runtime settings and flags.
           'use_openmax_dl_fft%': 1,
@@ -1298,14 +1298,7 @@
       # TODO(glider): set clang to 1 earlier for ASan and TSan builds so that
       # it takes effect here.
       ['os_posix==1 and OS!="mac" and OS!="ios" and clang==0 and asan==0 and lsan==0 and tsan==0 and msan==0', {
-        'conditions': [
-          ['OS=="android"', {
-            # We directly set the gcc_version since we know what we use.
-            'gcc_version%': 46,
-          }, {
-            'gcc_version%': '<!(python <(DEPTH)/build/compiler_version.py)',
-          }],
-        ],
+        'gcc_version%': '<!(python <(DEPTH)/build/compiler_version.py)',

[Torne, 2014/03/11 11:15:35]

Is this correct? We're forcing gcc 4.6 at present..

[rmcilroy, 2014/03/11 11:42:19]

I think x64 requires 4.8 - is that right Zhenyu?   We should keep other Android
arches at 4.6 for now though (fdegans@ is investigating whether we can move to
4.8 without size regressions right now).  Could you make this 4.6 or 4.8
depending on architecture here please (assuming x64 actually needs 4.8).

[Zhenyu Liang, 2014/03/12 10:27:23]

Yeah, we are using gcc 4.8 for x64 porting.
The change means it will determine the gcc version of android toolchain later
rather than assume it. Here, the gcc_version is the version of host compiler.

[rmcilroy, 2014/03/12 11:04:08]

Is there a reason you cannot do:
    ['OS=="android"', {
        ['target_arch=="x64"', {
           'gcc_version%': 48,	
        }, {
           'gcc_version%': 46,	
        }],
    }, {
    ....

As I suggested above?  I think this would be more obvious what it was doing.

[Zhenyu Liang, 2014/03/12 11:30:53]

I had tried this way initially. It doesn't work. GYP complains "target_arch is
not defined". It seems that target_arch is not defined in the stage parsing
variables.

[rmcilroy, 2014/03/12 15:09:53]

Are you sure?  When I try this myself it seems to works with no mention of
target_arch not being defined.  What is the setup you are using to build chrome?
 Are you using envsetup.sh and android_gyp?

[Zhenyu Liang, 2014/03/12 18:46:32]

Sorry, I misremembered that _toolset is what I tried.
target_arch is OK. Updated.

       }, {
         'gcc_version%': 0,
       }],
@@ -1427,6 +1420,12 @@
               'android_ndk_sysroot%': '<(android_ndk_root)/platforms/android-14/arch-x86',
               'android_toolchain%': '<(android_ndk_root)/toolchains/x86-4.6/prebuilt/<(host_os)-<(android_host_arch)/bin',
             }],
+            ['target_arch == "x64"', {
+              'android_app_abi%': 'x86_64',
+              'android_gdbserver%': '<(android_ndk_root)/prebuilt/android-x86_64/gdbserver/gdbserver',
+              'android_ndk_sysroot%': '<(android_ndk_root)/platforms/android-19/arch-x86_64',
+              'android_toolchain%': '<(android_ndk_root)/toolchains/x86_64-4.8/prebuilt/<(host_os)-<(android_host_arch)/bin',
+            }],
             ['target_arch=="arm"', {
               'conditions': [
                 ['arm_version<7', {
@@ -1473,6 +1472,9 @@
         # Location of the "readelf" binary.
         'android_readelf%' : '<!(/bin/echo -n <(android_toolchain)/*-readelf)',
 
+        # GCC version of Android toolchain
+        'gcc_version%': '<!(CXX=<(android_toolchain)/*-g++ python <(DEPTH)/build/compiler_version.py)',

[rmcilroy, 2014/03/11 11:42:19]

Why is this required?  Isn't it done above?

[Zhenyu Liang, 2014/03/12 10:27:23]

It determines the gcc version of android toolchain here (by using the script
with CXX environment), and overwrite the gcc_version.

+
         # Determines whether we should optimize JNI generation at the cost of
         # breaking assumptions in the build system that when inputs have changed
         # the outputs should always change as well.  This is meant purely for
@@ -1736,7 +1738,7 @@
       ['use_titlecase_in_grd_files==1', {
         'grit_defines': ['-D', 'use_titlecase'],
       }],
-      ['OS=="android" and target_arch=="ia32"', {
+      ['OS=="android" and (target_arch=="ia32" or target_arch=="x64")', {
         # WebAudio on Android/x86 is disabled by default, unlike
         # everywhere else, so use appropriate message.
         'grit_defines': ['-D', 'use_webaudio_enable_message'],
@@ -3259,6 +3261,30 @@
               }],
             ],
           }],
+          ['target_arch=="x64"', {
+            'target_conditions': [
+              ['_toolset=="target"', {
+                'conditions': [
+                  # Use gold linker for Android x64 target.
+                  ['OS=="android"', {
+                    'cflags': [
+                      '-fuse-ld=gold',
+                    ],
+                    'ldflags': [
+                      '-fuse-ld=gold',
+                    ],
+                  }],
+                ],
+                'cflags': [
+                  '-m64',
+                  '-march=x86-64',
+                ],
+                'ldflags': [
+                  '-m64',
+                ],
+              }],
+            ],
+          }],
           ['target_arch=="arm"', {
             'target_conditions': [
               ['_toolset=="target"', {
@@ -3892,6 +3918,15 @@
                       '-target x86-linux-androideabi',
                     ],
                   }],
+                  # Place holder for x64 support, not tested.

[rmcilroy, 2014/03/11 11:42:19]

Add a todo associated with a bug here please (so that the todo can be removed
once it's tested).

+                  ['target_arch=="x64"', {
+                    'cflags': [
+                      '-target x86_64-linux-androideabi',
+                    ],
+                    'ldflags': [
+                      '-target x86_64-linux-androideabi',
+                    ],
+                  }],
                 ],
               }],
               ['asan==1', {
@@ -4005,7 +4040,6 @@
               ['_type=="executable"', {
                 'ldflags': [
                   '-Bdynamic',
-                  '-Wl,-dynamic-linker,/system/bin/linker',

[rmcilroy, 2014/03/11 11:42:19]

This should probably be ok, but have you tested this being removed on older
32bit platforms (e.g. ICS) to make sure it works without the explicit linker
attribute?

[Zhenyu Liang, 2014/03/12 10:27:23]

Yes, I had tried with the original ndk in third_party/. gcc version 4.6 can
generate proper .interp section. I think we can remove this line safely.

Quick check:
% strings arm-linux-androideabi-gcc | grep /linker

                   '-Wl,--gc-sections',
                   '-Wl,-z,nocopyreloc',
                   # crtbegin_dynamic.o should be the last item in ldflags.