Bug 880419: disable AVX2 asm if the compiler/assembler don't support it r=glandium

build/gyp.mozbuild

@@ -24,6 +24,7 @@ gyp_vars = {
     'build_libvpx': 0,
     'build_libyuv': 0,
     'libyuv_dir': '/media/libyuv',
+    'yuv_disable_avx2': 0 if CONFIG['HAVE_X86_AVX2'] else 1,
 
     # saves 4MB when webrtc_trace is off
     'enable_lazy_trace_alloc': 1,

configure.in

@@ -1351,6 +1351,20 @@ if test "$GNU_CC"; then
                      AC_MSG_RESULT([no]))
     CFLAGS=$_SAVE_CFLAGS
 
+    case "${CPU_ARCH}" in
+    x86 | x86_64)
+      AC_MSG_CHECKING(for x86 AVX2 asm support in compiler)
+      AC_TRY_COMPILE([],
+                     [asm volatile ("vpermq      \$0xd8,%ymm0,%ymm0 \n");],
+                     result="yes", result="no")
+      AC_MSG_RESULT("$result")
+      if test "$result" = "yes"; then
+          HAVE_X86_AVX2=1
+          AC_DEFINE(HAVE_X86_AVX2)
+          AC_SUBST(HAVE_X86_AVX2)
+      fi
+    esac
+
     # Turn on GNU-specific warnings:
     # -Wall - turn on a lot of warnings
     # -Wpointer-arith - good to have

media/libyuv/include/libyuv/row.h

@@ -174,8 +174,8 @@ extern "C" {
 // The following are available on all x86 platforms, but
 // require VS2012, clang 3.4 or gcc 4.7.
 // The code supports NaCL but requires a new compiler and validator.
-#if !defined(LIBYUV_DISABLE_X86) && (defined(VISUALC_HAS_AVX2) || \
-    defined(CLANG_HAS_AVX2) || defined(GCC_HAS_AVX2))
+#if !defined(LIBYUV_DISABLE_AVX2) && !defined(LIBYUV_DISABLE_X86) &&    \
+    (defined(VISUALC_HAS_AVX2) || defined(CLANG_HAS_AVX2) || defined(GCC_HAS_AVX2))
 // Effects:
 #define HAS_ARGBPOLYNOMIALROW_AVX2
 #define HAS_ARGBSHUFFLEROW_AVX2

media/libyuv/libyuv.gyp

@@ -13,6 +13,7 @@
   'variables': {
     'use_system_libjpeg%': 0,
     'yuv_disable_asm%': 0,
+    'yuv_disable_avx2%': 0,
     'build_neon': 0,
     'conditions': [
        ['target_arch == "arm" and arm_version >= 7 and (arm_neon == 1 or arm_neon_optional == 1)', {
@@ -120,6 +121,11 @@
             'LIBYUV_DISABLE_MIPS',
           ],
         }],
+        [ 'yuv_disable_avx2==1', {
+          'defines': [
+            'LIBYUV_DISABLE_AVX2',
+          ]
+        }],
         ['build_with_mozilla==1', {
           'include_dirs': [
             '$(DEPTH)/dist/include',
@@ -136,6 +142,8 @@
         # 'LIBYUV_DISABLE_X86',
         # 'LIBYUV_DISABLE_NEON',
         # 'LIBYUV_DISABLE_MIPS',
+        # This disables AVX2 (Haswell) support, overriding compiler checks
+        # 'LIBYUV_DISABLE_AVX2',
         # Enable the following macro to build libyuv as a shared library (dll).
         # 'LIBYUV_USING_SHARED_LIBRARY',
       ],