Avoid /arch:AVX[2] in Skia on Windows.

skia/BUILD.gn

 # Copyright (c) 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//printing/features/features.gni")
 import("//testing/test.gni")
 import("//third_party/skia/gn/shared_sources.gni")
 
@@ skipping 175 matching lines @@
       "/wd4244",  # conversion from 'type1( __int64)' to 'type2 (unsigned int)'
       "/wd4267",  # conversion from 'size_t' (64 bit) to 'type'(32 bit).
       "/wd4341",  # signed value is out of range for enum constant.
       "/wd4345",  # Object is default-initialized if initialization is omitted.
       "/wd4390",  # ';'empty statement found in looping;is it what was intended?
       "/wd4554",  # 'operator' : check operator precedence for possible error
       "/wd4748",  # compiler will disable optimizations if a function has inline
                   # assembly code contains flow control(jmp or jcc) statements.
 
       "/wd4800",  # forcing value to bool 'true/false'(assigning int to bool).
+
+      "/wd4752",  # We use AVX but don't let the compiler do so itself.
+                  # See crbug.com/666707.
     ]
   }
 }
 
 component("skia") {
   sources = [
     # Chrome sources.
     "config/SkUserConfig.h",
     "config/sk_ref_cnt_ext_debug.h",
     "config/sk_ref_cnt_ext_release.h",
@@ skipping 337 matching lines @@
       visibility = [ ":skia_opts" ]
       configs -= [ "//build/config/compiler:chromium_code" ]
       configs += [
         ":skia_config",
         ":skia_library_config",
         "//build/config/compiler:no_chromium_code",
       ]
     }
     source_set("skia_opts_avx") {
       sources = skia_opts.avx_sources
-      if (!is_win) {
+      if (!is_win || is_clang) {
         cflags = [ "-mavx" ]

[brucedawson, 2016/11/18 21:00:26]

It feels odd to use -mavx on a Windows build, but if it works...

[mtklein_C, 2016/11/18 21:03:56]

Yeah.  It's the only way to express things like -mssse3 and -msse4.1, so we do
this for consistency.

       }
       if (is_win) {
-        cflags = [ "/arch:AVX" ]
+        defines = [ "SK_CPU_SSE_LEVEL=51" ]
       }
       visibility = [ ":skia_opts" ]
       configs -= [ "//build/config/compiler:chromium_code" ]
       configs += [
         ":skia_config",
         ":skia_library_config",
         "//build/config/compiler:no_chromium_code",
       ]
     }
     source_set("skia_opts_hsw") {
       sources = skia_opts.hsw_sources
-      if (!is_win) {
+      if (!is_win || is_clang) {

[brucedawson, 2016/11/18 21:00:26]

This may have unintended consequences because now four previously unused flags
are being passed to clang-cl.

[mtklein_C, 2016/11/18 21:03:56]

Hmm.  I think it should be okay, especially because it's restricted to only
clang-cl.  We've been using these flags with clang-not-cl for a while now.

         cflags = [
           "-mavx2",
           "-mbmi",
           "-mbmi2",
           "-mf16c",
           "-mfma",
         ]
       }
       if (is_win) {
-        cflags = [ "/arch:AVX2" ]
+        defines = [ "SK_CPU_SSE_LEVEL=52" ]
       }
       visibility = [ ":skia_opts" ]
       configs -= [ "//build/config/compiler:chromium_code" ]
       configs += [
         ":skia_config",
         ":skia_library_config",
         "//build/config/compiler:no_chromium_code",
       ]
     }
   }
@@ skipping 136 matching lines @@
 
     deps = [
       ":skia",
       "//base",
       "//base/test:test_support",
       "//build/config/sanitizers:deps",
       "//build/win:default_exe_manifest",
     ]
   }
 }