skia: Simplify SSE2 logic a bit.

skia/skia_library_opts.gyp

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This gyp file contains the platform-specific optimizations for Skia
 {
   'variables': {
       'skia_src_path': '../third_party/skia/src',
       'includes': [ '../third_party/skia/gyp/opts.gypi' ],
       'include_dirs': [
         '../third_party/skia/include/core',
         '../third_party/skia/include/effects',
         '../third_party/skia/include/utils',
         '../third_party/skia/src/core',
         '../third_party/skia/src/opts',
         '../third_party/skia/src/utils',
       ],
    },
 
   'targets': [
-    # Due to an unfortunate intersection of lameness between gcc and gyp,
-    # we have to build the *_SSE2.cpp files in a separate target.  The
-    # gcc lameness is that, in order to compile SSE2 intrinsics code, it
-    # must be passed the -msse2 flag.  However, with this flag, it may
-    # emit SSE2 instructions even for scalar code, such as the CPUID
-    # test used to test for the presence of SSE2.  So that, and all other
-    # code must be compiled *without* -msse2.  The gyp lameness is that it
-    # does not allow file-specific CFLAGS, so we must create this extra
-    # target for those files to be compiled with -msse2.
-    #
-    # This is actually only a problem on 32-bit Linux (all Intel Macs have
-    # SSE2, Linux x86_64 has SSE2 by definition, and MSC will happily emit
-    # SSE2 from instrinsics, which generating plain ol' 386 for everything
-    # else).  However, to keep the .gyp file simple and avoid platform-specific
-    # build breakage, we do this on all platforms.
-
+    # SSE files have to be built in a separate target, because gcc needs
+    # different -msse flags for different SSE levels which enable use of SSE
+    # intrinsics but also allow emission of SSE2 instructions for scalar code.
+    # gyp does not allow per-file compiler flags.
     # For about the same reason, we need to compile the ARM opts files
     # separately as well.
     {
       'target_name': 'skia_opts',
       'type': 'static_library',
       'includes': [
         'skia_common.gypi',
         '../build/android/increase_size_for_speed.gypi',
         # Disable LTO due to compiler error
         # in mems_in_disjoint_alias_sets_p, at alias.c:393
         # crbug.com/422255
         '../build/android/disable_lto.gypi',
       ],
       'include_dirs': [ '<@(include_dirs)' ],
       'conditions': [
-        [ 'os_posix == 1 and OS != "mac" and OS != "android" and \
-           target_arch != "arm" and target_arch != "arm64" and \
-           target_arch != "mipsel" and target_arch != "mips64el"', {
-          'cflags': [ '-msse2' ],
-        }],
         [ 'target_arch != "arm" and target_arch != "mipsel" and \
            target_arch != "arm64" and target_arch != "mips64el"', {
+          # Chrome builds with -msse2 locally, so sse2_sources could in theory
+          # be in the regular skia target. But we need skia_opts for arm
+          # anyway, so putting sse2_sources here is simpler than making this
+          # conditionally a type none target on x86.
           'sources': [ '<@(sse2_sources)' ],
           'dependencies': [
             'skia_opts_ssse3',
             'skia_opts_sse41',
           ],
         }],
         [ 'target_arch == "arm"', {
           'conditions': [
             [ 'arm_version >= 7', {
               'sources': [ '<@(armv7_sources)' ],
@@ skipping 151 matching lines @@
           'ldflags': [
             '-march=armv7-a',
             '-Wl,--fix-cortex-a8',
           ],
           'sources': [ '<@(neon_sources)' ],
         },
       ],
     }],
   ],
 }