Introduce arm_version to allow building for armv5, v6 or v7.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index d39128b1e23488a54a4aa840dd5caf5af1b20df6..908d4f72c25234aa3ca2dc0fb2898e5f01b15c78 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -211,11 +211,11 @@
       # Python version.
       'python_ver%': '2.6',
 
-      # Set ARM-v7 compilation flags
-      'armv7%': 0,
+      # Set ARM architecture version.
+      'arm_version%': 7,

[Torne, 2013/04/11 13:04:22]

This changes the default; is this intentional?

[Fredrik Öhrn, 2013/04/11 13:42:19]

Maybe I misunderstood your comments on the previous version of the diff. I
thought you guys wanted the gyp defaults to be changed to match what was
previously configured in envsetup.

I can restore the armv5 defaults and set arm_version to 7 in an OS==android
condition if you prefer.

[Torne, 2013/04/11 13:55:00]

That envsetup.sh script is specifically for Android builds; what you've changed
is the global default for Chromium. I don't know what other users of Chromium on
ARM may want the defaults to be, so leaving it alone seems preferable.
I'm not sure that the default is intended to be armv5, either; the Android
config uses that when armv7 isn't set, but that's not true of linux/chromeos as
far as I can see..

[Fredrik Öhrn, 2013/04/11 15:18:46]

Well, I could perhaps add an arm_version 0 default that sets no compiler flags,
that would leave the defaults more or less unchanged for other products.

 
-      # Set Neon compilation flags (only meaningful if armv7==1).
-      'arm_neon%': 1,
+      # Set Neon compilation flags.
+      'arm_neon%': 0,

[Torne, 2013/04/11 13:04:22]

Same here.

[Fredrik Öhrn, 2013/04/11 15:18:46]

I have to keep arm_neon disabled when changing the arm_version default back to
<= 5 or it won't build.

This is because third_party/libvpx/libvpx.gyp uses arm_neon without testing that
it's also a v7 build.

[Fredrik Öhrn, 2013/04/11 15:37:13]

Turns out libvpx throws some handcrafted armv6 assembler into the mix as well,
so building armv5 isn't currently possible.

I'm guessing none of your projects are building anything less than armv7 or
these two problems would have been noticed.

Perhaps bumping the defaults to armv7 isn't such a bad idea?

 
       # The system root for cross-compiles. Default: none.
       'sysroot%': '',
@@ -610,7 +610,7 @@
 
         ['OS=="linux" and target_arch=="arm" and chromeos==0', {
           # Set some defaults for arm/linux chrome builds
-          'armv7%': 1,
+          'arm_version%': 7,

[Torne, 2013/04/11 13:04:22]

This is setting it to the same value as above; if the change of default is
intentional then this is unnecessary.

           'linux_breakpad%': 0,
           'linux_use_tcmalloc%': 0,
           # sysroot needs to be an absolute path otherwise it generates
@@ -709,7 +709,7 @@
     'fastbuild%': '<(fastbuild)',
     'dcheck_always_on%': '<(dcheck_always_on)',
     'python_ver%': '<(python_ver)',
-    'armv7%': '<(armv7)',
+    'arm_version%': '<(arm_version)',
     'arm_neon%': '<(arm_neon)',
     'sysroot%': '<(sysroot)',
     'system_libdir%': '<(system_libdir)',
@@ -926,16 +926,6 @@
     # Set to 1 to link against gsettings APIs instead of using dlopen().
     'linux_link_gsettings%': 0,
 
-    # Set Thumb compilation flags.
-    'arm_thumb%': 0,
-
-    # Set ARM fpu compilation flags (only meaningful if armv7==1 and
-    # arm_neon==0).
-    'arm_fpu%': 'vfpv3',
-
-    # Set ARM float abi compilation flag.
-    'arm_float_abi%': 'softfp',
-
     # Enable use of OpenMAX DL FFT routines.
     'use_openmax_dl_fft%': '<(use_openmax_dl_fft)',
     
@@ -1036,6 +1026,9 @@
     'windows_sdk_default_path': '<(DEPTH)/third_party/platformsdk_win8/files',
     'directx_sdk_default_path': '<(DEPTH)/third_party/directxsdk/files',
 
+    # Backward compatibility only, use arm_version.
+    'armv7': 0,

[Torne, 2013/04/11 13:04:22]

This shouldn't be necessary; this value will always be overwritten by the one
set below.

[Fredrik Öhrn, 2013/04/11 13:42:19]

I had to put it in or gyp would throw and undefined error for no good reason
when reading a gyp file in third_party.

This was when I initially wrote the patch back on top of 25.0.1364. Seems the
problem is gone now, I'll remove it.

+
     # Whether we are using the rlz library or not.  Platforms like Android send
     # rlz codes for searches but do not use the library.
     'enable_rlz%': 0,
@@ -1174,7 +1167,7 @@
             }],
             ['target_arch=="arm"', {
               'conditions': [
-                ['armv7==0', {
+                ['arm_version<7', {
                   'android_app_abi%': 'armeabi',
                 }, {
                   'android_app_abi%': 'armeabi-v7a',
@@ -1593,6 +1586,54 @@
       ['branding=="Chrome" and (OS=="win" or OS=="mac" or chromeos==1)', {
         'enable_rlz%': 1,
       }],
+
+      ['android_webview_build==1', {
+        # The WebView build gets its cpu-specific flags from the Android build system.
+        'arm_arch%': '',
+        'arm_tune%': '',
+        'arm_fpu%': '',
+        'arm_float_abi%': '',
+        'arm_thumb%': 0,
+      }, {
+        'conditions': [

[Torne, 2013/04/11 13:04:22]

I generally prefer not to use nested conditions sections like this because deep
gyp nesting is hard to read; it may be neater to just repeat "and
android_webview_build==0" and have all of these blocks at the same level.

+          # Set default compiler flags depending on ARM version.
+          ['arm_version==5', {
+            # Flags suitable for Android emulator
+            'arm_arch%': 'armv5te',
+            'arm_tune%': 'xscale',
+            'arm_fpu%': '',
+            'arm_float_abi%': 'soft',
+            'arm_thumb%': 0,
+          }],
+          ['arm_version==6', {
+            'arm_arch%': 'armv6',
+            'arm_tune%': '',
+            'arm_fpu%': '',
+            'arm_float_abi%': 'soft',
+            'arm_thumb%': 0,
+          }],
+          ['arm_version==7', {
+            'arm_arch%': 'armv7-a',
+            'arm_tune%': 'cortex-a8',
+            'conditions': [
+              ['arm_neon==1', {
+                'arm_fpu%': 'neon',
+              }, {
+                'arm_fpu%': 'vfpv3-d16',
+              }],
+            ],
+            'arm_float_abi%': 'softfp',
+            'arm_thumb%': 1,
+          }],
+        ],
+      }],
+
+      # Set armv7 for backward compatibility.
+      ['arm_version==7', {
+        'armv7': 1,
+      }, {
+        'armv7': 0,
+      }],
     ],
 
     # List of default apps to install in new profiles.  The first list contains
@@ -2793,25 +2834,31 @@
                   '-Wno-abi',
                 ],
                 'conditions': [
-                  ['arm_thumb==1 and android_webview_build==0', {
+                  ['arm_arch!=""', {
                     'cflags': [
-                    '-mthumb',
-                    ]
+                      '-march=<(arm_arch)',
+                    ],
                   }],
-                  ['armv7==1 and android_webview_build==0', {
+                  ['arm_tune!=""', {
                     'cflags': [
-                      '-march=armv7-a',
-                      '-mtune=cortex-a8',
-                      '-mfloat-abi=<(arm_float_abi)',
+                      '-mtune=<(arm_tune)',
                     ],
-                    'conditions': [
-                      ['arm_neon==1', {
-                        'cflags': [ '-mfpu=neon', ],
-                      }, {
-                        'cflags': [ '-mfpu=<(arm_fpu)', ],
-                      }],
+                  }],
+                  ['arm_fpu!=""', {
+                    'cflags': [
+                      '-mfpu=<(arm_fpu)',
                     ],
                   }],
+                  ['arm_float_abi!=""', {
+                    'cflags': [
+                      '-mfloat-abi=<(arm_float_abi)',
+                    ],
+                  }],
+                  ['arm_thumb==1', {
+                    'cflags': [
+                    '-mthumb',
+                    ]
+                  }],
                   ['OS=="android"', {
                     # Most of the following flags are derived from what Android
                     # uses by default when building for arm, reference for which
@@ -2837,23 +2884,9 @@
                         '-fuse-ld=gold',
                     ],
                     'conditions': [
-                      ['arm_thumb==1 and android_webview_build==0', {
+                      ['arm_thumb==1', {
                         'cflags': [ '-mthumb-interwork' ],
                       }],
-                      ['armv7==0 and android_webview_build==0', {
-                        # Flags suitable for Android emulator

[Torne, 2013/04/11 13:04:22]

This block doesn't seem to have a replacement..

[Fredrik Öhrn, 2013/04/11 13:42:19]

It's replaced by the arm_version==5 block on line 1600.
The defines are redundant, they are compiler builtins.

-                        'cflags': [
-                          '-march=armv5te',
-                          '-mtune=xscale',
-                          '-msoft-float',
-                        ],
-                        'defines': [
-                          '__ARM_ARCH_5__',
-                          '__ARM_ARCH_5T__',
-                          '__ARM_ARCH_5E__',
-                          '__ARM_ARCH_5TE__',
-                        ],
-                      }],
                       ['profiling==1', {
                         'cflags': [
                           '-marm', # Probably reduntant, but recommend by "perf" docs.