From 3226325016558c5a139cb5569b04bb7fe0005d74 Mon Sep 17 00:00:00 2001
From: Vincent Rabaud <vrabaud@google.com>
Date: Fri, 3 Feb 2017 16:47:59 +0100
Subject: [PATCH] Add a flag to disable SIMD optimizations.

Change-Id: I83c33076e8afd1b20de1e9b191bdad6669998a0b
---
 CMakeLists.txt  |  1 +
 cmake/cpu.cmake | 11 ++++++++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index b7203315..aa023935 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,6 +3,7 @@ cmake_minimum_required(VERSION 2.8.7)
 project(libwebp C)
 
 # Options for coder / decoder executables.
+option(WEBP_ENABLE_SIMD "Enable any SIMD optimization." ON)
 option(WEBP_BUILD_CWEBP "Build the cwebp command line tool." OFF)
 option(WEBP_BUILD_DWEBP "Build the dwebp command line tool." OFF)
 option(WEBP_BUILD_GIF2WEBP "Build the gif2webp conversion tool." OFF)
diff --git a/cmake/cpu.cmake b/cmake/cpu.cmake
index 95fafcb9..94c021a1 100644
--- a/cmake/cpu.cmake
+++ b/cmake/cpu.cmake
@@ -1,6 +1,11 @@
 ## Check for SIMD extensions.
 
-function(webp_check_compiler_flag WEBP_SIMD_FLAG)
+function(webp_check_compiler_flag WEBP_SIMD_FLAG ENABLE_SIMD)
+  if(NOT ENABLE_SIMD)
+    message(STATUS "Disabling ${WEBP_SIMD_FLAG} optimization.")
+    set(WEBP_HAVE_${WEBP_SIMD_FLAG} 0 PARENT_SCOPE)
+    return()
+  endif()
   unset(WEBP_HAVE_FLAG_${WEBP_SIMD_FLAG} CACHE)
   check_c_source_compiles("
       #include \"${CMAKE_CURRENT_LIST_DIR}/../src/dsp/dsp.h\"
@@ -56,11 +61,11 @@ foreach(I_SIMD RANGE ${WEBP_SIMD_FLAGS_RANGE})
   # (especially on Android).
   unset(WEBP_HAVE_${WEBP_SIMD_FLAG} CACHE)
   set(CMAKE_REQUIRED_FLAGS)
-  webp_check_compiler_flag(${WEBP_SIMD_FLAG})
+  webp_check_compiler_flag(${WEBP_SIMD_FLAG} ${WEBP_ENABLE_SIMD})
   if(NOT WEBP_HAVE_${WEBP_SIMD_FLAG})
     list(GET SIMD_ENABLE_FLAGS ${I_SIMD} SIMD_COMPILE_FLAG)
     set(CMAKE_REQUIRED_FLAGS ${SIMD_COMPILE_FLAG})
-    webp_check_compiler_flag(${WEBP_SIMD_FLAG})
+    webp_check_compiler_flag(${WEBP_SIMD_FLAG} ${WEBP_ENABLE_SIMD})
   else()
     set(SIMD_COMPILE_FLAG " ")
   endif()