GN: turn on easy libjpeg-turbo SIMD backends (ARMv7 and ARMv8)

These are so easy we might as well...

I did a quick check of relevant-looking defines:
   - GYP defined WITH_SIMD, but it looks like that's already defined (by jconfig.h?);
   - GYP defined RGBX_FILLER_0XFF, but that affects only x86/x86-64;
   - GYP defined STRICT_MEMORY_ACCESS, which does nothing;
   - GYP defined MOTION_JPEG_SUPPORTED, which does nothing (and we'd probably not care anyway).

BUG=skia:5875

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4745

Change-Id: Ib1f28d354630be472c4d9648d5ade74a452a9e24
Reviewed-on: https://skia-review.googlesource.com/4745
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 14 insertions, 1 deletions

diff --git a/third_party/libjpeg-turbo/BUILD.gn b/third_party/libjpeg-turbo/BUILD.gn
index c0382a719c..927df49a0e 100644
--- a/third_party/libjpeg-turbo/BUILD.gn
+++ b/third_party/libjpeg-turbo/BUILD.gn
@@ -61,8 +61,21 @@ if (skia_use_system_libjpeg_turbo) {
       "../externals/libjpeg-turbo/jmemnobs.c",
       "../externals/libjpeg-turbo/jquant1.c",
       "../externals/libjpeg-turbo/jquant2.c",
-      "../externals/libjpeg-turbo/jsimd_none.c",
       "../externals/libjpeg-turbo/jutils.c",
     ]
+
+    if (current_cpu == "arm") {
+      sources += [
+        "../externals/libjpeg-turbo/simd/jsimd_arm.c",
+        "../externals/libjpeg-turbo/simd/jsimd_arm_neon.S",
+      ]
+    } else if (current_cpu == "arm64") {
+      sources += [
+        "../externals/libjpeg-turbo/simd/jsimd_arm64.c",
+        "../externals/libjpeg-turbo/simd/jsimd_arm64_neon.S",
+      ]
+    } else {
+      sources += [ "../externals/libjpeg-turbo/jsimd_none.c" ]
+    }
   }
 }