Provide support for CMake on Android studio 2.2.

Change-Id: Ib3508c20a220b29d42f963cf154cd9ab5236ed6e
(cherry picked from commit a80e8cfdf2)

cmake/cpu.cmake

@@ -1,27 +1,7 @@
 ## Check for SIMD extensions.
-set(WEBP_SIMD_FLAGS "SSE2;SSE41;AVX2")
-set(WEBP_SIMD_FILE_EXTENSIONS "_sse2.c;_sse41.c;_avx2.c")
-if(MSVC)
-  # MSVC does not have a SSE4 flag but AVX2 support implies
-  # SSE4 support.
-  set(SIMD_ENABLE_FLAGS "/arch:SSE2;/arch:AVX2;/arch:AVX2")
-  set(SIMD_DISABLE_FLAGS)
-else()
-  set(SIMD_ENABLE_FLAGS "-msse2;-msse4.1;-mavx2")
-  set(SIMD_DISABLE_FLAGS "-mno-sse2;-mno-sse4.1;-mno-avx2")
-endif()
 
-set(WEBP_SIMD_FILES_TO_NOT_INCLUDE)
+function(webp_check_compiler_flag WEBP_SIMD_FLAG)
-set(WEBP_SIMD_FILES_TO_INCLUDE)
+  unset(WEBP_HAVE_FLAG_LOCAL CACHE)
-set(WEBP_SIMD_FLAGS_TO_INCLUDE)
-
-list(LENGTH WEBP_SIMD_FLAGS WEBP_SIMD_FLAGS_LENGTH)
-math(EXPR WEBP_SIMD_FLAGS_RANGE "${WEBP_SIMD_FLAGS_LENGTH} - 1")
-
-foreach(I_SIMD RANGE ${WEBP_SIMD_FLAGS_RANGE})
-  list(GET WEBP_SIMD_FLAGS ${I_SIMD} WEBP_SIMD_FLAG)
-  list(GET SIMD_ENABLE_FLAGS ${I_SIMD} SIMD_COMPILE_FLAG)
-  set(CMAKE_REQUIRED_FLAGS ${SIMD_COMPILE_FLAG})
   check_c_source_compiles("
       #include \"${CMAKE_CURRENT_LIST_DIR}/../src/dsp/dsp.h\"
       int main(void) {
@@ -30,10 +10,60 @@ foreach(I_SIMD RANGE ${WEBP_SIMD_FLAGS_RANGE})
         #endif
         return 0;
       }
-    "
+    " WEBP_HAVE_FLAG_LOCAL
-    WEBP_HAVE_${WEBP_SIMD_FLAG}
   )
+  if(WEBP_HAVE_FLAG_LOCAL)
+    set(WEBP_HAVE_${WEBP_SIMD_FLAG} 1 PARENT_SCOPE)
+  else()
+    set(WEBP_HAVE_${WEBP_SIMD_FLAG} 0 PARENT_SCOPE)
+  endif()
+endfunction()
 
+# those are included in the names of WEBP_USE_* in c++ code.
+set(WEBP_SIMD_FLAGS "SSE2;SSE41;AVX2;MIPS32;MIPS_DSP_R2;NEON;MSA")
+set(WEBP_SIMD_FILE_EXTENSIONS "_sse2.c;_sse41.c;_avx2.c;_mips32.c;_mips_dsp_r2.c;_neon.c;_msa.c")
+if(MSVC)
+  # MSVC does not have a SSE4 flag but AVX2 support implies
+  # SSE4 support.
+  set(SIMD_ENABLE_FLAGS "/arch:SSE2;/arch:AVX2;/arch:AVX2;;;;")
+  set(SIMD_DISABLE_FLAGS)
+else()
+  set(SIMD_ENABLE_FLAGS "-msse2;-msse4.1;-mavx2;-mips32;-mdspr2;-mfpu=neon;-mmsa")
+  set(SIMD_DISABLE_FLAGS "-mno-sse2;-mno-sse4.1;-mno-avx2;;-mno-dspr2;;-mno-msa")
+endif()
+
+set(WEBP_SIMD_FILES_TO_NOT_INCLUDE)
+set(WEBP_SIMD_FILES_TO_INCLUDE)
+set(WEBP_SIMD_FLAGS_TO_INCLUDE)
+
+if(${ANDROID})
+  if(${ANDROID_ABI} STREQUAL "armeabi-v7a")
+    # This is because Android studio uses the configuration
+    # "-march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16"
+    # that does not trigger neon optimizations but should
+    # (as this configuration does not exist anymore).
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -mfpu=neon ")
+  endif()
+endif()
+
+list(LENGTH WEBP_SIMD_FLAGS WEBP_SIMD_FLAGS_LENGTH)
+math(EXPR WEBP_SIMD_FLAGS_RANGE "${WEBP_SIMD_FLAGS_LENGTH} - 1")
+
+foreach(I_SIMD RANGE ${WEBP_SIMD_FLAGS_RANGE})
+  list(GET WEBP_SIMD_FLAGS ${I_SIMD} WEBP_SIMD_FLAG)
+
+  # First try with no extra flag added as the compiler might have default flags
+  # (especially on Android).
+  unset(WEBP_HAVE_${WEBP_SIMD_FLAG} CACHE)
+  set(CMAKE_REQUIRED_FLAGS)
+  webp_check_compiler_flag(${WEBP_SIMD_FLAG})
+  if(NOT WEBP_HAVE_${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})
+  else()
+    set(SIMD_COMPILE_FLAG " ")
+  endif()
   # Check which files we should include or not.
   list(GET WEBP_SIMD_FILE_EXTENSIONS ${I_SIMD} WEBP_SIMD_FILE_EXTENSION)
   file(GLOB SIMD_FILES "${CMAKE_CURRENT_LIST_DIR}/../"
@@ -54,10 +84,13 @@ foreach(I_SIMD RANGE ${WEBP_SIMD_FLAGS_RANGE})
     if(SIMD_DISABLE_FLAGS)
       list(GET SIMD_DISABLE_FLAGS ${I_SIMD} SIMD_COMPILE_FLAG)
       include(CheckCCompilerFlag)
+      if(SIMD_COMPILE_FLAG)
+        unset(HAS_COMPILE_FLAG CACHE)
         check_c_compiler_flag(${SIMD_COMPILE_FLAG} HAS_COMPILE_FLAG)
         if(HAS_COMPILE_FLAG)
           set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${SIMD_COMPILE_FLAG}")
         endif()
       endif()
     endif()
+  endif()
 endforeach()